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Eaton M90 Supercharger Teardown!

This is your blower.

This is your blower on drugs.
Any questions?

Click on the thumbnail to enlarge for full view.

Photo 1
draining oil.JPG (31468 bytes)

Photo 3
plastic coupler.JPG (29531 bytes)

Photo 5
removing rotors.JPG (30298 bytes)

Photo 7
v-underneath.JPG (24311 bytes)

Photo 9
inside inlet 1.JPG (21783 bytes)

Photo 11
inside inlet closeup.JPG (21989 bytes)

Seriously though, (not that drugs aren't a serious problem, but we can't help you there), we figured there just may still be some of you out there who haven't been crazy enough to totally rip your blower apart in a desperate search for power gains, so we thought we'd do it for you!

For those of you who've opted to replace the nose cone rather than invest in a reusable pulley removal/installation tool which provides a simple means of changing the pulley size on yours and everyone else's car, (we had to get a plug for our product in there somehow, ya know!), you're already intimately familar with the first few steps of this process!

Photo 1:  The first step to disassembly would be to drain the oil from the nosecone before removing the nosecone.   This is done by removing the breather nut, and tilting the blower on end and letting the oil simply drain out the end (be sure to catch it in a clean container!).   First remove the filler plug (on the side of the nosecone) with an allen wrench to relieve the pressure to allow the oil to flow out faster.  So, (show of hands) how many of y'all that replaced the nosecone knew of this trick already?  How many of ya that didn't wish ya did before you spilled that oil all over?

Photo 2:  This is the way things look with the nosecone off.  Obviously, remove the bolts holding the nosecone on and pop it off - you've already drained the oil so it's a fairly clean job!  Photo 3 shows the plastic coupler that couples the driveshaft in the nosecone to the rotor gear, and Photo 4 shows the rotor gears.  Nuthin' we haven't seen before from all the nosecone replacement photos.

Photo 5:  Now comes the cool part - the twisted helix rotors!  We very carefully slide these out, being careful not to touch and scratch the cavity walls with the rotors edge, and here's your teflon coated rotors in Photo 6.  Notice at the end of each rotor is a relatively small greased pin that inserts into the housing cavity.

Photo 7:  This is how the output of the blower looks viewed from the outside without the rotors, and Photo 8 shows the same view from the inside.

Photo 9:  Here's a view looking into the rotor cavity.  The "top" of the blower is in the left hand upper corner, while the "V" shaped output port is oriented in the left hand lower corner.  Photo 10 shows the same view zoomed in a bit closer.   Notice the opening to the throttle body on the upper side of the cavity.  The rotors suck in air through this opening and force it down and out the "V" shaped output port.  You can clearly see the two openings that the rotors insert into.   These contain precision needle bearings that appear to be greased with high temp wheel bearing grease, much like the needle bearings in a universal joint (in the drive shaft of a RWD car).  Notice the walls of the cavity - these must be precision machined as the tolerance between the rotors and the cavity walls must be very tight - any slop there and your boost pressure would suffer greatly.

Photo 11 is a closeup view of the inlet and a bearing, while Photo 12 shows the same inlet from the throttle body side.

Click on the thumbnail to enlarge for full view.

Photo 2
nose off.JPG (33217 bytes)

Photo 4
gears.JPG (28854 bytes)

Photo 6
rotors.JPG (22086 bytes)

Photo 8
v-inside.jpg (36687 bytes)

Photo 10
inside inlet 2.JPG (20781 bytes)

Photo 12
into inlet.JPG (16806 bytes)

Seeing this teardown, you can also clearly see why Eaton's specs list the max speed of this blower as 12,000 rpm for continuous operation, with momentary spikes allowable up to 14,000!  The obvious question is, what can I port or modify to improve blower efficiency and performance?  Sorry, but we don't have the answer to that one!  It would appear that some polishing and porting on the inlet and outlet would be beneficial, but we'd caution you not to try this at home.  A very informed source has indicated to us that without intimate knowledge of the flow patterns inside the blower, some things that intuitively seem beneficial can easily ruin the blower's efficiency!  It appears that some major porting work could be done inside the rotor cavity where the incoming air enters and initially "hits" the spinning rotors, and obviously the outlet could be smoothed over as well.  But, our understanding is it takes knowledgeable experience with these blowers to accurately and consistantly port/polish them correctly for improved performance.  We won't lie to you, we feel our experience in this area is insufficient at this time - not to say we won't be experimenting on the engine dyno just out of curiosity though, but we currently have no plans to offer modifications in this area.

  For more detailed information about roots type blowers and their adiabatic efficiencies please visit our intercooler page.

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