UK fella needs supercharger help!!!

Hi All,

I'm not overly familiar with these motors, residing in the UK. However - i am after an Eaton M90 to supercharge my next street racer engine with (2000cc / 122ci). The M90 as in the Supercoupe seems to fit the bill perfect, both in boost output and dimensions, from the pictures i've seen of the units.
FYI - The unit it's going into is a Vauxhall (opel) 16v unit, and will need around 18psi - hence why i'm choosing the M90 rather than the M62 - it is also going to have a redline around 7000 rpm, so according to my calcs (not taking into account overlap mind - cam spec still undecided!), will give 17.5psi with a 1.7 drive ratio (blower = 11900 rpm) at 7K rpm....
From what i understand of the Eaton M90, it can be overdriven past 14k rpm (was surprised to read the speed is around 15k on some SC models!!!), but the efficiency is dropping well off much over 12k rpm.

So - i have many questions!

1) What exactly do these engines appear in, and how common are they over your way?

2) How many different 'generations' of M90 have been on these engines, and what were the differences - somone over here told me the gen3 on used 'teflon coated' rotors???)

3) What years of motor can i get these 'chargers from?

4) Is there anyone who would be willing to export complete
units - ie inlet/throttle body/bypass unit, top-hat, and supercharger complete - whether in one off or bulk purchase?

(now we get a little technical)
5) What is the difference (before and after results for example) between the earlier M90 and the later M90s?

6) What do people modify the 3.8 supercharged engine to (both mild and wild) - bear in mind i'm more interested in the effect on the supercharger characteristics, blower reliability at higher pressures, etc...

7) What can be done to improve them? Does porting the inlet and outlet really make a difference (before and after tests for example?)

8) At what pressure / power does that 'top-hat' become restrictive? (it looks just the ticket for me, but is it worth modding to make it flow better?)

9) What are the checks to a 2nd hand 'charger, how long do they last, and what goes wrong with them?

As i said, i need a M90 from a SC. The only superchargers really available here are the M45 and M112 - nothing in-between.
The SC has the right kinda manifolding that i need aswell - again, any blowers sold over here are usually bare units, you get a blower with a pulley, and that's it!!!

So, if anyone has a complete setup consisting of top-hat, inlet arrangement and a good supercharger, or even just piece parts that are surplus to your requirements, let me know! I have two freinds who would be interested aswell...

Many thanks!
Dave


davecoxon@eaton.com - the gearbox, not supercharger division unfortunately!!!

1) What exactly do these engines appear in, and how common are they over your way?

Ford used the M90 in Thunderbird SC's from 89-95 and Cougar XR7's from 89-90. They are very common and can be found on Ebay (or from many members myself included) in varying condition from $150-$500.

Gm used a similar version on the Grand Prix GTP, Bonneville, and some others from 98-up I believe.

2) How many different 'generations' of M90 have been on these engines, and what were the differences - somone over here told me the gen3 on used 'teflon coated' rotors???)

Really the only ones available are the gen1,3,and 4. The Gen 1 was from 89-93, Gen 3 is the 94-95, and Gen 4 is the GM version. The later generations used a coated rotor which greatly added to efficiency expecially at lower rpms, however these coatings are subject to failure at high mileages.

3) What years of motor can i get these 'chargers from?

4) Is there anyone who would be willing to export complete
units - ie inlet/throttle body/bypass unit, top-hat, and supercharger complete - whether in one off or bulk purchase?

Sure.

(now we get a little technical)
5) What is the difference (before and after results for example) between the earlier M90 and the later M90s?

Most people see a 1.5psi boost increase and about 20 HP for the newer versions.

6) What do people modify the 3.8 supercharged engine to (both mild and wild) - bear in mind i'm more interested in the effect on the supercharger characteristics, blower reliability at higher pressures, etc...

This motor puts about 185HP to the wheels stock, and up to 400 to the wheels modified. The Eaton blower is not ideal at high boost levels. Power consumption and heat become major factors over 15psi. Reliability is not an issue although at speeds above 20K rpm can result in case distortion and there have been some issues with front seals leaking at pressure's around 20psi.

7) What can be done to improve them? Does porting the inlet and outlet really make a difference (before and after tests for example?)

It makes a lot of difference, however it is a bit of a science and what seems like a good idea doesn't always increase performance.

8) At what pressure / power does that 'top-hat' become restrictive? (it looks just the ticket for me, but is it worth modding to make it flow better?)

Keep in mind that a positive displacement blower is not generally affected by restriction. The biggest problem with a restriction in the pressurized air pathway is the heat generated by the resulting pressure node. So a restriction = heat which is already a problem with this blower design.

9) What are the checks to a 2nd hand 'charger, how long do they last, and what goes wrong with them?

They bearings/seals go bad in the nose cone. There is also a nylon coupler which wears out in the cone. Fore/aft rotational play in the nose cone is typical in a 100-200K mile unit. Rotors can be damaged by debris in the intake tract. Both items are easy to check visually.

Check these sites for more information.

www.magnumpowers.com

www.magnusonproducts.com

Another difference between the Ford and GM versions is the bypass valve. This is done externally on the Ford and internally on the GM version. An internal valve could be easier to adapt depending upon your application setup.

The GM versions are also setup to "blow" out the bottom where the Ford version is set to "blow" out the top. If you want intercool your setup each one type can have it's pros and cons.

The early style (89-93) Ford blower can be identified by the oval opening on the rear of the blower case. The later style (94-95) has a larger rectangular opening.

Thanks for the reply's thus far! I'm so glad i found this board!!

The Eaton blower is not ideal at high boost levels. Power consumption and heat become major factors over 15psi. Reliability is not an issue although at speeds above 20K rpm can result in case distortion and there have been some issues with front seals leaking at pressure's around 20psi.

When you say this - do you mean when applied to the 3.8 lump, or just generally - i mean, is the power and heat related to the speed it is driven at, or down the the basic design? Or to put it another way - I reckon i'm unlikely to see the same problems at the higher boost levels with only a 2000cc engine - you agree???

As a matter of interest, what CR do these engines have as std? And what RON / Octane fuel are you limited to? (we can get 98RON at Shell Fuel stations - great for the turbo engines!!!)

As I said - If you have M90 units, ideally with the top-hat and inlet units, and are happy to post to UK, please Email me!

davecoxon@eaton.com

D

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