heres what i want, 325-350 rwhp out of cam/HSR 400 sbc bored to a 406 with MAF and the stock L98 heads, i will also be using some 28.8# LS1 injectors i have sitting on the shelf at the shop. i realize it would need one hell of a tune, which isnt a problem because theres a guy in town that can do that for me, but is it going to be possible? the plan was to use an LT4 hotcam in my 350, but after tearing it down and looking at it ive decided to go with a 400 and i dont have a clue what kind of power they will make.

if i can get 325-350rwhp out of it what cam will i need to run? i doubt the LT4 cam will be big enough, but i had been told that 300 at the flywheel would be possible with the 350/LT4 hotcam. any ideas what the LT4 cam will do in a 400?

depending on budget im going to try to have the heads worked a little, bigger valves maybe port them a little, but i dont think ill be able to. (college kid on a low budget)

anyway, im open to all opinions and suggestions, thanks in advance

 

Kevin91Z is making 325RWHP on a 350 with the Hot Cam. However he is running a modified TPI and ported Corvette heads. So the key will be your heads and intake system and lets not forget the compression ratio. To answer your question yes it is entirely posible.

 

Your going to need a cam that pulls to 5500 - 6 grand and around 10.0:1 compression ratio...you can have the heads milled to get higher compression fairly cheap.

 

The LT4 HOT cam is pretty small for a 400ci engine. Plus its a roller cam and all factory 400ci blocks are non-roller. You'd need to get an aftermarket 400ci block.
If your engine builder cant get 350+ HP out of a 400ci and a StealthRam, he needs to go back to school. We have guys in CA making 370+ RWHP with a 355 and a SuperRam.
I would personally stick with the roller 350 combo, its cheaper and the HP/$ ratio is higher.

 

i agree with these guys, keep the 350 roller block and rebuild that if you are going to build something. Then take the money you will have left over from what you would have spend on parts for the 406 and put it towards better heads/intake

 

Quite honestly a 400 with stock Iron L98 heads and a MAF would be a bad idea.

Q: Why?

A: My 385 Stealthram put down 300rwhp and 315rwtq with the convertor UNLOCKED. With the factory MAF and a 3" Mandrel CAI, the engine would max the MAF sensor at 4000rpm at 75% throttle. Now granted my heads are a bit better than the L98's (Edelbrock 170cc's) But you're packing on 21 more cubes, you'll max the MAF marginally sooner, depending on cam of course. So to get rid of this problem, and I know someone will pipe up and say that the 254g/sec issue of the MAF doesn't matter because of such and such, but it does, because a 3" tube (the MAF) can only flow so much air. And with the amount of obstruction in it, it will need to either be gutted to not be a restriction or you'll have to do what I did, converto to a 730 ECM and run a 2bar MAP sensor. (I plan to supercharge one day soon)

My $.02

 

I agree, I would not use L98 heads, either cast or aluminum on anything bigger than a 350ci. motor. And even with "max" out aluminum head it's only going to be good to about 5500rpm. Use what you have (350ci.) and save the money for a large mouth TPI or SuperRam intake. You will get the desired 350wrhp easily.

 

just to clarify, i already have a holley stealth ram on my 350.

BUT i did some thinking and since im on a low budget and i want to get the car done before i go back to school im just gonna rebuild the 350 with the stock rods/crank and hyper pistons put in the LT4 hotcam and ive found a nitrous kit for about $225

 

thats exactly my plan 12's here we come

 

you can take that hotcam (w/retro rollers), stealthram, and 406 shortblock and make near 400rwhp with a decent set of heads. ~10-10.5 compression.

 

dont think i can quite make 12s where im at. ive never raced on a day where DA was below 5200ft (ok once it was 4800 but it was also 33* outside) i ran 15.0s before the cam/nitrous, now im hoping for a 13.4 or so