C7 Corvette Mid-Engined?

[NSXType-R]

Dunno where I heard it but I did hear of this rumor. It'd be interesting to see.

[Zytek_Fan]

Originally Posted by Turbo.Jenkens

The Pratt & Miller team has the resources to compete at the next level for sure, but I haven't herd anything about the ACO requiring a homologation to run in LMP evolution or whatever it will be called. I got this image from mulsannescorner.com.

Fortunately that's someone's photoshop mockup. Looks like Corvette + Pagani Zonda + Nissan R390 GT1

[NSXType-R]

Originally Posted by Zytek_Fan

Fortunately that's someone's photoshop mockup. Looks like Corvette + Pagani Zonda + Nissan R390 GT1

That actually looks pretty good. Imagine if they made a road going version.

[Pitwork]

Corvettes won't be winning Le Mans overall any time soon. Diesels are the future and imagine the outcry if GM put a diesel in a Corvette

Maybe Kenworth has a chance

[Ferrer]

Originally Posted by Pitwork

Corvettes won't be winning Le Mans overall any time soon. Diesels are the future and imagine the outcry if GM put a diesel in a Corvette

Maybe Kenworth has a chance

I doubt an hipotetical GM LMP1 would be based on the Corvette at all (either stylistically or mechanically). If they make 10 (I think that was the number, someone correct me if I'm wrong) of those mid engined sportscars they could still homologate it in GT1.

[Bob]

Originally Posted by Pitwork

Corvettes won't be winning Le Mans overall any time soon. Diesels are the future and imagine the outcry if GM put a diesel in a Corvette

Maybe Kenworth has a chance

That's quite debatable. Whether Diesels are truly better or not is irrelevant. It's the regulations that will make or break the diesels in Le Mans. I believe the goal of the governing body is to keep the field balanced. So it's possible more restrictions will be put on future Le Mans Diesel entries. Even possible that the corrections will be too great and leave the diesel vehicles at a disadvantage.

[MRR]

Originally Posted by clutch-monkey

well the fanboys keep telling me the Z06 already has 50/50 wieght distribution, and that it's already mid engiend because the engine is behind the front axle, so what's the point...

No its fairly close but that figure is more like 51-52/49-48. It still drives well from what I have read but I keep reading that it doesn't have enough weight over the drive wheels making it tricky to drive at the limit. Off course making it mid engined would tip the balance in the other direction which isn't necessarily a bad thing.

[MRR]

Originally Posted by Pitwork

Corvettes won't be winning Le Mans overall any time soon. Diesels are the future and imagine the outcry if GM put a diesel in a Corvette

Maybe Kenworth has a chance

Won't happen and who knows, maybe regulations will force all competitors to stay petrol based or put them at such a disadvantage (as Bob said) that they won't compete

[fpv_gtho]

Originally Posted by MRR

No its fairly close but that figure is more like 51-52/49-48. It still drives well from what I have read but I keep reading that it doesn't have enough weight over the drive wheels making it tricky to drive at the limit. Off course making it mid engined would tip the balance in the other direction which isn't necessarily a bad thing.

Depending on who you talk to changes what sort of balance is optimal. Some people rather a static 50-50 balance, where under braking it puts more weight over the front and under acceleration more weight over the rear. Some rather a rear static bias where under braking it goes to 50-50, and under acceleration theres even more weight over the rear.

[Turbo.Jenkens]

Originally Posted by Ferrer

I doubt an hipotetical GM LMP1 would be based on the Corvette at all (either stylistically or mechanically).

Mechanically-no-except for an aluminum smallbock. But, if GM hypothetically made a LMP1 I think it would bare the Corvette name and borough a few styling cues. GM needs to sell some Vets on monday . Besides it wouldn't be the first GM prototype to be called a Corvette.

I am only speculating though

[Ferrer]

Originally Posted by Turbo.Jenkens

Mechanically-no-except for an aluminum smallbock. But, if GM hypothetically made a LMP1 I think it would bare the Corvette name and borough a few styling cues. GM needs to sell some Vets on monday . Besides it wouldn't be the first GM prototype to be called a Corvette.

I am only speculating though

I knew of that, and if I'm not mistaken there was also a Ford Probe, but those were only race in the IMSA series in the US IIRC, a car which races at Le Mans needs to appeal a wider audience. I'm not saying it isn't possible I just find it unlikely.

Not that GM is going to build an LMP1 prototype soon anyway.

[Turbo.Jenkens]

Originally Posted by Ferrer

I'm not saying it isn't possible I just find it unlikely.

Agreed, sometimes I get a little too caught up in speculation and rumors. Having an imagination is a good thing, right?

[culver]

Originally Posted by fpv_gtho

Depending on who you talk to changes what sort of balance is optimal. Some people rather a static 50-50 balance, where under braking it puts more weight over the front and under acceleration more weight over the rear. Some rather a rear static bias where under braking it goes to 50-50, and under acceleration theres even more weight over the rear.

From a vehicle dynamics point of view, a 50-50 split is only ideal if you have identical front and rear tires (size and type) and you are turning without accelerating or braking. The rest of the time 50-50 is not necessarily ideal and in many cases like a FWD car it is far from ideal.

That said, like many numbers used in marketing it's easy for those who don't understand the subject to grasp that what sounds like a simple and surefire concept; even is best. Kind of like the CPU with the fastest clock speed must be faster. That's why my 4 year old Celeron (2.0ghz) is faster than my new Core Duo (1.8ghz). It's wrong but it's easy to market it to those who don't understand computers.

