16g tech help

[madtech707]

This past weekend i got a hold of a used 16g turbo, and according to all the info i could find online the casting numbers say its a small 16g with a 7cm housing. Out of curiosity i mic'd the turbine housing inlet and it mesured 60.5mm(6cm)! Then I search the forums and found out that there are 16g's out there with 6 and 7cm housings. Ok. But then i looked up a new EVO3 16g (which are only suppost to come with the 7cm housing) on the Dejon site and found the turbine inlet porting option "62mm for the ported sbr exhaust man". 62mm! Thats just a little over 6cm. So my big question is "Do 7cm housings/manifolds really measure out to 7cm or is that number just a reference.

 

[madtech707]

Anyone? This is my first turbo upgrade and i dont have much hands on experiance with them, I only know what i read online, and some info is contradicting. Any insight would be much appreciated.

 

[brisvr4]

The size of the 7cm housing does not actually refer to the size of the opening in it.
It is a reference to the a/r ( area/radius ) of the housing - 7cm2 = 0.49ar.
Does the housing have an 070 cast on it?
The following page should help explain it a bit more for you.

http://www.xtremeboost.com/tb101_ar.html

 

[madtech707]

Ok. So the 7cm2 refers to the A/R in the housing. Gotcha. The housing does have the 070 in the cast so it does mean its a 7cm2 then. Thanks brisvr4.


I was still a little confused to why they call manifold to turbo gaskets "7cm gasket" and "6cm gasket" but i just found out from looking on the Forced Performance website that it is just a reference title to the turbine housing, not the inlet size. "I see!" said the blind man.

 

[romeen]

That is understandably a common misconception that the 7cm2 gasket refers to a 7cm diamter but as mentioned that is not the case.

7cm2 turbine housings have an inlet diameter of 60mm (2.36") and the i.d. of the oem 7cm2 gasket is 61mm.

6cm2 turbine housings have an inlet diameter of 54mm (2.13") and the i.d. of the oem 6cm2 gasket is 55mm.