Eaton M90 supercharger Question

[RonPorter]

Personally I'm not into putting any blower or turbo on a SHO.

But.....I am always into spending the $$$ to do things right the first time.

And, just following the thread, if I were doing it, I would go with the Gen V. Wait awhile to save the $$$ for it, but it just seems to be the right way to go, without needless compromises.

 

[SHOguy 92]

Gen V really won't need porting, not many gains to be found with it. So the cost difference really won't be that large, I would go JY hoping.

 

[CplPflummUSMC]

Ya the Gen V is the way to go. So keep your fingers crossed for me.



Looking at the graph it looks like I will be able to keep the SC running in the +50% efficiency for most of the time which from what I have read is pretty good since the old GMC style blowers that were and still are the standard for drag racing were extermely lucky to operate this well at there best, yet alone over a subsantial RPM range. Hope I read that right. Feed back is appreciated.

 

[rubydist]

The chart does a wonderful job of displaying why the M90 is not large enough to do the job efficiently on the SHO motor.

First issue w/ the roots design is that its max efficiency is at pressure ratios of 1.5 or less - 7.5 psi boost or less.

Second issue is that a SHO motor at 7000 rpm ingests about 600 m^3/hr of air when naturally aspirated - this will be over 900 at pressure ratios of 1.5 (7-8 psi) and over 1200 at pressure ratios of 2 (14-15 psi).

This is why netting over 300hp will be a difficult challenge.

Does that mean you can't/shouldn't use one? No, I just want you to be aware of the constraints on the system.

 

[shomethe$$$]

I agree, if you are firm on your goals then the M90 is fine, it will do 300whp and even 400whp depending on if you keep the intake and charge cooling, I was running my heavily ported 94-95 M90 up to 18300rpm @7000 engine rpm, that's about 930cfm or about 15-18psi on a 3.0L SHO motor but the power goes flat around 6000 rpm...but if you want more like I always do, then the M90 isn't going to get you there, heck the SHO motor is about to take my Whipple 2.3 out of its efficiency range, I'm waiting on a smaller pulley to be custom made, thinking of upgrading to a Whipple 2.6.

 

[SHOguy 92]

The chart does a wonderful job of displaying why the M90 is not large enough to do the job efficiently on the SHO motor.

First issue w/ the roots design is that its max efficiency is at pressure ratios of 1.5 or less - 7.5 psi boost or less.

Second issue is that a SHO motor at 7000 rpm ingests about 600 m^3/hr of air when naturally aspirated - this will be over 900 at pressure ratios of 1.5 (7-8 psi) and over 1200 at pressure ratios of 2 (14-15 psi).

This is why netting over 300hp will be a difficult challenge.

Does that mean you can't/shouldn't use one? No, I just want you to be aware of the constraints on the system.

The Gen V will push 14 - 15psi just fine with an IC. Without one it will spit out air thats over 300F, but with the IC thats the peak you want to go, tons of guys in the GP world spin them that fast, thats about how much boost mine pushes out.

But I do agree that a MP112 is a better choice, but it's larger, the Gen V should work just fine if he IC's it though.

 

[CplPflummUSMC]

Like I have stated I am shooting for like 325ish at the wheels. I figure if OffRoadSHO could get 280 with a Gen I M90 then I should be able to get my goals with a 3.2block with 3.0 heads, Y-pipe and PP/BBB. I'm not really shooting for big numbers as the MTX well not hold together. I do have a question on where you gentleman are getting all the numbers on the flow rate of the yamaha? I am very interested in how you can computate this factors. So far you guys have been great with all the info. I really appreciate it. Thanks again and Semper Fi!!

 

[rubydist]

The flow rate calculation is very simple - the engine displaced 3.2 liters, a 4 stroke engine moves 1/2 of its displacement per revolution or 1.6 liters/rev at a VE of 1.0 (which is a little high, but not a lot) so 1.6 l/rev x 7000 rpm and then convert units to match the chart.

 

[SHOguy 92]

Judging by those numbers then, it should be fine. I got 3.8l and I'll be running my car to about 6400, the extra displacement should make up for the extra rpm's, and I'll be running around 14 - 15lbs which many others are doing with Gen V M90's. It seems at least i nthe 3800 world that they peak out at around 380whp, theres quite a few people to hit around that number with them, most common high end builds like the one in my sig are usually around 360whp.

 

[CplPflummUSMC]

Just wanted to let everyone know about the new development in my quest for a boosted SHO. Today I closed the deal on an intercooler (sized 5x5x18) from a Porshce 944 rated to 450Hp and a 2003 4K mileage Eaton M-112 from a Cobra Mustang. Got both for $300. This can be added to my Lighting MAF and complete fuel rail with 42# injectors. So far I am only about $700 in. Just need a FPR and fuel pump now. On that point what fuel pump is reccomneded? I am only shooting for 350WHP. Thanks again for all the help. Semper FI!

 

[LOUDSHO92]

255, we do sell them...