You'll need a bigger cam than the 503 to make 400whp at 4000-5000 ft altitude. 400whp is just a number tho. Do you have an ET number in mind or a mph to trap? That can be a better idea of what power you 'need'. Cant go wrong with AFR, LE or AI. All capable of making 400whp. Just need a big enough cam to do so, and spin it up alittle bit. Depending on how aggressive you get with the cam lobe, you may need the upgrade 8019 spring and may even need to shim it up alittle for more pressure to keep things stable. I like AFR's due to the lightweight 8mm valves. Makes it alittle bit easier to control valves at high rpms. Or have someone setup the heads with hollow valves, 200-250 buck adder. Or use titanium retainers...patriot extreme gold spring kit with titanium is a great bang for the buck. Other retainers can be around 300 bucks alone, and the patriot complete kit with springs is less than that.

Becareful with cam lobes and dont go too aggressive if you want decent mileage out of your topend

 

Dyno software corrects for weather/altitude.

 

I guess if you put in the right inputs and the dyno doesnt "overcorrect" like alot of them like to do, then yes, 400whp corrected may be achieved, but that car wont run the same as a 400whp car at low altitude.

 

If you want to go with AFR's call them and talk to Tony Mamo. Tell him your goals and he will set you up.

The same thing w/ A.I. except don't ask for Tony. LOL. I personally haven't dealt with A.I. but have heard/read nothing but amazing things about their products.

I will be going w/ A.I. and one of there cams for my next build.

Let us know what you decide on.

 

Hey guys,

I went with AI 200 CNC LT1 heads and custom cam and intake porting.

Hopefully it works out well.

 

It should work well. Most always do when the tune is finally done and correct.

 

Sweet let us know what it puts down.