The Ram's Eye - A Driver's Blog


Sunday, 5 February 2017

2018 Ford Mustang Upgrades!

Ever since I bought my Mustang, I have been gradually growing loyal to the brand. I’m not sure why. I like a lot of different cars and never felt like picking a camp, but I guess when you buy a car, you start to have to defend its honour (and your decision) whenever someone takes a stab at it. For someone who is so into cars, I think only one of two things can happen: you are either convinced of what “foes” claim and start to regret your decision, or you find more conviction as you defend your decision and love the car even more. Count me among the latter and, needless to say, I was properly excited when I found out about the updates Ford is bringing to the 2018 Mustang.

For starters, the Mustang finally (probably.. hopefully) will get its horsepower mojo back. When Ford unleashed its 5.0 litre Coyotes to prey on the competition circa 2010, it was basically undisputed. The Camaro SS was usually slower in tests. You couldn’t say Challenger R/T in the same breath; you had to go up to the mighty SRT8 to compete, and even that couldn’t stand its ground until Mopar minions bestowed the 392 (6.4 litre) V8 upon the Challenger that it was really competitive and it wasn’t until you got into serious lose-your-license speeds that the Challenger hp advantage started to show. Otherwise, its weight disadvantage let it down. GT500 vs ZL1? Well, we all know how that went.. Chevy debuted the 570 hp Camaro ZL1, but before it had any chance to be proud, Ford unleaded the 663 hp GT500. But all that changed with the new S550 Mustang..

The GT500 went the way of its S197 platform.. The 5.0 litre V8 made a little more hp but not enough to make up for the weight gain, making the new one a little slower than the old S197. To make matter worse, the new Camaro came out with more hp AND less weight. The GT wasn't the only issue. Ford neutered its V6, which used to be easily quicker than the Camaro and Challenger V6’s. The EcoBoost barely kept up with a last generation S197 V6. If hp and speed were the reason you wanted a new pony car but you weren’t loyal to a brand and you didn’t care too much for modifying, the Camaro was calling your number (assuming you could put up with the sight lines, which aren't as bad as people make them out to be, but still seriously compromised). You can read my comparison of a 2016 Camaro SS vs 2016 Mustang GT here. Of course, there's a lot more to buying a car than horsepower and acceleration numbers, but they are very important to a lot of buyers.

You might say: BUT you are forgetting the Shelby GT350, you idiot! Why aren’t you talking about that?? Sure, it’s a fantastic thing. I love the GT350. There is a local dealer that has a few (yes, a few) new ones and every time we drive by, I just want to drive in and stare at them. Trouble is: it’s quite a few grand more than a Camaro SS, and A LOT more if you factor in Camaro discounts and GT350 markups. The gap is even bigger compared to a Mustang GT because that is cheaper than a Camaro SS to start with, which is much cheaper than a GT350. So if you were Mustang loyal, you had a very sizeable gap between the Mustang GT and the Shelby GT350. You could tap into the Ford Performance parts catalogue, but those reduce powertrain warranty from 5 years to 3 years, and make the car basically as expensive as a Camaro SS, which handles better and has a better warranty. It wasn’t the best solution, but it may have been the only one. However, it looks like Ford is looking to light some fire under the class again..

Fire, let’s take a moment to mourn the death of the 3.7 litre V6.. Ok, moment is over. Don’t get me wrong, I was a big fan of it and I always thought it punched above its weight but it was long overdue for an update. An update that Ford didn’t want to provide because of its EcoBoost-infested vision of the future. Might as well let it die in peace. Speaking of the EcoBoost, it's getting more torque with an overboost function, although Ford isn't saying how much. People have been tuning them with great results so we all know it has more potential. It'll be interesting to see how much difference it makes, but Ford says it was substantial enough to warrant a transmission upgrade. Sound good? You bet! Hopefully, it's not just marketing talk.

But the real treat is the V8, which will finally get direct injection but will retain port injection, overcoming fueling issues at high rpm and valve fouling associated with direct injection-only engines. Direct  Injection allows for better atomization resulting in better combustion, and better power as a result. Moreover, that results in a cooling effect which, when combined with better control on fuel delivery, allows for higher compression ratio, again resulting in more power. The end result? Ford won’t say yet, but I think it will come real close to the Camaro’s hp (at least). I’m hoping for 470 hp, but that may be too optimistic. And better yet, Ford didn’t just focus on power.

The handling is addressed too, with a retuned suspension and stiffened chassis, plus the option of magnetic shocks across the board, including the EcoBoost! Ford says the base suspension now is as good as the Performance Pack. But the highlight of all is, IMO, is the tires. The Michelin Pilot Sport 4 tires are the successor to the excellent Pilot Super Sport. One of the best street/track tires available in the last few years IMO. There were plenty of tires that were much stickier, better in the wet, longer lasting, or forgiving but none could match the balance the PSS provided between of all these criteria and more. The new one can only be better. This is the area I care about the most, as I pointed out in the review I posted above, the Mustang became more grown up than the last generation while the Camaro became more playful. As a car guy inflicted with the track bug, I couldn't be happier that Ford is improving the handling and overall capability.

And if you thought that was all, you’re wrong! Things just keep getting better. It may be trivial, but I wasn’t a fan of the front end at all since it debuted. It wasn’t ugly by any means, but it was too much corporate Ford and not nearly enough Mustang. The headlights were the worst offenders and I’m VERY happy to see them GONE. The new headlights are more of an evolution of the S197 headlights that are made “squintier” and pulled into the fender. They are still not as good as the S197 IMO, but they look much more modern and sinister, yet far more muscular the very-nearly-identical Fusion headlights that are available now. Better still, the upgrades to the front fascia make the car more aerodynamic, reducing drag and lift at higher speeds. Hard to complain. Out back, the GT switches to quad exhausts and Ford will offer electronically controlled exhaust valves to vary tone, something I liked a lot about the Camaro SS in my comparison posted above.

The end result is a Mustang that looks better, handles better, goes faster, and still packs a V8. What is there to complain about? If I had to complain about something, it would be that Ford made the new Mustang so much better that I really want one now..

Wednesday, 25 January 2017

AMG GT R First Drive - A Closer Look

Motor Trend basically started the first drive review (2nd paragraph) by saying that the folks at AMG have a sense of humour for naming this car "the Beast from the Green Hell." Maybe I don't get German sense of humour, but the joke is completely lost on me. Of course, that's assuming there is a joke there to begin with.. You see, I highly doubt the response AMG hoped for is a chuckle. And if I'm right, I think they can rest easy, because beasts aren't funny, and those that come from hell are probably less so, whatever colour that hell may be. Now, fierce, brutal, menacing, loud.. those are the things you might expect a beast to be. And if that name alone doesn't conjure any of those beastly characteristics, play the video below and skip to 0:28.

What a NOISE! This will be one of those cars that, should it roll up next to you at a traffic light, you quiet everyone down and roll down the windows to hear it pull away. If you're tired of hearing about how AMG knows how to make a V8 sound great, I don't blame you, but the only reason why everyone sings poetic about it is that they ARE very good at it. And remember, this isn't a deep breathing big V8 like what you used to find in all V8-powered AMG's. It's a relatively small 4.0 litre that was designed to be able to rev to 7,900 rpm (source: C&D Deep Dive). It's even got a pair of noise-muffling turbos strapped to it. The end result has no business sounding this good. Yet, it does. So it has the noise to match the name, an angry face, and a gaping maw that even looks like it has fangs. The big question then is this: does it drive like a beast?

At first glance, I'm afraid not. For one, compared to the sort-of predecessor - the SLS - this always sounds like a much more manageable car in reviews. Beasts aren't manageable. Then you have rear wheel steering helping you keep the back end more obedient and cooperative. And, reading the review, you find that AMG put Bernd Schneider, a five-time DTM champion, at the wheel to give Car and Driver a ride along. Instead of demonstrating the car's traction and tactility at the limit by switching all assists off, he pinned the throttle to the floor in corner exits and relied on traction control to sort it out, with "no subtlety." It has a stability control system that can't be completely turned off and allows you to pay no mind to "separating braking and steering inputs. Rather, this is a full-commitment reliance on technology." It all sounds very wrong. But there's more to it than the above would suggest.

For starters, the upgraded coil-over suspension is adjustable. The front track has been widened by almost one inch. On each side! The rear track has been widened by MORE than an inch on each side. And despite all the suspension upgrades, the downforce, the big sticky tires, and the rear weight bias, it still effortlessly turns the rear tires into smoke if you aren't careful, a sign of a true AMG. But above all, the one thing that really made me think the car is serious is chassis tuning. In Motor Trend's words, "The GT R’s chassis, like nature, abhors a vacuum: If you’re not on the brakes, it wants you to be on the throttle—even lightly—to feel absolutely balanced." This is a car that doesn't like coasting; a sign of a proper thoroughbred. You know what other type of car doesn't like coasting and asks you to always push? Race cars.

