Different turbine flanges and A/R effects???

NickTF

NickTF

Single turbo turd.
Joined
Jun 4, 2007
Messages
5,887
When you have a .84 a/r with a t3 flange and a .84 a/r with a t4 flange wouldn't that result in different dimensions because the flange being A of the A/R is bigger with a t4 then t3? Or is the area (A) measured in the volutes? Thanks.
 
So I guess there wouldn't be a lot of difference in a .84 t4 vs t3 turbine housing. Ok, thanks for the reply!
 
Yes they would be different even if they are numbered the same. That number is merely a ratio. The volute area of a 1.25 T3 is smaller than the area of a .9 T6. The larger mounting flange series usually denotes a larger area and scroll as well to handle the increase in exhaust gas. The scroll radius doesnt increase as rapidly as the area does so the larger housings end up with smaller numbers than you would think by looking at them.
 
carfichris said:
Yes they would be different even if they are numbered the same. That number is merely a ratio. The volute area of a 1.25 T3 is smaller than the area of a .9 T6. The larger mounting flange series usually denotes a larger area and scroll as well to handle the increase in exhaust gas. The scroll radius doesnt increase as rapidly as the area does so the larger housings end up with smaller numbers than you would think by looking at them.
Click to expand...
I think I'm missing a number- Did you mean the volute area on a T6 is 1.9 square inches?
 
I wasnt giving an equation Brandon. It was merely a reference to the internal volume and physical appearance of a smaller numbered T6 housing versus a larger numbered T3 housing.
 
So in other words chances are my .84 t4 turbine housing equiped t66 is probably a good bit larger in the turbine section generally speaking then Matt's .84 t3 turbine housing?
 
Ah. I was missing the units and didn't realize it was A/R, not square inches as I imagined it. I understand now and agree with the synopsis.
 
NickTF said:
So in other words chances are my .84 t4 turbine housing equiped t66 is probably a good bit larger in the turbine section generally speaking then Matt's .84 t3 turbine housing?
Click to expand...

Yes Nick that more than likely is the case.
 
Any idea how to determine the exact diference in square centemeters between an
84ar T-3 & an 84ar T-4 ?
 
ok...The way I undrestand it, flange size is in no way relevent to A/R. The measurment starts well inside the flange. Using the centerline of the mainshaft as refrence, start at the tighter end of the scroll & work out, untill the point where the area(A) & radius(R) numbers are no longer constant, & that should be where it begins.
http://www.protonus.ws/img/cars/turbo/arratio.jpg
http://f1.grp.yahoofs.com/v1/0AmRSb...t1R1qQL-zdOH0IDfmrrTY3Cg/AR_EXPLAINED/AR1.jpg

Now...using an adapter to put a t4 turbo on a T3 manifold is where there might be a performance difference, as that might screw with the exhaust volume / pulse energy between the manifold & where the scroll begins.
(No idea if it would be significant or even noteable)

:pop: :pop:

came up with the following on the net.... (take it for what it's worth)

conversion formula to convert CM^2 to A/R.

cm2-a/r conversion formula:

((cm2x8)-7)/100=a/r


6 cm2 = 0.41 A/R
7 cm2 = 0.49 A/R
8 cm2 = 0.57 A/R
9 cm2 = 0.65 A/R
10 cm2 = 0.73 A/R
11 cm2 = 0.81 A/R
12 cm2 = 0.89 A/R
14 cm2 = 0.97 A/R
15 cm2 = 1.05 A/R
16 cm2 = 1.13 A/R
17 cm2 = 1.29 A/R
19 cm2 = 1.37 A/R

http://www.protonus.ws/img/cars/turbo/arratio.jpg

http://f1.grp.yahoofs.com/v1/0AmRSb...t1R1qQL-zdOH0IDfmrrTY3Cg/AR_EXPLAINED/AR1.jpg

http://f1.grp.yahoofs.com/v1/0AmRSb...bcnOcwosHdaw-LLK07LnPOGQ/AR_EXPLAINED/AR2.jpg
 
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there isn't a conversion... the cm2 measurement is an actual area measurement... the A/R is a RATIO...

A/R is easier for me to understand because it doesn't require you to know the diameter of the turbine wheel and exhaust housing.

look at the popular S300 turbine housings... 12cm = .70 14cm = .80

now, change the turbo to a much larger frame/size/turbine and an HT3B with a 22cm housing might be like a .90

the whole cm2 thing has driven me crazy ever since I got into these Cummins... leave it to the Brits to come up with a lame measurement that requires taking yet another measurement and then doing math to figure out where you're at vs. just telling you the answer to the question! :mad:
 
furthur example... the 66/68-.84 I just installed on my 06... there is a .58 A/R housing available for it... but it's probably larger than a .63 T25 housing
 
That formula would only work for a certain housing, as it doesn't take the radius into account.

Comparing a housing with a t3 flange and a t6 flange is apples and oranges, since the chances of the same turbo using both flanges is low. How about something on the same turbo. On a Garrett GT42, you can get a T4 1.01 AR, T6 1.01 AR, and Tial makes a stainless V-band inlet with a 1.0 AR. Are the areas going to be the same?
 
Tate said:
Comparing a housing with a t3 flange and a t6 flange is apples and oranges, since the chances of the same turbo using both flanges is low. How about something on the same turbo. On a Garrett GT42, you can get a T4 1.01 AR, T6 1.01 AR, and Tial makes a stainless V-band inlet with a 1.0 AR. Are the areas going to be the same?
Click to expand...

Not having all 3 in front of me or having seen the Tial piece. I would say based on other examples, the common features would be similar A/R equation results and a common center section mounting surface. Thats not saying that two of the three aren't identical except for the turbine inlets. Tial would have been smart to take a known good design and just change the inlet if they wanted to offer a V-band stainless housing.
 
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