Thanks to BfB for doing the research in an old post

see https://www.f150online.com/forums/sh...ght=blower+rpm

I created a spread sheet that compares many existing lower pulley setups and calculates the resulting PSI increase.

If you have Excel, try downloading http://www.ncs-stl.com/Files/BlowerRPM.xls

cell k3 is unprotected to accept ANY lower blower pulley

The blower efficincy is assumed to be about 70% to calculate the estimated increases.

Have fun.

 

Nice work!

 

I worked on the program to acomodate blower drag. Try downloading the Excel spreadsheet not at

http://www.ncs-stl.com/Files/BlowerRPM.xls

or the non active version from

http://www.ncs-stl.com/Files/BlowerRPM.htm


Also see http://www.eaton.com/supercharger/M112.html regarding spinning these blowers fast.

Hope this all helps

Andy

 

I changed the excel sheet to work any combination of top and bottom pulley and it now estimates torque increases.

try http://www.ncs-stl.com/Files/BlowerRPM.xls

 

Nice work Andy

 

Thanks Andy, very well done.
George S. NLOC #542

 

Andy, that's a great tool you've made there. You do need to make a few corrections though. The 4lb pulley should be 8.5 inches (PSP or JL, they measure the same) and the 6# pulley should be 9 inches (PSP is 9 inches). We don't do a 5# pulley, but it should be roughly 8.75. Rule of thumb we've found in testing is that every 1/4 inch larger on the lower pulley is 1 pound of boost increase. Thanks again for the great work.

 

Thanks Sal I don't own any of this stuff so I was trying to put together the info from misc. posts. I made the changes

Andy

 

Lordy.
So, you folks w/#5lb lower and a (2.8 = 2lb upper?) are turning 17,211 blower rpm @ 5500rpm.
Thats a 3301 rpm difference from stock
Great work Andy, thanks from all of us that are too busy or too lazy.

 

Andy

You think to much

Mike

 

Andy,

I have modified your file to calculate total blower load and blower belt load (at 5250 rpm). See this thread for reference:

http://www.f150online.com/forums/sho...threadid=66460

Let me know if you are interested in using any of this.

 

YES, PLEASE POST THE CHANGES.

 

lurker

E-mail it to me at awhittle @ ncs-stl . com

Just take out all the spaces. (but leave the dash)

Andy

 

Lurker

The problem that I am having is that if you start suming the moments about the center of the crank, you can't ignore the mass of the pulley cantaleavered off the front of the last main bearing that I hear is only 3/4" wide. The other force is the belt tension pulling up on both sides of the pulley. The difference of these two loads is the 70 or so hp that the blower is eating. Without a dought, the rotating mass of the assembly is lower on a PSP style setup. The other issue is the sound control that the rubber gives as the blower takes bites of air and the crank vibration as it hits resonent frequencies.

Engineers can drive normal people nuts

Andy

 

Do we have anyone familiar with thermodynamics and heat exchange systems & efficiency? Find the key to that, and you may infact find the best boost/$$ ratio.

That file seems to be quite useful. Except for one thing, "hp over stock"

This is the thing that gets me the most, what in the world will an extra 11 or 22 hp to a truck that already weighs 5000lbs?

The difference is area under curve. I have noticed pretty much with each and every dyno graph on the internet, the graph starts around 3000 rpms. Thats 3000 RPMS that we have absolutely no idea whats going on. If only we could get a dyno from idle to max rev, calculate the area under curve, STOCK. Then add these hp goodies, then do another full band dyno pull, and calculate the increased area under curve. I can imagine the curve jump up 11hp or 22hp and stay that way throughout the powerband. Does anyone follow me? With the 3000 RPM floor, one can calculate something similar, but again, thats more than half the power band missing, and I GUARRANTEE that there isn't a gen2 lightning (I dont care what elevation) that can launch their truck at 3000 rpms.

I may try to look into it, but my main concern is global logistics, which is second in line to that peice of frozen chicken patty in the freezer....

Remember, max hp and usable hp can very well be two different things.