BADBOYVETTES.COM - Corvette Racing Pre-Sebring Report

Damn, the car looks sexy as hell! I love what the vette stands for. Hopefully I will be able to make one of the California stops of the ALMS. And hopefully I will be driving a vette by then too.

--- Brice from Ridgecrest CA on 03.01.08 at 1:51am

The car looks great, can't wait to see it in action. Also has anyone heard anything about the Race in Houston?? Hope it is still on!

--- God-Speed from Austin, Tx. on 03.01.08 at 2:59pm

The race in houston is still on, but this could be the last year. The Champ cars and Indy merged, so I don't think enough people in Houston will have interest in a ALMS race only.

--- Kenneth from Houston on 03.01.08 at 4:28pm

I think the ride look's better than ever !!!!

--- johnnyoooo from Rochester N.Y. on 03.02.08 at 3:39pm

nice to see the hard work stateside. For those who dont know, Corvette Motorsport released their 2nd part of their 2007 Corvette Review film. It looks like the bad boys are everywhere!

--- Brian from Europe on 03.02.08 at 9:14pm

The Houston race is cancelled. See grandprixofhouston.com

--- Jeff from Oregon on 03.04.08 at 10:21am

ACO rules do NOT give an advantage to the Aston Martin DBR9. The DBR9 revs higher which gives it greater top speed at Le Mans.

Ray

--- Ray Smith from Costa Mesa, CA on 03.04.08 at 6:54pm

Top speed (a rate) is a function of Horsepower (also a rate). The formula for Horsepower is HP=Torque*RPM/5250

The C6.r produces more Torque (a force) but is limited to the number of RPM it can produce because of its pushrod valve train. The Aston V-12 is a DOHC which produces less Torque but more RPM. More RPM for a given amount of Torque means more Horsepower, which means greater top speed.

Ray

--- Ray Smith from Costa Mesa, CA on 03.04.08 at 7:01pm

thanks Ray for your knowledgable explainations!

--- eddie from unknown on 03.04.08 at 8:46pm

Also, the vette's can't take in enough air, due to the restrictors, to feed the engine at higher RPMs. The Astons have a smaller displacement and larger restrictors, therefore they can rev higher before their restrictors cause a big enough choke in the air supply. And it's not a simple matter of pushrod vs DOHC that determines the RPM capability.

--- KillerBrink182 from Texas on 03.04.08 at 9:42pm

...and thank you, KillerBrink, for accurate knowledge and more complete story behind the AM / CR difference.

--- Shishi Ryoshin from unknown on 03.05.08 at 11:50am

Show me the ACO rule that mandates a smaller restrictor for the C6.R. There is no such rule.

--- Ray Smith from Costa Mesa, CA on 03.05.08 at 12:34am

My apologies Ray. When running in ACO trim there is no restrictor advantage. My post was in now way ment to be an attack towards you. However, when both cars are running the same size restrictor, air is still the limiting factor to RPM. The C6.R's are trying to feed 7 L while the AM's only need to feed 6 L.

--- KillerBrink182 from Texas on 03.05.08 at 2:32pm

The V-12 is feeding 6 liters at 9,000 RPM while the C6.R engine is feeding 7 liters at 7,000 RPM so there is no advantage to the DBR9. It is the ability of the DOHC V-12 to turn more RPM that accounts for its speed advantage at Le Mans, not ACO duplicity.

The C6.R kills the DBR9 at short tracks with slow corners since the C6.R produces more low-end torque where RPM is less relevant. But on long tracks it simply can not produce enough top speed. Torque is king on short tracks. On long tracks RPM is king, ceteris paribus.

--- Ray Smith from Costa Mesa, CA on 03.05.08 at 3:17pm

Technically speaking, our forum fans are the BEST and most well informed on the internet. Now let's deal with the politics and the realities of racing. Corvette has NEVER been on the pole at Le Mans. Corvette has NEVER had the highest top speed at Le Mans. The closest the Vettes have EVER come to the Ferraris or the Astons was in 2006. When that occurred, Aston panicked and lobbied for a larger restrictor and got it. So, 2007 saw the greatest disparity in top speed and lap times between the Vettes and the Astons. Not good for racing but GREAT for Aston. The ACO equivalency now sucks...clearly
favoring the Astons. All that means is Vettes work harder and smarter and will bust their ass to regain the championship position they have rightfully earned and deserve.

