Turbo A/R breakdown info needed

OT-OF-Here

OT-OF-Here

Owner of the Black Beach
Joined
May 18, 2007
Messages
950
Anyone know how A/R breaksdown vs Exh cm housing size.

For instance,.. and this probably isn't right but,...

90 A/R = 14cm
100 A/R = 16cm


ETC, ETC,.. does anyone know how these compare???
 
I would say bigger, it really isn't a direct cross, if you look what they use to figure the a/r.

I would say a .90 would be close to a 16.
 
zstroken said:
I would say bigger, it really isn't a direct cross, if you look what they use to figure the a/r.

I would say a .90 would be close to a 16.
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Thats all you got Dan? You always got some good turbo info. I never use any of them and am curious on this one. And you give this for an answer. Geez
 
tony597fitter said:
Yeah, .70 is close to 12cm
and .80 is close to 14cm.
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Holset uses CM...everyone else uses A/R...there really isn't any way to cross numbers between them, since A/R is based on the relationship of the wheel and housing area...what is Holset's CM figures based on??

Chris
 
Signature600 said:
Holset uses CM...everyone else uses A/R...there really isn't any way to cross numbers between them, since A/R is based on the relationship of the wheel and housing area...what is Holset's CM figures based on??

Chris
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Don't the holset housings actually say cm^2??
So it is a crosssection, my guess it would be a cross section at a certain point in the volutes.
 
2Tone12V said:
Thats all you got Dan? You always got some good turbo info. I never use any of them and am curious on this one. And you give this for an answer. Geez
Click to expand...


Sorry, you change trucks before you have a turbo that needs a rebuild!
 
Signature600 said:
Holset uses CM...everyone else uses A/R...there really isn't any way to cross numbers between them, since A/R is based on the relationship of the wheel and housing area...what is Holset's CM figures based on??

Chris
Click to expand...

Yes I know, thats why I put "close"
 
A/R is literally Area/Radius.

At any point on a turbine scroll the relationship between the cross-sectional area and the radius from the centerline of the turbine shaft will be consistent with that same ratio when taken from any other point on the scroll.

The 12cm so on and so forth must be the cross-sectional area at some point. Possibly that found at the flange itself...

One thing to keep in mind is that you can retain the same A/R while increasing both of the constituents by jumping from say, a T4 to a T6 flange where the net effect is actually a much looser housing having the same A/R ratio.

I think I have an old turbine housing off of an HX35 in the back. I'll go measure it and see what I come up with... maybe the numerical values given really are the cross-sectional area at the flange. I'll check.
 
zstroken said:
Don't the holset housings actually say cm^2??
So it is a crosssection, my guess it would be a cross section at a certain point in the volutes.
Click to expand...

I have seen a few with a "cm" but not every one...I think the one's I saw that one were old ST50's off of Steigers...

There has to be some relationship, but I'm probably not intelligent enough to grasp it:D

Chris
 
a sidebar of the same question

It would seem then that in a twins setup that the big huffer would also have a larger A/R,.. like a 1.10 or 1.32,.. a couple that I've noticed for s400 variants. True?
 
Well I was going to go measure that Holset housing, but I can't find the little sob.
 
I was told the .99 a/r on my secondary was about a 17cm. My primary is a 1.15--- whatever that works out to.
 
It will vary with turbine size. If you have a .7 A/R on a 65mm turbine, you come roughly to a 12 cm^2. If you have a .7 A/R on a 86mm turbine, you will have a much larger cm^2.
 
zstroken said:
Sorry, you change trucks before you have a turbo that needs a rebuild!
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Ya this one has only been ran enough to start the truck and go down the track once. Well twice after this coming weekend. How big is the exhaust housing on my charger Dan? You study them s4 chargers alot. Bullseye S483 comp. 1.32 a/r
 
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