Here is the setup.

383 stroker
LT4 Heads 56cc with valve job. NO P+P
224/236 cam on 114
52mm throttle body
30# inj
msd ignition
FLP longtubes
mezeir water pump


The motor currently puts out
350 ft lbs from 2900-5300
375 ft lbs at 4000

390 HP at 6200

It seams to me that there is more potential there.

Our next step is going to be a 58mm throttle body, an aftermarket MAF, and dyno tuning again unless the consensus is that the heads or cam is holding it back in its current state.

Any suggestions to put down some more power are appreciated.

Thanks in advance,

 

What's the compression ratio?

Did you port your intake?

What do your heads flow?

Is that rwhp or fw hp?

Is your car auto or M6, what stall

All of these things can affect your hp and tq.

 

that is RWHP on a 6 spd

10.43:1 compression

I don't have flow numbers. They weren't flowed because they only got a valve job. So they should be slightly better than the stock lt4's.

As far as i know the intake was not ported. The motor was built by the pervious owner, we are just now trying to tweak the setup.

Feel free to dissect any part of the buildup.

 

well, heres my take on it. with more compression say up into the mid 11's if not close to 12. you will see some more power across the board but your hydrocarbons will increase... i dont know if emmissions was a problem or not judging by the cam choice. and if all that was done was a valve job theres almost assuredly more in the heads. if you're on a budget have lloyd elliot (nighttrain66) do it for you since you already have springs cam etc. if you're not on a budget you could have TEA do them.

i dont know how high of a lift your cam has or if you have aftermarket lifters but going to a 112 lsa and grinding cam straight up along with more agressive lift would do nothing but give you power if you were to stick with the same duration #'s all of the above done properly and tuned right might net you another 40-50rwhp. and i dont know if you had LT's or not.. that'll make a difference at that level. other things i can think of is if the guy payed attention to how heavy his pistons and rods were and the type of rings he used... that all goes to parasitic loss.. you probably dont wanna screw around with that since you've already got a bottom end.. i wouldnt want to.

edit i dont know what block machining was done on your engine or what your quench hieght is but that will have as much to do with what CR you can get away with on pump gas as anything.

 

390rwhp ain't bad for unported heads!

 

Jordon is right, When you look at your power items (383, cam on the small side, and exhaust) 390rwhp is pretty good. Yes there may be more to find in some areas or tweeking, but i wouldnt be at all upset.

Since the nature of the question doesnt fit Adv Tech i will be moving this to the proper area- Thanks.

 

OK, so we are maxing out the heads.

How much would a 58mm TB help though?

AFR 195s, or 210's

What cam would you recommend with AFR 195cc heads?

I don't want to move the powerband any higher in the rpm range.

 

have the Lt4 heads ported by somebody that knows what they are doing.

 

a 58 tb won't do much. i'm with jordan on the head thing dont go afr you already have lt4 castings, just spend the $$$ and have them ported right. should peak up in the high 280's or mid 290's cfm wise. have em milled a little and use impy gaskets to bump up compression. the cam i suggest is close to the one you already have but a little different grind, but to support it you'll need GOOD springs and GOOD lifters like comp r's. if i were you i'd run the 224* lobe with .605" lift for intake, and either the 230 lobe with .622" or the 236* with .624" for exhaust. it just depends on a couple of things which i would go with. have it ground on a 112 lsa and a 110 or a 112 intake center line. i dont want to get into a big discussion about cam selection but the lobes i've suggested are VERY aggressive. and although the @.050 duration numbers dont increase at all the lobe area does just look at the .200 duration numbers if you dont believe. the other thing is with lt4 heads they can flow damn good at higher lifts might as well utilize it. once again this is all just mho.