Custom Supercharger Possibility???

[alias06]

I am debating about building a relatively "cheap" supercharger for my 08 liftback. I understand that their is the Blitz supercharger kit made for the Yaris and is more or less a bolt-on setup. My idea though is to have a custom supercharger setup instead. With the research that I have done, I know that I'll need a blower of some sort, larger injectors, custom intake manifold or custom piping to the stock manifold, custom brackets to hold the supercharger, belts, etc. The reason as to why this idea came to mind was the fact that I have been able to source a few Eaton M90 superchargers for roughly $100-$250. I understand that the CFM the supercharger is capable to push is much more than needed for our little 1.5L as the M90 was designed for engines of greater displacement, but since it is relatively cheap (and cheaper than a M45 or M62) I figured that it might be worth the while. I also understand that the physical size of the supercharger might make it impossible.

The horsepower goal that I have in mind isn't crazy but around 120 whp is what comes to mind or whatever 5-6 PSI of boost can get me without heavily supported mods. With some mathematics I have came up with that our 1.5L is roughly 91.5 cubic inches with an estimated VE of 80 at 2500 RPM our engine would breathe in roughly 53 CFM of air while with a VE of 70 at 5000 RPM the CFM would be about 93, according to the equation #2 found from http://www.ehow.com/how_7953457_size...ercharger.html

Assuming that I am making 90 whp and want to reach the 120 whp goal and that everything else is proportional it appears that about 5 PSI is the magic number to get there by using the equation in step #4. The needed pressure ratio then can be determined as 1.34, using this pressure ratio and multiplying it by the calculated CFM from earlier to get compressor CFM I get 71 CFM @ 2500 RPM and 124 CFM @ 5000 RPM with the combination of equations #5 and #6.

With interpolation and the compressor map of the M90 (5th Gen) I should fall within the 55-60% efficiency of the compressor. By converting the CFM requirement to M^3/Hr as the map I get a range of 120-210 M^3/Hr (I understand that this doesn't fall in the compressor map and it is interpolation which can be totally skewed and way off), but it seems that I should be able to spin the supercharger at roughly no speeds higher than 4500 RPMs. (I know that the efficiency isn't the greatest and there are other chargers out there that would work better for the application but cost is the biggest driving force in this theoretical project)




Now my question is if anyone could double check and let me know whether or not my calculations and assumptions are correct.
I have found an old thread showing where a Jimze charger (M45) was used (http://www.yarisworld.com/forums/showthread.php?t=43995) and the pre-hack DIY Eaton Supercharger thread which didn't seem to come to completion (http://www.yarisworld.com/forums/showthread.php?t=10720)

The idea is to basically replicate the same setup as with the Jimze supercharger but with a different blower and stock engine, is there anything else that I am missing? Thanks in advance...