And this is where I was stuck with this car. I didn't know what to make of it. Is it a triumph of technology or a proper driver's car? Then I figured it out. You know what AMG has done? It has in, fact, built a beast. But most of us aren't The Stig so, while a few people can perfectly handle a beast, the rest can't. Instead of taming said beastie, AMG decided to saddle it, so that you can more easily ride it. Make no mistake, a bucking bronco is a bucking bronco, saddled or not. Saddling it just makes it easier for you to get a handle on things, but doesn't change the nature of the beast itself. What AMG has done is use all the electronic aids to build a really good saddle for a very capable beast. That makes it a very cool car IMO, but there are a couple of issues with it, although they have more to do with other cars than the AMG GT R itself.

The first is its sort-of predecessor; the SLS AMG. This car can't quite match its elegance or charisma. And it looks a lot more "corporate Mercedes" as opposed to a one-of. Don't get me wrong, the AMG GT R is better in every way, as a car. But the SLS had something the AMG GT doesn’t – some flair, perhaps, and stunning looks. And while this AMG GT sounds glorious, it can't quite match the snarl of the naturally aspirated M159 6.2 litre V8. On the other hand, you have the 911 (991) GT3 RS. Yes, I know, it's technically out of production, but if the AMG GT was meant to compete with the 911, what is this GT R version meant to compete with? It may be out of production but the target market and performance is the GT3 RS and here, again, the GT R falls a little short. It's a lot more of a brute and a bruiser. It isn't quite as pure a driver's car as far as I can tell and I can't imagine it being as rewarding to toss around and push at 10/10th.

That's where I am at with this car. It's not quite as mad as traditional AMG's, yet it can't match the excellence of the GT3 RS. For some people, I'm sure it strikes an absolutely perfect balance between the two ends of the spectrum but, for me, it just comes off as being less special than either. For a car that basically costs $200,000, it needs to feel a lot more special than that. I may never have that problem, but if I had that kind of money and I was looking at a German track car, it would have to be the 911 GT3 RS, even if it meant getting a slightly used one. The only thing I would be missing is that AMG V8 noise..

Wednesday, 4 January 2017

2017 Ford GT - A Closer Look

"The new GT is so purposeful, so exactingly and innovatively designed, that it reaches beyond the genre of European two-seat screamers built for maximum envy induction at felony speed. Ford hasn't built a supercar. It's created a weapon." How could you not desperately want to drive this car? Of course, what we already know about it from Ford, the way it looks, and the name should be more than enough reasons to start dreaming. But if they aren't to you, the above - what Road & Track had to say about the new Ford GT in the first ride review - should easily push you in the right direction. For me, though, I've wanted to drive it since I first saw it after its debut at the 2015 North American International Auto Show. This car is very, very special.

The story of the original GT, the GT40, is all too familiar. Ford wanted to buy Ferrari but Ferrari backed out. Ford wanted to show Ferrari who is boss so it built the GT40 and took it to Le Mans. After fiddling with it for a couple of years, the GT40 won for four consecutive years; from 1966 to 1969. Very impressive, but more importantly, it established the name GT40 and demonstrated that Ford is capable of building a car that not only can go head to head with the best in the world, but beat them at their own game. Now, the second generation, which came out in 2004 - the first Ford GT, sans 40 - was not a true successor to the GT40 in my opinion. Don't get me wrong - it was a fantastic thing. It is on my must-drive bucket list of cars and think it should be on everyone's list. But it was a tribute. It was an excellent tribute, but a tribute nonetheless. It couldn't trace its own roots in racing. It didn't come out with the purpose and focus of the original; track dominance. This new one, though, has all the right ingredients.

Back in the day, it was much more common for production cars to be homologated cars to allow competition in racing. Such was the case for the original BMW M3, for example. The original Mustang Boss 302 and Camaro Z/28, original (C2) Corvette Grand Sport, a myriad of Porsches, etc. That isn't the case anymore, though, as you can see by the rarity of modern homologation cars (as of 2010) listed on FIA's website (link: FIA - List of Previously Homologated Cars). Porsche, for example, has 59 cars listed and non of them (that's zero) are from the year 2000 or newer and only 4 are 90's cars. That could be for one of two reasons, I suspect. First is that even base versions of production cars now are very good and can serve as great starting points for race cars (mechanically, not electrically) as opposed to back then, where base engines, suspension, and chassis would have required many more modifications so you had to create a special edition that's a road-legal version of the race car. The second is race cars now being more heavily modified and further removed from the production cars they're based on. Either way, the result is the same. Cars on the road are more loosely tied to their distant racing prepped cousins. The GT, though, is a breath of fresh air of true racing-based development.

I don't know if the guys at Ford first decided they want to race a factory mid engine car or they first wanted to produce another Ford GT and wanted it to be a thoroughbred. But that matters little at this point, because this one has already had one season of racing under its belt, even before Ford rolled a single road going version off the line. Oh, and it already has secured a Le Mans (class) win. How can you argue with that? This car has heritage and pedigree in spades. To an average car guy or gal who likes it, the GT is just a cool mid-engine car that may be special because it pays homage to the original GT40. For a motorsport-stricken, slightly crazed car guy, this is very special. The kind of car that you get all giddy just reading about. Count me with the latter. Of course, if you count yourself with us in the latter group, you may have some explaining to do every time you hear something along the lines of, say.. I don't know.. IT'S GOT A V6!

In an era of downsizing and turbocharging, you may have a leg to stand on. But, this isn't actually the era of downsizing and turbocharging.. you're led to believe it is, but it isn't, not yet anyway. Not unless you look at mainstream cars. The Mustang GT350 has a 5.2 litre V8, for example, to replace the 5.0 litre that was in the car it replaced, the Boss 302. The Corvette lives on with a 6.2 litre V8 that can be naturally aspirated or supercharged. Dodge is stuffing a 700+ hp supercharged 6.4 litre V8 in anything it can get its hands on. Lamborghini will only sell you two cars, one that can only be had with a V10 and the other a V12. Aside from one generation of M3 and M5 preceding the current iterations, the current ones maintain cylinder counts - straight six and V8 - as the previous couple of generations and actually beat the originals. They may have lost a little displacement, but they gained a couple of turbos, each. The 991 GT3 RS has the largest displacement yet, tied with he last gen; a 4.0 litre flat 6. Sure, a few joined the downsizing trend like Porsche with the rest of the lineup but it's hardly the age yet. So what is Ford doing sticking a V6 in the GT?

As far as car news, learning that the GT won't have another supercharged V8 or the 5.2 V8 in the GT350 was very sad. Learning it won't even have the 5.0 litre V8 from the Mustang GT was devastating. But then, I am almost ashamed to admit, I started to warm up to the idea.. For starters, it has been racing in a Daytona Prototype with Michael Shank Racing since the 2014 season. That gives it pedigree. If that's not enough, it has set the fastest lap (ever) on the Daytona oval of 40.364 seconds. And it set a new record top speed of 222.971 mph, blowing the previous record of 210.364 mph out of the water. And it set a new record for the first 10 kms and the first 10 miles from standing starts. If the only problem you have with the engine is the smaller number of cylinders vs a competitor with eight or more cylinders, then fight fire with fire. The numbers above should not only make up for the smaller cylinder count, but provide enough ammunition to defend the engine till we're blue in the face. But for me, and many car guys, numbers aren't the only thing that matters. And here, too, the little 3.5 V6 makes a very strong case for itself.

For starters, it has the same soul and good, humble nature that the previous engine had. It's based on a truck engine, just like the 5.4 supercharged V8 in the last GT was. It's a working class hero, as Jeremy Clarkson put it multiple times. Then you get to packaging, where the smaller engine means a smaller engine bay that allows for the stunning teardrop shape with the flying buttresses where air-to-air intercoolers live. That, in turn, also allows for excellent aerodynamics. The only thing that could hurt it is lag, tactility, and linearity of throttle response but, assuming (reasonably) that they'll all be excellent, the only problem, really, is noise. But the first drive indicates that Ford got that covered too.

To quote Road & Track again, they said: "Fear not: The street-legal GT sounds excellent. Turbo whoosh is subtle, an undertone of boost beneath the engine note. The sound is somewhere between a silken straight-six and an exotic small-bore V8, a subdued but purposeful growl. Imagine a McLaren 570S with a higher redline and a little less rasp, and you'll be on the right track. It's worlds away from the woeful moan of the Le Mans racer." Nice. I'm genuinely looking forward to hearing it now, and that's far more than I can say for any downsized engine that replaces a previously bigger, naturally aspirated engine with a higher cylinder count. And better still, all of the above, when combined, draws a much better overall picture. Don't get me wrong, I still would have preferred to see a V8 in there, but I cannot reasonably defend the preference in any way. I can only say I just prefer a V8 and leave it at that.

So what do you have? A stunning mid engine supercar with legendary heritage, forged in the fire of motorsport, powered by a record-breaking engine, that goes, drives, and sounds like nothing else. I truly can't fault the car for anything. But I could fault Ford for one thing.. the price. I can't get over the price - estimated to be north of $400k. I can kind of understand the selection process, if Ford really is picking people so that it can make sure that whoever buys it will use it and showcase Ford's efforts instead of locking them up in a pristine garage. But with production numbers being so low and price so high, it really isn't a working class hero. Not even close. It's as blue blooded as the most exotic Euro supercars and it doesn't even come with an exotic brand name. It's a more rare and expensive car than most Ferraris, and you can actually buy a Ferrari if you can afford one, but not this. If this car walked into a big Cars & Coffee, it would stick its nose up at Lamborghinis and McLarens. But here, once again, I can kind of reason myself out of it..

