The 10.5cm is the area of the nozzles in the turbine housing (turbine housing inlet), which is also the ares of the outlets on the mani. So, no matter how much porting you do, the biggest it's going to be is 10.5cm^2 because the gasket is likely what is truly 10.5, while the casting ends up undersized.

 

Oh, really? I did not know that. I thought it had to do with internal turbine housing volume or something.

I found this here: https://www.evolutionm.net/forums/ev...ml#post2769621

"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.

Quote:
What's the difference between 6cm2, 7cm2, and 8cm2 turbine housings?

Contrary to what your friend told you, a 7cm2 turbine housing does not have an inlet that is 7cm across. The 6cm2, 7cm2, and 8cm2 designations given to Mitsubishi turbine housings refer to the area of the cross section of the housing, known as the nozzle area."



So, how do I get someone to measure my gasket then. Also, if true about non-ported units, that means most people running one don't have a 10.5cm housing lol

Also, I checked my MHI housing last night, and it's A3N material...which is a slightly better Herculite formulation from Hitachi. I think my old housing was F5N.

 

The 10.5cm^2 is not the diameter of anything, its the "cross sectional area" of the inlets. Since they are not a circle, they don't have a diameter. You really wouldn't be able to measure it by hand since the corners are round. You would need to use a scanner and scan the housing into a modeling software and measure them that way.


If the number was housing volume, it would be a cubed (^3) number, not a squared (^2) number.

 

Right, sorry. Should have been more clear when I pulled those quotes.

Question is, where does Mitsubishi measure the cross sectional area? Not the actual openings, but probably further in at the scrolls, correct?

 

I'm fairly certain its the opening.

 

Found this (everything you read on the Internet is true):

The cm^2 that you see on mitsubishi turbines is actually the smallest cross sectional area at the throat of the turbine, right before it opens up and hits the wheel. This tells you a bit about what the velocity will be going into the turbine.

I'm just curious and looking for info at this point.

THat quote came from the 7th post in this thread:

http://www.galantvr4.org/ubbthreads/...page=8&fpart=1

This was also interesting. Porting doesn't change area, but it changes A/R.

"Also, when you port a turbine housing, you are basically changing the A/R ratio by increasing the area. The reason you get better spoolup from porting is that the higher A/R performs better at higher flow and boost pressures. Up to the stock boost level, the turbine will spin up slower, but above that, the lower restriction wins out over the higher velocity because it gets too turbulent (it works exactly like head porting - there's an optimum "mach number" that results in the most efficient flow)."

 

Yeah, I'm not sure, I've found conflicting info on where it's measured. Although, the housing gets TINY down by the turbine, so Idk if it's 10.5 down there. It certainly doesn't look like it.

 

you are not really gonna find a good explanation of how a/r is calculated. you will find plenty of conflicting info. I started this thread when I was trying to determine what size a/r the new housing I had actually was. I think I have a pretty good grip on what a/r is. its bascally the area above the wheel. called volute. also called snail. also called nozzle area. all referring to same thing. bigger a/r has more area. which both cools and slows the gas.
http://www.dsmtuners.com/threads/6cm...post-153565537

 

Way to ruin this mans thread guys LOL

 

I feel like we expanded on the discussion with lots of good information

 

So, how long until the old MHI housings crack. I am thinking this with a Magnus intake, and an optimized intake (cold air) and with the car I am thinking of getting I can be close to 600whp w/o over-spinning the turbo on E85. That being said, 575 is just as good if it is FUN FACTOR/TORQUE.

 

First thing you want to do is look and see if the housing says F5N or A3N. Those are two different formulations of Hercunite from Hitachi. The A3N can resist temperatures of up to 950* C, while the F5N has an upper limit of 900* C.

http://www.hitachi-metals.co.jp/e/pr...eg/p06_01.html

I checked, and luckily mine is A3N. I also got mine cryotreated and ceramic coated inside and out. Not sure if the cryotreating will help, but it was cheap. THe ceramic coating should definitely help keep heat out of the housing.