Thread: Do you know when your supercharger runs?...ALWAYS
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Old Aug 15, 2008 | 03:07 AM
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waldig
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From: VA
Talking Re: Do you know when your supercharger runs?...ALWAYS
The position of the throttle body (TB) controls the amount of air admitted to the "engine". The s/c is in the stream and is constantly turning to compress the air flowing thru it.

The condition that causes the manifold to have a boost or vacuum condition is the balance of the air supplied versis the amount consumed by the cyclinders. Internal combustion engines typically operate at high vacuum, ie up to 20 inches of mercury while running.

My 440 6 pack is 15 inches as I cruise at 50 mph. This is because the motor is being partially charged and the cyclinders are not operating at their full potential, I am at cruise. At wide open throttle I have 1 or 2 inches of vacuum and thus my volumetric efficiency (VE) is less that one. This inspite of 3 carbs that have a flow rate rated at 1050 CFM. Carbs aspirate fuel due to flow and the movement of air is the result of a pressure differential.

The TB controls the air and thus the motor speed, at Idle it has a high vacuum and as the power output is increased the vacuum falls until the net manifold pressure becomes positive and therefore becomes a boost condition. The s/c is after the TB and is along for the ride,when we go hard it assists the engine by drawing in more air and charging the cyclinders above atmospheric pressure to raise the VE above 1 so that we get 300+ hp out of 3.2 liters.

I forget the conversion, my pinto was 2 liters at about 122 inches so were in the neighborhood of 200 inches. And were making 300 hp, thats way over a VE of one to achieve that. At a boost of about 15 psig we are looking at an angine that thinks it is 400 cubic inches due to the 2 atmosphere intake charge pressures.

Bottom line is the I/C pump runs almost immediately from a cold start because the car is cooling the charge to reduce the intake tempertatures. The heat is part is from the abadetic compression and losses in the s/c.

Its too early to spell,sorry. The s/c cooling is marginal at best and from the interest in this thread, Ill let it sink in before I write up my styck about the overall cooling efforts I have now completed. Our cars are simply warm air engines and the simple act of adding heat to the atmospheric gases (air) in the cyclinders causes that air to expand.

As the air expands it liberates energy that we use to turn the wheels and gizmos in our cars. To make more power we only need to increase the amount of heat added(fuel, in the proper ratio of 13 so to one to air), the amount of air heated (displacement and or boost), the rate this happens (rpms), and the efficiency of this process (design of the internals).

Later, Woody
 
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