It may be confirmation bias, but that kind of requires that I already believe something, not be against it and then change my mind. I hated the price of this car when I found out and the selection process. But when you think about cost a little, it seems more reasonable. Alright, maybe reasonable isn't the right word for a car that costs more than a nice house. Let's say it's somewhat justified.

The first car that comes to mind when you start thinking about the price is the C7 Corvette Z06 with the Z07 package - the best bang for the buck track performance you can get. It starts at just under $100k. If you want to go another step up, you can't do better than the Viper ACR, unless you wait for the Corvette that's been spotted testing with a big wing - presumably the ZR1. The Viper ACR is basically $140k and I suspect that upcoming Vette won't be a whole lot different. No one confuses the Viper or the Z06 with fancy cars - they're expensive because they have expensive hardware. Now, factor in added costs for a more expensive chassis layout, more exotic materials, more complicated transmission, active aero, etc. and it seems very reasonable to go much higher from $140k.

At that point, it really doesn't matter a whole lot if it's $200k or $400k, for the purpose of being a humble car. The price isn't humble either way. The car will have to be far out of reach for most. But think of it this way: it's the big brother that stands up for you against bullies. Sure, you can't actually buy this car and stand up for yourself against the likes of Ferrari and Lamborghini, but you can call on your big brother, who is still part of the humble family, to go give them a bloody nose. Ferrari would never sell a $20k car. Neither would Lamborghini or McLaren, or Aston Martin. That would tarnish the image and dilute the brand. The GT, though, has no problem sharing the family name with its little sisters. That is why it is still the people's supercar, even if it can't be bought by "the people."

I doubt there is a lucky owner in our region so I have no idea when I could be seeing and hearing one in person, but I sure hope it'll be soon. Finding out how it performs and just how capable the production version is? That can't come soon enough!

Thursday, 22 December 2016

Chevrolet 1LE & Grand Sport - How do they do it? Part 3

In Parts 1 and 2 (Links: +Chevrolet 1LE & Grand Sport - How do they do it? Part 1 & Part 2), I concluded that grip is where Chevys excel and decided to try and figure out how they do that by looking at test data from Car and Driver's Lightning Lap features. The first thing that stood out to me when the 5th generation Camaro 1LE came out was the wider tires compared to the Mustang Track Pack of the time and even the Boss 302. The tires on the ZL1 and Z/28 stood out as much.. only on those, they stood out compared to just about anything that isn't a supercar. So I decided to start looking there; tire sizes.

To evaluate tire sizes, I calculated a weight-to-tire-section ratio for each car. Similar to the idea of power to weight ratio, where the number tells you how much weight each hp is burdened with, this tells you how much weight each mm of tire section is burdened with, so to speak. For example, a BMW M235i weighs 3,490 lb, as tested during the LL feature. It has 225/40/18 front tires and 245/35/18 rear tires. The total available tire width footprint, pressure, tread, and tire deformation notwithstanding, is 940 mm (225 x 2 + 245 x 2), which gives it a weight-to-tire ratio of 3.71 lb/mm. Here is where the trust in measured data that I hopefully established in Part 2 comes into play. Without a monumental amount of work going into looking up tire pressure specs, tire wall and tread stiffness spec (IF manufacturers share in the first place), and calculating actual contact patch areas for each car, we can look at measured data (i.e. lap times) and see if we find a correlation strictly between tire size and lap times. Here's a plot of that weight to tire section ratio for each car vs that car's lap time.

You may have read or heard about how wider tires don't increase contact patch size and are only useful for managing thermal stresses and changing the shape of the contact patch. Whether it's due to the contact patch size increasing, better thermal management and patch shape, neither, or both is irrelevant here so I won't get into the theory. What's relevant is the real world result: cars tend to go faster on wider tires. It's unarguable that quicker cars have more tire width for every pound of weight. I couldn't find an advantage in specs in terms of power, weight, downforce, etc. but could tire size be a factor? Below is a table listing different weight to tire width ratios for Camaros and Vettes and a few other cars. If you arrange cars tested over the last three Lightning Lap features in terms of weight/tire mm, the Corvette GS is 4th best, Z06 is 8th best, and 5th gen Z/28 and 6th gen SS 1LE are 14th and 15th, and that's out of 50 cars (excluding special features like race and police cars).

Car lb/mm
Viper ACR 2.62
SRT Viper TA 2.64
911 GT3 RS 2.67
Corvette GS 2.78
Alfa Romeo 4C 2.81
Cayman GT4 2.83
Corvette Z06 2.86
Shelby GT350R 3.00
911 GT3 3.02
Ferrari 488GTB 3.12
McLaren 570S 3.13
Audi TTS 3.16
(5th gen) Camaro Z/28 3.17
Camaro SS 1LE 3.17

Clearly, Chevys measure up really well here. This is something you might have noticed in the past by looking at specs, and Chevy even bragged when it released the Z/28 and said it had the widest front tires (305) fit to a production car. You might have also found a lot of angry anti-Camaro comments on reviews that go along the lines of this: "throw wider tires on [insert car] to match the Camaro and see how it stacks up!" There is reason to the madness. Now, slapping a set of huge tires on a car not set up to handle the grip won't win races without a proper setup and supporting hardware, but the point is that you do need big tires. Chevy's clearly got that base covered. So, is that all, you just need wider tires?

Although they do have good tire-to-weight ratios, you can see from the table above and the one posted in Part 2 that they beat cars (in lateral g forces) with better numbers and, as mentioned in Part 2, they rank above nearly 200 cars in lateral g forces measured in the first corner of the track, which is especially impressive for the current Camaro SS 1LE, since it doesn't use the same type of aggressive tires like the Z/28 and top dog Vettes. If it's just down to this ratio, that shouldn't be the case, so it's likely not the only factor/advantage. What else could it be? Bear with me on this one.. I think it's wheel size. Now, everyone avoids big wheels like the plague. But what if the bigger wheels actually help? Let's first look at why big wheels are bad.

First is weight. Weight is the enemy of speed. Bigger wheels tend to be heavier, so that's more weight you have to accelerate, brake, and turn. Weight is also critical because wheels and tires are unsprung – meaning the car’s springs and entire suspension is downstream of it (relative to the road) and can’t directly respond to forces generated by the road on the wheels. Wheels actually have a suspension system, but it consists of just the tires and air filling them, and those components form the spring and damping properties. Since they aren't nearly as effective as a car's suspension system, especially on low profile tires, they transmit a lot of those forces from the road to the car instead of absorbing and dissipating the energy, and the heavier the wheels, the bigger those forces are. The suspension’s job of keeping tires in contact with the road, then, becomes harder with heavier wheels, resulting in relatively compromised grip and ride, all else being equal.

Then there's moment of inertia and rotational energy. I can't adequately cover these properties here but, putting it simply, moment of inertia is comparable to mass but for rotational motion as opposed to linear. Just as it gets harder to move something the heavier it is, it gets harder to rotate something the heavier it is, but also how far it is from the axis around which you are trying to rotate. If all else is equal, a bigger, heavier wheel results in a higher moment of inertia, making it harder to change its state/speed (i.e. accelerate and brake it). But worse yet, a wider diameter wheel pushes the weight of the wheel's rim/barrel and the tires further out, making that moment of inertia even higher. Moment of inertia, typically referred to as I, is defined as:

I = mass * r²,

where r is the "effective" radius - A distance from the axis of rotation that the entire mass can theoretically be concentrated at with the same result, similar to the idea of a centre of gravity. The heavier something is or the further it is from the axis, the higher the moment of inertia - I - and harder it is to turn. Then there is rotational (kinetic) energy, defined as:

E = 0.5 * I * ω²,

where ω is the rotational speed. That means that the higher the moment of inertia, rotational speed, or both, the more energy there is that you have to deal with. Pretty straight forward.

But what if you could minimize those disadvantages? Chevy has been using forged wheels on their high performance models for a while now. I can't find specs on the 6th gen SS 1LE wheels yet, which may be even lighter, but their 20" x 11" wheel on the 5th gen weighs approximately 28 lb. That's definitely not light, but if you do some research, you'll find that most good aftermarket cast aluminum 18" x 10" wheels weigh low-to-mid 20's lb, unless you get into the more expensive sub 20 lb options. And a cast aluminum would probably have a thicker rim/barrel since it's weaker than forged, so more of the weight is put further out away from the centre, which is worse than just adding weight. In fact, that 20" x 11" wheel is lighter than the 19 x 10" wheel Ford used on the back of the 2012-2013 Boss 302 Laguna Seca, which weighs approx 33 lb, although these were cast. 991 GT3 20" centre-lock wheels weigh 24 lb and 27 lb front and rear (source: Rennlist Forums: 991 GT3 Stock 20 Wheel Weights) and they have to deal with a good 300-400 lb lower curb weight. So, while no featherweight, the weight of those 20 inchers aren't nearly as bad as off-the-shelf 20" wheels that people upsize to for looks and are clearly well designed. 

