Eaton M90 ?'s

drivinhard

Registered User
I'm new here, somewhat familiar with the 3.8L S/C motor, etc, but have some specific ?'s about the Eaton M90 blowers. Have spent some time on search engines and FAQ's, but have some questions on the M90.

Interested in setting one of these up on my 89 Taurus SHO. Car has a later year transplated 3.2L automatic motor with higher lift 3.0L cams, making about 265 hp n/a right now. Have a couple of possible mounting locations, may end up similar to what the comptech kits do with the honda's, a drive shaft across the front of the motor with a hanger bearing, blower mounted near the TB, plumbing to IC, to TB, etc.

Did the 94/95 SC's switch to the "3rd gen" M90? How much of a real world performance difference is there between the older M90 and the 94+ (3rd gen I assume) units? I'm assuming the newer M90 units are more sought after, and more expensive.

Assuming you could pick one up fairly cheap used, what does a rebuild kit run (bearings, seals, etc) and is there anything ultra special (ie special tools, or such) about rebuilding them? A good manual or write-up anywhere? Just wondering how much you can expect to sink into a good solid used unit, as a core, with a rebuild kit on it (assuming you are doing the work). Hate to trust an unknown used unit, but new is obviously expensive.

Have followed them on ebay, etc, but if anybody has any leads on used units from here (figured you guys would be the place to go!) that would be great.

Thanks for your help, looking to build a mini '03 Cobra motor (ie Eaton on an efficient 4 cam)
 
Well, not an expert on these obviously (far from it actually) There are a lot of guys on here who could answer this question better if they looked at this post. Anyways, the blowers themselves will last easily 150,000 + miles. I know this actually because I thought about rebuilding mine once and we had called eaton and talked to one of the engineers and they said there is no way that mine would need a rebuild at 100,000 miles (which is what it had on it at the time). So If you even found a blower with half-way low miles don't think it would require a rebuild necessarily. Changing the fluid tho that can be bought at hte GM dealer (because its cheaper) would be a good idea. As far as blower I do beleive the 94-95 were more efficeint. A lot? Wouldn't say a whole bunch but the difference in HP from one the old ones (210 hp) to (230 hp in the 94-95). But I am not sure if that all came from the blower. Best bet is to just find a blower and have it S-Ported. Plus....are you even going to need a blower that is as effeicent as the 89-93 years? I doubt you will be pushing the kind of boost the normal SC pushs which is roughly 12 PSI. And the M90 blowers work ideal at 7-8 PSI from what I have learned. And the compression already on that SHO engine has to be off the map.
 
If I understand my Ford notes correctly, the SC blower (at least 89-93) with a stock pulley turns at 2.6x the engine speed. I'm under the impression the safe rpm limit for the M90 is 14k, which means if I stick to the SHO's factory rev band, I can only turn 2x engine speed (14k on the blower at 7k redline). Fuel cut-off on the SHO is 7300 rpm, but with stock cams in n/a form, the torque is falling off pretty good past 6k. In boosted applications it tends to hang on a little longer, but still has to follow the cam characteristics somewhat. So if I spin the blower slower at only 2x engine speed (am I on the right track here, in limiting the blower to 14k?), I'm wondering if the older M90 units will be able to provide substantial cfm?

Yes the SHO's 9.8:1 compression isn't what you probably call "boost friendly" but with a good intercooler, good gas, and some timing retard, shouldn't be a problem. The SHO's combustion chamber (pent roof, central plug, large quench area, basically hemispherical) is excellent for preventing detonation in n/a, nitrous, and boosted applications. I run up to 100 shot of N20 with pump gas and no timing retard, never have had a problem in 2+ yrs. Typically the aftermarket on these cars lends itselfs to centrifugal blowers, which build killer torque at high rpm, especially with some higher lift/duration cams, but I'm looking to build lower end torque with the stock cams, intake, and larger displacement motor. The centrifugal blowers tend to take a couple thousand rpm to build boost.

