did i over port my m90?

ericjimmysfl

Registered User
Well this was my first time porting something just wanted to know if i over ported please let me know thanks
 

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Its hard to tell

The M90 needs about 120° of case between the inlet and outlet for the rotors to seal properly.
Without the rotor pack installed to visually confirm that they are sealing its hard to tell. If you did over port you will see a drop in performance.
All I can say for sure is that most port jobs focus on the inlet and do minimal work on the outlet and it appears you took quite a bit of material on the outlet side.
 
I would say yes It is overdone. The blower inlet is where the porting matters. Will it affect performance? I think it will not make a measureable diffrence. Any diffrence, I think would be toward the negative, just my 2 cents

Ken
 
What are some red flags to look for when checking out a late model super charger?

Porting for certain. You need to look at who did the porting, rebuild, ect. Your best bet is going to try and find an unmolested one and have it done right. That would be your safest bet
 
Porting for certain. You need to look at who did the porting, rebuild, ect. Your best bet is going to try and find an unmolested one and have it done right. That would be your safest bet

Also, look at the rotors and see if the coating is coming off or the leading edge of the rotors look worn. Ask if they ran any overdrive on the blower. If you can look at it in person before buying turn it by hand and look at the end of the snout behind the pulley to see if the nose seal is bad. If its hard to turn by hand then you may want to avoid it. You can also buy one and plan to have it rebuilt just to be sure everything is in good working order.

Also to give you ideas on inlet porting look closely at this thread http://sccoa.com/forums/showthread.php?t=94951
The idea being to remove the sharp steps in the lower corners of the inlet.
 
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How easy should it be to turn by hand? Should it spin, keeping its momentum for a few rotations?

It should spin easily with no binding feelings. If you feel it binding at 1 point in the rotation that could mean the rotors are hitting one another, which is not good
 
Another thing to note is that late model blowers had a spring loaded coupling between the nose and rotor pack. This means if the blower is a late model and unmolested you can turn the pulley about 1/8 of a rotation before the rotors start to turn.

I know the first time that happened to me I almost went off on the person who sold me a good condition late model. :eek:
 
Another thing to note is that late model blowers had a spring loaded coupling between the nose and rotor pack. This means if the blower is a late model and unmolested you can turn the pulley about 1/8 of a rotation before the rotors start to turn.

I know the first time that happened to me I almost went off on the person who sold me a good condition late model. :eek:


lol, that's good to know.
 
Im not sure if ur porting will help alot, or id its over ported
Heres a pic of mine I removed 1/4" from the outlet and a little bit more on the tip honestly I had thought I overported mine but it turned out quite great for me
How much did u remove ? U did measure right

From all I read the gains come from the inlet
The outlet doesn't matter much
My blower still worked great after porting and its a late model made .5psi more after i ported it ~16.5 psi on 10% pulley and flaked off rotors
however opening the outlet makes it more of a top rpm range in my opinion its how I felt it

Not much u can do to early cases I hear but there is some work u can do
I say
Get a late model and do some homework on porting before u do it
Or send it to someone that knows how
 
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If u replace the coupler with a solid 1

Another thing to note is that late model blowers had a spring loaded coupling between the nose and rotor pack. This means if the blower is a late model and unmolested you can turn the pulley about 1/8 of a rotation before the rotors start to turn.

I know the first time that happened to me I almost went off on the person who sold me a good condition late model. :eek:

NO SLACK WILL IT HARM THE LATE MODEL SC ????:eek:
 
All the replacement couplings I have seen are solid. As far as I know the solid piece won't hurt anything. Fewer moving parts are always a plus in my book

My $0.02 is that a solid coupling is one less part that can break and get into the timing gears.
 
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