turbine housing volume

[Scheibins]

My cp is really slow tonight. Making search a PITA.



I have two hx-35 turbine housings and was trying to figure out how big each one is. One is supposed to be a 12 and one a 14cm. Now that is cubic centimeters, right? The High Tech Turbo site makes referance to cm2. I'm sure that's a typo.



My question is how is the turbine housing measured. I've read this before, but can't find it. I duct taped the compressor side and the exhaust side off and filled each one with water, making sure all the air was out of all the crevises. I came up with 680mL in one and 740 mL in the other. The conversion to cm3 is the same 680cm3 ... ... ... ..... Either it's not cm3 or I'm not measuring it even close or I'm having a brain fart on the conversion.



Thanks, Jay

 

[vssman]

For some reason I thought it was cross sectional area at a certain point in the housing and not volume.

 

[wsteffes]

12cm housing refers to the cross section area of the housing. It would be cm2.

12cm to 14 cm housing

Bad example is like comparing 1. 5 in pipe flow to 1. 75 in pipe flow.



Bill

 

[Scheibins]

I think you are right, I've seen they cm2 again.



Does anyone know how this is measured?



I would have thought the volume difference between these two housing would have been greater.

 

[Hohn]

Actually, wsteffes' example is pretty good.



The measurement is, in fact, cross-sectional AREA, not VOLUME. Think of it this way:



If you open the window on your house, does the thickness of your wall affect how much air can move through the window? All that matters is the area of the window (square inches).



Similarly, the flow capability of the housing is dictated by the sectional AREA of the housing. Unfortunately, Holset doesn't tell us WHERE this sectional area is measured.



That, and sectional area by itself is pretty worthless for determining flow, because it ignores the size of the turbine wheel.



That's why most turbo makers spec in terms of A/R ratio (Area/radius), which tells us the cross sectional area at a given radius from the turbine's root. This is a much better apples-to-apples system.



Justin

 

[Joseph Donnelly]

Neither system is perfect. The cm2 is measured where the volute first opens to the wheel. You can easily compare housings if radii are similar. A/R could be a small area with a tight scroll or a loose scroll and larger area; they will perform very differently, so again, you need to interject other elements of comparability. Over the years we diesel enthusiasts have tried many housings and have good "rule of thumb" comparators to tell us which housing from which turbo series will work well.

 

[Diesel Freak]

A/R becomes easier to understand when you know the major diameter of the turbine

 

[RKohn]

So back to the question...

If you look inside the casting, There "should" a 12 or 14 there. Unfortunately, mine's a 12 and I need a 14.



rick

 

[Scheibins]

Justin and Joe,

Thanks for the explanation, I understand what you are saying. And understand you could have a bigger cm2 area with a smaller cm3 volume in the housing, but I'm pretty sure in these housings from holset increased cm2 equates to increased cm3. So, even though my volume comparision of 680mL to 740mL doesn't mean anything, or much anyway, I'll take it as one is bigger than the other. Since they are hx35 housings I'll assume one is in fact a 12cm2 and the other 14cm2.

Rick,

City Diesel told about that stamp inside the housing's edge, where the manifold attaches. I see where it was stamped at one time, but it was not legable in either of my housings. There are several numbers on the outside of each of the housing, but I don't know what they mean. I register on holset's web page in order to post a question and did, but my question did not appear in there forums.



Oh well, appreciate the help.



Jay