Building a NASA ST2 Race motor. HP to weight restricted.

[peej410]

Good morning,

I did a search but did not come up with much, my search criteria may have been the issue but I figured I would post up.

Build is Gen III LS based. Running stock EFI and 60lb injectors

We have a hp ceiling of 400 whp.

We would like to make significantly more Torque than HP.

We chose heads valve train and shortblock for durability reasons more than anything.

Heads.
AFR 210 #1510
Stock rockers
Morel Link bar hydraulic roller lifter

Shortblock
Texas Speed 383
3.903 bore
4.00 stroke
-3 Wiseco pistons
6.125 callies rod

Head gasket is FelPro MLS
4.100 bore
.041 compressed

Camshaft is comp part #54-416-11 LS1 XR273HR-12

We made exactly 400hp and 400ftlbs and the curve is awesome.
I talked to Katech, they suggested bringing the RPM range down 1000 rpm, putting in a bigger cam and restricting behind the throttle body or in the intake snout somewhere, I am left wondering if we could have got more torque.

What do you guys think?

Petronis_Vette_Dyno_73115.jpg

[Olefud]

I think I understand your point. Are you drive chain restricted? If not, you may be better advised to think in terms of a broad, flat horsepower curve. More torque at higher RPM is better as long as you don't exceed the HP limit.

[peej410]

Well, I was curious if the guys at Katech are on the right train of thought. Build the motor to make 500hp/ftlbs then restrict it down so it doesnt breath up top to take the peak off of the hp curve.

[wyrmrider]

why such a big bore on the gasket?

[peej410]

Almost all of them are 4.100
http://www.summitracing.com/search/part ... 4294918235

[wyrmrider]

cometic?

[ap72]

How much time/money do you want to put into this?

Instead of a "restrictor plate" you could go through the effort of filling the heads and intake to the exact size needed for your desired hp and torque peak.

You'll be able to get more power at a lower rpm this way (more torque), but it can be very labor intensive.

[wyrmrider]

IDk about building a high hp motor and chocking it down
you end up with no top end and no low end
I'd go for 400 hp as low as I could get it and flat to redline

[BlitzA64]

With an ignition you could program could you pick up the bottom end then kill the top with timing?

[peej410]

Pulling timing up top is what we have done.

Right now in the Tudor series they have what would be 800hp engines choked down to dual 31(?)mm restrictors.

The engins make in the 500hp range and 600+ftlbs

[mag2555]

First off have you any idea what the average rpm band is going be on the track, other wise how do you know where to focus your golds on!

[peej410]

Average rpm will be 4200-6500.

Which is what we shot for with the camshaft