# what is extrude honed and housing sizes?



## Murph (Aug 8, 2002)

Can someone pls explain the "housing" of the compessor and turbine. I know what they are, but what does .65 and .83 numbers mean? The AR things?

Also, what exactly does extrude honed and such mean?

Thanks again guys.


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## spdracerUT (Jun 11, 2002)

I'm pretty sure the A/R is the inlet vs. outlet sizes. And extrude honing... well, most of the parts are made from casting which leaves a rough surface. Extrude honing uses this slurry mix stuff which they flow through the part which basically polishes the surface smooth(which improves airflow, power, etc).

Khiem


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## Murph (Aug 8, 2002)

so if its .83 is it .83 of an inch or relative to something else?


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## James (Apr 29, 2002)

A/R is the area of the scroll divided by the radius from the center of the scroll to the shaft centerline.


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## Murph (Aug 8, 2002)

James said:


> *A/R is the area of the scroll divided by the radius from the center of the scroll to the shaft centerline. *


can you dim it down a shade  

i dont want to be annoying, but i think im close to grapsing this.

what is the scroll?


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## James (Apr 29, 2002)

You ever seen a sea shell cut in half?


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## James (Apr 29, 2002)

well I gotta go soon but if you look housing sourronding the comrpessor/turbine then you'll see it looks like a shell. you take the area of the opening at any given place and divide that area by the distance of that opening to the centerline of the compressor/turbine... that's A/R area/radius


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## bahearn (Jul 15, 2002)

A/R is effectively the leverage the gas flow can impart to the turbine shaft, and by extension, the impeller.

A = cross-sectional area of the turbine inlet.
R = radius of the turbine.

A larger diameter turbine (bigger R) will generate more pressure than a smaller one for a given flow VELOCITY at the expense of longer spool time due to higher mass. 

As A get larger, flow velocity drops for a given volume of gas but max flow goes up. Smaller A = higher velocity and more leverage on turbine for a given R but will choke at a lower total flow.

A/R = .65 should spool quickly and have good mid-range response with lower total power while the .83 A/R will be a top-end biased unit.


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## Murph (Aug 8, 2002)

I GET IT 

thank you so much!!


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