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

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):

[You must be registered and logged in to see this image.]

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:

[You must be registered and logged in to see this image.]
Engine pic 1

[You must be registered and logged in to see this image.]
Engine pic 2

[You must be registered and logged in to see this image.]
Engine pic 3

[You must be registered and logged in to see this image.]
Engine 4

[You must be registered and logged in to see this image.]
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.

Porch wrote: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.

Well... It used to be a 5K car, but agreed, most do not chose the 944 platform for an extensive build.

The alternative is to build a super modified or TA car, but I prefer a 2400lb/600hp car to a 2800-3200lb/800hp car.

By the way, there are some 700hp 951 cars that have been running around in SCCA for years; tube chassis, re-located firewall, etc.

lbp wrote:

Hmmm, I wonder what happened to his set up

He has one of the most dialed V8 setups out there, but his N/A 5.7 makes less power than his built 951 motor.

I'm sure you're just playing around on the V8 forum and know this stuff already , as it will be hard to beat that Milledge monster you have there. Hmmm, perhaps a Katech Track Attack LS7 is in order:

[You must be registered and logged in to see this link.]

DVC wrote:

lbp wrote:

Hmmm, I wonder what happened to his set up

He has one of the most dialed V8 setups out there, but his N/A 5.7 makes less power than his built 951 motor.

I'm sure you're just playing around on the V8 forum and know this stuff already , as it will be hard to beat that Milledge monster you have there. Hmmm, perhaps a Katech Track Attack LS7 is in order:

[You must be registered and logged in to see this link.]

Thanks for the link. It is a good example of why I am on this forum. Many of you, who have been at this for a while, might have more experience to share than you realize!

This is research as much as play, so thanks again for that link. For sure it is a set up I should look into further.

I did call Katech about their TA LS7 last week. The base price is $9,400 "plus core" so add $5k for a useable starting point and probably another 3-5K in misc expense and you have a $20k package.

And yes you can do that to a 944 motor, but at more than double the cost.

Happy Motoring & thanks again..