--- godug from top secret on 03.05.08 at 11:38pm

According to the 06/15/07 Autoweek article written by Travis Braun, badboyvettes is a "Corvette-funded Web site". As such one could reasonably expect that the opinions expresssed are those of GM management and not of well informed "fans". The inference one might draw from Doug's post is that since the C6.R has never won the (GT1) pole at Le Sarthe, somebody must be receiving an unfair advantage. In reality, as Doug well knows, Corvette Racing never placed much importance on the GT1 pole, preferring to win the race on reliability, and quick pit stops. After all, the offical name for the race is "The Grand Prix of Endurance and Efficiency".

--- Ray Smith from Costa Mesa, CA on 03.06.08 at 2:11pm

Ouch, Ray...and this after I called out your knowledgeable explanations (see above)! GM has no editorial control over our content. The editorial is entirely ours. (As a matter of fact we've gotten more than just a little in trouble with some of our entries.) As I told Travis myself at Le Mans, Corvette Racing helps fund this site to help get the word out to a new audience. We embrace the Corvette Race team as the greatest and encourage (& love) their participation when they can give it. See godug's comment above. And as you know, we encourage all views!

--- eddie from unknown on 03.06.08 at 4:18pm

What "Ouch"? It's a fact.

The Corvette Racing effort is the most successful American-based racing effort of all time: Not just in terms of Corvette, but in terms of American racing overall. As such it stands on its own merits and does not need alibis when it fails. After owning 5 Corvettes, their 2001 Le Mans victory inspired me to buy a new Z06. And I just bought another one, based on the technology derived from the racing effort. I'm hardly anti-Corvette but believe you've gotta call a spade a spade. Read the article I wrote for Corvette Magazine. Everyone loved it except Doug.

--- Ray Smith from Costa Mesa, CA on 03.06.08 at 4:31pm

Ray. You say the DB has NO advantage. BUT, the restrictors are NOT the same on the 2 cars. Read your rules- ACO LM GT1 Specifications [see Appendix 1].

There is an equivalency formula for ‘2-valve’ vs '3 or more valve’ engines. And while this is intended to “balance the performance” [so sayeth the rules], as any race fan or engineer knows, equivalency formulas = guessing = potential inequities. The formula defines the C6R restrictors, which may, or may NOT be the right equivalency to your beloved Aston.

Do you know for certain this is the right balancing math? If so, the ACO really needs you, as does NASCAR, ALMS, and The Fed, the EU, and every Currency Exchange Trade Market. Raaaayyyy?

--- Shishi Ryoshin from unknown on 03.06.08 at 4:32pm

Let me first address your sarcasm. They are not "my beloved" Astons. I own two Z06s, because dollar for dollar they are the best performance deal on the planet. Read the article I wrote for Corvette Magazine to see my opinion of Corvette v. Aston.

Second, while the ACO rules do mandate restrictor sizes based on number of valves per cylinder and displacement, Corvette Racing knew that going in. There was no complaint when they won Le Mans 5 times: I don't understand the complaining when they lose one year (and the loss had nothing to do with restrictor sizes).

--- Ray Smith from inference on 03.06.08 at 5:01pm

Ray, a C6.R can't supply enough air to its 7 L engine at 7k RPM because the restrictors have choked the air supply to a point where air delivery is essentially capped. On corvetteracing.com the reported specs of the LS7.R is 590hp@5400rpm and 640lb-ft@4600rpm. The production LS7 sports 505hp@6300rpm and 470lb-ft@4800rpm. Now it's obvious that something has moved the power peak way down . . . air. The LS7.R just can't get enough of it to make enough usable power up that high. Basically a 7L engine requires more air than a 6L engine at the same RPM. So if the C6.R's and the AM's had the same size restrictor, The AM's would still turn higher revs not because of valve train differences, but because they would run out of sufficient air supply at a higher rpm. I'm not trying to argue restrictor sizes here, or rule changes, or who's-better-than-who . . . I'm just saying that in this situation, the limiting factor for RPM in both cars is air supply.

--- KillerBrink182 from Texas on 03.06.08 at 5:32pm

No question that volumetric efficiency comes into play here. Since an internal combustion engine is basically an air pump, getting air to the engine is vital--No make that the sine qua non. However, given unlimited air, the C6.R engine would still be limited in terms of top speed because it simply cannot rev as high as a DOHC engine without disintegrating the valve train. Ever stop to consider that tiny (by American standards) Formula One engines rev to 19,500 RPM to produce horsepower?

