Thread: Of Long Posts and Superchargers...
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Old Jan 20, 2009 | 11:53 AM
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waldig
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From: VA
Talking Re: Of Long Posts and Superchargers...
Please allow me to get back upon one of my basic beliefs related to the supercharger. Building boost.

The S/C data provided above AND taken at face value reinforces my point, and that is the boost provided is a function of the Pressure differential across the s/c [inlet to outlet pressure]. Colder weather adds to the boost as we all know, because the inlet air is DENSER TO BEGIN WITH.

If you have a boost ratio of 2.2 or other number, going beyond that is possible at the cost of lower efficiency and much greated stress - heat - input power.

I have instrumented and measured the inlet pressure at the throttle body. Using the standard Needswings CAI inlet and filter, I was getting a VACUUM of 30" of water column. That LOW restriction intake has about 1 PSIG of pressure loss due to velocity turbulance and amounts for 1 out of 14.7 or about 7% loss in density. The stock intake is much worse than that!!

By adding a second cold air inlet I was able to get 1 MORE PSIG OF BOOST without any other changes. THis is in part of why I was able to hit 20 PSIG of boost with the 178 mm pulley alone. THIS GAIN IS DUE TO EVEN LOWER INTAKE RESTRICTION, FREEING UP MORE ATMOSPHERIC PRESSURE TO REACH THE THROTTLE BODY.

Your S/C only compresses what is delivered to the input and there is where the output [Boost] comes from. A 6.8% gain in H/P is A BIG TIME gain and up to about 20 HP. I have shown this on the dyno and the gain is most prominent at the LOW rev end. THis is where you lose time on the track - just getting it rolling - going.

I have addressed many issues [technical] with a very mixed forum response; however the proof is in your hands. Just remove your intake at the throttle body for a short test, and watch your boost gauge to confirm the results for yourself.

Intercooling helps reduce the charge temperature and again increases the density of the inlet air within the cyclinders. The cooler the better; for both power and a greater safety margin for detonation prevention.

I will be doing some testing of the S/C boost with a185 size pulley this spring. I have now run the 178 [ currently], the 181 pulley , the Code 3, and the combo 178 & code 3 "stacked" pulley setup. The 185 is the last step in the evaluation phase, as I want to uncover information and the power locked within.

Forza1, thanks for the stimulating and thought provoking article.

Enjoy, Woody

 
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