BC

81 auto. Just for fun:

If I get a Postive Displacement Blower to put on the top, Ihave to:

Make sure it fit under the hood
Fab an intake that will fit under IT
Fab the throttle body assembly
Fab a crank wheel
Water mist in intake
misc

If I get a centrifugal, I will have to:
Fab a bracket
Fab some pipes
Fab intercooler, or mist intake
NOT fab throttle stuff
NOT fab intake stuff

So?

Fab

Dozman

It depends on what you expect from the blower.

BrianG

In both cases you'll have to worry whether the cast pistons will tollerate the stress!! <img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />

John.

You could go to JE and get the same pistons I am having made.

Personally, I would go with the centrifugal, if I am right, these heat the air less than a positive.

Setting up a centrifugal would not be that bad, you could then place a nice air to air charge cooler up front and be done with it.

My advice: Do not exceed 8 psig at the manifold with the cast pistons.

BC

The ONLY reason I would doa positive unit is to get low end grunt. But if you size a centrifugal right, you will have good low end, and SUPER high end.

It also looks cheaper to do, except for the fact that the Paxtons and Vortechs are much more expensive then the positive.

John.

It would be easy. The V8 already gives you lots of low end grunt. You could probably set up a moderate 5 psig of boost quite easily...you might even be able to go without a charge cooler at that level, it depends on the efficiency of the compressor you use.

Personally, I would keep the intake as is, and just fab pipes. If you do it right, you can keep the stock air filter and just pipe out under the spider intake and then feed back up past the distributor and into the throttle body. This is what Callaway did on my car, you get to keep the cold air intake and the stock box and it doesn't look like some Frankenstein creation with a cone air filter sitting in the hot engine bay. I never understood why people insist on doing that???

Might I recommend using a split sec mass air flow calibrator or the like. You will need larger injectors as well. 914 1.7 liter injectors will do the trick, but are costly. You might also use a 944 turbo injector. If you can find a spot, you might be able to use the old AFM and just increase the spring tension....but keep it on the draw through side, not the blow through side like Callaway did with my car. Blowing through the AFM is a no-no. Best method is to go with a MAF conversion and larger injectors, then signal calibrate. You could see about a MAP conversion, but since there is no throttle position switch, this might get tricky quickly.

GoRideSno

Brendan,
Fabing the bracket for the centrifugal has to be quite a bit easier than fabing the intake and the inlet plenum for the positive displacement(not to mention cheaper). It has taken me many many hours to design and build my intake (aluminum) and inlet plenum (aluminum and carbon fiber). I finally bolted my intake and blower on this weekend to stay. I started the M112 project in mid Janurary.

You can add fab belt tennsioner to both of your lists.

If you decide to go positive displacement I will be glad to help.

Did those wheels work out for you?

Andy K