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Trying to determine what size exhaust housing I currently have.
The numbers cast into mine are partially eroded away.

What is the norm for the layout of numbers?
Is there a dimension I can measure?
Is there a Holset/Cummins part #

The best I can come up with looks like a 12 in the lower right.
Ex:
5**3**
**** 12
 

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Good luck, I flew a lot of loops on this one! Good news is there's only so many housing sizes avaliable, bad news is there's no easy way to measure. It's not a direct linear measure, like 12" on a ruler. It's a cubic volume measure and most of us have no way to take and calculate such measurements: FROM WHERE TO WHERE is the question.

I contacted HTT Turbo before purchasing a turbo upgrade. Somehow from my Holset part number on ID plate on side of compressor housing and with knowledge of stock application he determined mine was a 16cc2 exhaust housing. The smallest is 12 cc2. Trying to write cubic centimeter, don't know if I noted it correctly with cc2.

Many 6BT Cummins Dodges with H1C had 18's, and some larger. Supposedly most step van 4BT applications run the 16, primarily because there's less exhaust volume in a 4 cylinder compared to a 6.

Don't know if any of this helped, but you might try to post a good clear picture and let the guys compare to theirs.
 

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This definately wont be conclusive but my new 12cm housing was considerably smaller, physically, on the outside than my stock 16cm housing. I can try to get a measurement on both for you to compare if you would like.
Carl
 

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I'm trying to figure out what I have too.. Help us out here with some measurements -- Please....
 

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The critical area is cm^2 (centimeters squared). Below picture shows the typical casting p/n & critical area format (upside down). In addition, many of the housings have larger cast number just inside of the exhaust inlet. The critical area measurements are covered in another thread.. I'll try to look for it. But it is basically the area at which the exhaust inlet opens into the full volute... which is few inches inside. Also, remember the cast p/n is just the casting which always defines the critical area but the casting can be machined for several different sizes of turbine wheel profiles. Holset makes various critical areas for H1Cs... some of the more common are 22, 18, 16, 14, 12.
 

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This definately wont be conclusive but my new 12cm housing was considerably smaller, physically, on the outside than my stock 16cm housing. I can try to get a measurement on both for you to compare if you would like.
Carl


OK, on the 16cm turbine housing, with the exhaust inlet turned up, measured across the outside of the housing at the turbine shaft: 6-11/16". If yours measures less than 1/8" +or- this figure , you prob have 16cm housing.

I havnt measured my 12cm yet but from memory I would say it is at least
5/8" smaller across this same area. I would guess an 18cm (ford) is prob 1/4" to 3/8" bigger.
This aint brain surgury folks but it will get you thinking in the right direction.
 
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