Rassel

ALMS has a GT2 regulation of 400hp?!

trumperZ06

No !!!

The ACO uses a very complicated " Engine Equivalences" formula...

info @ www.lemans.org

Strickly speaking... this is not necessary a "horsepower standard".

Following the regulations in the specification and choosing (GM's evaulation) the best possible solution within those specs.

resulted in GM/Corvette's 6.0 liter engine producing:

470 hp. @ 4800 rpm

535 torque(lb-ft) @ 4500 rpm

Corvette is NOT competing in this year's GT2 championship... and ALMS allowed Corvette to use a 6.0 liter engine for 2009.

Next year, the engine size for the GT2 Corvette is being reduced to 5.5 liters using a new block. That will allow Corvette to compete for the 2010 GT2 Championship.

Hope this helps.

mark kibort

hmmm, when was your last race tough guy?? yeah, exactly.
Bryan, this is a discussion board. I just think its very interesting to see how these organizations or marketing arms of teams quote hp. Its funny, and just wanted to talk about it. remember world challenge? 300hp for touring cars and 400hp for GT cars. better yet, JGT? 300 500 class? funny!

Anyway, dont be such an axx. that works on the BMW boards, but not here.

mark kibort

exactly!

Rassel

I'm very familiar with the ACO regulations and calculations. I call it "MAF-standard", but it's figuratively meant.

But rather than interpreting your initial text as incorrect or that ALMS had adjusted rule-set, I figured I'd ask. Much friendlier conversations also.

mark kibort

Look, I asked you, in the same tone and words you used.

Do you understand HP/torque graphs? Or does this map of performance, elude you?

Do you know how near impossible it is to have 535 engine torque at 4500rpm and 470hp at 4800rpm without a rev limiter at 4800rpm? Is there a revlimiter at 4800rpm???

The point is a discussion to what the vets really have as far as HP. Yes, we all know that the motor is a de-stroked 7 liter block to 6 liter. we all know it can keep up with the Ferraris and porsches which generally have near 525hp (dynos show a stock ferrari with a set of headers makes 450hp at the rears)

So, at a heavier weight, dont you think the vets will have near the same power?

Yes, and we all know that the rules will allow the Vet to go to a 5.5 liter motor, and have mod that allow it to probably make near the same HP as it does today. Now, will they dyno it, or give specs that the pros will review to satisfy that it will not be any more powerful?? I dont know. The point is, its just interesting that they talk about how little these cars have as far as HP. probably marketing, in that when Chevy sells a Vet, it can say, "hey, this is a ZR1, its faster and has more power than ALMS GT2 racers!

So, back to the original question. Does anyone think that the GT2 vet,as it is today, at its weight, puts down 400rwhp??? (i.e 470flywheel hp). Again, big torque only means that hp is or COULD BE, available over any operating range of engine speeds. HOWEVER, if the specs are correct, even in proportions, this wouldnt even be possible. (due to a rising hp curve due to simple math)

Hey, if anyone has any reason how it is conceiveably possible, let us know.
In my opinion, the specs are bogus , the car is probably very close to the 6 liter run in WCGT, but at a 300lb lesser weight and on Slicks. Anyone else agree?

mk

trumperZ06

Yeah, I "de-tuned" my response... figuring you already knew the answer to...

" ALMS has a GT2 regulation of 400 hp " ?


Mark is the one who brought up the horsepower issue...

and implied that GM was "cheating" !!!

Kibort didn't have a clue about Corvette's GT2 6.0 liter engine, but he's sly enough to edit his posts... deleting mistakes.

This torque vs, horsepower issue's been beaten to death, but GM intentially max'ed the torque on the 6.0 liter engine. They must have had good engineering data to support that decision.

mark kibort

If you read my post, I have known about the 7 liter destroked to 6 liter in WCGT. Heck,I think i had the first pictures published of that fact. Anyway, I edited out the the LS6, as it was a misprint/mis-thought. (was thinking 6 liter, not LS6) I didnt mean to say LS6, everyone knows that is the old 350ci'ish motor. I was talking about the destroked 7 liter to a LS2 6 liter size. (I went back an highlighed this correction in red.)

Now as far as HP goes, Ive NEVER meant to say they were cheating, it was more about the accuracy of the marketing specs. The ALMS rules makers are for sure monitoring their performance with all sorts of evidence. Im sure the guys that know are rolling on the floor laughing when the specs are published and say, the cars only have 470hp.

Go ahead, just try and use all your creativity to make a set of curves that can satisfy 470hp and 535hp at the RPM limits mentioned. Its near impossible. I provided a set of curves that were the closest I could find in reality-land. If they have a rev limiter set at 4800rpm, its possible. ALSO, the torque benifit would be completely negated as well, becasue of the shape of the curves (dictated by the simple math) of a 4500rpm max torque engine peaking out at hp at 4800rpm. The shape of the curve would be worse than the peaky curves of the ferrari and porsche. Does that make sence?? Now, if you "have a clue" you might voice your opinion on how the specs are remotely possible, instead of looking like the facts are "eluding" you.

