Time For New Heads....But Which Ones?
 

Hey everyone. I've had my 383 LT1 for about 3+ years now and IMO it doesn't quite seem to be as powerful as I think it should be. Could the fact that I have near stock heads on the car be why? That's a good start. The heads I am running right now are stock heads, but ported and polished with stainless valves, heavy duty springs, and that's about it! Not to mention my valve sizes are stock! From my understanding, the heads on an LT1 can be very restrictive, and with a stroker motor fighting to make power, I feel as even though I have slight head work done, I am not near the potential of power I could be making. So without getting into too much detail about the engine specs and all that I am looking for some opinions on heads, and valve sizing that i should lean towards. If anyone has any first hand experience or just general knowledge that'd be great.

I have been looking at Patriot Performance and AFR leaning towards a 2.02 / 1.60 valve sizing. And as for the cc I don't know if I head towards 195cc or 215 cc or even if there is something else out there. I also saw an intake valve size of 2.08 as an option but I'm really not that familiar with what is good. i will also be adding hardened pushrods and 1.6
roller rockers.

How much are the heads I have on now really hurting me.......

My 383 is naturally asperated if that helps. Well thanks everyone -

Giovanni

Street car or race car?

Whats the operating range of the motor?

Cam in it now?

stay away from patriot for 1, afr make the best street bolt on head, stock heads on a 383 is def. gonna choke performance. without knowing what rpm range u want to spin and without knowing cam size, intake, injector size, exhaust system, compression,etc...etc..etc... i cant tell u which head is best. although i can tell u that on a 406 with 195's they can make 550hp+ on pump gas. and excellent street ability. u can pm me for more details if needed.

street car that sees the strip sometimes for fun
30lb injectors
pacesetter long tube headers with y pipe to an SLP LM1 cat back
58mm TB
ported intake manifold
ss ram air intake
i believe compression is about 10.9:1
intake/exhaust lift 372/372
intake/exhaust duration @ 0.50" 240/244



does that help?

What kind of rotating assembly did you use?

eagle forged rotating assembly with.....SRP pistons....

it helps,

that cam lift is at the valve? or at .050?

lobe sep?
intake centerline?

cylinder head and piston cc?

i dont have an answer to any of those last questions you asked me.....as for the cc of the heads, i mean...they are stock basically so i'm not sure....

well judging from the info provided, i wouldnt use anything larger than a 195 head.
this will keep your engine very torquey and make a good range of usable power.

if needed i can set u up with a pair

Just found this link on AFRs, gets good after the first page or two.
http://www.ls1tech.com/forums/lt1-lt...ads-lt1-3.html

as for u that dont know, tony mamo who is on that forum, is afr, he is the designer of all afr heads.

so basically AFR is a real good choice? or AFR is a real good choice but there are lesser expensive heads that can do the same thing?



.....i think AFR is what I'm looking for.....i've only heard real good things about them....

Eh, you can have your stock heads ported to outflow the AFRs unported, but you have more potential with the AFRs for later on. All depends on your goals with the car, the AFRs can grow with you.

And your swapping cams I hope?

there may be less expensive heads out there, will they provide the same power ? possibly?
why f around, when u know you have found a good product that will get u the power u want.... i dont only use afr, but highly recommend them, especially in ur case

well it has a cam in it already....so no i wasnt planning on swapping to a new/different cam...i was just under the impression that with stock sized valves, i am not doing myself any favors......

Well, you won't gain much if your cam is not matched the flow numbers of your heads...

hmm.....well now i dont know what to do - i dont understand enough about cam specs and head flow and all that to try and start matching cams and heads.....i guess i will have to do some research....too bad...i just wanted to throw some heads on there.....i dont really plan on swapping my cam out - so i wonder if the heads I have now flow well with the cam i have...putting me at my max power output for my motor....that would suck quite a bit....

Part Number: 109651 Grind Number: HR-302-2S-10.04 IG
Engine Identification:
Start Yr. End Yr. Make Cyl Description
1987 Up CHEVROLET 8 ROUGH IDLE, PERFORMANCE USAGE, GOOD UPPER RPM TORQUE AND HP, BRACKET RACING, AUTO TRANS W/3500+ CONVERTER, 4200-5000 CRUISE RPM, 10.5 TO 12.0 COMPRESSION RATIO ADVISED, 370+ CU. IN., SUPERCHARGED AND/OR NITROUS, 1.040" BASE CIRCLE FOR LONG STROKE CLEARANCE. BASIC RPM 3500-7000
Engine Size Configuration
305-350 C.I. V

Valve Setting: Intake .000 Exhaust .000 HOT

Lift: Intake @Cam 372 @Valve 558 All Lifts are based
on zero lash and theoretical rocker arm ratios.
Exhaust @ Cam 372 @Valve 558
Rocker Arm Ratio 1.50

Cam Timing: TAPPET @.004
Lift: Opens Closes ADV Duration
Intake 42.0 BTDC 80.0 ABDC 302 °
Exhaust 84.0 BBDC 42.0 ATDC 306 °

Spring Requirements: Triple Dual Outer Inner
Part Number 99846
Loads Closed 125 LBS @ 1.800 or 1 13/16
Open 321 LBS @ 1.350
Recommended RPM range with matching components
Minimum RPM 3200
Maximum RPM 7200
Valve Float 7200

Cam Timing: TAPPET @.050
Lift: Opens Closes Max Lift Duration
Intake 15.0 BTDC 45.0 ABDC 105 240 °
Exhaust 57.0 BBDC 7.0 ATDC 115 244 °

Remarks:

that is the crane cam that i believe i have ...... basing that on the information i was given when the motor was built ...i am taking that minimal cam information that i gave 'you' early in the post and matching it upto what crane cams web site offers.......


that seems to be the only match .......

ur heads are too small for that cam. bolting on a set of 195's will feel like a small shot of spray.

it would be nice to have the actual grind # off the cam to be 100% sure that that is the same cam u have.

ok i was getting worried for a second there....i knew when they built the motor that it was a respectable motor that could put out good numbers...i just wanted to help out my cause and i figured my weak spot was the heads.....everything that i thought i knew about the motor and the LT1's in general was telling me that my heads were inadequate for my bottom end......i will persue contacting crane themselves over the phone to get a better feel for my cam -

my dyno numbers were 360rwtq and 340 rwhp i just figured a better flowing head set up would push the numbers higher because i assumed the cam i have was an upgrade ..... so a good head set would just really open things up for her....


so a 195cc with a 2.02/1.60 sound like a good place to head for.....?

if that is actually ur cam specs, a 195 with i believe 2.050 intake valves, will be just fine.
if u want my honest opinion, go with the competition package with the 2.080. more money but well worth it.

yea i saw those.....i didnt know if that would be overkill or not....but i will double/triple check my cam situation tomorrow and assuming the info. that i gave you is accurate....i think i will make that move to one of those AFR set-ups....

i appreciate yours and everyones help....

anytime!