I have been researching the pulley situation and come up with this. Eaton is supposed to call me back but:: Their web site says the M112 charger has a maximum RPM of 14000. I calculated the 3" upper pulley and the 7.75" lower stock pulley and came up with a multiplyer of 2.58x enigine RPM= blower RPM, or so my notes are at home. With a 1/2" larger lower pulley ie PSP the multiplyer is 2.75. I calculated it and stock the blower at a 5400 RPM shift point is turning 13932 RPM. With the PSP pulley it would turn 14850 RPM at the blower. You could change the shift point to just under 5100 RPM and stay below the 14K RPM redline of the blower. Is anyone worried about going past design spec RPM? What gains are being seen with the lower pulley? 3/10ths? 40HP? 2-3 lbs of boost is going to affect timing and fuel curves too. It will make the program a lot more advanced and maybe even leaner.

 

None of us believe the 14000 figure because we don't believe ford would put it that close to max for warranty reasons. Mine shifts at about 55-5700 and runs great, so does everyone elses. Sal ran it for over a year on his 99. It's uuummmmm good!
noelvm

 

Here is the notes I used. From Excel, hold on....

formula
(Lower pulley diameter/upper pulley diameter) * shift point (RPM) = Blower RPM at shift point

OEM lower /OEM upper = (7.5 / 3) * 5500 = 13750 RPM
PSP/JDM lower/ OEM upper = (8 / 3) * 5500 = 14666.667 RPM
OEM Lower/ASP upper = (7.5 / 2.75) * 5500 = 15000 RPM
PSP/JDM Lower / ASP/Metco upper = (8 / 2.75) * 5500 = 16000 RPM (egads)

Please advise as I am not sure what the diameters of the ASP/Metco upper pulleys are.

 

Here is the info I use...Crank pulley diameter/accy pulley diameter=pulley size ratio

Engine rpms X pulley ratio= accy RPM

So... stock Lightning blower speed is:

7.5 / 3 = 2.5 5300rpm x 2.5 = 13,250rpm blower speed

At 5500rpm x 2.5 = 13,750rpm blower speed

With PSP lower pulley:

8.0 / 3 = 2.6 5300rpm x 2.6 = 13,780rpm blower speed

At 5500rpm x 2.6 = 14,300

With PSP lower AND ASP upper:

8.0 / 2.78 = 2.87 5300rpm x 2.87 = 15,211rpm blower speed

At 5500rpm x 2.87 = 15,785rpm blower speed

 

So is the stock lower diameter 7.5"? I measured more. Also the PSP measures over 8". How can you guys say tha Eaton's listed max RPM for their product is irrelevant? Now I know what the magazines meant by the blower operating at near max limits. It is already near design max RPM.

 

Guys,

Does anyone have the actual specs (diameter and weight) from each manufacturer of the lower pulleys? Ive searched for a bit, but didnt find any actual numbers.

Thanks,
Mike

 

This same topic was recently discussed. I included all the data that everyone is trying to figure out in that topic.

 

I believe this is the thread Sal was talking about:
https://www.f150online.com/forums/sh...threadid=34166

The JDM pulley is listed on his forum as being 7.800 in. diameter and 3 lbs. Also has stock listed at 7.400 in.

Thanks Sal,
Mike

 

Is 14k the static maximum rpm, or momentary? Also, you can bet your a$$ that 14k number has a safety factor built into it...probably more that once. Meaning, the bearing mfg gave it a safety margin, then Eaton assembled the blower, and added some more margin.

But, beware, most bearings are rated with a L10 spec. The"10" means 10% of the bearing will fail at that rating.