Apparently my recollection about the article on the Olds mid 90's cars was not correct as pointed out by garcr4. I can't find much on rpm limit on the Group 7 cars.

http://www.bruce-mclaren.com/the-cars/canam.html

http://www.camaros.org/copo

That may shed some light. Second article said ZL-1 427 was limited to 6750 rpm.

 

I'll take a stab at it and say the motor you are describing would make about 530- 550 flywheel HP. That is more than enough to motivate a well set up road racer.

I have found that suspension tuning, braking performance, tire & wheel combination, weight, TORQUE........and tightening up the nut behind the wheel are key for optimal road course performance.

 

We are speculating closer to 600flywheel, my LS1 that just blew made 540fly wheel (460rwhp) and we are going to use a superior cylinder head and a touch bigger cam.

The nut behind the wheel is probably where the bulk of the problem lies...and that can't be improved until we have a running car again. So we are full speed ahead on the build.

How important are a high quality rocker (like T&D), limited travel lifters on something like this?

 

Great information guys.

Read through it all and it made me think of this.

 

The Grand Am teams use Jesel and T&D Rockers for endurance applications, however I understand the Nascar K&N Series motors (carb LS2's with 243's) run stock rockers with the Comp Cams trunion upgrade. I think they twist those in the 7600 range.

I had T&D shaft rockers on the Vette and removed them due to clearance issues with my fabricated valve covers. Have gone back to stock with trunion upgrade and stock valve covers. Have not race it since, will report back.

 

Thanks sscamaro.

Garcr4, do you know how high the Can-Am group 7 big block 494ci V8s revved to? And do you have any details on the C6.R Vettes racing in ALMS, Rolex, etc? How high did the old Trans-Am Boss 302s, Camaro D/Z 302s, etc rev to? If you know..

Thanks.

 

I don't know for sure, but I'll give an opinion:

The old Can Am Motors: 7200 area

C6R 7.0 liter: under 7000

Old TA cars: pushing 8000, no torque there, but they geared the hell out of them and ran em up.

 

We are going to select a cam that will make power to 7k, but setting shift point at like 6500, with flexibility to run to 7500 if necessary. I hope to keep it under 6500 (for longevity purposes)...but when you are racing, sometimes the competitiveness takes over and you do stupid stuff. I think we will just stick with stockers + trunion upgrade, select a quality limited travel lifter and call it a day.

 

I do not have experience with autocross but I do have experience driving and setting up my car and engine for running road courses (track days events). First, beef up the brake system... use the largest diameter rotors that will fit in your wheels. Get a good thick vented type rotors. Second, get your chassis set up so the car stays flat in the corners, is balanced, and is stable at high speeds. Make sure you have a good solid platform that will handle the horsepower safely.

As far as the engine goes.... I have found that an engine that has a smooth linear power with good power right off the bottom is good. When you roll on the throttle coming out of a corner you don't want the engine to bog or hit too hard. Also, a nice wide power band is good so you don't have to shift as much. I drive my car on a 2 mile road course with a chicane and a couple of straights (120mph+) and I can do the whole track using only two gears. High average torque and horsepower over the range that you will run is better than a high peak number. My current engine is a small block that puts out 450Hp and 450Trq with peak power at 6,500rpm. This combo was great for learning how to set up the car and how to drive.

Currently I am building a naturally aspirated 427CI LS2 with LS7 heads. This engine will put out high average torque and Hp from 3500 up to 7000 + rpm. The 450 Hp small block cost about 10K to build and the 427 LS engine with dry sump oil system will cost more than twice that. I would recommend to do a good solid 500 + horsepower engine to start out with and work on getting the brakes and chassis set up and then go for the big power when you wear that one out.

Thats my 2 cents... good luck with your project!

 

Just my .02, but I think you would be better off camming the motor for the actual intended range you plan to use. If you cam it to turn 7500 you are going to move the power band up in the range and lose some low end torque and power.

For road racing LS motors we try to cam for good power and torque from 3500-7000 max. Most of our motors seemed to only like about 6800 then they screamed "shift me". A couple of years ago when the Grand Am Rolex GT cars were using LS2's they were not even allowed the stock cam. They had to use a dummed down cam yet they still ran some amazing lap times equal to and some cases better than National type SCCA GT-1 cars with upwards of 800 HP.
The lesson I have learned is "Torque is King."

 

We were thinking like your suggesting. My last cam (LSL lobed 231/239 113lsa) had nice average power and a great TQ curve for a stock cube LS1, while it didn't peak really past 7k, it did carry the power pretty well, and this is to which I am referring. I just want it NOT to fall on its face passed that RPM range...in the event I'm needing to hold a gear (vs taking the time to shift in the situation where you are coming upon a turn or curve or a stop). I have seen several folks have to hold gears on autox because it just didn't make time sense to shift. This is the setting where having the extra RPM I think could give you some seconds.

