regorih inHous.

Heres the story i first did a heads and cam package and got my stock heads ported. After i was finished with the car it spun a bearing, so instead of rebuilding i bough a 383.. anyways i put some parts in and the motor only put 360rwhp on a mustang dyno. Let me give you my list of parts that are on the motor and im hopeing all of you can give me suggestions on what i should do to get more power... I would like to know what it might take to get to 475rwhp and up on a dyno-jet.. thanks

List of parts:

-383 LT4 block 4 bolt main
-4340 forged eagel crank
-Forged "H"beam rods, 6in
-Forged JE pistons
-FMS custom grind cam: 235, 242, at .585in. .595ex., LSA112+4
-LT1 ported heads with double coil springs, flow 260@.600 lift, stock vaules 1.94in and i think 1.50ex. with 53cc head
-1.6RR
-CompCam liftes
-Ported Intake
-58mm TB
-commpresion is 11:0:1
-K&N CAI
-MSD 6AL box,with MSD Coil,and wire
-NGK TR55 plugs
-SVO 30lb. injectors
-Walbro 255 intank pump
-Electric Water Pump
-March Crank pully

GreenDemon

What exhaust setup are you running?

If you're gonna put good money into the bottom end, you might as well invest in some nice heads. Air Flow Research, Edelbrock, and Trick Flow Specialties offer good castings that will flow better than the stock stuff.

Also, how does the engine run? Who did the tuning on it?

regorih inHous.

3in borla cat-back . but what kind of heads would you reccomend? i looked at AFR heads and they all flow low.. the 210 AFR head only flows like 288cfm at .600 im thinking of something in the 305+cfm.. what do you think

GreenDemon

Good luck on the 305. The AFR 227s only do 295 @ .700. If you're looking for more than that you're going to have to get expensive and adapt some SBC heads to your LT1. Some brodix 18* heads would be nice, just be prepared to shell out some big cash. Keep in mind that the stock LT1 only flows about 190/145 @ .500. Even the Edelbrocks outdo that by a lot (242/184 @ .500) and that's with the stock port volumes. Don't get too caught up in the big numbers, the average of the numbers between .3 and .6 is much more important.

Z95m6

I don't know about that. I think www.advancedinduction.com can get 300+cfm's out of LT1 heads.

ABA383

I see two things.. heads and cam mismatch and there is no mention of a computer tune...You already know that your cam is huge. I keep seeing Joe Overton and Lloyd Elliot mentioned alot on this board for proper cam/head selection. Although I've never dealt with them they produce outstanding dyno and more importantly TRACK numbers. I also believe that Mustang dynos generally read lower than the DynoJet.

You've got power to be had. It's all in the combination. I've got a small cam, 211/219 .533" .560" in my 11:1 383, but its matched to the heads CNC/hand ported 2.00"int/ 1.56" exh. and the intake was then hand ported and matched to the heads. John Lingenfelter himself put my motor together and tuned it on the dyno. Its been 10 years but I made 420rwhp. 475 rwhp is another animal altogether. Concentrate on the combination and attention to detail and you should make huge RELIABLE power...
--Alan

regorih inHous.

ok, so ill let the cam stay, so now i just have to find a pair of heads and intake to match my the cam,right? So who would I do that? What would you say is my best choice.

IrocSS85

damn dude, thats just about exactly the same as my story, and engine now. I feel your pain. Im hopeing for more around 400 rwhp though. that would bum me out too if mine does that low considerin some guys are putting down over 350 with stock shortblock and stock heads! what headers do you have? who tuned it? was it dyno tuned? whats the A?F ratio if so? I think the fella above meant your not goin to get 305cfm w/o porting the aftermarket head. who ported your stock heads? do you have a flow chart?
chris

SS MPSTR

AFR 227's only capable of 295 @ 0.700"? They are capable of a lot more than that. My LT4's are well over 290 @ 0.600", and AI is getting over 300 on AFR 210's. You're right though, there is way more to this than comparing peak flow, and it's always expensive

To the original post: You need a competent dyno tune - period. It looks like you have a nice combo, but there could easily be a half dozen small things wrong. Although the power does lie in the combo, I think your combo is relatively good, and should make you happier. 475rwhp is a bit of a stretch, but 420-440rwhp seems acheivable with what you have.

Z-RATED94

Short and sweet. You need better heads and a better exhaust system. Anyone will tell you, stock heads will not cut it with a 383, I don't care who ported them, not with that cam. And as far as your exhaust, a hi out put 350ci motor needs at least a 3 1/2 inch pipe after the long tubes. You do have long tubes, right? I think you need to tell us a little more about your set-up.

SS MPSTR

Please elaborate.

Z-RATED94

Just what I was told by people that know a lot more about performance than me. (So I guess that could be just about anybody) LOL If running a Y pipe make the I pipe at least 3 1/2 inches back to the muffler. I believe a 3 1/2 single pipe is equal to 2 1/2 inch duals. Someone correct this if I'm mistaken.

IllusionalTA

I'm thinking tuning is more the issue than the heads.. But!! Them heads are not going to get ya nowhere near 475rwhp.. I'd say a AFR 210 or at least the Trick Flow's worked By A.I.. Avg HP Is way better that Peak IMHO.. Then you get a cam cut to your specific heads.. To make the most of everything..

WS Sick

I'd definatley invest in some ported AFRs for your set-up. But to make the 475 rwhp # you'll need alot more.

regorih inHous.

The hole set up is on top, But the car has slp shorties with 1 3/4 and 2 and half inch. y-pipe with 3in borla. Ok so i need some heads..... i know that, but what heads, and how much do they need to flow to work badass the the cam that i have..