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**Learned a bit today, have some "new" thoughts (long post)**

I have LOTS of thoughts in here and I'm not sure how to organize them so bear with me.

(note, I made a mistake and used engine rpm as 6700, it was changed to 6200)

I spoke to a tech at Magnuson today and got a little insight on the M62. I asked what the maximum rotor speed for the M62 was and the response was that 14,000 was the reccomended limit for this unit and this number was based primarily on efficency. He said additionally that he has spoken to people that have turned the unit into the 20,000 rpm range but this was done with less than stelar results (blower went boom in one case). Aditionaly he said that turning the rotors beyond 14,000 isnt just a issue with charge air temps, the bearings apparently are suseptible to failure due to extreeme heat in the blower body. One thing he did point out that was interesting is that the blower will eventually "tip over on its self" exceeding what the throttle body and inlet side of the supercharger will flow. Kind of left me thinking just how much was left in the M62.

I know Psi-Fi have been working with pulley upgrades and it will be interesting to see what they come up with. It was mentioned in a previous post that the pulley ratio was believed to be 1.85 to 1. This would mean that the rotors are spining at 11,470 rpm @ 6200 rpm for engine speed. Just for reference the M62 moves 1 liter of air per revoloution so it is displacing:

*11,470 liters of air per min @ 6200 rpm and

*409 cubic feet of air per min @ 6200 rpm

Just for refference there is 28 liters per cubic foot.

Looking into this further using the pulley ratio of 1.85 to 1, I came up with some interesting math. If the motor is opperating at 12 psi of boost at 6200 rpm from the factory (supposidly ECM limmited) then there should be more in the motor. Here's my thoughts:

First off lets figure naturally aspirated flow; cid x rpm x 0.5 x Ev / 1728

Our engines displacement is 122 cid, figuring Ev (volumetric efficency) of an assumed .90, you come up with 196 cfm @ 6200 rpm.

Now figure the pressure ratio; 14.7 + Boost / 14.7

The pressure ratio here using 12 psi of boost is 1.82

Multiplying the pressure ratio and the n/a cfm @ 6200 rpm i came up with 356 cfm. Now upping the boost to 15 psi in there with a p.r. of 2.02 the number jumps to 395 cfm.

Ok, this means the pulley ratio mentioned above is wrong (I think). The correct pulley ratio should be 1.61 to 1 to get to 356 cfm @ 6200 rpm or if indeed out motors are set up for 15 psi and regulated to 12 the pulley ratio should be 1.78 to 1 to get 15 psi flowing 395 cfm.

Now assuming that the pulley ratio is 1.78 to 1 the rotor speed @ 6200 rpm is only 11,036 rpm, far below the 14,000 rpm eaton says is max safe range. 14,000 rpm would be achieved using a pulley ratio of 2.25 to 1 moving 500 cfm of air.

Now, using the above math the max speed of 14,000 rpm should be able to make 23 psi flowing aproximately 500 cfm.

All of the math I used is from maximum boost, granted it is geared tward turbos but the basic math is for forced induction. If somone in the field could please take a look at this to see if it is accurate or if I'm just way off the ball I would certinly appresiate it.

If it is right and we do have a ratio of 1.78 to 1 with the rotor speed at 11,036 @ 6200 rpm engine speed there is a lot of room for improve ment.

Who knows, mabyee I am just dumb and thinking about this all the wrong way.