ckin62

I have a couple HP-500's that I want to put Prochargers on. The kits I have are M-1's. I plan on doing some head work a cam swap and going thru the motors to make sure everything is happy. There motors have less than 50hrs on them since there last build. However one ingested water and dropped a valve seat. So have a little investigation work there. Anyway, I keep thinking that the stock rods will be fine. Should I be thinking of swapping the rods for some aftermarket H beams? I would expect to get somewhere around 700hp out of the motors when done.

Young Performance

The rods are fine. I would invest in a set of ARP bolts for them. If you install new bolts, the rods must be resized. I would be more concerned about the M1. It is a little small for that setup, especially if you do any head porting or cam change. It is really on the verge of being to small on a stock 500. You will have to keep the boost at 5 psi or less with head work and a cam change, depending on what cam you go with. Let me know it I can help.
Eddie

Jammin'

M1 is fine. Just ask Procharger. I did it. HP500 engines with HP525 cams. Stock Merlin square port cast iron heads. Holley Strip Dominator intakes. Holley 800 cfm carbs. Procharger M1SC superchargers and AW-162 intercoolers. MSD ignition. You're not going to make 850hp, but they work. I made 701 hp at 5700 rpm on the dyno.

ckin62

I expect to be around your performance, 700 +/- HP. I have about the same components. I read on either GM's site or Mercruiser's that the stock HP500 rods are good for 575Hp and up to 7000RPM. I more expected a CR rating for the rods, but have not found that. I am fairly tame with my equipment due to the cost of repair. Jammin are you running stock rods?

Jammin'

Stock rods and a 5400 rpm limiter. It made 680 or 685hp at 5400 rpm. I'd have to dig out the dyno sheets to see. I didn't start out to build such healthy engines. I had the M1's on hand from another project and thought I'd give them a try. I've got Aeromotive 750 fuel pumps and I'm using IMCO Powerflow exhaust, but the dyno numbers were with dyno headers.

t500hps

I bought my boat with stock 500EFI's that had 8PSI Prochargers....I removed (and sold) them. Reportedly made 830 hp.....I was told it was closer to 790 hp. We saw signs of water getting to 1 or 2 pistons when we tore them down. otherwise seemed OK with 100hrs easy hours on them.

Made mine 540's instead with compression, cam, TB and made 630 hp/ 700 tq fully dressed on a dyno when finished.

NEVERSATISFIED

t500hps
What heads are you using and did you retain the stock 500EFI setup with just a ECU reprogram?
I am considering leaving my 500EFI's at 502cid and changing cam and adding alum heads vs. 540cid with stock heads. I would like to retain the EFI and see 600-625 hp
Thanks Steve

t500hps

I wrote the checks....a buddy came up with the "recipe" and did the builds for me.

540CI
ported 308 Iron Eagle heads
9.75 compression
monoblade TB
custom cam "slightly bigger" than the 741
completely stock in appearance except for larger air breathers

internal goodies like double chain timing chain, good head bolts, etc.

HP and TQ numbers were made running water through MY seawater pump all the way through MY wet CMI's.

Using the same "recipe" but at 502 CI I'd expect something in the 575-580 hp and 650 tq range. (that's what my buddy made but at a slightly lower compression)