Id really like to know the A/Rs on my Mitsubishi turbo (TD-07 25A) used on my Panspeed turbo kit. If this is possible to do just from the measurements, and anyone knows how and wouldnt mind, Id appreciate it. Id just like to know what to expect from this. Here are the measurements I took:

Compressor Inlet: 66.5mm
Compressor Outlet: 54mm
Exhaust Outlet: 73mm

Thanks alot.

 

ALso, these are measurements of the ID of the actual housings, so take maybe 1-2mm off for diameters of the actual turbine fins.

 

My guess is it's the ratio of input area (rectangle circumscribed by two fins, housing, and turbine base) divided by exit area, to give compression ratio. It may be hard to do if the fins are curved on the inlet. That would require cutting.

 

Thanks , anyone else know for sure?

 

^

 

The "A" in an A/R ratio is the cross-sectional area of the smallest intake passage in the turbine housing before the passage spreads around the circumferential volute that leads to the turbine wheel. The "R" in the ratio is the distance from the center of the "A" to the center of the turbine wheel. The MHI "6cm2" designation is just the "A" in the A/R ratio, that is, it is just the cross-sectional area. Like A/R, the smaller the size of the "cm2" number, the faster the exhaust gases will discharge onto the turbine wheel, and so the faster the spool up will be (less "lag"). The size of the "cm2" number or the A/R ratio also determines the amount of exhaust gas backpressure and, thus, reversion into the combustion chamber. A larger "cm2" number (or larger A/R) means less backpressure at high exhaust flow. Extreme Turbo says that the TD05H-7cm2 housing is equivalent to a 0.50 A/R. I would guess the TD04-6cm2 would be equivalent to an A/R of close to or a little less than 0.50.

 

So to find "A" I would just take the area of my compressor inducer ( A=Pi * R^2, which would = 208.91), but then youve lost me on what the R calulation is.....

 

The thing is, A/R is very relative, the stock TII turbo is a 1.00 (S5) or very close too, but I think we can all agree a turbo with a Ptrim exhaust wheel and a .96 A/R will flow a WHOLE lot more. Since you have a TD07H exhaust wheel it'll be very hard to compare with Garrett turbo A/R because since its a ratio even though 2 numbers may be the same they describe a very different situation.

 

Yea, I was trying to get a idea of size to compare to Garret A/Rs, being they are more common and would give me a good idea of what to expect, I guess I didnt think it would be that difficult.

 

 

You can't compare A/R ratios between different turbos. It is only relative to each particular model of turbocharger. You can only compare your turbo with the experience of other people who have used that particular turbo on a similar engine as yours. Sorry, but there is no magic A/R number that works for all turbochargers attached to a 13B. You will need to figure out what works best for your situation on your own.

 

Thanks Evil, guess Ill just have to try it out and see what it does.I thought that by finding the A/R I could at least have an idea of what turbo it would be comparable to, being very few people use the Mitsu turbos, and I could judge from a similar garret setup, but I see now that it doesnt really work that way.

 

I'm not familiar with the Mitsubishi turbos, but I would imagine that a turbo shop (Majestic, etc.) could change out the housing if you feel it is too big or too small.