What Rpm range dose the eaton M90 become ineficent

blown96bird

Registered User
I have the allen supercharger kit on my 96 v8 thunderbird. It uses a eaton m90 supercharger. The car has a 6.5 inch harmonic ballancer and has a 2.5 inch pulley. I am turning the blower 15100 rpm at 5800 rpm with the smaller pulley. I was turning it 13500 with the stock pulley. @ what rpm dose the rpm start losing efficency and just heat in the air.
 
Most of the the data on this link stops at 12,000 rpms. I believe effeciency starts dropping like a rock after 15,000 on a stock M90. The earlier generation versions are even worse.

http://www.capa.com.au/eaton_m90data.htm

I'm spinning my MPII/ESM Frankenstein M90 to over 22,000 rpms and only showing about 130 degrees on the air temp sensor.

David

PS: This site also contains lots of data on the M90

http://www.magnusonproducts.com/m90.htm
 
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David Neibert said:
Most of the the data on this link stops at 12,000 rpms. I believe effeciency starts dropping like a rock after 15,000 on a stock M90. The earlier generation versions are even worse.

http://www.capa.com.au/eaton_m90data.htm

I'm spinning my MPII/ESM Frankenstein M90 to over 22,000 rpms and only showing about 130 degrees on the air temp sensor.

David

wow david, is there anything special about your blower? or should i be able to spin my magnaport II that fast? is it worth it to spin it faster than a 10% would? or does it just get to inefficient at that point?
 
wow david, is there anything special about your blower? or should i be able to spin my magnaport II that fast? is it worth it to spin it faster than a 10% would? or does it just get to inefficient at that point?

The blower is a little special, and is basicly a cross between a Magnaport II and ESM Dominion IV. It has late model rotors, MP II case, MP inlet plenum, ESM nose cone with titianum shaft and upgraded high speed bearings, viton snout seal and most recently a heavy duty seal retainer from MP. I use BP2380 jet/turbine engine oil instead of the supercharger fluid supplied by Ford or GM.

Just about everything imaginable has been modded on my engine to flow more air in and out and to make sure there is plenty of fuel to go with it. I have to overdrive the crap out of it, or I won't get enough air to make good power. Eventually I'm hoping to get a more efficent supercharger, like the 1.6 Autorotor.

I wouldn't overdrive your MPII more than a 10% unless you have exhaust work, better flowing heads, matching cam and upgraded fuel system. It's very important to get a dyno tune after adding an upgraded blower like the MPII, because your most likely going to be running lean. Without that stuff, higher boost just provides more bottom end torque but kills your top end HP. Don't go over 15 or 16 pounds of boost, unless you have a stronger bottom end.

David
 
Why not upgrade to a whipple 2.3 L

Why not upgrade to a whipple 2.3 liter. That way you won't have to spin it that fast.
 
food for thought

wow Dave ...I do know the stock nsk bearing part# 6203DDU8AC3E**X28U01 have a max rating of 18,000 rpm ...talk about living over the edge ....

effeciency..as Dave lightly mentioned ..air temp... is the key to effeciency..the cooler the charged air ..the more volume of air that can be forced into a cylinder to be ignited ..pressure equals heat ...heat expands meaning less volume ...this is on the intake side ..next it has to leave the cylinder..on the exhaust side ..and depending on how restricked the exhaust is..the more back pressure it will create ...on the intake ..that will allow the precharged air in the intake manifold and intake runners to start to heat soak and expand from heat transfer ..once the intake valve closes ..in short it has to get out of the engine .. to keep the intake charge cool for combustion.. through out the rpm range ...next comes how much power does it take to turn the supercharger ..I heard it's some where near 70 hp at high rpm stock ..so you could be loosing hp by trying to spin it really high ...and as most SC owner know 89-93 m90 spin faster than the 94-95 m90 but the 94-95 is more effecient turning at a slower speed .. and has the numbers to back it up ..
I know I haven't really answered your question ..I'm hoping you can see how .. spinning the blower faster through out the rpm range will effect the effeciency of the motor ....
 
Blown96,

I think the 2.3 is overkill and is also too large to fit under a stock hood. Because of it's width and length it will only fit the top of an SC engine using the bottom exit with an air to liquid IC. I'm sure a 1.6 with top exit going through the MP front mount IC that I already have will make all the power I need to run high to mid 11s.

I'm told this has already been done several years ago on Jerry W's SC and he was running 11s with far fewer mods than I have.

MercsSC,

I'm not using stock bearings, the ones I have are part of the upgraded ESM nose cone and are intended for use in a high speed CNC lathe. I believe they are rated for something over 25K rpms. Since I'm usually only spinning at max rpms for a few seconds, I don't think it's going to hurt anything.

Yes, heat and HP consumption are the big problems with the M90. After talking to Charles Warner, I believe some of the heat soak is coming from the engine and could be reduced by using some type of phenolic spacer between the SC and inlet plenum an also between the SC and intake manifold. The Lightning guys are getting good results using similar heat isolating spacers. Charles said he is looking into doing something similar for the SC, but there may not be enough room.

David
 
I read that the stock configuration (2.6:1 ratio) on an 89 turns the blower at 15900 @ max engine rpm. So it is safe, not sure about efficient.
 
David,
I got a big block of phenolic with the intention of making heat spacers, but like many things I have been too lazy to follow up on the idea. One problem with doing this with stock IC and tubes is that if you raise the blower and the return plenum by 1/4 or 3/8 inch, the lower tube is not going to fit properly under the P/S pump. You might be able to do it with FMIC or other set ups.
 
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