Rotational energy is a double edged sword. On one hand, a bigger wheel, generally being heavier, negatively affects the weight element of the moment of inertia, making it more resistant to accelerating and braking (i.e. needing more power to do either). On the other hand, a wider diameter wheel and tire package has a longer circumference/perimeter, so one revolution covers a longer distance, which means it can spin slower than a smaller wheel and tire package while the car's speed is unchanged and, therefore, the speed element of the rotational energy goes down. To illustrate, if you compare the BMW M4, which has 255/35/19 front tires, and the M235i, which has 225/40/18 front tires, to the Camaro, you'll find that, because the Camaro's wheels and tires are bigger with a longer circumference, they spin less for the same speed. The Camaro's front tires have a circ. of 7.00 ft, the M4's are 6.81 ft, and the M235i's are 6.57 ft. That means that the M4's tires need to spin 2.79% faster and the M235i's 6.5% faster than the Camaro's to match its speed. And because rotational energy is a function of the square of the rotational speed, the M4 front wheels and tires would have 5.7% more rotational energy than the Camaro's and the M235i's would have 13.4% more energy while all three cars are going at the same speed, if moment of inertia (I) is the same in the E equation above for all three cars.

In other words, more braking power and acceleration (engine) power are needed to brake and accelerate the smaller M4 19" and M235i 18" wheels and tires, compared to the 20" Camaro wheels, assuming an equal moment of inertia (I). I expect the Camaro's wheels to have a higher (worse) moment of inertia, but it has to be at least that much worse for the Camaro's wheels and tires, in comparison, to need the same amount of rotational energy to accelerate and decelerate, let alone more energy. A similar story is true for the rear tires. The overall net affect is impossible to calculate without knowing the wheel's effective radius around its centre, but the point is that, once again, it isn't as bad as people think for well designed and constructed wheels.

So let's say you use light weight and well designed wheels to overcome most of the downside, what's up the side, just looks? I don't think so. Looking back to the data for answers, here are lap times vs (rear) wheel diameter.

Could it be? Do quicker cars tend to have bigger wheels? Only one car with a lap time under three minutes (3:00) uses 18" wheels - the Cadillac ATS-V - but everything else is 19" or larger. Ironically, the ATS-V rides on the same chassis that gave birth to the current Camaro.. and it has very slightly more power along with a fast shifting 8-speed auto vs the manual in the Camaro. Yet, it is noticeably slower, to the tune of a very significant five seconds (for the ATS-V sedan, the coupe is "only" 4.4 seconds slower than the SS 1LE). And, aside from the Viper, every car with a lap time under two-minute-fifty (2:50) uses 20" or larger rear wheels. Quicker cars tend to be expensive, special performance models, exotic, or any combination. You could argue that this makes them more likely to have larger wheels just for looks to match the "status". But there are two problems with that thinking. One is called the 991 GT3 RS and the other is called the Viper ACR.

These two cars are two of the most, if not THE most, hardcore production cars that are dedicated to the noble cause of speed and track performance. The 991 GT3 RS uses not 19" or even 20", but 21" rear wheels. What does that tell you? Keep in mind, that's the same car that, in pursuit of saving weight, does away with door handles and gives you something that James May described as "little bits of rag," in his review of the last generation Boxster Spyder on Top Gear. Do you think they would do that just for looks? The list of weight saving efforts on the 991 GT3 RS includes stuff like carbon-fiber panels for the engine cover, the front trunk, and fenders, a magnesium roof, lightweight lithium ion battery, removal of air conditioning, removal of audio system, centre locking wheels, and lightweight suspension components. It is hugely unreasonable to expect them to go through all of that and simply through big wheels on for looks. The GT3 (non RS) uses 20" wheels, not 21", by the way. The 911 R, the less hardcore, less capable, manual-transmission option that is not obsessed with lap times also uses 20" wheels. The story is similar for the Viper, where the less hardcore TA model uses 19" rear and 18" front wheels. The ACR uses 19" wheels front and back. You can draw your own conclusions.

Do you need more proof? Well, in a Car and Driver test of upsized wheels and tires (link: Effects of Upsized Wheels and Tires Tested), they found that 235/35/19 wheels generated 0.01 lat-g's less than the smaller 225/40/18 (0.88 g vs 0.89 g). Test tires were Goodyear Eagle GT so C&D asked Goodyear for their explanation and "they postulated that the added [tire] width may have given the outside tire more grip, which would increase body roll and could therefore decrease the load on the inside tire enough to lose 0.01 g on the skidpad." No mention of bigger wheels, more weight, etc. or even the suspension not being able to handle the added weight, despite the test car being a 2010 VW Golf with stock 15" wheels that, combined with 15" tires in stock size, weigh 14 lb LESS than the 19" ones.. EACH, meaning the suspension is guaranteed to not be designed to handle the added weight. The trouble was too much weight transfer. A little off topic, but the reason for that is the non linearity between the ability of a tire to generate grip and weight. In other words, two tires with 800 lb on them, each, will generate more grip overall than one tire with 1,200 lb and another with 400 lb, because the increase in friction forces at the loaded tire due to an additional 400 lb of vertical load is less than the drop at the unloaded tire due to losing 400 lb of vertical load.

Back to topic, if you dig a little deeper, the theoretical reason why bigger wheels help is their effect on tires. Bigger wheels better control tire flex under load. Limiting tire flex results in a stiffer tire. You'll hear people refer to sticky tires as "soft compound" sometimes, but there's a difference. You want a soft surface to conform to the road texture and shape but you want a stiff tire structure. Limiting tire flex effectively increases stiffness. And tire grip is directly proportional to its cornering stiffness. Increasing tire stiffness is why high performance cars have low profile tires. The stiffer tires also provide a lot of benefits like better response, less deformation and heat buildup, better stability at high lat-g loads, etc.

Chevy doesn't use the biggest wheels. That would be the rear wheels on the GT3 RS (21") and the front and rear wheels on the Audi RS7 (21"). But aside from those, it uses either the biggest in its class or tied for the biggest. The Camaro uses 20" front and rear wheels on both 1LE models, the V6 and the SS. The Corvette Grand Sport and Z06 use 19" front and 20" rear wheels. I suspect the reason why the Corvette doesn't use front 20" wheels is that it doesn't need to, because its front end isn't nearly as loaded as the Camaro, with a better rear weight bias combined with a more rearward engine placement. As a result, the tires have to deal with less load and can be downsized from the Camaro's. What Chevy is doing is more effectively using wheels and tires to maximize available grip that can be extracted from the tires. This thinking of maximizing available grip extends beyond wheels and tires. Going back to the weight transfer issue from one paragraph up, all manufacturers try to minimize weight transfer for better handling but Chevy goes a step further.

Since weight transfer minimizes available grip, you could throw the best wheels and tires available but if you transfer too much weight, you can't use them to their capacity. Plus, a lot of weight transfer means delayed responses, less stability and confidence, etc. An easy solution is to just increase roll stiffness through springs and dampers, but that also increase vertical stiffness and you may not want to do that. Roll bars are better in that regard, but you increasingly couple left and ride sides if you rely on them too much. The best solution is widening track - the distance between the centre lines of the two wheels and tires on one axle. Performance cars use a combination of all the above, but here's how Chevy's push one step further.

If you exclude light cars like the Fiesta ST and Miata, and exclude very front-end-light cars like mid-engine and rear-engine cars (including front-mid engine like the Corvette, Viper, and AMG GT), the Camaro 1LE has the widest front track for its weight of all cars tested over the last three years, with the exception of the spiritual successor to the BMW 2002 - the M2. Meanwhile, the 5th gen Z/28 had the widest track, period, of any car ever tested by C&D for Lightning Lap features over the same period, tying the Ferrari 488GTB for the honour. Does that matter? Once again, if you look at the data and plot front track widths, you'll find a very clear correlation between quicker lap times and wider tracks. The same is true for rear track.

So far, everything is done to maximize overall grip. The final piece of the puzzle is focusing on longitudinal grip and putting power down - the differential. Namely, the electronic limited slip differential. A differential that can make better use of available traction makes a massive difference in a car's ability to put power down and bringing down lap times. And, to quote Sir Jackie Stewart: "The exit of the corner is far more important than the entry of the corner, with regards to smoothness." You obviously have get the entire corner right to get the most out of a car, but corner exit is more important than corner entry as far as lap times. That's especially true for non-momentum cars like these. I have experienced first hand the improvement different types of limited slip diffs can make but, going by the numbers, a good comparison to demonstrate the difference was done by Car and Driver in 2015 (link: What's the Diff?), putting a Lexus RC-F to the test with the standard limited slip diff and the optional Torque Vectoring diff. The difference was 0.03 lat-g around a 300 ft skidpad (0.94 vs 0.91 g) and nearly half a second (0.4 s) on a minute-nineteen-second (1:19.1) course. That's on an otherwise identical car.

Now, Chevy doesn't use a torque vectoring differential, but a good, electronically controlled, variable locking limited slip differential should be able to provide the same traction benefits of a torque vectoring differential, just not the yaw control due to the steering effect from torque vectoring. The V6 1LE does away with an electronically controlled diff all together, like the one the V8 Camaros and Corvette use, but I suspect that there isn't much to be gained beyond a good mechanical LSD, considering the much lower power output of the V6, combined with the much, much lower low end torque compared to the V8's.

