Need Help sorting out a Procharged 502. Advice Really needed!

[tyoneal]

Hello:

Helping a friend put a Procharged 502 in a 2nd gen Camaro, and it is just not working right. It has been professionally tuned and they don't know why it is not putting out more power.


He picked up a HO 502 from GMPP rated at 450/550.


1979 Camaro
Transmission is a 4L80e built for 1000 hp.
Differencial is a 12 bolt with 4.10 Gears


He bought the GMPP HO 502 and wa sgoing to run a D-1 Intercooled Procharger on it for some great improvement. Below are the specs of the New Engine:

Block (P/N 19170540): Cast-iron with 4-bolt main caps
Crankshaft (P/N 10183723): Forged steel
Connecting Rods (P/N 19170198): Forged steel, shot peened
Pistons (P/N 12533507): Forged aluminum
Camshaft Type (P/N 24502611): Hydraulic roller
Camshaft Lift (in): .510 intake / .540 exhaust
Camshaft Duration Part Number: 12568778
Engine Type: Chevy Big-Block V-8
Displacement (cu in): 502
Bore x Stroke (in): 4.470 x 4.000
Cam: Lift .510 intake / .540 exhaust
Duration (@.050 in): 211° intake / 230° exhaust
--------------------------------------------------------------------------------
Removed and replaced with Brodix race rite heads (See below)
Cylinder Heads (P/N 12562920): Iron rectangular port; 118cc chambers
Valve Size (in): 2.190 intake / 1.880 exhaust
--------------------------------------------------------------------------------
Compression Ratio: 8.75:1
Rocker Arms (P/N 12523976): Stamped steel
Rocker Arm Ratio: 1.7:1
Water Pump (P/N 19168606): Cast-iron, long-style
Flexplate (P/N 10185034): 14"
Recommended Fuel: 92 octane
Ignition Timing: Base 8° BTDC, 30° Total
Maximum Recommended rpm: 5,500
Balanced: External
=====================
It has Headers and will be used with the upgraded stock EFI off a 1997 Chevy 7.4, with 65 psi injectors. He picked up a pair of Brodix Oval Port Aluminum Heads to work with it.


http://www.brodix.com/heads/big-bloc...block-series26

Competition Valve Job
• Intake Valves:
2.250 x 5.218 o.a.l. – BR 81040
2.190 x 5.230 o.a.l. – BR 70019
• Exhaust Valves:
1.880 x 5.394 o.a.l. – BR 81038
• Valve Springs:
1.550 Hydraulic Roller Valve Spring – BT 120121,
140 lb Closed, 400 lb Open,
1.950 Installed Height,
.600 Maximum Lift
1.550 Roller Valve Spring – GA 1000,
240 lb Closed, 550 lb Open,
1.950 Installed Height,
.700 Maximum Lift
1.640 Roller Valve Spring – MA 221424,
250 lb Closed, 745 lb Open,
2.050 Installed Height,
.800 Maximum Lift (Spring Upgrade)
• Retainers:
1.550 10° Steel – CC 752
1.625 10° Titanium – MA 23640
• Valve Locks:
10° Jumbo – CC 611
• Rocker Studs:
7/16 – BR 716L, AR RRS-4I
• Guide Plates:
3/8 – CC 4806
• Valve Seals:
11/32 – US VS529V


The Distributer required updating and a proper MSD was added.
WITH 9 psi of Boost


Max rwhp @ 4250 rpm's = 307.18
Max rwtq @ 3800 rpm's = 397.36


The figures decline from there to 214 rwhp and rwtq @ 5300 rpm's.


Where has he gone wrong? We figured a Drivetrain Parasidic Loss of 30% which should still support a rwhp of 519 hp, and rwtq of 635 pound feet.


Any help you can offer would be really helpful. We called Procharger and they thought it was suffereing from belt slip, however things were re-checked and that doesn't seem to be the case, plus the boost stayed constant at 9 psi through the pull, I was told.


It is running Large Duels, but maybe the headers are to small? I couldn't find the specs on them but they look like 1 5/8's w/ 3.5 collectors.


I thought maybe the EFI was too restrictive, but I still can't figure how power would continue to drop if the boost was constant and the A/F remained balanced?


We REALLY NEED SOME SOUND HELP with this.


The tune was done by a Procharger Dealer.


I hope this is enough information to start getting some hard answers.


Thank you in advance for any help you can offer.


Ty O'Neal

[no go nova]

Throw a blow thru carb on it. I think its not liking that boost and probably doesnt flow enough air.

[andrewb70]

So it's running a stockish intake and a 2 barrel throttle body? Please elaborate on the intake and what ECU you're using?

Andrew