Chewbacca

Don't follow much racing I take it? The C6R has not held a 7.0L engine between its shock towers in competition since Lemans of last year (June).

The new 5.5L displacement is required by the ALMS rules. The Corvette team dropped down from GT1 to GT2 right after the 2009 Lemans race.

With nobody left running in GT1, the class was scrapped and GT2 has become simply GT.

Proof...

http://www.corvetteracing.com

BTW, as pointed out in the link, the car is now supposedly ZR1 "based".

jcamere94z28

that's mainly because almost no one could compete with the: corvette team on GT1... :lol

Chewbacca

Correct, no one except Aston Martin who beat Team Corvette at the 2007 Lemans.

Aston has since gone into the LMP1 class.

Your point that the Corvettes were quite dominant in GT1 still stands though.

2010_5thgen

i know the 7.0 isnt in the c6.r and yes i do follow racing.and yes iknow they dropped down a class. i also know that the engines in the race cars are normally used as prototypes for future cars. and as far as the v6tt in the vette, like i said i didnt make this up, it was quoted in a CORVETTE magazine. maybe the corvette enthusiest havent gotten the memo from corvette that they will not use the v6tt.

Chewbacca

So tell me, when will I be able to put a deposit on my 2012 carbureted 358 ci RWD Impala?


The C6R carried a 7.0L because it had to. Ever hear of homologation?

You're telling me that GM / Pratt & Miller spent untold amounts of money to develop a 7.0L race engine only to see it saddled with some ridiculously undersized restrictors? And then much more money was spent to detune it for the street? Right....

Here's what happened:

ALMS GT1 was supposed to be production based. Therefore (with a bunch of obvious exceptions) you must run the car as it is available to the public. This means a 7.0L engine. Such a race prepped engine would be a monster in the class, so series officials mandated air inlet restrictors (among other hindrances).

In short, the street car did not have a 7.0L engine because the C6R had one. The C6R had a 7.0L engine because the street car had one.

Your assumption that the tail wagged the dog is off base here.


Well then it is obviously fact.

Carry on.

I have to ask though, if you believe that race engines are simply prototypes for future cars, why does the revised C6R not run such an engine combo?

99SilverSS

Here is an article in AutoWeek where they asked Karl-Friedrich Stracke, GM vice president of global vehicle engineering about a Mid engine C7 and if a TT V6 would be a powerplant option.
http://www.autoweek.com/article/2010...#ixzz0wV5RLxim

Again its just an article and certainly not the final word but it does go with the general consensus of what direction GM is going with the C7. And that it's from the VP of global vehicle engineering adds some weight to the comments. It's also worth mentioning that Karl-Friedrich Stracke has been rather candid since taking over the job. Seems that he is taking over the roll Maximum Bob since Lutz has moved out of the spotlight.

HAZ-Matt

So why did the C5-R have a 6.0L and then 7.0L engine when none such displacement was available in in a C5? I am not as familiar with the specific rules of LeMans or ALMS regarding engine displacement, but I think they have quite a bit of leeway with the displacement itself as long as the motor is production based. I had read that the 7.0L displacement while necessitating very small restrictors actually was choosen due to fuel economy benefits from running relatively less revs. In fact there is a quote from one of their engineers who stated as much on Corvette Racing's website.

I'm still highly skeptical that we will see a C7 with a V6.

Chewbacca

Unfortunately I don't have a good answer for you. Probably related to that leeway you mentioned.

Rules change year to year in some series. It's been quite a while since they made the changeover and I have no way of looking back to see how things were worded before vs after. I can say, however, that the C5R 7.0L had a number of very exotic components bolted to it that make no sense if they were simply shaking down a future production engine. Take a look at the induction...



And a pic of the C6R induction....


What possible relevance would that have to the street car?

IIRC GT1 was also allowed to be a bit farther removed from the street car than GT2.

Ultimately, without the backstory on the decision process, sometimes things just don't make sense from the outside.

For example, Team Corvette opted to homologate the ZR1 for competition yet a supercharger is not used and the 6.2L displacement is not allowed. The ZR1 based C6R race car actually has a smaller engine and significantly less horsepower than the street car. In fact, that 5.5L engine was even developed from the 7.0L engine, not the 6.2.

http://www.corvetteracing.com/history/2010releases

I can only hypothesize that they chose the ZR1 for its aero tweaks. Like I said, a lot of this might not make any sense to us because we weren't sitting in on those meetings.

The most I can see happening with regard to the tail wagging the dog on the C6 Z06 street car is that perhaps the Corvette engineers thought the 7.0L Katech race engine was really cool and wanted to do something like that for the street car. I seem to recall that some things had to change on the race car when the 7.0L street car appeared but I can't find that info anymore.

Might have had something to do with the blocks. Apparently the C5R 7.0L block was a good bit different than the street car's 7.0 block.

http://www.vetteweb.com_chevrolet_corvette_427_cylinder_b locks



Yes, here is the quote....
As you can see, Team Corvette did not choose the restrictors. the restrictors were mandated by the ALMS rules committee.

http://www.corvetteracing.com/cars/c6r/engine

HAZ-Matt

GT1 definitely had a lot less in common with street cars than GT2 or the new GT class, certainly. They did in fact switch to "ZR1-based" because of that allowed them to use some of the standard ZR1 aero package which is significantly superior to the Z06, especially the rear spoiler which is synergistic with the GT size wing.

As far as the motor, engine displacement was limited to 5.5L as that is max in the class. It is LS series based as you said. Again, I don't pretend to know the specific rules, but if they ran a supercharger I imagine there are penalties to max displacement or other areas; restrictor plates, ballast I have no idea. In addition, I imagine they may have calculated that a 5.5L NA motor would get better fuel economy which is a big advantage in endurance racing.

As far as my comments on choosing the 7.0L, what I was conveying that they chose to run 7.0L despite the harsher air restrictor requirements for fuel econ sake, not that they chose to run restrictors.

SSCamaro99_3

Working strictly from memory, the C5-R block was a completely different casting (I think mostly in the webbing, and other areas for durability) from a more "standard" LS series block. The mounting points were all there (it could replace a LS series block). The Z06 7.0 engine uses the production style block with siamesed (to house the 4.125 in bore) pressed in iron liners.