After I concluded that the above seem like the advantages, I started testing my conclusions by comparing those components in Chevys vs cars they beat to see if the advantages do hold up. And they seemed to. For the most part.. there two cars stood out; the 991 GT3 RS and the Cayman GT4. The above components or a combination of them (big wheels and tires, wide tracks, and good LSD's) point to a Chevy advantage for the vast majority of cars but not the Porsches. They do beat their closest Chevy competitors (if classed by specs) - namely the Corvette Grand Sport and the Camaro SS 1LE. But Just.

The GT3 RS is darn near 300 lb lighter than the Vette. It has 40 hp more and far better power to weight ratio (6.3 lb/hp vs 7.5 lb/ hp for the Vette). It has rear wheel steering. It has more downforce. It also uses a variable electronic locking differential, big, wide, lightweight centre locking wheels, and even has a slightly better lb/tire section ratio (2.7 vs 2.8 for the Vette) and upsized wheels (20" and 21" front and rear vs 19" and 20" for the Vette). How is it that all of this nets no more than one tenth - that's 0.1 sec - advantage, despite having Porsche's excellent PDK, which should alone save a multiple of 0.1 sec in total shift times compared to the Grand Sport's 7 speed manual? A similar story is true for the SS 1LE vs the Cayman GT4, although with a bigger time gap (0.8 sec), no auto transmission, but much better tire to weight ratio (2.82 lb/mm vs 3.17 lb/mm for the Camaro). Both Porsches should have a big traction advantage because of engine location. It seemed like it should be a bigger gap for both cars, especially the GT3 RS. That kept hanging over what I concluded, convincing me I must be wrong. But after going through the numbers (a few times), I finally found a consistent advantage - gross tire footprint.

The GT3 RS has a slightly better tire to weight ratio than the Vette as mentioned, but, if you sum up its total tire footprint at all four corners, it comes up 60 mm short of the Vette's - nearly one fifth of a foot narrower. The Cayman has an even bigger discrepancy, with a total tire foot print that's 100 mm narrower than the Camaros, darn near four inches or a whopping one third of a foot narrower. Does it matter that much? Going back to that table of lb/tire section ratio, showing cars that have better lb/tire ratio but don't beat the Camaro in lat-g forces measured in the first corner, you'll probably conclude a resounding yes. Every single car that has a better tire to weight ratio but lower grip (judged by lat-g) has less overall tire footprint, with the exception of the GT350R. But, assuming my earlier conclusions are true, that can be explained with the other factors since it doesn't use an electronic LSD like the Camaro SS 1LE and it has smaller wheels.

Obviously, suspension design and tuning is critical. If not done properly, everything falls apart. And it's critical to ensure the car is fun to drive, stable, predictable, etc. The C&D test I mentioned earlier of upsized wheels and tires is critical in remembering that you have to think of the complete package and the entire car. Putting my conclusions together, assuming they are true in the first place, and making modifications to a car on that basis without proper development, testing, and supporting upgrades is like pitting a Mustang GT and a GT500 against each other in a drag race and, when the GT500 wins, you make the conclusion that you need a supercharger, so you go out, buy one, and slap it on top of the engine in the GT and call it a day. Without supporting modifications and tuning.

The point here is that, assuming proper development from all manufacturers, that seems to be how Chevy carves an edge; wide tires, big but light and well designed wheels, wide suspension track, and good differentials. It seems that, when those are combined with a great chassis and a genuine focus on performance and handling, the results on track or a good back road are very impressive.

Wednesday, 21 December 2016

Chevrolet 1LE & Grand Sport - How do they do it? Part 3

GM, in general, is starting to build a very strong reputation for chassis engineering but Chevrolets, in particular, have very strong performance on track these days, not just good handling feel and fun to drive attitude. In Part 1 (link: Chevrolet 1LE & Grand Sport - How do they do it? Part 1), I looked at different aspects and concluded that Chevys appear to have the advantage in grip. If you are still unsure that grip is where those cars excel, perhaps this number will change your mind: 1.11. That's how much lateral forces, measured in g, the 2017 Camaro SS 1LE generated in Turn 1 of Virginia International Raceway (VIR) during Car and Driver's Lightening Lap 2016 feature. 1.11 g also happens to tie the 2014 Viper TA, the 2014 Ferrari F12 Berlinetta, and even the 2016 Ferrari 488GTB. It gets more interesting too..

Car Max Lat-g
2015 Chevy Corvette Z06 1.20
2017 Chevy Corvette Grand Sport 1.19
2009 Mosler MT900S 1.16
2015 Chevy Camaro Z/28 1.16
2015 Porsche 918 1.16
2015 Nissan GT-R NISMO 1.15
2016 Dodge Viper ACR 1.15
2016 Porsche 911 GT3 RS 1.14
2015 Lambo Huracán LP610-4 1.13
2014 Ferrari F12 1.11
2014 SRT Viper TA 1.11
2017 Chevy Camaro SS 1LE 1.11
2016 Ferrari 488GTB 1.11

If you pay attention to the order, you'll notice that the list isn't arranged in order of age or model year - i.e. starting with the Camaro, being 2017, then the 488GTB, being a 2016, then the Viper and F12, both 2014 cars - or vice versa. Despite all being listed at 1.11 g, the order goes F12, Viper, Camaro, and 488GTB; two 2014's, a 2017, and a 2016. Unless you want to believe it was random, that must mean that if you look at more decimal places, the Camaro beat the 488GTB and was beat by the F12 and Viper. That's a humble pony car beating a purpose built, mid-engine (new) Ferrari in grip.

It also places 12th out of every car ever tested in Lightning Lap features. The tally adds up to 201 cars and this Camaro beats 189 of them, including cars like the 458 Italia, 911 Turbos (pick a generation, it beat them all), 991 GT3 (non RS). Cars that beat the 2017 SS 1LE include stuff like the GT-R Nismo, Viper ACR, 911 GT3 RS, Porsche 918, you get the picture. Going further up the hall of fame, you find that three of the top 5 cars are Chevys, taking 1st (Z06), 2nd (Grand Sport), and 4th (fifth gen Camaro Z/28). The Mosler MT900S managed to just barely beat the Camaro (both are listed at 1.16 g, meaning they must be separated by a few 1/1000th's), but everything else is beat by the top dog Corvettes. I think I rest my case that Chevy knows grip. And it's easy to see why Chevy focused on grip.

If you can't grip the road properly, you can't put down power, you can't brake as aggressively, you can't carry speed through turns, etc. That's why everyone who's been around a track a few times will tell you that tires are one of, if not the most, crucial piece of the going-fast puzzle. If you have good tires, generally resulting in better grip, any individual under-performing aspect of a car doesn't necessarily have the same effect on others. For example, a low-powered car doesn't necessarily mean it's slow - it could have great brakes, great handling, great downforce, or any combination. Not having much power hurts acceleration, but the brakes can still do their job slowing the car down, suspension can do its job keeping tires in contact with the road, aero components can still generate downforce to increase grip at high speed, etc.

Even within one aspect such as handling, for example, you could have a car that understeers on entry - a bad handling characteristic - but it could very well be good at putting power down. You could still be quick if you slow it down, turn it, nail the apex, and hammer the throttle. Tires, on the other hand, can single handedly ruin all aspects of a car setup and prevent ALL of them, simultaneously, from performing properly if not chosen well and grip is compromised. Conversely, they can improve every single aspect of the car, if maximized. The question then becomes this: how do they generate more grip? It isn't compound because, while they do use good tires, they don't use anything more aggressive than what other manufacturers use (aside from manufacturer specific tuning).

To try and figure out where Chevy's stand out in any one area, or if they do at all, I looked at Lightning Lap numbers in more detail. I collected data from the last three Car and Driver's Lightning Lap features about each car, including lap time, front and rear wheel and tire sizes, front and rear track widths, power, torque, and weights. Then, I trended a bunch of different parameters about the cars vs lap times to see if I find any correlations pointing to a Chevy advantage. First, look at this graph of lap times at VIR during C&D Lightning Lap features vs power to weight ratios (expressed here in the inverse, lb/hp ratio) for the cars.

This isn't relevant to figuring out how those Chevys go quicker, but I just want to establish trust between you and data, if you're someone who isn't used to looking at empirical data, and making observations and conclusions, without knowing all factors. Generally speaking, cars with better weight to power ratios are faster. You probably already know that. But if you didn’t and you had no idea how power and weight affect a car, you’d look at that graph and say that as this weight-to-power ratio number goes down, lap times go down. Here's another graph.

This one is of lap times vs weight distribution over the front wheels wheels (i.e. the lower the number, the less weight there is on the front axle and tires as a fraction of curb weight; more rear weight bias). You could also look at the lap times vs weight distributions and say that front end heavy cars tend to be slower and as you move weight to the rear wheels, cars tend to be quicker. You could make this correlation, and the above between power-to-weight ratio and lap times, while all other factors are unknown - some of which are actually crucial to the going fast puzzle - just by looking at the test data. And you'd be right. With that in mind, can we use the data for more? Even without a deep dive into suspension geometry and roll centres, torsional stiffness, spring and damping rates, etc., can data point to a Chevy advantage, in the suspension or otherwise? Stay tuned for the conclusion tomorrow in Part 3 Chevrolet 1LE & Grand Sport - How do they do it? Part 3!

