Can the m90 make 20lb boost? Absolutely but your car wont like it. Boost is just the pressure in the manifold and is dependant on the air flow through the engine. A car with 8lb of boost can make just as much power as a car with 15lb of boost if it flows air better. If you tried to run 20lb of boost through a stock engine you would have no timing and your performance would suffer horribly.

If you want crazy boost, bring on the Turbo(*).

You guys are too technical and don't understand what this modified port actually does.

It doesn't simply make the supercharger move more air. What it does is it allows the supercharger to move more air at lower rpm'*, something Eaton obviously didn't think of when they designed our blowers. With the stock port, the supercharger has to pull air from the top of the rotors, and force it to the bottom. Obviously it doesnt know where its sucking air from, its just spinning and trying to do its job.

When the rotors are exposed, it allows the supercharger to pull air from the side and fill the veins more efficiently and effectively with less effort, and with no where else to go, its forced through the exhaust of the supercharger, making it much easier to move the air. This idea actually stems from the properties of centrifugal force.

That'* what allow it to make a possible 20lbs of boost. At 4000 engine rpm its producing 17lbs of boost, while the stock M90 (on a T-bird) is putting out 9-10 lbs(with yet another 2000 engine rpm left) At 6000 engine rpm, its making 19lbs of boost, while the stock M90 actually drops to 8lbs.

Obviously something was done right with the Magnumpowerz blower. Hmm odd, Magnum Powers, MP, MP90? Sound familiar?

Turbo kits cost way too much for most people on here.
Although its such an efficient way of making boost!

Yeah I know I got a bit technical there although I tried to explain it in a way that most would understand. I'll break it down a bit further though.

First the basics, as has been said before. Boost is directly proportional to space and airflow. Since the space (manifold and such) isn't changing the only way to make more boost is to push more air, right?

The M90 has 90ci of space. No matter what you do to the ports it can only hold 90ci of air, as that is how big it is. You'd think since its 90ci that it could put out 90ci of air but it doesn't work like that. Some air slips between the rotors and doesn't make it out. The difference between its possible capacity (90ci) and its actual output is called VE. Since its not possible to get 100% VE (90ci) and the M90 is already 95%, there really isn't a lot of room to play. If it was possible to play around with the output you would rather see low VE numbers like 70% or such.

The only possibility is to spin the supercharger faster thus producing more air. Thats why the smaller pulleys are in such demand. I hope that made more sense..

About Eaton neglecting to produce low end power, thats completely contradictory to the whole idea behind a screw or roots type supercharger. They produce their power down low, thats the whole point. Ever notice how quickly you go from -10 to 10psi of boost? For illustration purposes have a gander at the graph.



I hope this cleared a few things up.





PS ---- Wouldn't you think its just as possible MP stands for Magnuson Products, as they're the ones who make it?

Hmm.. I wish i thought of that.. wait a minute, didn't I?

No

Wouldnt porting the supercharger or whatever allow it to move the same volume of air but with less force? (ie. less HP to drive the pulley at x- boost)

Hmm, interesting thought...

Lets say thats true...Eaton says it takes about 44hp to spin it at redline. So even a very fair 10% gain is only 4.4hp at redline, less gain lower (where you make the most power anyway). If its true and you're after every tiny bit and have enough free time, hey go for it. I've been reading more and more about people doing it but it doesn't seem anyone has done realisitc before and after tests. This would be neat to look more into, but personally I wouldn't buy into it just yet.

it depends on how large the in and out ports are. I doubt Eaton was stupid enough to put ports that dont flow the capacity of the SC. You can machine the output port, sometimes it has casting flash, but this is a negligible gain, probably not worth it.

How do you figure out what the input port can flow? Anyone have measurements of a m90 or m62?