Need some

Ryan Need some input

7000 RPM X 7" pulley / 3.125 S/C pulley X 3 = 47040 Turbine speed.

I was told 36000 = 6 PSI

I have to run. I will get back to this later
"What is the smallest pulley I can run on my BD-10, 11, 11a?"

A gear-driven supercharger (like the Vortec of Powerdyne XB1A) can run performance pulleys all the way down to our 2.25" pulley. But the belt-driven BD-series cannot.

How small of a pulley you can use on your BD-series on it depends on your shift point, whether you have an automatic or a manual transmission, and on the size of your crankshaft pulley.

Those BD (Belt Drive) series superchargers like to run the impellers at 36,000 RPM internally, and will accept intermittent peaks of 40,000 RPM. They have a 3-to-1 step-up ratio internally from the supercharger drive pulley to the driven (impeller) pulley.

EXAMPLE: A Powerdyne BD Supercharger is equipped with a 3" pulley and mounted on a motor that has a 6" crankshaft pulley. If that engine shows 6000 RPM on the tach, the supercharger drive pulley is spinning at twice that, or 12,000 RPM (because the 3" pulley turns 2x for each 1x of the 6"pulley). Within the Powerdyne, because the drive pulley is spinning at 12,000 RPM, the driven pulley (and the impeller attached to it) is spinning at 36,000 RPM.

Here is the equation: (see picture below)

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

Plug the numbers in from your car and you'll know what is the smallest supercharger pulley you can run on your Powerdyne without sacrificing reliability.

Target 36,000 RPM at the Impeller if you want a long life from your Powerdyne and 40,000 RPM if you want more performance (and more frequent rebuilds

I had to be in Chi town for an assesment by 8 am. I had to run this mourning.

I need to eat and head to work. I plan on adding the other #'s after work along with more questions.

Reaserch Numbers

Portoin of an Q&A answer on Powerdyne's website
*****NOTE***** Unknown Crank Pulley Size
A: 6psi supercharger kits using a 3.125" diameter supercharger pulley

I READ SOMPLACE THAT 36000 IMPELLER SPEED = 6 PSI WITH THE BD-11A



I would like and had planed a CryO2 Bulb system.



I would not or could not run that 100% of the time.
I was thinking about running it of the AC compressor.
I would Tee it in like they do for rear AC systems.

4 PSI?

[This message has been edited by AJxtcman (edited 01-09-2008).]

boost is directly related to the amount of air your motor is moving per revolution. This is something that IMO is not even measurable, as I have seen 3.4 pulley gtp's run 13psi of boost, while others run 7psi of boost. (my friends 98GTP with headers ran 13psi, while my manual swap with 1.9 rockers ran 7psi.)

I would do all of your calculations based on "rated" CFM or equivalent measure of everything, not boost pressure.

it's hard to figure out the numbers for a blower like that. if you have a car with some serious port work done that same pulley might flow 2lbs. but it would make the same power. just more efficently. don't quote me on this, but the dohc cobra motor is damn near n* in terms of flow and performance. they also run a 7"crank pulley i believe. if you are trying to get only 6lbs then a base vortech v2sq with a 3.6 pulley would work or a procharged p1sc with a 4.0 pulley. it's been awhile since i've been around centrificals, but the powerdyne was junk. also you will never be able to run a 2.25" pulley on a blower. i saw belt slip on a procharger p1sc with a 3.0 6 rib and on a procharger 3.1 8rib with the F1R. also if you plan on intercooling then that will drop a pound or so off the total boost. also when you are trying to put numbers together, i can't think of any blowers that run the same step up ratio on the blowers themselves. the p1sc is 4.10:1, f1R is 5.40:1, and the v1 s trim is 3.45:1. so if you want something to look at and compare just look up dohc 96-98 cobras and that should give you a pretty close result.

i hope that helps.

I don't understand why the graph is not in mass airflow? Seems very confusing, and I don't see what compression ratio has to do with anything??

The graph represents a complete WAG about how much boost you can run with different power adders on a given compression ratio.

There won't be a set pulley size -> boost relationship. You'll have to analyze the compressor map for your supercharger and figure out what you can run with it, just like sizing a turbo. Or you could just install the darn thing and start playing with the pulley sizes...

when running forced induction, the less engine restriction you have the less boost , if you open valves more or longer or run headers thats less restriction compared to stock maifolds and rockers

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Vortech has graphs with MAF?

quote Originally posted by ryan.hess: Vortech has graphs with MAF?

I looked all over for a chart. I was on the Vortech sight, but I was looking at puuleys that time.

Thank Ryan I hope it helps.

Thanks again