The reason that stillen dropped the m90 project was simple...........if the motor wasnt built with a forged lower it will blow.The reason stillen never released the upgrade is simple.......most people would not listen to stillen and build the bottom end.That would have probably ended in legal problems for stillen and in that respect they were smart.
They made some real good power with the m90 and from what i have heard over the years it was in the 450rwhp and 500rwt figures kinda like the cobras.It would have had to have a major hood change to clear the much larger blower......but if they would have done it i would still have a bi old blower on my car.

 

i would rock a funky hood for 500 wt, shoot thing would be a monster. i have heard that m90 has similar bolt pattern so it would be something to think about.

 

The only thing is that scott at relentless was working on this and nothing has been heard of since.

 

Yea its been awhile since i heard of it. i was just in aww that 2.2 ecotec world is also looking at a m60 to m90 upgrade. surprized the z world has not been more interested. and hell buicks GPs have been doing it for a while.

 

It has to do with the way a roots style blower makes the boost. I really don't completely understand it myself. But a turbo, and a centrifugal SC compress the air in the intake by spinning a fan style blade rediculously fast. In a roots style blower such as the Stillen set up. It has twisted screws with lobes that actually squeeze the air as it gets caught in between the lobes, and moves to one end of the screws. That's what makes the whine.
And from what i think i understand about the process. having little to no resistance on the engine side of the blower will allow the air past through the lobes too quickly not allowing it to compress and "burst" (for lack of better words) into the plenum.

I could be all F'd up. Someone correct me if i'm wrong. But i know it's something like this.


read this is may help explain.

http://auto.howstuffworks.com/supercharger2.htm

This pic is the underside of my Stillen blower. You can see two screws in there.

 

yeah, i understand how that works but most people dont understand that there is a balance. going too restrictive is always bad. with swapping to a regular a/m exhaust, thats still more restrictive than you would want for a turbo or centri but for a roots its good because its a balance between psi and cfm.

 

^ like u said u need a balance in a aftermarket exhaust. but for sure the worst thing when it comes with the stillen is hfc's and headers. so im sure catbacks in any form would be ok, not much difference in performance with stillen (unless u go 3" dual exhaust)

 

I agree. I have a Nismo catback, and an E-cutout that dumps the exhaust just before the muffler. And i have seen no loss a the track by having the dump open. I think test pipes would kill power.