What part of the turbine housing defines the 9.8 or 10.5 dimension? Is it the diameter of the opening behind the turbine wheel. If so that means you can port a 9.8 up to a 10.5

So does that mean that a ported housing is a 11.8 or something bigger?

Or is it a dimension that can't be changed by grinding etc? A picture with it pointed out would be great.

 

So here are some pictures to help explain my question.

Is the 9.8 or 10.5 dimension A or B. Because each one is changable when you do some porting. As you can see in the second picture the RED dimension has been hogged out. BUT I'm almost sure the A dimension is the area that seats up against the turbo cartridge.

So it would seem to me that any turbine housing could be made into a 10.5.

 

It actually refers to the area on the inlet side of the turbine

 

So is that somewhere in this area? It seems like that could be ported out also.

 

bump

 

I actually think that it is the cross-sectional area of the actual turbine scroll area. Which is not really something that can be changed. Since no one would comment I decided to actually think about it.

I'll have mine all apart in a few weeks doing some porting, maybe I'll do some measuring and post some real info.

 

I was under the impression that the 9.8 or 10.5 is the actual displacement of the opening where the turbine wheel rests. Meaning, if you block off the large opening and fill the hotside with water, and emptied it into a graduated cylinder, it'd measure either 9.8 or 10.5 ML, or cm-squared. I'm not sure if the displacement is gained in the large opening or in the runners, though. Correct me if I'm wrong, it's just my guess.

Matt

 

It's the cross sectional area of the turbone outlet AFAIK. A turbine outlet area of 9.8 sq. cm has a 3.52cm diameter. The 10.5 has a 3.66cm diameter. It's approximately a 4% difference in diameer and a 7.1% difference in area.

I would imagine it could actually be ported larger if you could match the profile of the turbine outlet. It is a machined curved surface. I don't know what would happen if you went larger, say to a 11.0 or 11.5.

I'm going to take some measurements and check this out... the machine shop at my work could easily do this work, I'm curious as to what would happen. I'm assuming it would have a similar effect as to clipping the turbine wheel, but maybe not. Backpressure would decrease because more exhaust could bypass the wheel.

Stay tuned...

- Steve

 

Dave Buschur stated in another post that a 9.8 cannot be ported to a 10.5. Not sure where I saw it. I am sure that he said it.

Found it:

https://www.evolutionm.net/forums/sh....8+ported+10.5

 

Cm^2 is not volume, it is area - so you can't pour it into a volumetric measuring device. But I understand what you are saying. I do think the number refers to the area around the turbine wheel.

So another question. Does the porting around the "B" area increase spool-up. I say this because it seems to be removing material in an area which helps contain the exhaust gases that spin the turbine. Basically creating less velocity, or kinetic energy to spin the turbine?? Maybe it increases spool-up but it allows more airflow and thus more top-end power, with a loss in torque?

 

I'm pretty sure it's the A in A/R ratio.

The real question is, at what radius is Mitsubishi measuring the area? To that, I don't have an answer. But my educated guess would be the radius of the nozzle opening, which would be the minimum area of the nozzle, because this can give you a good estimate of choke flow with a few simple calculations.

A/R ratio definition from "Maximum Boost" (yes I realize the diagram isn't very accurate, but it gives you a good idea):

 

You would think that the 10.5 size is the maximum size or net gain that can be achieved with our turbo - going beyond may cause cavitation around the turbine. And also the 9.8 was perhaps put on the 03's and 04's with the sole purpose to regulate the newly realeased USDM Evo VIII's power to test new ground and to see how US agencies accept it (If Kerry were president I often wonder if the IX would be as slow as the 03's and 04's).

I remember reading info from 2003 about myths pertaining to some sort of HP regulation around the manifold/ turbo briefed to Mistubishi technicians and dealers. Rumores stated that it was a smaller sized gasket. When that was ruled out the myth slowly disappeared, but I bet it was the 9.8 hotside they were talking about.

I would leave the 10.5 alone for thats the sme size on the original TME competitor and any change in its structure would likely destroy the unit, but we would never know until someone has the courage to try it, would we?

 

The formula for area is pi * d^2 / 4.

10.5 cm^2 ==> 3.656366396 cm diameter
9.8 cm^2 ==> 3.532385531 cm diameter

So which part of the turbine housing can have such a diameter? Forced Performance has this written on their webpage.

 

I've never seen the formula for area stated that way. I've always seen pi * r^2 or pi * (d/2)^2.

 

That's the same thing