I understand boost, as basically pressure, which as I understand it differs greatly from flow. Ie with an efficient motor, it's harder to build higher manifold pressure, due to not as much of a restriction. The SHO engine is very efficient, so no I'm not looking to build 12+ psi of boost, I frankly don't think it could unless you wanted to overspin the blower at high rpm. To get 13-15 psi on a typical SHO engine guys have to run vortech "17 or 19 lb" pulleys on their V1's or V2s. I suppose it's a reflection of flow, and pressure, but I would say a safe goal is to build 7-8 psi max. If you can build that at low rpm and hold it, enough flow to create 7-8 psi of pressure in the intake on a SHO, you'll make a lot of power (and will be flowing a lot of air). I know of applications with 7 psi max boost, on stock engines, running 300+ hp at the wheels with a max of 7 psi boost around 6800 rpm.

I guess my concerns (with the older M90) are with keeping with the 14k rpm limit on the blower (is this really an issue?), running it 2x engine speed (slower), and it still providing sufficient flow/pressure. Thus my question on the 3rd gen M90.

I'm somewhat familiar with the changes done to the 94/95 units, I've seen side by side pics. What's a typically price to get an older unit modified to 94+ specs? (s ported, or whatever you mentioned).

Thanks for your help,
mark-
 
Here a couple of places that do upgrades and rebuilds for the SC M90

Magnum Powers
http://www.magnumpowers.com/

BlueTongue Motorsports (Embree Machine)
http://www.bluetonguemotorsports.com/

Magnuson Products
http://www.magnusonproducts.com/

Thrasher Performance (4th Generation GM stuff)
http://www.thrasher-ep.com

All of the SC blowers are 3rd generation M90s. The rear inlet port was redesigned in the 94-95 models for more flow. It was changed from the early oval style to a larger rectangular opening. The units are interchangeable on the SCs just by having the correct style inlet plenum. The “S” model often talked about was done by Magnuson Products on the 94-95 units and is mostly some porting and smoothing for better internal airflow. Both Embree and Magnum Powers offer mods to both the early and late style blowers that far exceed the “S” model performance.

The 4th generation M90s are found on some newer GM cars. These units have an integral bypass valve. The external bypass on the 3rd generation units might be easier to plumb in your non-stock application. As you have gathered, an early style is more plentiful and cheaper as well. It would probably flow all you need for your application. You’ll need a custom inlet plenum and bypass setup. You night be able to get the SC parts and then cut and weld up the adapters to hook up to your TB and intake manifold.

I would recommend staying with the bypass setup since it allows unused air to flow back through the supercharger in unboosted conditions. At lower boost levels that you might be running, I don’t know if an intercooler will buy you much, but it won’t hurt as long as it is free flowing and does not create too much of a pressure drop. The boost levels can be controlled by swapping pulleys to slow down the rotors. A lager pulley turns them more slowly and a smaller pulley turns them faster. Embree makes a nice interchangeable pulley set and could help you get one to turn the rotors at a good speed. The 94-95 pulleys are the biggest stock ones you can get. Also, as you work out how you will drive the supercharger pulley, you can also slow it down by making the driving pulley smaller. On a stock SC the supercharger is driven by an intermediate shaft (jackshaft), This jackshaft has a double pulley that is driven by the crank pulley and then has another belt going up to the supercharger.

Another consideration if you are going to all the trouble to mount a supercharger on your SHO, is to consider a Whipple Charger.

http://www.whipplesuperchargers.com/

(I'm putting one on my SC this winter!)
 
Ok so all the SC's are 3rd gens. Thanks for the info. So probably the way to go would find an earlier one and have the rear inlet modified. Among the 3-4 places listed, which would be the best to deal with, with any blower mods or work? Any first hand experience?

So is spinning the blower past 14k ok? I would imagine if you guys are running smaller pulleys you gotta be going past that at high(er) rpm, (excluding any belt slip if applicable).