The "Torque is King"...its that also a balance with traction. TQ applied is great, as long as you can put it down, if you over power the rear tires constantly on coming out of low speed turns, how useful is it? That is where we are. Somewhat limited by the minimum 200 treadwear rule, along with the fact that a 315 is really as big as I can go on the rear...I can imagine I will be needing to modulate throttle input quite a bit with even my stock cube LS2. But we will certainly select a cam that makes great "AVERAGE" power from 3500-6500, as this will be the sweet spot in terms of power production.

Here is my final LS1 dyno's, the lower curve was with Performance Induction 215's, the higher curve was Advanced Induction 5.3 heads (same cam, intake, compression etc)

 

That DOT treadwear rule of 200 is a killer. The Corvette has the Continental/Hoosier 325 in the rear and with less than 500 FWHP and 430 or so torque we have plenty of forward bite.

 

So it looks like I'm only looking at about another $1000 to build a 408 vs the 366. Seems kinda silly to leave that type of power difference on the table if we are only talking 1K difference.

What do you guys think? Based on my calculations the 366 would make around 485rwhp/439rwtq whereas the 408 would make 540rwhp/488rwtq.

Those are pretty big differences for just 1k. Plus I could run a less aggressive cam, so we potentially have more longevity with this setup due to being not as hard on valvetrain parts.

I am all for "learning to drive" with a nearly stock hp level car, then as you progress as a driver moving up to something that makes better power. But in this situation, the cost to remove/rebuild the stock cube LS2 after a couple years, to move to the 408, just seems like a waste. It would be way more costly to R&R that vs the 1K difference to build the 408 to begin with.

Am I stupid for looking at it this way?

 

I would probably do the same thing with cost as a factor. I wish we would have built a 408 instead of a 383 for the Camaro. But it makes 570 FWHP anyway, not too shabby. I went from racing a 250 HP SCCA EP/GT2 240 Z to a 500 HP GTA stock car. My first race was at Daytona and it was a little spooky the first time out hitting 180 in the trioval. However, my second race was at Palm Beach then Moroso) and I won over about 20 some stock cars in the Crane Cams V8 StockCar Series.

 

A little update...going LS2 based 408, dragonslayer crank, scat ultralight rods, Mahle pistons, ACL race bearings. Will top it off with Advanced Induction TFS heads, Custom cam, FAST 102 Intake/TB, ARH 1 7/8" headers, ORY, 4" DMH cutout. I am hoping we will be in the neighborhood of 500rwhp, but the dyno I use is considered "the heartbreaker", so IDK.

 

Sounds like 600 plus at the flywheel, I think you will make your target.

 

Yes, I am hoping 600ish flywheel, anything over that is just icing on the cake. Putting the power down, and dialing in suspension will be the hard part (and of course learning how to drive!)

 

Sorry for the thread hijack OP but what is the reason for using a carb as oppose to the stock EFI that comes on these motors? Do you have to run carb or is that a choice for tuning the power output on these road setups?

 

Carbs make more power, and you can probably run a larger cam along with a Carb intake
Which makes more high rpm power.

 

Geebus, some of the **** you see posted on the internet puked up by someone who read it somewhere.

RPM KILLS engines. The end.

In a autox or HPDE car you want tabletop flat TORQUE.

Most autox events in our cars should be run in 2nd gear.

I built a stock LS6 for my car to HPDE with, it works very very good. Makes 385 to the wheels and about the same in tq.

The reason you see cars on TV in races spinning the engine to the moon is because they have cubic inch limits or restrictors or both.

Listen to an ALMS GT2 C6 go around the track compared to all the others, sounds like a pulpwood truck.

IMO The LS1 has better oiling and is less likely to kill the bottom end in long sustained left handers.

Improved Racing makes a baffle that bolts into our stock pans to help with lateral G oil starvation, this issue really only shows its head when you get on good rubber(less than 200 treadwear) and really learn to push it.

If you think you need a 9000 rpm engine to go fast on a roadcourse you are mistaken, here is a vid of me at Roebling Road in Ga, never shifted the car out of 4th gear. I did this to teach myself momentum and corner entry speed. Passed damn near everyone in my run group that weekend with the exception of a Nissan GTR, Porsche 911 racecar and a BMW Z3 on race rubber with a damn good driver.

My car ran 137 MPH at the end of the front stretch and weighs 4000 lbs with instructor in the car.


This was my first weekend at this track.
http://youtu.be/qCNDermGiwg