LS3 GM Performance crate engine conversion P/N CT 525 for 89 951

Porch wrote:

lbp wrote:
Well... there are guys in both PCA & NASA running 2600-2800 lb. 911s with 700-800 crank hp.

Yeah, but they have all their weight over the drive wheels. The v8 torque curve is going to be much different than the turbo curve and these cars don't hook, especially with instant torque.

I doubt anyone here can tell you about fitting the LS7. That engine alone costs more than many of our cars are worth. Buy it and find out!

Having owned a few cars during my younger years, and now having an older guy's perspective, I understand what you mean. I'm not yet sure what I will do, but if the plan goes forward the 951 will get one more season & come out this Fall. SBC (whatever it is) proposed as a Winter project.

Based on your comments, perhaps I should look into a short stroke (302?) that makes its power up higher.. Might be better for the drive train too.

Actually though, what we are talking about here is not unlike a Cobra kit car that has a hi-perf V8 stuffed into that little AC Bristol... (drive train not-with-standing)

Thanks again for posting.

I spent a lot of time feathering the throttle trying to get traction at the track last week in mine and I only have 372rwhp. Running 275-40-17 Toyo RA1's and I just couldn't get the power down.

My friend behind me in his E36 M3 commented on it, where he said he backed off a bit to give me more space as the back end of my car was so lively.

lbp wrote:
Hoosier Slick 320x18 R100 rear & 305x18 R80 front, Moton Pro, Wrightwood Charlie Arms (bump-corrected), Tarrett f/r, Kokehln Cross member (replaces torque tube) & sol. trans mount, sol. motor mount, IMSA-style cage, car is lowered about 1.5 in. 50/50 dist. (driver's position moved back 10 in.), etc. Wing makes about 400# (est.), Hypercoil 700/700 - may seem soft but is needed to keep the power down (mindful of the shock settings). We are also working on the front aero, etc. to develop a bit more down force although currently the nose is not too light. 996 Turbo brakes.

That is an awesome setup. I would love to see some pictures of that car.

May I ask why you want to convert? It will be tough to get 4:1 with an LSx and you're not that far off with the turbo 4.

DVC wrote:

lbp wrote:
Hoosier Slick 320x18 R100 rear & 305x18 R80 front, Moton Pro, Wrightwood Charlie Arms (bump-corrected), Tarrett f/r, Kokehln Cross member (replaces torque tube) & sol. trans mount, sol. motor mount, IMSA-style cage, car is lowered about 1.5 in. 50/50 dist. (driver's position moved back 10 in.), etc. Wing makes about 400# (est.), Hypercoil 700/700 - may seem soft but is needed to keep the power down (mindful of the shock settings). We are also working on the front aero, etc. to develop a bit more down force although currently the nose is not too light. 996 Turbo brakes.

That is an awesome setup. I would love to see some pictures of that car.

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May I ask why you want to convert? It will be tough to get 4:1 with an LSx and you're not that far off with the turbo 4.

Well, many of the LSx track units I've looked into easily make 600+hp/500+tq.

race link:
NASA NE race at NJMP 4/17/11

I'm guessing those are flywheel numbers with no accessories. If i were to guess at the average rwhp of most "moderately" modified lsx, it would go like this:

ls1/6: 400
ls2/3: 450
ls7: 500

Of course there are plenty of cars making +/- 50hp, but for n/a i have not seen any making 600rwhp.

I googled "600 rwhp lsx" and this is a recipe for a 600rwhp lsx:
451 lsx block 12 to 1 compression built for a 300 shot
TFS 245 heads
custom cam motion cam
ported FAST 102 and NW TB
Halltech superbee
American Racing 1 7/8 headers, no cats, Z06 B&B Bullets
RPS BC2 clutch
"There is no traction below 70 anymore."

Keep in mind that headers will be an issue in the 944 as well.

Porch wrote:I'm guessing those are flywheel numbers with no accessories. If i were to guess at the average rwhp of most "moderately" modified lsx, it would go like this:

ls1/6: 400
ls2/3: 450
ls7: 500

Of course there are plenty of cars making +/- 50hp, but for n/a i have not seen any making 600rwhp.