Saturday, 5 November 2016

2016 Focus RS vs 2016 Mustang Shelby GT350R - Track Video

While testing a 2016 Focus RS for the comparison test (link: Ford Focus RS vs Subaru WRX STI vs Mitsubishi Evo X MR), I caught up to a 2016 Mustang Shelby GT350R and had a friendly head-to-head battle. Both cars were completely stock. The video doesn't capture just how good that car sounds. We had a chat afterwords and the owner was very cool about it. His rear tires were starting to look old and he told me it felt a little less grippy than he was used to, so they could have been heat cycled out. Our track is also short and technical, so high hp cars don't get much room to stretch their legs, robbing them of some of the advantage they'd have at a power and/or longer track. The Focus had the optional Michelin Pilot Sport Cup 2 tires. Check out the video below for a couple of laps.

Wednesday, 2 November 2016

Ford Focus RS vs Subaru WRX STI vs Mitsubishi Evo X MR

All these cars have one common Achilles' heel. The engines sit entirely ahead of the front axles; a great family recipe for understeer. Then tell the front tires - already taxed from trying to keep that front engine sitting outside the wheelbase from going straight - to put some power down and you can only make matters worse. There are ways to mitigate the understeer with suspension tuning, of course, but the toughest part is power-on understeer. I don't want to get much into tires, but the thing to remember is that because tires have a certain "grip budget" - how much total grip they can hold/generate before they let go - when you get on the power in a car that sends power to the front wheels (FWD or AWD), you will rob some of the precious grip you were relying on to turn the car in order to put all or some power down. You'll run out of front lateral grip sooner than you would have otherwise, as a result. Worse yet, because of the unideal engine placement, you need every last bit of lateral grip in the front. So what you typically do to mitigate that understeer is, generally speaking, give the front tires far more grip than the rears.

You know what all good handling front end heavy, FWD cars have in common? They turn into tripods and kick up the inside rear wheel when turning. You need as much grip at the front as possible to keep that engine hanging in the front in check so you tune for weight transfer to the front, lightening up the rear end in the process. That's great in a FWD car but with AWD, you make the rears less effective - the same tires you're now trying to send power to.. after having just added a whole lot of effort, weight, complexity, and cost to the car in order to be able to utilize them. As a result, you can’t let these cars turn into tripods and pretend the inside wheel doesn't exist half way around a turn. You are now using the rear wheels for power so they are far more useful, for one. For another, you can afford to lose a little grip from the fronts to the rears, since they don’t have to transfer all the power anymore. You can never lose sight of the unideal engine placement, though, that demands a lot of grip in the front.

Why is all of this relevant? Because you need to spend just as much effort managing power as you do managing available grip by tuning the suspension. That's how each car here defines itself. Where their characters and attitudes come from. And because differentials are a big factor in this, I made another post recently on various types of differentials in an effort to make this post more focused on the cars but still discuss diffs in a little more detail and answer some questions about the diffs discussed here. Here's a link to that post: Limited Slip Differentials - The Basics. With that said, let's start with the oldest car here; the Evo.

Mitsubishi Evo X MR

How many comparisons have thrown this out-of-production car into the mix of new entries to the segment? This isn't only out-of-production, it is also very old, with a platform that's a full generation and redesign older than the other cars here. You can notice that in NVH, the way the car looks, the way the interior feels.. but not the way the car drives.

Compared to the STI, the Evo X feels sharper, more nimble, and more agile. This is surprising because the STI, at first, seems to have the advantage. The Evo is heavier, to begin with. It's an older, presumably less stiff chassis. It uses a conventional bevel gear centre differential, giving it a 50:50 torque distribution. The STI's centre differential is a planetary type, giving Subaru the flexibility to gear it for a 41:59 torque distribution front to rear. To make matters worse, the Evo can bias torque to the front wheels by varying lockup in a clutch pack sending power to the rear. The STI can't (without slip and centre diff lock). The option of front power bias without the possibility of rear bias, more weight, and possibly softer chassis sound like a few strikes against the Evo. But the Evo is happy to return punches all day. 

Without slip, any power you send to the rear wheels will cause understeer. An open diff sends virtually equal torque to both wheels so there's no steering moment and your tractive forces push the car where the rear wheels are pointing; straight. A mechanical LSD sends more to the inside wheel around a turn until there is slip, so you even have a negative steering moment. What do you do? You CREATE steering moment! Enter torque vectoring differentials. The power you send to the back in the Evo goes through a torque vectoring differential to then distribute that power side to side - forcing it to the outside wheel creates steering moment. At the front, the Evo uses a gear-type LSD, maximizing use of available traction so you can put more power down. More power down at the front (without slip) is good, because the tractive forces are pointed in the direction you want to go, along with the front wheels. Both the Evo and the STI use limited slip mechanisms to lock front and rear axles if there is slip and shuffle more torque fore and aft. However, the centre diff in the Evo is strictly an electronic LSD. When going around a turn without slip, it is completely uncoupled. No lock, no resistance to turning. 

The final peace of the puzzle is power distribution. Why only 50% to the rears and why allow front bias? Well, you need a lot of grip in the front to keep the engine in check. If the car is turning, you need to allow weight transfer to the front to increase grip there because of the unideal engine placement. The downside is that you rob the rear wheels of their grip so they can't put down as much power as you'd like. Now, front power bias here is very different from what you hear people complain about in a performance car. That kind of power bias, typical in the tried-and-true Haldex AWD system, hurts because it is the default. You always get front power bias until there is slip, at which point the front tires are already struggling and the best you can do is ease their pain a little by lightening their load. In the Evo, power goes from the engine to the transmission, then to a differential that evenly distributes power front and rear. Then there is a clutch pack transferring power to the rear axle, which you can progressively disengage to put more power to the front if conditions allow (i.e. whenever you don't need peak lateral grip). So with that in mind, you either allow that (good) front power bias to be able to utilize more power there where you've put more of the available grip due to weight transfer, or you prevent a lot of weight transfer to the front so you can bias power to the back without losing traction, at the expense of front end grip and more neutral handling. The Evo chooses the former.

All of this translates into a huge difference on track. It turns in with surprising precision. You can still find some understeer at the limit but it is easy to avoid and manage. You can get heavy on the power very early and trust it. You need very little corrections and just let the car drive the proper line as if Mitsubishi taught it during development. I may be exaggerating but you'd probably be, too, if you've driven a few different cars on track and felt the difference. Another plus is that, because the Evo is close to neutral, if the centre diff locks due to slip, it will help the car rotate. Because, if locked, the front and rear axles' speeds have to be closer than they would be, unlocked. That means the tires on one axle have to slip a little to more closely match the others. If you have more front end grip, the rears will slip first, helping the car rotate and reducing power-on understeer. But don't confuse that slip with lack of stability. The Evo wants to make a hero of you. It is so stable, so easy to control, that you'd be forgiven to think it can't go wrong. The whole car is focused on managing power as efficiently as possible - front to back and side to side - to optimize the turn. You can just feel the car working under power, managing the grip, managing the power distribution. And it feels so eager to do so.

Forget about lap times for a moment. They can easily be improved (to an extent) with some relatively minor tweaks. For example, when it first came out, this car did a lap of 3:13.3 at VIR for Car and Driver's LL 2008. That's only half a second ahead of the 3rd generation WRX STI, despite reviews generally agreeing that the Evo feels much sharper and track ready. It wasn't until they brought it back (in SE guise) for LL 2011 and did 3:10.5, putting it a little over 3 seconds ahead of the STI. And one way or another, it was still an Evo X. The times don't tell the whole story. Focusing on the times is missing the point. Despite the age, despite the crappy interior, the relative lack of refinement, the dire image of Mitsubishi, and even being out of production, this car feels just as sophisticated, track focused, and special as the other newer cars here. That's the point.

Subaru STI

I'm not sure if Subaru's reputation is what is influencing current design philosophy or current design philosophy is what's fueling the on-going reputation. But I imagine that at every design meeting during the STI's development, the head engineer always asked everyone involved: "so what have you done since the last meeting to make sure it better puts power down?" I can picture someone, at some point, suggested big rear anti roll bars during development for better turn in. He probably got fired. That's not to say the STI handles badly. It's still sharp with great turn in. It has a lot of grip and does not plow straight under power. That's just not its party piece. It's not its specialty. 

The STI claws the road under power. If it were an animal, it would be a big cat - a lion or a tiger - and every time you got on the power, it would crouch, wag its rear end sticking in the air, and pounce forward. Whereas the Evo is all about managing power, the STI is all about putting it down. Traction seems to be the priority. You need just a little more patience than the Evo before getting back on the power but then it will put power down with absolute tenacity.

It uses a gear type front diff like the Evo so there is no difference there. In the centre, though, it uses not one, but two types of limited slip mechanisms - a gear type and an electronically controlled clutch pack. The planetary gear centre diff utilizes helical gears to create thrust forces and provide some lockup under power. That means, as you roll into the power, the diff progressively locks. That’s great for traction as it locks before slip occurs (remember how the STI is all about traction?) but more lock means resistance to turning so it won’t be as agile. The second LSD is an electronically controlled clutch pack – similar to the Evo – to supplement the gear type for more locking if need be or if you want to manually select and lock the torque distribution instead of letting the computer do the work.