Also I would assume keeping the TB pre-blower would be better for tractability and tuning? Should be able to extend the throttle cable, custom mount the SHO TB to the inlet, and run the piping from the IC back to the stock TB location on the SHO intake. Could probably use a "dummy" TB here, keep the crankcase vent to attached, just take out the throttle valve and leave it fully open.

What size stock are the SC TB's? SHO's use a 65mm, same size as the opening of the intake behind it.

Thanks again for any info and help,
 
A little more insight...

As george accurately mentioned, the 94-95 Blowers Flowed more air at the same RPM as the 89-93 blowers mainly due to the larger inlet at the back of the supercharger. It was a rectangular opening rather than the earlier oval opening. This increased cross sectional area around 40%.

Another "advancement" that the 94-95 blowers brought were the specially coated internal rotors and lighter wieght nose cone drive shaft. The coated rotors allowed for tighter tolerances between the rotors since they wouldn't heat up as much and as such heat discharge was reduced. The lighter weight nose shaft meant reduced rotating mass and thus reduced parasitic drive losses.

Overall, the 94-95 blower was efficient enough that Ford spun the blower 3% less than the 89-93 blowers, also helping to contribute to extend blower life. Yet, the engine produced 20 more Net HP over the 89-93. THis is the main difference between the two engines.

Having said that, 14K is Eaton's "conservative" figure for these blowers. With proper porting of the Superchagers passages, a higher RPM limit is fine. Also a Machine shop like Embree will perform a rebuild with heavy duty bearings in the nose cone and even offers a high strength titanium nose cone shaft (for 89-93 blowers) that will allow a blower to spin much higher.

I would definatly make sure that your intercooling was in order before blowing boost on a high RPM 9.8:1 CR engine. 8psi boost will feel very dynamic and the sudden push of low end torque that holds steady will probably spin the crap out of FWD tires. Hope you have your traction issues already sorted out cause you're gonna have them pushing past 300hp to the front wheels.

Will an 89-93 blower accomplish your wants? Yes. But like every hotrodder, you want more and more, and it doesn't leave as much room later on to go faster. Not sure how much you want to spend, cause the whipple idea is really a good one, it has efficiency like a centrifugal but it builds boost like a Roots. Just wish I had the money for it!
 
Yes that would be nice! If i wanted to spend big bucks, I'd go with a turbo set-up. The idea is to keep the cost down though, and do something different. I've got a buddy looking to upgrade to a different IC (from a 1 core to 2 core spearco) so it's possible I could pick that up fairly inexpensive. It has worked fairly well on his SHO platform running 15 lbs of boost (450+ hp at the wheels)The idea of the M90 is to pick a used one up fairly cheap, run moderate boost and pick up the torque curve a fair bit.

Traction issues are not a problem, as I'm running close to 100 hp worth of N20 currently, with slicks it'll pull 1st gear at the strip with virtually no wheelspin. I also open track the car a lot, and I'm looking for an inexpensive way to get a nitrous-like torque curve on a budget, a used M90 roots seemed like a good possible idea. Will be nice to have a little more meat for open track, instead of running n/a (even though the car is still pretty quick n/a).

Thanks for the leads on the blower upgrades, I will check into those.
 
Well Good luck...

And let us know how you make out in relation to your tuning issues and what not.

Eaton's sucked through the throttle body, so Ford could retain the MAF.

A Good Used 89-93 Blower would probably run you in the $500 range. If I remember correctly. That's just the blower mind you.

A good used 94-95 blower would probably run you $800-1000. You'd see a bigger power increase over what you are running now with the 94-95. I just don't want to see you run about $2000 in blower and Computer and custom machining mods just to see a 50hp or so increase with a 89-93 blower running 8psi......

But if it is torque you are looking for, both blowers will provide plenty of it and in rock solid delivery.
 
Back
Top