I was thinking about superchargers and how they "take power to make power" and I want to start hacking apart a blower and trying to build something, I won't mention what I am attempting to do but if it works I'll let you all know.
I have a few concerns though:
- As the motor revs higher, the crank is spinning faster but is a supercharger building more boost at those higher RPMs or is it forcing a constant amount of air after a certain RPM?
- If so, around what is the specified RPM that it is forcing maximum air in at?

I'll be building a blown motor on a test stand, it's a real hack and slash job and you'd all think I was crazy for even thinking about it if I told you my goal; no idea if it will work even but I am trying it anyway.

 

That depends on what kind of blower you're talking about. Centrifugal superchargers build more boost the higher the RPMs.

 

Is their a problem with boosting fully at idle? I'm trying to figure out exactly what I need to do to make this idea work.

 

boosting at idle will create too much air with not enough fuel, you would need to provide fuel which will in turn raise the rpm

 

I have no idea why you would want full boost at idle, unless you mean off idle, or part throttle, not to mention what you consider full boost (30-psi?), and if this is the case, most guys will hit it with a shot of nitrous when they launch in conjunction with the blower for similar effect. Your tune better be spot on though....

 

Here is (just about) full boost off idle, supercharger w/nitrous....

http://videos.streetfire.net/video/F...III_687144.htm

The only other way is with a transbrake, but that wouldn't be considered @ idle then....

 

There was a good article in Car Craft a few months back breaking down the difference in the different styles of blowers. In a roots type blower for instance, they are designed more to move a volume of air than to actually build pressure. A centrifugal blower on the other hand, is designed to do the opposite. You might check their web site and see if you can find it.

Dan

 

that vid was awesome! that has to be hell on a car though, i cant see that thing holding together with that kind of abuse

 

Sounds to me like you're trying to have the blower spin max rpms almost all the time. That sounds cool and all, but would require a MASSIVE BOV unless you also have it spin much less rpm when not under a load. Actually if you were to adapt a belt/pulley system from a snowmobile, this could be very plausible.

 

Fast82Z,
Are you meaning like a reverse centrifugal clutch. So it has a smaller pulley diameter that would get larger as the RPMS rise to "slow" the blower as the engine RPM's rise. That would work great and be awesome for mid range power.

OP,
I know the twin screw type blower on the trailblazer SS makes boost pretty early in the rpm range and there is a relief valve on the blower that opens progressively to maintain at the maximum boost as the engine spins up. I am not sure of the exactly pressure levels though. This seems like what you are trying to accomplish with a centrifugal blower, if I am understanding correctly.

 

Ignoring the CV setup weighs around 55lbs, what benefit would he have from spinning the blower up where conventional methods dont. The engine would still be at idle and the blower at whatever RPM the CV spring was set for