You can forget all of that torque vectoring non-sense in the Evo. That's what the STI would say if it could talk. In a slalom test by Edmunds back when the Evo X was introduced, they found that the torque vectoring diff can be caught off guard in short and quick transmissions like a tight slalom and wag the rear end a little. The STI wouldn't have any of that and would happily give up the effective steering from torque vectoring. The rear diff in the STI is another gear type differential, unlike torque vectoring in the Evo, which again locks under power. It won’t wait for slip or a computer to think and shuffle power. It doesn’t want to slip. That’s the STI’s mission.

Then you get to weight transfer, where the STI refuses to rob the rears of their traction, giving them better grip at the expense of the fronts. It's more stable and means you can put more power down without slip. But it's at the expense of some lateral grip at the front and that precise point-and-go attitude of the Evo. Corner speeds have to come down some, but you should be able to make up for it in traction in corner exit.

With that said, the STI has a certain charm to it - a certain mechanical feel that makes it more natural. It drives almost like a RWD car, but not the best and most sporty of the breed. It drives like a very tame one - one that is very capable but has safe understeer dialed in and massive amounts of traction. As is to be expected of the front weight bias, you get a good helping of limit understeer. If you go on the power, you can help the car rotate, but you do so by slip. Just as you would in a RWD car, especially if it's locked in 59% power going to the back. You can break traction and get it to rotate. It also uses brake-based lock, which does help, but isn't nearly as effective as a torque vectoring diff. The slip also feels abrupt compared to the Evo and the RS. That could have something to do with the modifications - this particular STI had camber (-2.5 degrees all around) and sticky BFGoodrich g-Force R1 track tires (which are different from the tires used by the owner for the lap time quoted at the end). The abruptness could easily be attributed to those near-slick track tires, but I would be surprised if, even when stock, the rear end would step out as smoothly as the Evo and or anywhere as gracefully as the RS.

The mechanical feel and nature does more to impress too, depending on how you look at it. The Evo will make a hero of you, but perhaps at the expense of doing more for you. You'll always wonder how much you could do without the car's help. In the STI, you feel more in control and will get it out feeling more accomplished, especially with the option of locking front to rear torque. It feels like the car just gave you all the traction in the world on a silver platter and what to do with it is up to you. The Evo has a wider range of torque distribution front to back and then again side to side on the rear axle. Aside from the torque vectoring diff simply sending torque to the outside wheel to help the car rotate, it's hard to say whether the Evo actually does that much more for you, as far as managing power, or the STI just hides it better. But it certainly feels like the STI is less intrusive or in control, which is a big plus in my book.

Ford Focus RS

If this car had any more hype and people talking about it, it'd have its own reality show. Drift mode, torque vectoring, optional Michelin Pilot Sport Cup 2 tires from the factory (standard in Canada), 350 hp, the lot. Plenty of buzzwords. Ford set it up for disappointment. It has to deliver on so many things, and deliver well, to meet expectations, let alone impress. It's bound to disappoint.. Or is it?

The RS takes the neutral balance of the Evo and turns it up a couple notches. It then takes the STI's rear power bias and turns that up a couple of notches as well. What's the problem in a front-end heavy FWD car, understeer? Ford says, with a smirk, let's fix that for you. When I said you could either allow front power and weight transfer bias or rear power and weight transfer bias, I actually left out secret option number 3. Give the front end a lot of grip, let the back lighten up, and still send plenty of power back there. Better still, allow the rear axle to use up to 100% of that power to one wheel to help the car steer. The RS has a very noble mission - make you forget it's a FWD-based hot hatch. And boy, does it ever try. You drive this car properly, and you may actually forget that you are driving a FWD-based hot hatch. The rotation under power is not only helpful, but very refreshing. And massively entertaining. Plus, you can't help but get all giddy when driving a humble Focus that power oversteers coming out of corners. The Evo makes use of an AWD system to beautifully manage power and maximize corner speed. The STI makes use of an AWD system to give you traction a 911 would envy. What Ford does, though, is use an AWD system to make the car turn. Speed seems like a byproduct since, you know, you do have to turn to get around a track. And the RS is very good at that.

The RS uses a torque vectoring rear differential like the Evo, although of completely different design that does not rely on a traditional differential at all. Instead, it uses two sets of hydraulically actuated wet clutch packs that individually control the amount of torque each rear wheel gets at all times. In the centre, the RS, once again, does away with a traditional differential and relies on those individual clutch packs to proportion power to the rear. If both clutches are disengaged, you get no transfer to the rear. If both clutches are equally locked - fully or partially - you get torque transfer in proportion to the amount of lock up, split equally between the two wheels. Or you could vary lockup between the two sides to individually send torque to either wheel. Using clutch packs to proportion power to the rear is very common in mainstream AWD vehicles, although is typically done via a clutch pack before the rear axle and a conventional rear differential. This is much less desirable than a differential in FWD-based performance cars, as discussed earlier. So how does the RS overcome this? It over speeds the rear wheels.

Similar to how the STI gears the centre diff to bias power to the back, the RS is geared at the power takeoff unit to drive the rear wheels faster, although much more aggressively at a ratio of 1.7 the speed of the fronts, thereby having a higher load and transferring more torque, resulting in rear bias. And, like the Evo, this also allows good front power bias if conditions allow by progressively reducing lockup on the clutch packs. At the front, the RS uses an open differential with brake-based lock, a disadvantage to the Evo and the STI. But, because of the aggressive front weight transfer, how much grip the the front axle has as a result, and how much power it sends to the back, I didn't run into the limitation of the front axle (i.e. excessive inside wheel slip). I have no doubt that you'd see an improvement with a true LSD at the front, but you'd probably struggle to get even near the same improvement that you'd see in a FWD car like the Focus ST.

Some people ran into overheating issues where the rear differential/drive unit (RDU) got disabled and the car basically became FWD. A friend of mine has an RS and ran into that problem the first day he was on the track. I never had a hiccup. That could be because of how little time I spent in the RS - a 15 minute stint, a 10 minute stint and a 5 minute stint. It could also be because of my driving style that we suspected strains the AWD system less (more on that in a moment). Or the fact that the car I drove was well broken in with over 12k kms on the clock, about 7.5k miles, because that same friend who ran into the issue the first time he was on track had no issues in subsequent times with more mileage. That lead us to thinking it might be an over protective feature during early break-in since the first time he was out, the car had just 1,800 kms on in, or just over 1,100 miles. I hope that we can say with more certainty with more track time next season whether or not that's an actual problem, but for now, it seems like a non issue.

So what does all of this mean on track? You'll have to recalibrate your turn in points and steering angles compared to a car with similar turn in response and handling balance because you simply don't need as much steering from the front wheels. You can feel the car working like the Evo but it doesn't seem "smart" in the sense of correcting your line. Where the Evo feels like it knows the right line and reads your mind, the RS doesn't. Yaw in the RS seems to be directly linked to your right foot - give more power and you get more rotation. If you are using a lot of steering and too much throttle, the car thinks you really want to turn and will put plenty of power outside to get the car turned hard, even if that means running out of the room on the inside and basically hitting an early apex. The Evo, I believe, knows exactly how hard the car should turn based on steering angle. If you're turning a certain amount and the yaw sensor says the car isn't turning enough, you have understeer, and it will shuffle power outside to turn the car. If yaw is too much, it will shuffle power inside to put the car back in line. The RS seems to have more faith in you, for better or for worse. The car gives you what you demand with your hands and right foot. Kind of like the way the STI gives you traction on a silver platter, only the RS gives you a hyper ability to turn

There are many excellent RWD cars that let you steer with your right foot. The difference is how much steering you can do and, let's not forget, that this is an AWD car. It still has a huge traction advantage. You can go flat out very early. In fact, in a lot of turns, I was flat out before apex because power no longer makes you go wide, it actually helps you turn. And you never have to worry about spinning out because it is massively easy to manage at the limit. It's fastest with some rear slip. The thing that you'll have to learn is trusting the car. Because it can hold and recover from huge yaw angles, all while still putting power down and gaining speed. You have to learn when to put your foot down and be able to put your foot down. Hard. That's the way you can maximize the AWD system. You need a lot of sisu or experience to do that, when your past experiences and your brain are telling you that you cannot do that here, otherwise you'll either spin out or plow straight.

It isn't without fault. The engine is still sitting far ahead and you can find limit understeer. But, compared to the other cars, it's like finding a lost sock in a dryer. The trick, in my opinion, is to not drive this car fast the way you do other cars. You don't maximize corner entry. In fact, you sacrifice corner entry just a little. The trouble is that, if you maximize corner entry, that means that you are coming in basically at the edge of grip. Right up to the limit. The car is as close to neutral as you'll probably get in an AWD hot hatch, but there's still some safe understeer left on the table. You'll find that and get frustrated. You can go on the power to correct, but because you're on the edge, you'll mostly correct by spinning, not by torque vectoring, because the tires are near the limit already in lateral grip and can't put much more power down without slipping. There's nothing wrong with that. That's what you do in a good RWD car to help the car rotate. But it's missing the point of this car and wasting all that went into the AWD system along with a good chunk of the torque vectoring benefits. You need to conserve some grip at the rear tires to use for putting power down because that power is going to help you turn.

