I always here people saying the conversion kit should run around 425 HP, what I do not understand is that the LT4 vettes and Camaro did not come close to producing that kind of power with a stock LT4. I was wondering is all this extra power just made form having an LT4 hot cam?

Chris

 

The hot cam gives you more than a stock LT4, but 425 is really pushing it. I did the conversion, added headers, forged the internals and raised the compression to 11.2 and saw 352 at the wheels whis equals about 415 at the crank. I dont think anyone will see even that with just a plain conversion.

 

I think everyone (Pace, Summit) bases the HP rating on a dyno test that was done several years ago by More Performance, and documented in a couple of the popular Camaro and Pontiac magazines. I believe More got 429HP on the engine dyno. What More did not include in the articles was the fact they also installed LT's, a larger TB, possibly several parts not included in the "LT4 Conversion Kit", and then used the capability of a $4,000+ MoTeC engine management computer to optimize performance. The MoTeC has many features and capablilities that the stock PCM can not do... individual fuel trim by cylinder, individual timing trim by cylinder, higher definition injector drivers, end-of-event injector timing tables, huge fuel and timing maps, etc.

If you used all the advantages of the many "bolt-on" type mod's that man y of us have used over the years, use a really good CAI, a really good exhaust, and some decent tuning, you will have a chance to get to the numbers quoted. But if you just slap the LT4 kit on a stock engine, and do little or nothing else to it, its unlikely you are going to see 425HP.

 

I'm just over that with a lot bigger cam, and like Fred said quite a few additions.

 

Yeha I was thinking of getting the kit and just selling the cam and replace it with a CC306.

 

Save your money and buy a heads/cam kit that has already ported heads. The stock LT4 heads are nothing to get excited about as far as heads/cam kits go.

 

It might be different if someone does an LT4 conversion theirself or just buys the entire LT4 kit. The kit may have modified parts or something that give it 425 hp. Maybe the kit will give you better gains than just doing each piece by yourself or something. I dunno.