Porting Your Supercharger

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Originally Posted by 87IROCZOWNER69

Some people have talked about blocking those "silencer holes" in previous threads, however no one has come to conclusion on the best way to do so really. All I have heard is to not use JB Weld or anything else that could break up. Those who have said it is very noticeable sound difference and you can even hear the supercharger whistling on idle.

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Don't waste your time with it. Doesn't make much of a difference and puts you at risk of tossing something down the intake.

The best way to do it is to machine in a recess so a blockoff plate can be put in to cover the silencer ports. Someone did it, I forgot who.

Do you use a dremmel or what?

Dremel is going to take a long time. Pneumatic die grinder carbide bit and a good 2-stage compressor.

Please don't ever ruin your supercharger by porting it like the ported blowers in this thread.

how would you port it?

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Originally Posted by SnowFlake

Please don't ever ruin your supercharger by porting it like the ported blowers in this thread.

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lol?

work on the inlet, remove the bolt bosses, chamfer outlet while remaining stock size.

ok thanks

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Originally Posted by SMazza

The main difficulty with M90 blowers is getting the air in so the rotor cavity is filled. These particular blowers (GM Gen 3 and Gev 5) have pretty generous inlet ports to begin with, so the main problem is out of the way already.

If you compare the inlet ports on these blowers to the early M90s as used on the Thunderbird SC, you will see how much the inlet has grown over the years. Aftermarket products like the Magnum Powers MPX case have gone even bigger on the inlet that these blowers ... but those are designed to be spun very fast and give major high-RPM boost. There is a trade-off between minimizing boost leakage at low RPMs and maximizing airflow at high RPMs, and the MPX is skewed toward maximum performance.

Here is how to tell how far is too far. At the point where the leading rotor opens to the outlet port, the trailing rotor had better not be open to the inlet port. Otherwise, the pressurized air in the LIM will force air back out the inlet port. So that is the key thing to check.

Don't worry about the two small silencer ports ... they might let a small amount of air bleed back from the LIM, but it is by design, to keep the blower less whiny. Old people buy Regals, you know.

As for beveling the outlet port: Don't bother beveling the edge facing you. What would it do, help the air make the turn out of the outlet and shoot to the sides of the case? That doesn't make sense. Beveling (or filleting) the edge on the inside of the case is a good idea. It will help the air make the turn out of the case. Removing the bolt bosses (or not) is up to you. At a minimum, remove a little material to smooth out the airflow from the backside of the bosses out of the case.

The other problem that the early M90 had was control of the rotor clearances. The coated rotors in the second generation helped that issue, and the Gen 3 and Gen5 benefit from it.

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Very interesting post.