The smallest pulley available being 3.0" is logical; any smaller and there is not enough surface to prevent belt slippage. That's also why they tell you if more ratio is needed to install a larger crank pulley. We haven't really talked much about the power limits of 6-rib belts... that can become a factor too. I used to break 6-rib belts so often I carried two spares with me.
The intercooler with the kits are small and large intercooler is almost always better (unless you're Ford Motor Company apparently). It comes more into play at higher boost pressures where the compression of the charge air is making more heat. I wouldn't start throwing parts at it - you can make these decisions with data. Once boost gets to where you want it you log intake air temperature. Let the numbers make your decisions.

 

By the way, Steve knows exactly which head units bolt up to the ProCharger braket you have!

 

hell I've owned most of them.

P1SC/D1SC (same blower different impeller) with a 4.1 internal ratio, and then there's the F1 (none of the R stuff thats the crazy race crap) has a beautifully helically machined impeller flows a bit more air and has a 5.0 internal ratio, comes in harder, but seems to take more work to spin.

My recommendation? get a bigger crank pulley, there should be enough room with your accessories for some higher rpms on them, bigger drive pulley allows a bigger driven, more surface area is more wrap and more to work with staying 6 rib, 8 rib setups run about 1k on a LS motor, the BBC should be less since its just a pulley on a balancer, vs an integrated balancer.

Just a silly side note have you ever dyno'd the truck with NO boost, just to make sure the 502 is running the way it should? I think I still have a dyno for my truck NA making around 350ish at the wheels with a 4l80 stock sized convertor, and a 14 bolt 9.5 rear with 4.10's...

(alright just read backwards....and saw this)

I'm really just in a position to finishing it off in exactly the right way. Currently peak power is at 3800 rpm's at 305 rwhp and rwtq @ 4200 rpm's and 398 pound feet.

Not steller numbers by any stretch, but when these items are corrected the rear wheel numbers should show 550 - 600 rwhp, and 700 - 750 rwtq.

My 502 is 9.5 to 1 yours is 8.75, My guess is those are your corrected numbers....if I made a hair more with more compression I don't see much more NA.

you have a bunch of room for boost, heck these days I'd aim for 9.5 on a blower motor to have some snap out of boost.

so your numbers seem reasonable, I'd think you could get a solid 10 pounds into it without headaches on 93, most likely more with meth.

 

thinking back to the old days I think some guys ran pressure fittings before and after the intercooler to see how badly the intercooler was/wasn't flowing.

but I know that 2 core was a bottle neck for me on the 350. A 502 should theoretically want more air, but truth be told my 502 has a 48mm L98 throttle body on it as it came out of the crate, it was part of GMPP's paperwork cracking jokes about it.

 

Since the 3.0 is the smallest pulley you can run, with the ability to only get an additional 3.5 more pounds of boost (Every 10th of an inch = 1 pound of boost), I think if I moved directly to a 7.5 Crank pulley, it would really kick that engine in the "****" changing it to a totally different personality. Going from 410 rwhp @ 4750 RPMs. to an eventual 600 hp/ 750 tq. rw power. (Whoo-Wha!)

Going from a 6.0 inch to a 7.5 inch crank pulley would give me a 15 psi change from where I am now (3.35 pulley). If it is to much addition boost, I can always go to a larger SC pulley, not hot enough THEN go to a 3.0 pulley.

I imagine what is so confusing is the fact that the engine I have now in it's current configuration, is really nothing like the original engine (J29) that was in it, or the HO 502 that was originally going into it with the procharger.

It is different from the HO 502 Crate. (in these ways)

1. Iron Rectangular Port, Open Chamber, 2.19/1.88 valves 118 cc combustion chambers, to Aluminum Oval Port, Open chamber heads with the larger 2.25/1.88 valves and 119 cc combustion chambers.

2. Aluminum Low Rise Oval Port intake, with the recommended 750 cfm. carb., to Aluminum Oval Port Victor Jr. intake, and a 4150 Fast Throttle Body Port EFI with 65 pound injectors.

I imagine the SC has to spin fairly quick at this type configuration just to not be an intake restriction. It only has 8.75:1 Compression. We are theoretically still approximately 200 rwhp. and 300 rwtq. Short of the expected final engine output.

I'll get this started asap, along with the Boost gauge installed.

Do the above thoughts seem to be a reasonably educated explanation of my current situation? I tend to get long winded on these because I really want to make sure I am learning the technology along the way.

Thanks,

Ty O'Neal

 

rectangular ports are usually better on high rpm combos, I obviously have the factory oval ports which are a lil more torquey...

Sounds like you have a ton of airflow I wonder if thats limiting your boost.

The larger crank and larger blower would be more ideal for driving the blower and belt slip....the pulleys and idlers for the vortec 350 kit sucked, I'm going to imagine the 454 kit is very similar (the accessory brackets are) the belt wrap wasn't great. Procharger really had some crap bracketry back in those days, and I doubt they invested any r&d to redesign an outdated kit.

 

If I put a blow off valve on the system, and ran into some crappy gas somewhere out in BFE, could I change the spring and bleed off a lot of boost to avoid detonation until I could find some "good" fuel?

The engine would just be running rich (Right?) until I corrected the low Octane problem. I know you can carry "Race Gas", Methanol injection, or keep a second tank with some 93 Octane, for backup in situations like these. I was just trying to find away around the crappy gas that would be quick, easy, simple, and cheap you find in some rural towns.

I'm tempted to tune to 91 octane because my wife and I go on real long road trips all over the country and you can't always get 93 octane. With the Aluminum Heads I've been told they are good for about 1 extra pound of boost. Does this sound right?

Do you think I could still get 8-9 pounds of boost with 91 Octane given the AL Heads, and the slightly larger combustion chambers on 91 fuel with an intercooler?

I know people running 4-6 pounds of boost and NO intercooler, with no problems.

Thanks for your input.

Best Regards,

Ty O'Neal

 

Ramjet straight out of the crate with colder plugs and a nitrous plate behind the throttle body.....so everything zz502 is what I'm working with. You can probably get away with it. I'm guessing the tuning for boost is the restrictor on the return line which bumps up pressure to add more fuel under boost? (at least thats what I had back in 02 with the 350 setup) Since the fuel restrictor is boost referenced if you make less boost it should theoretically add less fuel, of course its mechanical and not the easiest to fine tune.

These days with the LS stuff you can run speed density and a 2-3 bar map and have all of that tuned.

For now I'd say get some extra vacuum hose and tap in a quick barb fitting into the tubing before and after the intercooler you currently have, make some passes at XXX rpm where you know what you have for boost, then make the same pass measure boost before the intercooler and after, that should give us a decent idea if thats bottle necking you. Or if we need to get more speed out of the blower. Of course you do have to realize your driveline/accessories suck up a TON of power, at least my numbers with a crate engine and a known output show what you're really seeing at the wheels. (my numbers are corrected, think it was a dynojet but hell it was back in about 2004 so I might be wrong)

 

The stock crank pulley should already be 7.5". If it's only a 6" pulley then you must have some kind of underdrive pulley intended to slow down the accessories. If so, get rid of that and get a stock one back on there. That alone would be huge.

We're still guessing blind.

Need. Boost. Gauge.

 

Sorry I haven't been back in a few days.

I had my computer crap-out on me, and my "Apple-Care" warrantee was a life saver with 13 days to spare before it became out dated.

I'm going to check some things and get you all a up-date.

Thanks for you patience and of course the comments/help.

Regards,

Ty O'Neal