okay so i work at a local gm dealership here in hawaii and came across an lt4 long block that the dealership is willing to sell me for 1500. i went to go look at some specs of the lt4 engine and i thought that the lift on the cam on those with 1.6 RR's were .525? specs show different. it also has a rating of 330hp. i thought the horespower on the lt4's were a bit more. summit is claiming with the lt4 conversion on an lt1 would be 425. so what makes the difference w/ the hotcam in the lt1 than the lt4? thanks

 

The LT4 does not have the Hot cam. It has a production cam that's a little more aggressive then a regular LT1 cam.

Rich

 

The LT4 is not "all that" but for $1500 I would take it and run.

 

That is a good price ,you should get it before someone else does.The LT4 will have better internal parts :stronger crank ,1:6 rocker arms, better flowing heads and intake .So if you need to replace your longblock due to high mileage this is a perfect buy.

 

You won't make 425HP even with the LT4 HOT cam. That claim was based on ENGINE dyno tests done in the late 1990's by MORE Performance. Engine was stripped of all accesories (= SAE Gross HP, not SAE Net, used by manufacturers), equipped with several unidentified upgrades and tuned using a $3,000 aftermarket ECU.

Stock cam specs:

 

Honestly I don't see why it wouldn't make 425 at the crank these days. These days it seems that there are more and more stock head, bolt on, hotcam cars making 330-340 rwhp which is around 400 at the crank. Are tuners getting better or are dynos reading higher?

 

That's what a dyno may say. Is it accurate? Who knows...
I'm not exactly sure how a bolt-on car where bolt-on's haven't really evolved that much for several years can all of the sudden magically make more hp than a bolt-on car from 5 to 10 years ago. A good bolt-on car with all the gadgets running stock weight usually run on average 105 to 107mph through the traps (of course depending on track/weather conditions). And by bolt-on I mean not even the valve covers removed for 1.6 rockers, but that can bring on a whole other argument... Opinions of a bolt-on car have changed over the years.