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Discussion Starter #1
Hey everyone.

I have the PLP powerdyne S/C kit. Now as some of you may know the kit is non-intercooled. In the spring I will be going to Tony the Tiger to do some upgrades :) .

We will be doing a custom intercooler setup for the kit. As common knowledge I know I will "lose" some boost pressure by adding an intercooler. Generally speaking, how much will I be looking at? About 2 psi im guessing?

Now in order to compensate for this I am going to move to a smaller pulley. This powerdyne unit has been rebuilt by 928 motorsports so its not one of the many powerdynes that took a crap very early in its life.

Regular BD-11a's had a normal operating range of 26,000 RPM and a peak ceiling of 32,000 rpm (not 100% sure about peak) at the impeller. My unit has a normal operating range of 36,000 to 40,000 rpm, and a peak of 46,000 rpms at the impeller.

In order to be certain I don't overspin and bust the bearings, I need to know our stock crank pully diameter. Anyone know this infomation?

This is the equation:

(Engine Redline or Shift Point) x (Crankshaft Pulley Diameter) divided by (Supercharger pulley diameter) x 3 = Impeller Speed



Thanks everyone!
 

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Discussion Starter #2 (Edited)
just an update for those of you curious about this information. Tony the Tiger helped me out. He measured 150mm give or take. Which would give us a crank pulley diameter of just about 6 inches.
 

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read the reviews of this compressor, it doesn't do well with smaller pulley's. slipping belts is the norm with much more rpm than standard
 

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Guru of Supercharged ISs
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as long as you have enough belt wrap it will be fine.....


I tested smaller pulleys onthe PD & it was not a problem...withthe inherent bearing problem that was on going at the time...it was hard to see failure after failure of supposedly ABEC-7 rated bearings.......but after consulting with a tech at PD......we used larger crank pulleys & spun it to almost 50k before it blew......that was their (Powerdyne's)" RACE SHOP rebuilt version they built for me that also fell apart faster than you can drive thru Downtown LA on a friday night.....

if you have a 928 MS built unit you should be fine... stay below theoretical redline at YOUR redline & no sweat... generally, you should only touch redline occasionally by driving hard...just remember to recirculate the BOV into the intake to help avoid excess impeller bearing stress & premature failure...
..WHen you lift at high speed the pressures running thru the system are much greater and so the need for a stress relieving recirc on the BOV if you are going to run it hard is greater as well.



The Raptor is a belt driven unit as well... VERY quiet and SUPER smooth .. it is very finely dynamically balanced, a properly balanced and operating Powerdyne should also be fairly quiet and smooth aside from induction noise and whine.... My little raptor whines like a Jet turbine.... it sounds SICK when you are hammering it past 5k....









ed G
 

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Guru of Supercharged ISs
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Discussion Starter #7
I would glady run a raptor if I had the choice before. It sounds like an amazing product!

I am probably only going to go with a slightly smaller pulley at the moment; 2.87" or 2.75" pulley. The stock ones were 2.93". Since you've tested the powerdynes before edgy, would I have to swap the belt that came with the kit? Or could I just use the one I already have? If I do end up having to swap the belt would you happen to know of the part number?

In the future I'm probably going to get the 928 impeller, and really see what the powerdynes can do when beefed up.
 
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