I googled "600 rwhp lsx" and this is a recipe for a 600rwhp lsx:
451 lsx block 12 to 1 compression built for a 300 shot
TFS 245 heads
custom cam motion cam
ported FAST 102 and NW TB
Halltech superbee
American Racing 1 7/8 headers, no cats, Z06 B&B Bullets
RPS BC2 clutch
"There is no traction below 70 anymore."

Keep in mind that headers will be an issue in the 944 as well.

Thanks,

Here's another one from a reputable builder:
Schwanke Short Blocks

Again, that's 600/650 hp at the flywheel and probably without accessories. It will probably translate to about 475/525rwhp with all accessories. The stock LS3 heads included in that deal don't flow enough to support 600 n/a rwhp.

The major benefit to putting a v8 in your car will be reliability and cost. The engine you listed could probably be beat on all day every day for 100,000 miles with only regular oil changes. Compare that to a 944 Turbo motor...

Porch wrote:Again, that's 600/650 hp at the flywheel and probably without accessories. It will probably translate to about 475/525rwhp with all accessories. The stock LS3 heads included in that deal don't flow enough to support 600 n/a rwhp.

The major benefit to putting a v8 in your car will be reliability and cost. The engine you listed could probably be beat on all day every day for 100,000 miles with only regular oil changes. Compare that to a 944 Turbo motor...

Observations noted..

The only thing I can add is that we are currently making 493 whp and 550 chp on the 951. I was hoping to go a little more with sbc, maybe 10-13%. And yes, 600 whp would likely overwhelm the trans-axle.

Regarding trans-axle, keep in mind we do not dump clutch, pull hole shots or use other such techniques on the (RR) track.

docwyte wrote:I spent a lot of time feathering the throttle trying to get traction at the track last week in mine and I only have 372rwhp. Running 275-40-17 Toyo RA1's and I just couldn't get the power down.

My friend behind me in his E36 M3 commented on it, where he said he backed off a bit to give me more space as the back end of my car was so lively.

...Were your tire pressures, spring rate & shocks set up correctly? Do you have an adjustable sway bar? Suspension plays a big role. Too stiff in the rear will prevent the car from putting power down. If you still have the 944 torque tube, you will have little control over these parameters regardless of shock quality & settings or other component selections.

Still running torsion bars in the back. Tire pressures were proper, 39psi hot.

You can get more power from the SBC, but for the power levels you're talking about an LS7 would be the way to go.

docwyte wrote:Still running torsion bars in the back. Tire pressures were proper, 39psi hot.

You can get more power from the SBC, but for the power levels you're talking about an LS7 would be the way to go.

Did you get the tire surface temperature (taken across entire width - inside/outside/center) using a probe-type pyrometer? Infrared will not do the job. Also, have a buddy take your temps immediately in pit lane when coming in. Do not drive to the paddock & check as temp will change.

39 psi would seem high to me, but I know nothing about Toyo. We run Hoosier slicks & look for 30 psi hot (20-22 cold).

Hoosier temp range is 160-180 deg hot across tire. Do not know about Toyo.. Differing temps across tire may indicate alignment issues.

...You probably know this stuff, above.

...I guess no one refers to LS7 as sbc (shows my age!!)

Are you very familiar with v8's in general?

On your turbo motor you have a power curve--things start out at about what you'd expect from a 2.5L 4-cylinder, and end up at ___ horsepower.
In a v8 the power curve is much more linear. You make ___ torque from 2000rpm to redline.

In other words, peak horsepower is only half the story.

If you're considering the swap, i would highly recommend you go test drive a C6 Z06 or equivalent. I think you'll be surprised how different 450hp feels in an n/a v8 compared to a turbo 4-banger.

I don't know much about your particular class but i know that TonyG has been very competitive in his class with only 400hp. With too much power you may spend so much time fighting to keep control of the car that your lap times end up being slower.

