Thread: ported gen 3 blower tend to increase boost?

I've been out of the wbody for a while but cant recall if/when porting a gen 3 outlet if it generally increases boost at all? I had thought not, since it's merely to lower the amount of heat due to the sharp edges in the outlet. the story here is that im helping out a local member where when I tuned his car it was on a stock blower running 7-8psi. before I sold my gtp, I swapped blowers with his so he was able to get a ported gen 3 blower. I believe the inlet's also been opened up a bit. he's now reporting via ls1m scanner that it's running on average 9.5psi and max of 3* of KR with 1-2* constantly on stock pulley. he also has u-bend delete but I believe stock manifolds still. for the time being, he's running with the BBV unplugged so boost is cut at 3-4psi safely. thanks for reading.

wtf?

tanks, im hoping to get feeback from users in this community who has had experience with the roots type gen 3 blower housing.

Boost should increase if it's ported properly. However, you will probably not notice it on boost gauge. It may even be hard to spot via the map sensor.

Found this a couple hours ago. Had trouble linking to the specific page after I got back, used fb for the text.

Hopefully, this is more helpful. This is reference to a GenIII, not Gen V. (sorry it's a wall of text)

"Ok, Well I've been doing some searching around for answers to see if i should do this, and for the most part, the average lightly modded engine will see no big gains from doing this kind of work. However, a gain is a gain, just dont expect any night and day differences here.

A few other things i happen to know about this charger; Shaving down Rotor Wall is not recommended, AT ALL. The tolerance built into the m90 is exact and to open it up would only allow the air somewhere else to go rather than being compressed by the rotors. Do not do this. You'll lose boost or efficiency, or both in the long run.

Reffering to Harps500's "After" picture of the triangle portion of the outlet, where he removed the two humps, the two slits on the left and right side of the triangle's are silencer ports. (the pic no longer exists) They are there to bleed off some airflow and cause reversion which is what the Eaton engineers use to help reduce noise. You can fill them in and smooth them out and the blower will whine louder...It's also argued that it further smoothes out the flow and will yield marginal gains because the reversion is not only turbulant, but reheated as well, two power no-no's.

Be very careful on how you accomplish this as warping the M90's alloy case is easy to do if not allowed to cool completely between welds. A High Quality epoxy can be effective.

[irrelevant]

Thrasher's stance on this subject can be found here; (Cannot find Thrasher Performance)

L67 Supercharger Teardown - Thrasher Engineered Performance 3800 & 3800SC Pontiac Grand Prix GTP & Buick Regal GS

Also, Stiegemeier has made quite a name for themselves doing this kind of work on the Mustangs however they specialize in Eaton blowers. I hit them up and they do a full porting service and offer a 1yr gaurentee on their work. They were about $400 on a 1 week turnaround. They could do a show quality finish as well for more, although i dont remember what that price was...

You can find them at Stiegemeier Porting Services, LLC - (link in post above)

A guy that I work with has used them on his 600hp Cobra and says these guys are the real deal.

If you're going to do anything to these things, I would put an intercooler on your short list of mods. It will only enhance EVERY other mod you do in the future and free up tons of power. Of course this is a porting thread, not an upgrade, but food for thought nontheless.

Knowing i will only see minimal gains, My plans are at this point to do it anyway, just because I have access to a lathe and will only be out the cost of a few gaskets"

That answered alotta my own questions. If all you want to do is dial out that KR, there's probably cheaper/better ways.

Funny thing is that there's really nothing NEW to find on this platform. If your looking for that long lost Unicorn that nobody has found forget it. The real problem is that web sites, forums and whatnot that HAD the information as slowly dying off...

The M90 is terribly inefficient and when you consider dropping pulleys, exceeding the spec design, you really have a lot of loss from heat and rotation drag, etc. is why KNock is a killer. You will increase volumetric efficiency by porting, smooting the flow, but this must be coupled with ported TB or a N*, and imo manifold and even heads to reap full benefits of porting the blower.

and you will be at a disadvantage as well to not know the success and failures in the past of experimentation with the M90, there were major threads about both Trasher and Steigemeier. Bottom line is that it is best to just get a GenV if you want better efficiency! If you want max boost, you'll have to make some major changes and put an Whipple on there ; )

^like animuL did years ago lol. I only wanted to confirm with my friend that's on stock pulley whether a ported gen 3 m90 would increase boost or not that's all :-)

I dont think porting on a stock setup will change a thing. You may increase flow a little bit, but early ZZP research on their SC dyno showed that even a stock setup suffered from a vacuum deficiency due to a restrictive TB design. That is, you could improve the flow but the stock TB is unable to flow enough air to keep up. Drop a pulley, free up the exhaust, install an intercooler and a ported TB or N* and then you could look at porting the SC outlet and smoothing the hump out of the inlet.