supercharger(m90 or eaton) rotors rear end clearance to case needed A.S.A.P.?

suutari

Registered User
if anyone has a blower lying around somewhere near and would be generous to measure the cap between the rotor ends and the case at the rear end with feeler gauge that would be really nice :). The feeler has to go all the way and touch the rotor shaft to get accurate measurement and do it couple of times for different lobe and lobe angle.

should have measured it before dissassembly,but I think I lost the notes :(.... front end has 0.006-0.008in now, but as we know the blower rotors are expanding to the rear end direction..

This is the project that I need the info.
http://www.student.oulu.fi/~samila/ahdin2/new/

some new pics :). almost done..tomorrow I´m assembling the gears and still have to do a spacer from really thin sheet metal to bring the case clearance to normal since the rear end has warped little during the tig welding. anybody happen to know the rear end case clearance stock? Other roots blowers normally are set to 0.01in...but how about eaton m90? Well anyhow, the leakage will be minimal after it spuns up since volumetric efficiency increases as the blower speeds up so I´m not going to worry about it+if the clearance is more, I can speed it up even more ;)...Just that it doesn´t expand to the wall and..you know what.

PS: by the way..old type blower clearances between lobes are 0.01 on both sides of the lobe... With new bearings. Sounds quite a lot. Rotor tip goes somewhat closer to the chamber walls. I would estimate aprox. 0.005in(if I remember right). I can measure it tomorrow after I get the gears assembled to the rotorback. If these measurement are of the regulars you can write here your results so we can compare. Rear clearance I can shim to whatever if I can find good sheet metal like offset print aluminium etc :) and machine the case later to exact dimensions if it seems not to work with little more rear end clearance. If anyone is interested the aluminium peace that has been casted inside the blower is attached with loctite epoxy that is rated up to 180'C and for aluminium joints. It has been torqued down to case with 4*M3 bolts too..

Well see what comes out of this anything more than broken parts ;)...
 
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good stuff

i was looking at the pics you had and thats pretty good work buddy, what have you improved on it though? rather how much more efficient is the SC now? is it better now than if you bought a new one?
 
It`s the same kind desing+port shapes that magnuson uses on magnaportII...
clearance problem if somewhat solved ;)..and the main reason was the front bearing plate distortion by little from removing the rotor bearings.
The charger needed complete rehaul so why not port it the same time :).
billet,billet billet...

I´ll see the results when I can get to the car and measure the volumetric- and thermic efficiency of the blower..until that a lot of work :)...


cheers, sami

PS: specs still needed if someone has them. I can tune down the clearance later too if needed etc. any measurements are okay. Now the clearances are pretty good. Between rotors 0.25mm eather side,front plate/rotor face 0.15mm, rear plate/rotor face 0.25mm, rotors tips to case 0.15mm
 
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