[Matra et Alpine]

Originally Posted by culver

From a vehicle dynamics point of view, a 50-50 split is only ideal if you have identical front and rear tires (size and type)

no.
same size is a MUST when it's AWD.
It depends on suspension dynamics whether the tyre size makes a difference for RWD. For FWD it's pretty irrelevant

and you are turning without accelerating or braking

During those times is when a 50:50 split is ideal.
By applicaiton of braking ( esp trail-braking ) and throttle you can adjust the balance and hence grip and thus improve the handling. This is much harder to achieve if the balance is more in favour of front or rear.

The rest of the time 50-50 is not necessarily ideal and in many cases like a FWD car it is far from ideal.

No layout is "ideal" so aiming for the best compromise is "ideal".
WHich gets you back to 50:50

easy for those who don't understand the subject

[culver]

Originally Posted by Matra et Alpine

no.
same size is a MUST when it's AWD.
It depends on suspension dynamics whether the tyre size makes a difference for RWD. For FWD it's pretty irrelevant

During those times is when a 50:50 split is ideal.
By applicaiton of braking ( esp trail-braking ) and throttle you can adjust the balance and hence grip and thus improve the handling. This is much harder to achieve if the balance is more in favour of front or rear.




No layout is "ideal" so aiming for the best compromise is "ideal".
WHich gets you back to 50:50

I was going to type out a long post about this but I think it's correct to say, yes, you are right because I didn't put in all the needed disclaimers.

50-50 is ideal assuming you have identical tires at all four corners and you are intent on maximizing lateral grip while neither accelerating or braking. AWD cars certainly can have uneven sized tires front and rear however, unless you want to play some tricks with the gearing you want equal diameter front and rear (I assume that is what you meant). Equal width isn't a requirement at all.

Here is a post I wrote on this topic:

Originally Posted by me

I put this post together to look into the whole matter of 50:50 weight distribution. I’ve seen this come up many times and I suspect that many people don’t know why it is good or when it may not be good. I have a friend with a BMW who swore the car handled well because of the 50:50 distribution. He seemed to have overlooked so many other reasons and stuck with the one delivered by BMW marketing. Of course please keep in mind that I am going into general terms and the handling devil is often in the details.

As for 50:50, it’s not really the best but there are reasons would want it. For straight line pure performance cars you would want a rearward weight bias. It helps in both acceleration and braking. It’s in cornering that we have to look at the details.

Start with changing direction. When changing direction the front tires act like a lever turning the car about the center of gravity. When dealing with a lever a longer lever always makes it easier to move something. So how do we get a longer lever, we either make the wheelbase longer or we move the CG back. A rearward weight distribution will move the CG back and effectively act as that longer lever. This is why mid/rear engine cars typically have very quick steering response.

Now that we have started to turn we need the tires to hold that turn. The next thing we need to know is that tires grip more with more weight (go figure) BUT the increase in grip is proportionally less than the increase in weigh. So if increase the load on a tire from 500lb to 1000lb you will not get twice as much grip. Also, grip is proportional to area. This is a surprise to no one. We all know wirer tires grip more than skinny ones.

So you want to pull some Gs while turning. Well if you are going into a turn without accelerating or decelerating the lateral load on the tires will be split between the front and rear wheels based roughly on weight distribution. So if you have 50:50 weight distribution half the cornering load will be on the front axle. That works out nicely for most cars as they normally have equal sized tires front and rear. However, if we have more weight in front we would want larger tires in front to balance out the grip (GM does this on the V8 Grand Prix). If we have more weight in back we want larger tires in the back. The larger tires, in combination with the heavier load effectively make it so that the front and rear tires have the same load/ square inch of contact pact. That will make the front and rear tires slide at the same time (neutral handling) when cornering. It may seam odd, but GM put larger tires in the front of the Grand Prix because that makes the car more neutral rather than understeering.

So what about braking while turning or accelerating while turning. Each of those will transfer weight fore or aft while cornering. Shifts in tire size or weight distribution can make the car under or oversteer more or less based on the same principle I mentioned above. Increasing the front tires in size or adding load relative to the rear will make the car more likely to over steer at the limit (not talking about initial understeer). Going the other way makes the car more likely to understeer.

So do we still want 50:50 weight distribution? Well that depends. If the car is FWD, 50:50 doesn’t help acceleration. That rearward weight shift moves too much weight off the front wheels and we get wheel spin. For that reason I might want my FWD car to be nose heavy. Of course I can deal with some of that nose heavy understeer with some larger sized tires in the front and suspension tuning. Then again, most people would prefer equal sized tires just for convenience. For the other reasons (braking, cornering) we would want a rearward weight bias even in a FWD car.

In a RWD car we don’t need weight over the front axles for acceleration so we want something like 50:50 or even rearward biased. If we are going to have equal sized front and rear tires we want around 50:50. That will help keep the car approximately neutral in most handling situations.

If we aren’t stuck with equal tires front and rear then a rearward weight balance can work quite nicely.

While many car companies love to brag about the 50:50 weight distribution, it’s really only good under certain circumstances. Depending on other design decisions it may be undesirable (FWD, RWD with a rearward weight bias and wider tires in back).

PS: The above is certainly not the end all be all on this subject. There are lots of detailed reasons why designers may want to do something different than what I have listed above. All that typing is largely meant to illustrate why something that many people think is a pillar of handling isn’t a pillar in all conditions.