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The path of the warrior.
 
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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?
Old 12-30-2006, 02:39 PM
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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.
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Old 12-30-2006, 03:51 PM
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Crotchety Old Bastard
 
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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.
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Old 12-30-2006, 04:40 PM
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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.
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"930 is the wild slut you sleep with who tries to kill you every time you "get it on" - Quote by Gabe
Movie: 930 on the dyno

Last edited by Craig 930 RS; 12-30-2006 at 04:51 PM..
Old 12-30-2006, 04:49 PM
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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 .
Old 12-30-2006, 06:41 PM
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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.
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Old 12-30-2006, 08:47 PM
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I would do the IC first, could save you a small fortune...
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Old 12-31-2006, 03:32 AM
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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 just fixing that little problem now
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Old 12-31-2006, 05:11 AM
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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.
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Old 12-31-2006, 07:21 AM
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Thanks for all the info guys. It sounds like the IC is definietly a worthwhile addition. I guess I have a new project.
Old 12-31-2006, 08:23 AM
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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?
Old 12-31-2006, 08:50 AM
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