You certainly don’t need any help from this quarter, professor.

Enjoy reading and learning from your posts as always. Keep ‘em coming.

 

The problem with turbos' and the boost spike is that the boost is seen before the throttle body plate. If you let off of the throttle the boost will continue to push forward and can cause damage to the throttle plate. To relieve the boost spike a blow off valve (BOV) is used. The BOV senses the boost spike and releases it rather than letting it "slam" into the throttle plate or blow off your intake hoses.

My 8/71 super charger does have a BOV located after the output of the blower. It's not there to relieve pressure from boost, it's there in case you get backfire from the engine (granted if you produced enough boost it would override the BOV spring pressure). When I let off the throttle air simply stops flowing and thus the boost stops.

And yes the blower could be turning 6000 rpm and still show a vacuum condition if the load is not high enough. Example, accelerate at a medium pace say to 55 mph and observe your vacuum gauge. While the actual acceleration is occurring you will see boost, once 55 mph is reached and you are cruising you will see that your boost gauge is now showing vacuum. And yes, your supercharger is still engaged.

Make sense?

 

[quote=tighed1]The problem with turbos' and the boost spike is that the boost is seen before the throttle body plate. If you let off of the throttle the boost will continue to push forward and can cause damage to the throttle plate. To relieve the boost spike a blow off valve (BOV) is used. The BOV senses the boost spike and releases it rather than letting it "slam" into the throttle plate or blow off your intake hoses.

My 8/71 super charger does have a BOV located after the output of the blower. It's not there to relieve pressure from boost, it's there in case you get backfire from the engine (granted if you produced enough boost it would override the BOV spring pressure). When I let off the throttle air simply stops flowing and thus the boost stops.

And yes the blower could be turning 6000 rpm and still show a vacuum condition if the load is not high enough. Example, accelerate at a medium pace say to 55 mph and observe your vacuum gauge. While the actual acceleration is occurring you will see boost, once 55 mph is reached and you are cruising you will see that your boost gauge is now showing vacuum. And yes, your supercharger is still engaged.

Make sense?[/quote]

Well, no.

All I can say is I notice with the ignition turned on, but the car not started, a small amount of power is sent to the intercooler pump. This reading made me think the pump ran anytime the key was turned, even if the engine wasn't started. Well surprise surprise, the pump doesn't run until the engine is started, AND it doesn't run when the car is shutoff, like previous thought. So my electrical readings said one thing, but in reality the pump did another.

Of course that doesn't mean I doubt Woody. At all. I think we're just victims of good 'ol over-engineering and now we're trying to unravel the mysteries.

some good info in this thread!

 

I think one way of thinking about what woody is saying is to realize that with an electronic throttle and complex engine control software you can meter the air so that even if it is being compressed (which a twin screw always does by design) it can still be less than the engine is using at part throttle cruising. This is the definition of a vacuum, a pressure differential. so yes the charger is spinning at an rpm that is a certain ratio to the crank pulley, but if you supply it with very little air, it wont actually send a boosted charge to the pistons. also the intercooler pump will always run because if the coolant was just sitting there it would heat soak even if you never hit any boost, just from the heat of combustion that is conducting through the engine block and all metal parts bolted to it.

 

Hey Woody,

Hard wire the clutch to be on all the time and then go out and floor it through the gears and tell us what happens. Since you say the clutch is always engaged you should notice no difference.

 

This should bo a sticky!!

Geezer

 

The clutch is to unload the engine for Idle and starting operation-s. I would not try to power it on as I know that it runs but moreso that if you backfeed power into the electronics, you may see way big bills for a fried contorl module. The fan controller is listed at over $600.oo, this is not a simple car, be cautious with jumpering power leads, meters for that matter. Woody ENJOY>