I need to have the car dynoed but with the cam it should be around 400 rwhp, LS6s produce 405 at the flywheel.

 

What cam are you running? The rest of the motor is stock? Ie, no head work, FAST intake or throttle body?

It's alot harder to get 400rwhp on these then you think. My last motor made almost exactly 400rwhp, stock LS1 bottom end and 241 heads, Kooks long tube headers, no cats, dual 2.5" exhaust, FAST 92/92 and a 230/234 cam...

 

My motor is a full LS6 (block, heads, intake) with milled 243 heads and Manley valves, the cam is a 226,229 575,585 with 116 LSA, I also have a 85mm TB and 30lb injectors.

Most LS6s dyno in at around 365rwhp, I have got to be close. The only item that could be keeping me away from 400rwhp would be the stock exhaust system, I do plan to install a set of headers and rebuild the exhaust system.

I see you are using 241 heads. With you mods, I would have gone to 243 heads or had the 241s ported and polished. From what I understand, when you upgrade intake, cam, TB and exhaust, a good set of heads are a must to see the benefits, stock heads can only flow so much.

 

243's are really only worth 1-0-15 crank hp over the 241's. Regardless my current setup is a 383 stroker with RHS heads.

Your cam is pretty small and with the stock exhaust system I think you'll be lucky to hit 375rwhp. For whatever reason these motors in our cars don't seem to perform the same as when they're in an F body or a Corvette HP wise. TonyG being the exception, his motor always made a ton more power than the rest of us.

 

Unless they are CNC ported with a good program. Then their worth more.

I don't know about the rest of us.... but I don't pick parts from catalogs.

I pick parts based on hours of running everything through a computer simulator. My engine builder has not only great software... but he has ALL the data about every minute aspect of the engine. So it's easy for me to alter the intake port cc or change the rocker ratio, change cam timing or duration or lift... and actually see the difference in the HP & TQ. And what the computer says turns out to be very close to what the dyno says (amazingly close in fact).

What I use is designed on the computer to work together. No guessing involved.

The other aspect is that if you have to make compromises because you drive the car on the street... then your're never going to make the same power, apples-to-apples, that I make on with a track only setup. Big difference. I don't need to run a MAF. I don't need cats. And I don't need the car to idle well or not surge rolling in 1st gear 15mph.

But hey... I've got a very nice set of CNC ported and assembled 243's for sale. Made 461RWHP on pump gas on a 5.7L. Almost zero time on them.

I've also got a set of cathedral TF, CNC ported, then further hand ported, flow benched, larger lighter valves, and assembled TF heads, Gold 1.8 rockers, with a FAST 102 intake also for sale. Made 575RWHP on 100 octane on a LS3 396 stroker...

TonyG

 

Ditto the simulator.

Before I selected new heads and a cam we ran it through a simulator to identify the right cam and flow for the job.

My local engine builder is an ex-GM guy that supports 12 racing LS motors including his own.

Current RWHP 425

 

It's all about the data.

The more [correct] data your simulation has... the more accurate it is. And it's really stunning to see how much data that these programs use to simulate the output of an engine.

If more people could see this in action... they could see why their engines aren't making the power they want or hope for.

I know within 2-3% what the car is going to make before the engine is even put together.

TonyG