PS-edit. A discussion point. Now, I dont know this, since you seem like you know about the 7 liter destroked block for ALMS GT2 and WC, how are the engines different? pratt and whitney built or K-tech built vs GM built? curious, and not that it matters anyway, but you seem to be so proud of your "clue" of these engines.

mark kibort

Based on what the Corvette team and ALMS is telling us. The GT2 vet will have the 6 liter motor that produces 535torque at 4500rpm , and 470hp at 4800rpm as rated at the flywheel.

Here is why this is near impossible to achieve and have the performance we have seen.

As I have posted, there are stock F430 ferraris with only a header upgrade that make 450rwhp and have an average of 420 hp over their entire operational range

If the vet was to have a rev limiter based on their specs, their flywheel hp would be near 385 average and at the flywheels that would be less than 330hp at the rear wheels! And even if they were able to shape the curves to maximize everything, and not have a rev limiter, their average power would STILL be 390HP. (or 330rwhp average) This means that in a best case scenario, the Vet would be down to the Ferrari by near 100hp. Now, if THEY are talking rear wheel hp numbers, the vet would only be down near 7% hp at ANY point on the track. And, this is a great example of the torque discussion points. There would be no advantage over the Ferrari, for example , at any point on a track based on these curves, EVEN if they were matched up to be equal in HP.

Example: at a post shift with the ferrari at 6200rpm would be the same as the corvette below at 3100rpm. the vet has a theoretical 520ft-lbs of torque there and everywhere it can, but the ferarri would have 6200rpm and over 300ft-lbs. (forget about at the rears or flywheel ratings.) it would have 2 x the gear ratio at the same speed making much MORE torque at the rear wheels exiting off ANY turn.

make sense??

Bottomline, the quoted numbers are impossible and are more marketing fluff.
Does anyone see any errors in the analysis above or on the graphs?

mglobe

OMG, I stopped in here expecting a discussion on how bringing the Corvettes into GT2 was changing the landscape in ALMS, and I get this crap?




Would someone PLEASE make it stop?

trumperZ06

Yeah right... we know what you meant... and it had NOTHING to do with marketing hype.

Hhmmm... Kibort,

now it's:

They (the Corvette guys) aren't Cheating...

just unbelievable performance !!!



Now to your questions.

Katech manufactured the racing Corvette engines for years, right up until the new 6.0 liter GT2 motors.

Pratt & Miller does the chassis, power-train supplied by GM.

GM took over the manufacturing for the GT2 engine at their Wixom plant...
where all the hand assembled high performance engines go together.

A lot can be done with cam lift/overlap/valve size to improve either the horsepower or torque curves... and GM appears to have sacrificed some horsepower... concentrating on maximizing the torque !!!

ALMS allowed Corvette to run the 6.0 liter engine in GT2 this year, as the Vettes came into GT2 half way through the season, and aren't running for the Championship.

Next year Corvette changes over to a new 5.5 liter engine... details still TBD.

After the Pilgrim/Caddy/Sebring escapade... it would be foolish for Corvette to "cheat"....

knowing they are being closely watched and are changing power plants next year anyway.

mark kibort

Thanks, its hard to keep track of where all those engines came from. I know full well, how cam and displacement can be used to make all sorts of curves.
I think you have missed the entire point I was trying to make. Its not that corvette is cheating, its that im tired of the BS marketing numbers to help sell cars. Why cant they just tell us what the real hp and torque are? as you can see from the simple graph I made, its near impossible that the vet is making the specs they talk about. If they needed to tell ALMS something to get the car in, then they are lying. I think they all know the real numbers.

If you can find one single error in the graphs that would lead you to believe that they are telling the truth, please, I would like to hear it.
Look at the curves I provided. I gave the best possible curves for the engine, while keepin in the limits of the 535torque and 470hp at 4500/4800rpm. I'VE MAXIMIZED TORQUE TO THE LIMITS of the math. You can see that if these were the limits, the HP /torque plots would be pretty weak. AND, coupled with those being flywheel ratings, its complete BS! again, average 330rwhp for the Vet is what i come up with and at 2900lbs, its not going to run faster than SpeedWC Touring cars!

Its on topic because we all know what a tough job it is to match up performances of different types of cars with different powerplants. they have done a pretty good job in my estimation. But, the numbers surely dont wash.

Benton

Ditto. I want my 5 minutes back.

mark kibort

Hey,

I want to know if this is possible to make an engine as they say. Based on the spec, it really doesnt pencil. Personally, its unfair to the porsches that have evolved in the series for 10 years, to have to go against an unfair advantage in my opinion. You give the Corvettes this advantage, without really seeing the dyno runs, and it sets the stage for them to dominate, and chase away all the competitors. (sound familar?). Im not saying its a possibility, but these specs they are starting with are a little fishy, and matching them next year with the new 5.5 liter engine, doesnt change anything.

Personally, I say just let the world challenge GT Vets run in ALMS competition as is. (simiar to the Viper they let run) put them on slicks and see how they turn out. they are a known quantity and have times at all the same tracks on DOTs. If they run slicks and dont pick up 2-3 seconds, then pull out some weight.

But guys, hear me when I say, I only brought this up becuase I am puzzled with the GM spec for the ALMS GT2 vet. It almost seems like they are using a Diesel engine.

Bryan Watts