And yes, a 7L engine requires more air than a 6 liter engine at the same RPM, but the V-12 is not turning the same RPM on the Mulsanne: it's revving higher. Therefore it is just as restricted as the LS7. With respect to the ACO rules: Hey, it's their race. And if you think they like the English, guess again.

I have no quarrel with you, your points are cogent, although there are some here who equate disagreement with disloyalty. Where have I heard that before...

--- Ray Smith from Costa Mesa, CA on 03.06.08 at 6:01pm

So you're in agreement that both cars do not rev as high as they are mechanically able to (w/o restrictors of course) because they've run out of "umph" due to lack of air supply? All I was trying to point out from my first comment was the fact that neither car revs as high as their factory counterpart not because of their different styles of valve-train, but because neither car can make sufficient power at those revs. As for a pushrod valve-train disintegrating at high revs, there have been companies building race big blocks that turn in excess of 9000 rpms. Now the durability of these engines are not up to endurance racing standards, but that's another matter.

Personally I don't consider F1 engines tiny like most other Americans due according to you, but I also don't see how they have anything to do with this situation. Their incorporation of pneumatic valve springs takes them far beyond the typical pushrod or DOHC valve trains. They're also not as limited on the materials that they can use as the GT1 cars are.

I'm not trying to defend pushrod valve trains, or call either them or DOHC configurations superior or inferior. But I think most people are unaware of the capabilities of pushrod valve trains. It is in no way a dead or outdated technology. When faced with the task of designing any machine, there are endless options which all carry their own benefits and drawbacks.

--- KillerBrink182 from Texas on 03.07.08 at 1:11pm

The problem with this type of communication is that all too often people do not read a post in its entirety before responding. In this case there seems to be a belief that I am writing in a derogatory manner with respect to OHV engines versus DOHC engines. Not true. Of the four cars I own, two are pushrod engines (the 2001 & 2008 Z06s) and two are DOHC (one is my GMC Envoy with a superb inline-6 cylinder DOHC 4-valve engine that revs like crazy and produces 271 HP: I’m a loyal GM customer). The advantage of a pushrod engine lies in the fact that it is less expensive to produce, and, given sufficient cylinder displacement, can produce prodigious amounts of Torque with a very wide Torque band. While NASCAR engines can rev to 9,000 RPM, remember that they do not vary engine speed at anywhere near the frequency of a road racer. Failures usually (but not always) occur during transitions from one engine speed to another. Since endurance racing requires extreme reliability, this is not an option at Le Mans as you point out.

The 2008 FIA engine rules mandate a V-8 engine with 2.4 liter displacement. I think most people would consider that tiny in comparison to the LS7, but huge in terms of a lawn mower.

It’s an age old dilemma in race car engineering: Do I produce horsepower with massive Torque via large displacement, or do I produce it with less displacement and more RPMs?

--- Ray Smith from Costa Mesa, CA on 03.07.08 at 4:10pm

Well I believe there is still some misunderstanding. I was trying to point out that it wasn't the valve train that was the culprit in this situation, but the air supply. Neither the AM's nor the C6.R's rev as high as their production counterparts simply because they cannot feed enough air to the engine at those higher revs. I didn't assume you were bashing pushrod engines, but I wanted to point out that both cars' valve trains were not the limiting factor to RPM here. I appreciate your break down of NASCAR engines, unfortunately those were not the engines I was referring to. As for race engines, I believe most engine builders shoot for the largest area under the curve.

--- KillerBrink182 from Texas on 03.07.08 at 7:27pm

Last comment:
Well I believe there is still some misunderstanding. I was trying to point out that it wasn't the valve train that was the culprit in this situation, but the air supply. Neither the AM's nor the C6.R's rev as high as their production counterparts simply because they cannot feed enough air to the engine at those higher revs. I didn't assume you were bashing pushrod engines, but I wanted to point out that both cars' valve trains were not the limiting factor to RPM here. I appreciate your break down of NASCAR engines, unfortunately those were not the engines I was referring to. As for race engines, I believe most engine builders shoot for the largest area under the curve.
--- KillerBrink182 from Texas on 03.07.08 at 7:27pm