low boost and about fed up...

scrunner22

Registered User
Ok so my motor mods are as follows: david dalke cam, ported heads, double ic, dual 2.5 exhaust, cai 3 in, 10% sc pulley, and fan and shroud for ic.
The problem im having is I am only making around 10 to 11 lbs of boost. Car runs good and smooth when driving but this same blower and pulley on my unmodded cougar made 15 to 17 lbs and it only had cai and crappy exhaust. I have checked for leaks and all the lines and no leaks or bad lines. The only thing different I have done different is I bought this double ic from Centexsc. Have these double ics been known to leak under boost? Any thoughts or advice is highly appreciated!

Todd
 
It woudl help to understand what supercharger you are running. Stock, ported stock, ported stock with MP inlet, MPX, etc.


BTW - boost is just a measurement of restriction. High levels of boost don't always go hand in hand with power.
 
A better flowing motor will always make less boost over stock. Think of boost as a measure of restriction. There is less flow restriction plus the cam is letting more air in. My car dropped 3 pounds of boost after I got the new motor in.
 
If the only changed variable is the double IC, i would check into having that pressure tested, as sometimes that can definitely be a source of leaking.

As Rob stated, knowing what blower you have would make it easier to diagnose.

Also, do you live at a high altitude? Higher altitudes yield lower boost numbers
 
A stock unported blower isn't going to make any boost or power with an engine that flows more air than stock. You need a better blower. Yes, the motor will make less power than stock with a cam and a stock blower. You have to get a better blower. 10psi is normal for your combination.

I'd have the IC smoke tested before doing anything drastic though. Double intercoolers are really bad for leaking if they haven't been properly epoxied after welding.
 
ok understood. Is there a kind of simple way to test the ic myself? im sure i could rig something up, just figured if someone else has done it maybe i could get tips. and the blower is an 89 model, no porting, no nothing just a 10% pulley on it. Thanks again guys..
 
ok understood. Is there a kind of simple way to test the ic myself? im sure i could rig something up, just figured if someone else has done it maybe i could get tips. and the blower is an 89 model, no porting, no nothing just a 10% pulley on it. Thanks again guys..

For starters you can look for a 94/95 blower/plenum that will help you out. I'm getting ready to pull one off of a 94 Supercoupe I bought for parts and put it up for sale..
 
Yes, the motor will make less power than stock with a cam and a stock blower.

Is it possible to gain back a bit of boost/power in that example, with some mod(s) (pulleys &/or late model blower?) and not sacrifice MPG?
 
Is it possible to gain back a bit of boost/power in that example, with some mod(s) (pulleys &/or late model blower?) and not sacrifice MPG?

Generally speaking, as long as you stay off the pedal and out of boost, there is no reason why a 300+ RWHP SC can't get 20+ MPG on the highway. I know of several on here that are fast and get good mileage
 
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