Trivia: C vs D blower

Hey,

I feel a bit silly, but have to ask here, since in my country there are exactly ZERO of either of them, because we have not imported them yet .

So what are exactly differences C vs D? Size, specs, tech etc wise.

Thank you,

Partel

 

d or c screw blower

yes i would like to know also
on a blown promod do you really need the c at 108 %
or can you drive the d 115% and get the same results
the reason i ask is you can find used complete d set ups
resonable like 9000.00 us
duane rister 618-781-4703

 

http://www.insidetopalcohol.com/showthread.php?t=7523&highlight=gizmo

 

The pictures I just viewed look like a D rotor PSI Screw Blower not a C. Kevin.

 

ta455, tack så mycket!

So, it's only rotors? Only twist? Same diameter, same case?

 

kena auto sul on seal

 

Hehe, actually just sold it to Finland recently, will run Outlaw (7.50 index) there. Pretty neat to export a self-built car. Also, they converted to E85. Cracked a damper or smth last weekend, hopefully be ok by FIA event.

 

Screw Blower Q & A

In an attempt to clarify the questions being asked and answered on this forum regarding screw blower displacement let me clarify and attempt to help anyone interested in this information.

PSI "D" is 422 cu.in.per/rev or 6.752 liters per/rev

PSI "C" is 476 cu.in. per/rev or 7.616 liters per/rev

Whipple R980 & A980 is 612.5 cu.in. per/rev or 9.8 liters per/rev

So if you look at SFI max overdrive based on safety and then parity based on swept volume per/rev in 1996 this is how NHRA wrote there rules,

Top Alcohol Dragster,

PSI "D" 422 cu.in. x 2.15 or 115% = 907.3

Whipple 601 cu.in. x 1.52 or 52% = 913 (.6% advantage in swept volume as it was wrote however based on the math 9.8 liters per/rev it should have read 612.5 cu.in. x 1.52 or 52% = 931 (2.6% advantage in swept volume)

Top Alcohol F/C,

PSI "D" 422 cu.in. x 2.25 or 125% = 949.6

Whipple 601 cu.in x 1.60 or 60% = 961.6 (1.2% advantage in swept volume however just as before based on the math 9.8 liters or 612.5 x 1.60 = 980 (3.2% advantage in swept volume)

Considering the fact that the swept volume per/rev is the only legitimate way to establish a fair and level playing field it is then up to the manufacture to design a supercharger that best meets the applications requirements for safe operation at a required operating overdrive limit per SFI regulations after that has been established the supercharger with the highest adiabatic and volumetric efficiency and the least parasitic loss at high pressure with a linear airflow curve will then allow the engine to create the highest net torque/horsepower curve based on superior air delivery.

There has been a few questions about how a PSI "C" and "D" compare so here it is in overdrive a "D" at 125% would be approximately the same as a "C" at 104% so just over 10% 2.25/2.04 = 1.102 - 1 = 10.2%

The last question that comes to mind is how to tell the difference between a "D" and a "C" measure the female or driven rotor lobe thickness, there are small variation based on application and date of manufacture or customers specific needs but on average a "C" will measure .483-.485 a "D" will measure .594-.596 both blowers have a open port in the housing between the front shaft/bearing supports.
I hope this sheds some light on the questions that have been asked.

Roger

 

is it better to run a high volume blower with less overdrive

 

PSI Screw Blower - B Model.

That information from Roger was good to compare models, Would Roger be able to compare the same with a "B " Model PSI . Thanks

 

Are the "B" and "D" the same rotor profile, or same output per revolution?

 

I believe so, but the case is different in the way the incoming air is delivered to the rotors.

 

thanks for the info!

 

psi-c

Im looking for a C if anyone knows of one!!!

Sean