Supercharger porting article

I don't think this is a re-post, but I can't remember if I ever posted this before. If so, this thread can be removed.

Semi detailed overview of the areas in positive displacement supercharger porting:
http://www.superchargerperformance.com/supercharger-performance-tips/positive-displacement-supercharger-modifications

(Also related check their power calculator: http://www.superchargerperformance.com/the-power-calculator/power-calculator-v2-3 has a free limited time trial with username: test, password:drive )

We can keep this post here, but please re-post in the SC Port & Polish Write-Up:

https://rivperformance.editboard.com/series-ii-engine-transmission-f4/write-up-s-c-port-polish-t6145.htm#87108

This article mentions raising the roof height, but wouldn't that ruin the seal that the rotors have with the casing?

Old article.

Raising the roof was believed to allow the rotors to have a little more "air-grab" available to assist in rotor filling at high speed. The general consensus now is that this causes too much turbulence along the rotor edge and actually does the opposite. The best method now for improving rotor fill is increasing the duration that the front of the rotor lobes see. Hense why the TVS blowers have a higher twist, and almost 120 deg duration. (The twist has other benefits, but also allows more duration.)

Interesting. It seems that nobody ports the inlet and the throttle body. I would think that gains could be made by slightly porting the supercharger inlet and the throttle body and creating a custom throttle plate that would be larger. Obviously it would have to be tuned, but wouldn't it allow the m62 to flow more air if paired with smoothing of the outlet?

The inlet on our blowers are hard to get an improvement on. The gen3 m90s sometimes have a slightly off center bore, and can improve by being bored to match the TB or to match a northstar TB.

An interesting note, the throttlebody on our series one is bigger than the stock series 2 one.

The Ford Super coupe crowd blower is often modified to great success by opening the gulp of air the blower can get. Basically they make it so the blower really doesn't have to do any work at all to take in air. Its esentially opening the inlet and the air exporure at the ends of the rotors. But our design of blower inlet makes it all but impossible to get in there and add that capacity. If you look in at a gen 3 m62, then a gen 3 m90, and then a gen V m90, you will see that Eaton slowley started opening that part up.

What makes the gen 3 m62 inlet difficult to enlarge, is it the shortness of the casing?

You could enlarge the inlet all you want, but the surface area where the path actually enters the rotors would always be the same. With the twist on the rotors, and the small diameter m62 rotors, you wouldn't have enough room to even open it if you could reach in there without killing the ratio of inlet/dwell/outlet.

IE: yes you could open our inlet, but there is not room on the m62 to open further up at the rotors without rendering it useless as a blower.

Thanks, that makes sense. The only rotor option for the gen 3 m62 is to customize it to fit the new m62 rotors am i right? Has there been any work with this?

no one has done this to my knowledge. The newer gen 5 m62 rotors are very much like the gen V m90 rotors. The bearing plate is thinner. Also they are pricey to find.

Dang, I guess it would probably be easier to modify the ford m90 to fit.(nothing i could do)

http://www.camarohomepage.com/THRSS/supercar.htm
(Part way down)

Another great article describing the new TVS blower. It also gives description as to the "scilencer" holes and Eaton's ratonale for them. This is the most direct quote I've found from Eaton themselves about the subject, right from the TVS development chief Mike Sitar.

Quote :

There was more work on efficiency and noise reduction at the supercharger outlet. "Backflow ports or 'slots' were added to the 3rd generation, primarily to quiet the sound of the supercharger," Eaton's Development chief for the TVS, Mike Sitar, told us.

"Backflow is the method of compression within a Roots device. Air enters the inlet port, gets closed off by the rotor faces, then transfers to the outlet at inlet pressure. As it hits the outlet port, if you didn't have backflow slots, the air would immediately rush backwards, through the outlet port, to bring that cavity up to outlet pressure, then the rotors would come into mesh and force the air back the other way, through the outlet. That's a full, air flow reversal in the outlet port.

"That reversal creates a high level of pulsation and noise. Backflow slots allow the air from the outlet to begin pressurizing that closed chamber before it moves to the outlet port. They allow air flow, into the supercharger, through those ports, then out the outlet port, maintaining one-way flow through two different ports. We took a percent, maybe a percent and half hit in adiabatic efficiency, but it, also, allows a one to three decibel decrease in noise. It does impact efficiency of the supercharger, but our biggest goal was noise reduction.

"The TVS does not have those backflow ports," Sitar continued. "Its backflow function depends on flow from the outlet to the rotor bore. There's actually a hole–we call it a "blowhole"–located within the rotor mesh. When the rotors mesh, there's still an open area that connects the rotors across the top of this cusp within the supercharger. In TVS, backflow occurs within the rotor set itself. The air is never moved to the discharge port, then brought back in.