ZR1 vs. C6R

[NORTY]

So, I'm reading the "comparo" of the Corvette street car vs. racecar in November's Road & Track mag, and a question came to mind:

They state: "The C6R's engine has been destroked by more than 10mm to make it displace 5.5L." Ok, this tells me they wanted more revs as piston speed would be less with less stroke and same rpm.
Then, I see the dyno #'s~

470HP@4800
535ft.lbs.@4500

It seems to me that there should be a higher # in the HP than torque, unless the engine doesn't rev past 5252rpm. I'm almost positive this 5.5L engine revs past 5252rpm!

Unless Chevrolet is only giving us a "snapshot" of what the HP is along the revrange and NOT the peak. Those sneaky devils!

Come to think of it, the torque # may be the same. (misleading)

I just looked @ my dyno pull, I could list my LS7 as:
270HP@3400
398TQ@3200


It's correct, but misleading as hell.

[motorman]

Originally Posted by NORTY

So, I'm reading the "comparo" of the Corvette street car vs. racecar in November's Road & Track mag, and a question came to mind:

They state: "The C6R's engine has been destroked by more than 10mm to make it displace 5.5L." Ok, this tells me they wanted more revs as piston speed would be less with less stroke and same rpm.
Then, I see the dyno #'s~

470HP@4800
535ft.lbs.@4500

It seems to me that there should be a higher # in the HP than torque, unless the engine doesn't rev past 5252rpm. I'm almost positive this 5.5L engine revs past 5252rpm!

Unless Chevrolet is only giving us a "snapshot" of what the HP is along the revrange and NOT the peak. Those sneaky devils!

Come to think of it, the torque # may be the same. (misleading)

I just looked @ my dyno pull, I could list my LS7 as:
270HP@3400
398TQ@3200


It's correct, but misleading as hell.

the intake air is restricted by the rules so maybe there is no more power up in the RPMs

[NORTY]

motorman~ I thought about that too, but it still doesn't make sense to have a racecar that doesn't rev as much as possible. Those 28.8mm restrictions are sure small!

I know that long, small diameter intake runners promote torque thru intake velocity, but those same narrow intake cause the engine to strangle @ upper rpms.

I'm thinking GM is sandbagging the numbers. Ok, maybe not sandbagging, but certanly misleading.

I wonder what the cam specs are for the 5.5L engine...

[motorman]

Originally Posted by NORTY

motorman~ I thought about that too, but it still doesn't make sense to have a racecar that doesn't rev as much as possible. Those 28.8mm restrictions are sure small!

I know that long, small diameter intake runners promote torque thru intake velocity, but those same narrow intake cause the engine to strangle @ upper rpms.

I'm thinking GM is sandbagging the numbers. Ok, maybe not sandbagging, but certanly misleading.

I wonder what the cam specs are for the 5.5L engine...

several years ago corvette racing started out with a 6 litre engine and a certain size air restrictor but they had to rev the engines too high and they had engine failures. they went to the 7 litre engine with a smaller restrictor and less RPMs and the engines lived and they did all the winning. with the smaller engines they have to rev higher and that is what happened at le mans last year. after the wrecks and they got behind they had to run the corvettes hard,higher RPMs to try and catch up and the engines let go. they keep RPMs in reserve for this purpose but they had to run too hard too long.