Thread: Do you know when your supercharger runs?...ALWAYS
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Old Aug 14, 2008 | 05:00 PM
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waldig
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From: VA
Talking Re: Do you know when your supercharger runs?...ALWAYS
I just went out to check the coasting response as it relates to the supercharger. Please remember that I am measuring the voltage applied to the clutch of the supercharger unit. See the photo, the leds are powered by the power source feeding the pump and the supercharger clutch

THe supercharger is off when:

The car is off
The engine is on and the transmission is in park or neutral (idle) or in reverse.

The supercharger has the clutch power on, ie it's ON

When the car is in gear, not moving and the throttle is above 1500 revs.

You are driving forward and the engine is above about 1500 rpm the first time. It stay on until:

You come to a stop or
You shift out of gear while still moving
It goes back on when you go back into gear and the transmission re-engages or
You coast over 30 seconds ( not speed related )

The manifold vacuum is possible with the supercharger clutch engaged, because the throttle body controls the air ( mass flow ) into the "engine". If the engine did not have a vacuum with the supercharger running the motor speed would be high and largely uncontrollable. Try to take the throttle body off of the engine and start it up for less than ONE SECOND or it will over rev terribly due to the loss of air control.

I expect some 'blowback' on this topic because it is AGAINST the common wisdom, but it is true. Just meter the cable feeding the clutch and you will see.
This is why my temperature reading did not make sense because I thought the s/c was under control of the driver (silly me) and therefore on and off etc.

Busses are full time superchargers and so are hot rods, they have no problem, its just a pump to add more air (density) to the motor to increase the output power.

The left LED is across the clutch magnetic coil
The right LED is across the I/C pump windings

ENJOY, Woody
 
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