The Ram's Eye - A Driver's Blog: Chevrolet 1LE & Grand Sport - How do they do it? Part 1



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Friday, 30 September 2016

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




Recently, Chevrolets seem to have been punching far above their weights and a lot of people (myself included) are impressed. Sure, Corvettes have always been formidable track cars, but they're low, light, purpose-built, and didn't blow expectations - just provided excellent value. Now, all +Chevrolet  track cars, especially Camaros, seem to be overreaching and, combined with excellent chassis tuning, have been doing wonders for GM's chassis engineers' image. I decided to take the time and do some research to try and figure out what GM is doing that others aren't (or can't). Before I start, I'd like to point out that this is based only on my own understanding and research, not an interview or publication by GM, so take that for what it's worth.

Since I haven't posted about the latest of Chevy's track-focused models/trim packages, I thought I'd first take this opportunity and talk about what you get. Whether you're looking at a Camaro V6, Camaro SS, or Corvette, choosing the 1LE package or Grand Sport will not bring extra power. Instead, those packages help you make the most of what's already available. You get no extra power but better track performance and longevity. Here's what you get, as best as I could find:




Camaro (V6) 1LE
- Functional front splitter (unique design to the V6)
- Functional rear spoiler (shared by V6 and SS)
- 245/40/20 front and 275/35/20 rear tires, mounted on forged wheels
- Oil cooler, bigger engine coolant capacity, and rear differential cooler
- Upgraded fuel pump and tank from the SS
- Upgraded dampers, rear sub-frame mounts, ball-jointed rear toe links, and anti roll bar, all taken from the standard SS
- Four piston front brembo calipers. Rears are unchanged, presumably one piston sliding calipers.
- Limited slip differential (standard on all V6 Camaros with the 6-speed manual)




Camaro SS 1LE
- Functional front splitter (unique design to the SS)
- Functional rear spoiler (shared by V6 and SS)
- 285/30/20 front and 305/20/20 rear tires, mounted on forged wheels
- SS already has oil cooler, bigger engine coolant capacity, rear diff cooler, plus transmission cooler so 1LE does not provide additional cooling capacity.
- Upgraded (magnetic) shocks and springs.
- Upgraded anti roll bars, rear toe links, rear trailing arms, and rear sub-frame mounts all taken from the ZL1
- Six piston front brembo calipers clamping on two piece, aluminum hat front rotors and four piston rear brembo calipers with one piece rotors
- Electronic limited slip differential (standard SS all get mechanical limited slip differentials).

Corvette Grand Sport
- The wide body of the Z06 (in other words, wide fenders to fit fat sticky tires) along with all cooling and aero ducts and passages
- 285/30/19 front and 335/25/20 rear tires, mounted on forged wheels
- Carbon ceramic brake rotors
- Upgraded aero package - the same spec as the stage 2 aero package on the Corvette Z06 (i.e. a Z06 with the Z07 package but not the Performance aero kit or stage 3). Stage 3 brings larger end plates to the front splitter and an adjustable, transparent wicker bill/gurney flap on the rear spoiler. Chevy determined that Stage 3 brings too much drag that isn't welcome without the additional thrust that the Z06 brings to the party.
- Dry sump oiling system (you can get with Z51 package)
- Dual mode exhaust with 460 hp (you can get with the Z51 package)
- Electronic limited slip differential (you can get with the Z51 package)
- Bigger brakes (you can get with the Z51 package)
- Upgraded springs, dampers, and anti-roll bars (you can get with the Z51 package, but the Grand Sport package then turns up the suspension stiffness a notch to sit nicely between the Z51 and Z06)
- Differential and transmission cooling (you can get with the Z51 package)
- Increased engine cooling capacity (you can get with the Z51 package)

So, in summary, all three cars provide downforce, or at least reduce lift for the Camaros (I haven't found data stating downforce numbers), additional cooling where necessary, more braking power, bigger tires, and stiffer suspension tuning. Additionally, except for the V6 Camaro, the cars can put more power down thanks to the electronic limited slip differentials. But what is special about Chevys? Every manufacturer addresses the same areas, if to different extents, but they can't seem to catch up.

The Corvette Grand Sport, for example, is only one tenth behind the GT3 RS, basically a dead heat at 2:47.1 for the Vette vs 2:47 flat for the Porsche, despite the Corvette having LESS power and weighing MORE. Consider this too: both use the same Michelin Pilot Sport Cup 2 tires, albeit tailored specifically for each car. The SS 1LE, at 2:54.8, is nearly tied with a Cayman GT4 (0.8 s behind), despite the GT4 being far lighter, enough to give it a superior power to weight ratio, and using even better tires - the same Pilot Sport Cup 2 vs the Camaro using Goodyear's equivalent to Michelin's Pilot Super Sport (that testing and reviews rate even lower than the Super Sport). How does Chevy do it?

