2a+RoN

Does anybody know how to convert cm^2 over to a/r ratios?

Evil Aviator

Is it a vaneless or multi-vane turbine?

badfish229

Are you asking to convert units to a unitless variable? Okay, Clapeyron. Good luck with that .

2a+RoN

I'm gonna say multivane. Badfish, I understand that there is a missing variable, but some manufacturers (holset, mitsu i think too) use cm^2 to indicate turbine size (although, I'm not sure what this measures) and its hard to be able to find the right size for my application when I am used to understanding a/r.

Badfish229, thanks for the help:P

Evil Aviator

Multi-vane turbines are sized by the cross-sectional area of one nozzle * the total number of nozzles. Since the scroll is designed differently than a vaneless turbine, there is really no way to convert the multi-vane number into an A/R ratio. However, sizing works the same as the A/R sizing method, where a bigger number will decrease turbine speed, and a smaller number will increase turbine speed.

A/R is the Area/Radius ratio. The Area is the cross-sectional area of the scroll at a given point, and the Radius is the distance from the centerline of A to the centerline of the turbine shaft. Vaneless turbines are sometimes just rated in the largest A of the scroll, especially by Schwitzer. To convert to A/R, you simply need to measure the Radius from the centerline of the turbine shaft to the centerline of A, and then do the math to solve for A/R. If it is difficult to determine which A the manufacturer used, then just choose one that is somewhere in the curved part of the scroll and not the straight inlet portion. Since R doesn't really change much, and the effects of A or A/R of one turbine are not comparable to a different turbine, I'm not sure what good it would do you to convert A to A/R, but whatever makes you happy.
http://turbominivan.com/tech/turbo201.htm

2a+RoN

I completely understand the concept of a/r and its ironic because I just directed somebody to that exact link yesterday only a few threads down on the page. I was just curious to find out which housing I need, but I have none on hand to do the math and calculate the a/r. If it is any help, I was looking at the holset hx35's and pondering between a 12, 14, and 16 cm^2 turbine housing.

Thanks,
Aaron

Evil Aviator

If you completely understand the concept of A/R, then you should also completely understand that there is absolutely no way for you to determine the proper housing for your turbo based simply on A/R or A without expereince with the particular product.

You are going to need to contact your Holset dealer for proper fitting to your application. That's why they get the big bucks.

Holset website:
http://www.holset.co.uk/flash/index.html