getting greedy with boost?
 

I currently run an 84 us spec 3.2 with a paxton supercharger. Bottom end (rings/rod bolts) was freshened up a few years back, and its got headers and 2 in 2 out sport muffler. Car puts out about 5lbs of boost, with a 3 3/4" pulley. Would it be safe to drop down slightly on the pulley to get 6 or 7 lbs? The car is very fast, as its in a 76 stripped out body, but you always want more. I guess what Im asking is how much boost is safe, before compromising reliability?

if you don't get a response from 3.2 SC owners, perhaps a good point of reference is a modern car with a SC added 'aftermarket' - what boost might they be running?
ie 996/997 SC cars.....

This *may* be a good starting reference. Or maybe not.

Modern cars are water cooled and have better head design so cannot be compared.

Have you calculated your boosted compression ratio?
What grade fuel do you run?
Do you have LM1 or Dyno A/F ratios graphed?
Are you running an intercooler?
Twin plugged?

Generally speaking 7lb of boost is acceptable in a 3.2L turbo application. I assume the same can be said for supercharging.

Head design paramount for boost determination?

Extended high power usage (track) will tax the thermal capacities of the air cooled design.

Brian makes a good point in that the AFRs/and IC are muy importante.
Especially for *any* track use.

TP isn't as big an issue with the flatter top pistons as it is with the domed NAs.

estimated comp ratio under boost is 11.1. currently using pump gas (CAL, 91oct) with an octane boost. Never any pinging, the car runs perfect. No intercooler as of yet, and it is a single plug version. This is an old SOK version that didnt require intercooling, but I am more than likely going to add one .

It stands to reason that if you add an intercooler you can also up the boost a little.
A buddy of mine had a whipple unit on an SC a few years back. The car was driven hard all the time and raced at every track in the midwest. I believe he locked down the boost at 6lb on pump gas and stock US compression with no intercooler. The car put down 260HP to the rear wheels with a freight train of torque.

I would do the IC first, could save you a small fortune...

most of us that have done the conversions run .4 bar non IC and .5 bar with IC's it kind of the changer over point right there.. you definalty do not want to over boost:o just fixing that little problem now

Check how many fins you have, on your cylinders. If you have 10 fins, keep it where it is at. 11 fins, .5 bar non intercooled .7 intercooled. Buy a a/f guage, that should tell you wheather your safe or not.

Thanks for all the info guys. It sounds like the IC is definietly a worthwhile addition. I guess I have a new project.

Yermancars, probably a dumb question but what is the significance to the number of fins? Mine is only a 10 fin, so if I leave the boost level where it is, will the intercooler still be a benefit?