Porch wrote:Are you very familiar with v8's in general?

On your turbo motor you have a power curve--things start out at about what you'd expect from a 2.5L 4-cylinder, and end up at ___ horsepower.
In a v8 the power curve is much more linear. You make ___ torque from 2000rpm to redline.

In other words, peak horsepower is only half the story.

If you're considering the swap, i would highly recommend you go test drive a C6 Z06 or equivalent. I think you'll be surprised how different 450hp feels in an n/a v8 compared to a turbo 4-banger.

I don't know much about your particular class but i know that TonyG has been very competitive in his class with only 400hp. With too much power you may spend so much time fighting to keep control of the car that your lap times end up being slower.

Good point worth looking at.

Note the 951 torque comes on appx. 382 fptq at about 4200;
Small Chevy build comes on appx. 380 fptq at about the same 4200.
Big Chevy build comes on appx. 475 fptq at about the same 4200.

Here are the dynos (Porsche left, Chevy right):

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One thing I should mention, if you are looking at the race video elsewhere in this thread, we are still tuning to get the power band back where it belongs. I have a suspicion that the cam was degreed incorrectly (following some recent work) and that we may be a bit retarded right now.

- Note that the 951 dyno sheet does show where the power should be (951 dyno sheet is previous to current work in progress), which quite frankly is not apples for oranges when compared with the Chevy.

Thanks for the pic. That is a serious car. How long does your motor last at 550fwhp? Is that with race gas?

I would talk to Tom Egan about the dry sump setup he built on his brother's track car. I would also talk to Tony Garcia on Rennlist. He tracks most weekends, and he told me his lap times are several seconds slower with the V8 than with the 420whp 2.8 he had previously. Granted, that's with an LS1 and I'm sure you're looking at a modified LS7.

DVC wrote:Thanks for the pic. That is a serious car. How long does your motor last at 550fwhp? Is that with race gas?

I would talk to Tom Egan about the dry sump setup he built on his brother's track car. I would also talk to Tony Garcia on Rennlist. He tracks most weekends, and he told me his lap times are several seconds slower with the V8 than with the 420whp 2.8 he had previously. Granted, that's with an LS1 and I'm sure you're looking at a modified LS7.

Fuel is Powermist 104UL. Engine has run for 5 seasons & received a light rebuild & larger turbo last year. We now make about 30 more hp. Did have some MoTeC issues from an "expert" who created a few problems...

I am friends with Tom's brother Pat & have seen their cars. Very well planned & executed builds.
I believe one of the cars was featured in Excellence Magazine.
By the way, is the LS1 a steel block engine? If so, that might impact lap times.

Hello the LS1 is all aluminum. the weight diff between the 4 and the 8 is not much.

kevin924kevin wrote:Hello the LS1 is all aluminum. the weight diff between the 4 and the 8 is not much.

Hmmm, I wonder what happened to his set up

Other pics:

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Engine pic 1

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Engine pic 2

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Engine pic 3

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Engine 4

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Cockpit

What do you mean?

kevin924kevin wrote:What do you mean?

Well, if not weight, something changed..

I think you quoted the wrong person. I'm assuming you're talking about TonyG's car losing a few seconds...

Who's engine is that?

Dawgz83948 wrote:Who's engine is that?

Jon Milledge.

lbp wrote:

Dawgz83948 wrote:Who's engine is that?

Jon Milledge.

That has to be a lot lighter than stock. What is that a $15-20k 944 engine?

Dawgz83948 wrote:

lbp wrote:

Dawgz83948 wrote:Who's engine is that?

Jon Milledge.

That has to be a lot lighter than stock. What is that a $15-20k 944 engine?

No, quite a bit more. The car weighs 2247 wet with driver (when corner weighted). Don't know engine weight.

I thought I had a cam timing issue in my last race, but I am thinking it may have been an improper fuel mix.

...Do any of you guys know of or have friends who race 944/LS7 cars?

It's very possible it hasn't been done. I have never seen it done.

$15k motor into a $5k car...not your typical swap.