The best part of all, I believe, is that you'll be just as fast if you suit your driving to the car. The same friend who bought an RS this summer complained about understeer in a few turns. He had better corner entry than me, with higher entry speed and later braking in nearly every corner on the track. His lap time? 0.28 s slower than mine. I could take much better advantage of torque vectoring because the rear tires weren't as burdened as they would have been with optimal entry. That means I can get the car rotated as I am on the power and gaining speed, giving me a better corner exit. I think throwing the car into a corner is good for fast turns. Conserve speed and momentum. In slow corners, though, you have to adjust your driving.

But no matter how you drive this car, the real treat is how close it is to absolute neutral handling. How easy it is to have fun with the power and how manageable and controllable it is when it lets go. It really does a very good impression of a true sports car, one that just happens to be a practical hatchback. And while it may fall short occasionally and let you know it isn't without compromise, it more than makes up for it by how much fun you'll have driving it.

VW Golf R

You might have noticed that the Golf R is curiously missing from the title. Or that the Evo X is in it, even though I previously posted and said that it is out (link: Mods and Update: Focus RS vs Golf R vs WRX STI vs Evo X). Initially, I was going to test all four cars (link to original post: Intro: Focus RS vs Golf R vs WRX STI vs Evo X). Some back and forth, scheduling conflicts, etc. meant that I could only get hot laps in the Focus RS, find out what the WRX STI and Evo X are like on track but no opportunity for a time, and no impressions at all in a Golf R. Such is the trouble without a big audience and manufacturer-provided cars for review.

I'm just as disappointed as you are. Due to the time of year, the season is coming to a close and I won't get another opportunity until the next season to test again so I thought I'd post what I have and hope for a better outcome next season

Lap Times 

Although I had no opportunity to do hot laps in the Evo and the STI, I got lap times and logs from the owners. First, here's a map of our local track, Atlantic Motorsport Park, to clarify a few turns. Namely, Turns 6, 8, and 10. All these turns don't need the use of brakes in entry or even backing off enough to scrub off speed. In fact, turn 6 is taken flat out from start to finish. As a result, they can't be marked well on the track logs so I hope the map below can clarify.

With that out of the way, here are the lap times, followed by track logs of the Evo vs the STI, Evo vs RS, and RS vs STI.

Best Lap
Evo X MR
- modifications:
  • Intercooler pipes
  • Cat-back exhaust
  • Cone air filter
  • Custom tune
  • --------------
  • Lowering springs
  • Rear anti-roll bar
  • --------------
  • 18x10 wheels
  • Firestone Firehawk Indy 500 tires sized 275/35/18
  • --------------
  • Carbotech track pads
  • Braided stainless steel brake lines
- modifications
  • -2.5 deg camber all around
  • Bridgestone Potenza RE-71R tires sized 265/40/18
Focus RS
- stock
  • Optional Michelin Sport Cup 2 tires (235/35/19)

STI vs Evo X: If they were stock and driven optimally by the same driver, you should expect higher corner speeds in the Evo but better exits in the STI. It's tough to say which car has the grip advantage as they stand, with modifications. The STI has stickier but slightly narrower rubber and very good camber for a street car but much narrower wheels. The Evo X has an AWD system more suited for maximizing corner speed, suspension upgrades, wider wheels and tires, but no camber and street tires. Their corner speeds are extremely close, suggesting it's wash if we assume comparable driver skills (remember, they're different drivers). The extra power in the Evo shows in steeper acceleration curves out of T2, T3, back straight, and T11 leading to the front straight and appears to have been the winning factor. Time wise, it looks like the Evo made all its lead on power, as they appear to be in a dead heat up to T5 leading to the back straight. The Evo should also have a slight advantage in shifting, being the MR with a dual clutch automated manual (it is quick).

Evo X & STI vs RS: Despite the stock suspension, much narrower wheels and tires, the RS appears to have a consistent advantage in corner speeds vs both cars through high speed turns - basically the second half of the track past turn 6 - presumably due to less understeer. The STI should have a huge grip advantage, with similarly sticky tires that are actually much wider and camber. The Evo is tougher to judge, since the RS has much better compound but both wheels and tires are a far narrower. I found that the Focus likes slightly slower-in-faster out approach in slow turns to utilize the torque vectoring, as I mentioned earlier, and this appears in the logs, where the Evo and STI have better corner entries into T2 and T3 but the RS seems to have better exits. 

The STI's modifications seem to provide it enough of a grip advantage to overcome the RS' handling advantage but without any more power, they're nearly tied. The Evo's suspension modifications seem to do the same, but the power advantage allows it to actually pull ahead slightly in just about every corner of the first half of the track. With that said, the RS was seriously held back by the 91 gas, IMO, since we don't have 93 locally.

It's clear, in my opinion, between T3 and T4 - just before braking point - the RS just loses steam and stops accelerating, then briefly gets back on. I could even feel that on the track. Between T4 and T5, the same thing happens. Then again between T5 and T6 and on the back straight. Finally, after exiting T11, the RS pulls power again before finishing on the front straight. How much is that worth? I went through the logs and adjusted the data as if the RS didn't lose power and here's the result:

Yep, just over a second. The lap time would have been 1:18.61, 1.01 s faster than otherwise. This is with absolutely no changes to the lap - same turn in, braking points, amount of braking, etc. - as you can see by the two laps being identical except for the sections where the RS seemed to have pulled power. How much is it making on 91? Don't know, but the Mustang EcoBoost is supposed to lose 35 hp when going from 93 to 87, 11.3% of peak. If we assume the same in the RS, it would be making 310 hp on 87 and somewhere between 310 and 350 on 91, which should actually be optimistic because the RS makes more boost so it should be more sensitive to octane than the Mustang. To calculate acceleration assuming no loss of power due to 91 gas, I used Car and Driver's test data of the RS, trended them, and used that data to calculate adjusted speeds had the car not pulled power. With the corrections, the lap times would look more like this:

Best Lap
Evo X MR      1:18.06
WRX STI1:19.72
Focus RS 1:18.61

Now, you can't claim the 1:18.61 time as the Focus time. Because it isn't. But I wanted to give it a more fair representation by correcting the time, in case you're curious how much better it could be on better gas. Another disadvantage for the Focus is seat time. Where best laps for the Evo and the STI were set by the owners, with hours of seat time in the cars, I had just under half an hour in the RS overall. The owners of both cars have had these cars for as long as I've known them, about two seasons. But even within one day, in a car you're already very familiar with, you can expect to get better as the day goes along (unless heat becomes a factor). Case in point; the 1:18 time in the Evo was preceded by slower lap times, where the first session was all 1:20's and slower, the second was 1:19's, and the third had the 1:18 lap. If we assume a similar drop in the RS with more seat time (~ 2 seconds), along with 93 gas or octane boost (another ~ 1 second), the RS would have the best lap by a substantial margin, with a best lap in the 1:16 range.

3rd Place: Subaru WRX STI: It was really tough between this and the Evo. Assuming all are stock, I really think the STI would be the easiest to drive fast for an average track guy who goes to a couple track days and HPDS's a year. It has the most traction so it puts power down really well and, because it would make most of the time in corner exit, you can still get a great lap even if you don't nail the braking and corner entry. The RS and Evo need you to work more on those areas. It is also the most natural feeling in terms of handling and it's the one I would put my money on when the white stuff starts falling because of the better stability and traction. But on track, compared to the other two, it just feels like it's missing an edge.

2nd Place: Mitsubishi Evo X MR: I still cannot get over how this car drives on track despite its age. It is hugely impressive. It had the best raw time, albeit helped a lot by the modifications. It feels so precise, yet so stable, and manages power really well. For someone who doesn't care about the added practicality of the hatch, the refinement, or the subjective fun to drive factor of the RS, the Evo would probably be a more appealing car.

1st Place: Ford Focus RS: If one of these cars would serve as a daily driver, you'd never regret picking this car just because of how much more refined it is, plus the practicality of a hatchback. And then you'd take it to a track and find out what a blast it is. It is more neutral than any other production hot hatch dares to be. It will powerslide and dance, at full throttle, with just the right amount of yaw in corner exit, in a way a FWD-based car has no right to. And, if you consider the modifications of the other cars, the lack of 93 gas and octane boost during the test, and the very limited seat time, you'll find the lap times to be very impressive. The potential, assuming better gas, is even more so and, with more seat time, it could be even better. Did I mention it's easily the most fun?

I've put a lot of time researching the AWD systems of these cars, especially the Evo X and the STI, since it seems no two people quite agree on exactly how they work. I cannot say with 100% certainty that I interpreted the countless articles, diagrams, and drivetrain sections properly, so take that for what it's worth. There are a lot of conflicting opinions out there and you may have done your own research and come up with your own understanding that's different. If that's the case, feel free to comment or message me and include links/source and I'll be happy to update if there's an error. 

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Photography by Kevin Doubleday and Albert Hofman