Well, we can tell right off the bat that power isn't the answer. These Chevys are typically outright under-powered on raw numbers or at least power to weight ratio compared to cars they can beat or keep up with. Braking? Highly unlikely. Competitors use gigantic rotors and calipers that can (safely) be assumed to be sized properly with appropriate brake boosters and system pressure. Handling? Read a review of a Cayman GT4 or a 991 GT3 RS and tell me they're lacking. They're stable, yet neutral, handle road undulations, put power down well, etc. Could one be a little bit better than the other? Sure, but we aren't comparing a Corvette to a Beetle here. Plus, declaring them better means stating that Chevy can better design cars to handle than Porsche..

Aero? I hate making assumptions based on such superficial observations.. I really do. But I'll challenge you to this: take a gooood long look at the spoiler on the back of a Cayman GT4. Now look at the.. let's be kind and say relatively handicapped deck-lid spoiler on the trunk of a Camaro 1LE. Then tell yourself that the Camaro has more downforce than the GT4. Can you keep a straight face? I'm not saying that spoilers are the be all end all as far as downforce. There are many ways of managing air flow to change speed and create areas of relative low and high pressures to generate downforce. But it gets harder to do in a compromised car, such as the Camaro, where there are more space constraints than, say, a 2 seater mid-engine car like the Cayman. Plus, a spoiler, an airfoil one in particular, is a very effective way of generating aerodynamic forces. Planes use them (wings). Wind turbines use them (blades). You get the point.






On a side note, you should never underestimate the capability of deck lid or lip spoiler to generate downforce. While pedestal spoilers are far more common in racing, deck lid spoilers can still generate serious downforce. The one on the back of the Camaro 1LEs is simply not very large, the lip doesn't stand very tall, and angle of attack doesn't seem aggressive. Compare it to the last generation Z/28 for example. Here it is, below, with the optional wicker bill or Gurney flap, without which Randy Pobst in Motor Trend testing found the Camaro Z/28 loose and unstable, even though the spoiler alone has a much larger surface area and more aggressive angle of attack than the one on the current Camaro 1LE. So, without real test data, I am making a somewhat-educated guess that they don't have superior downforce.




A comparison of the Corvette Grand Sport vs 911 GT3 RS tells a similar story. Although, in this case, we actually do have numbers. The Corvette Z06 with the Z07 package and Performance Aero Kit (i.e. Stage 3 aero) produces 350 lbs of downforce at 150 mph, according to an article posted by Jalopnik about testing the Z06 at Spring Mountain Motorsports Park, being invited by Chevrolet (link: 2015 Corvette Z06: A 650 HP All-American Middle Finger To Euro Supercars). Meanwhile, the GT3 RS produces 772 lbs at 186 mph, 386 lbs at 93 mph, and vary linearly in between, according to Porsche’s GT division boss, and ‘Mr. GT3’, Andreas Preuninger, who was interviewed by Car Magazine (link: A guided tour of the 2015 Porsche 911 GT3 RS – by the boss). That works out to 622 lbs at 150 mph for the GT3 RS - nearly double what the Z06 makes with its most aggressive aero package, which the Grand Sport does without and makes do with stage 2, as mentioned above.






What about traction? Maybe these pesky Chevys have great traction, allowing them to put power down better and, therefore, outperform their competitors despite being relatively down on power. They could be making better use of what they have, saddling and employing every single horse coming out of their more humble power plants whereas competitors don't. Perhaps.. but there is one big problem. The humble Chevy engines also find themselves placed in cars with more humble layouts - front engine RWD cars. Whereas the GT3 RS has a whopping 62% of its weight over the rear wheels, the Corvette has a relatively measly 51% (impressive for a front engine car). Likewise, the GT4 has a far superior 56% compared to the Camaro's 46%. Without better weight distribution, more downforce, or better tires, and possibly even handling, they couldn't have more traction.. Or Could they? Here's where it gets interesting. I think that it is possible they have better traction. But it's not just traction, I think they have more grip overall, allowing every component to perform better. How do they do that, despite (probably) being relatively handicapped or equivalent at best in all aspects mentioned above? Stay tuned to find out in Part 2 (link: Chevrolet 1LE & Grand Sport - How do they do it? Part 2)!


1 comment :

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