Twin scroll T3 manifold
Neither, it would be area.
If it isn't (and I don't know that to be the case), that would appear to be some 10-15% of the total area. That would effectively make a .70 fall somewhere between a .63-.61 A/R in conventional terms.
If it isn't (and I don't know that to be the case), that would appear to be some 10-15% of the total area. That would effectively make a .70 fall somewhere between a .63-.61 A/R in conventional terms.
Ted how would it be area? Isn't area just to do with surface where as volume has to do with the space it actually occupies?
Looking directly at the divided t3 flange the "area" it takes up is quite minimal compaired to the amount of volume it takes up, no?
->trying to learn, I have found you are wise
Scorke
Looking directly at the divided t3 flange the "area" it takes up is quite minimal compaired to the amount of volume it takes up, no?
->trying to learn, I have found you are wise
Scorke
A/R is a measure of the cross sectional area divided by the radius at any given point. This does not consider volume, only the cross section.
If the volume were likewise 10-15% smaller for a given A/R as compared to a conventional type housing, this could conceivably impact residual pressure at higher engine speeds, but I certainly can't speculate further.
If the volume were likewise 10-15% smaller for a given A/R as compared to a conventional type housing, this could conceivably impact residual pressure at higher engine speeds, but I certainly can't speculate further.
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Joined: Apr 2007
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A/R is a measure of the cross sectional area divided by the radius at any given point. This does not consider volume, only the cross section.
If the volume were likewise 10-15% smaller for a given A/R as compared to a conventional type housing, this could conceivably impact residual pressure at higher engine speeds, but I certainly can't speculate further.
If the volume were likewise 10-15% smaller for a given A/R as compared to a conventional type housing, this could conceivably impact residual pressure at higher engine speeds, but I certainly can't speculate further.
Yes, it would be essentially the I.D. of the volute, not the O.D. That does imply the divider is accounted in the calculation, and is what I would assume by default unless informed otherwise. After all, it wouldn't seem to make much sense to pretend it wasn't there when the engineers made those calcs.
Rest assured that the "A" (in A/R) of twin scroll housings represents the area of the actual flow paths of the volute. The area of the divider wall is not factored in.
Just to beat this to its engineering geekery extreme, "A" is the radial cross-sectional area of the flow path of the volute at the first section which is open to the wheel's inducer (where the tongue of the housing is). The "R" is the radius of the centroid of that cross-sectional area.
As you progress along the volute, the A decreases (until zero, duh) much faster than the R does, meaning A/R is not constant for the entire volute. So, the A/R of a housing is defined at that section located right at the tongue.
Just to beat this to its engineering geekery extreme, "A" is the radial cross-sectional area of the flow path of the volute at the first section which is open to the wheel's inducer (where the tongue of the housing is). The "R" is the radius of the centroid of that cross-sectional area.
As you progress along the volute, the A decreases (until zero, duh) much faster than the R does, meaning A/R is not constant for the entire volute. So, the A/R of a housing is defined at that section located right at the tongue.
Newbie
Joined: Apr 2007
Posts: 59
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Rest assured that the "A" (in A/R) of twin scroll housings represents the area of the actual flow paths of the volute. The area of the divider wall is not factored in.
Just to beat this to its engineering geekery extreme, "A" is the radial cross-sectional area of the flow path of the volute at the first section which is open to the wheel's inducer (where the tongue of the housing is). The "R" is the radius of the centroid of that cross-sectional area.
As you progress along the volute, the A decreases (until zero, duh) much faster than the R does, meaning A/R is not constant for the entire volute. So, the A/R of a housing is defined at that section located right at the tongue.
Just to beat this to its engineering geekery extreme, "A" is the radial cross-sectional area of the flow path of the volute at the first section which is open to the wheel's inducer (where the tongue of the housing is). The "R" is the radius of the centroid of that cross-sectional area.
As you progress along the volute, the A decreases (until zero, duh) much faster than the R does, meaning A/R is not constant for the entire volute. So, the A/R of a housing is defined at that section located right at the tongue.
A1/R1 = A2/R2 = A3/R3, and so forth.
Even just halfway around the volute, the A is halved, but the R is not even close to halved (if it was, you'd be in the wheel).
This is why A/R is defined at one specific section.
Efficiency-wise, twin scrolls take a small hit due to increased 'wetted' surface area imposed by the divider wall. However, this is way more than offset by the vastly superior pulse conversion you get.
Edit: I should probably clarify that last bit. Twin scroll turbines, as mapped on a gas stand (steady state conditions) will exhibit a slight drop in efficiency compared to an otherwise equivalent non-divided housing. On-engine, however, is much different. The flow conditions are highly unsteady. The ability of a twin scroll to utilize the pulsing, unsteady flow of the exhaust exiting the engine gives it a huge bump in "apparent" efficiency, and ultimately spools up the turbine that much sooner.
Twinscrolls also isolate the cylinders' blowdown events much better than a non-divided housing, preventing the exhausting cylinder's very high PEAK exhaust manifold pressures from finding their way into the other cylinder on its overlap period.
Last edited by JKav; Apr 24, 2007 at 08:26 AM.
The HTA turbo's are a line of custom compressor wheels designed by FP. Dave Buschur has one, the only one as far as I know, and it makes a little more power than a standard 35r. But, it makes a lot more midrange power, spools faster, just better in every way.
So I'm thinking about doing a twin scroll T4 flanged manifold, with a .85 a/r T4 twin scroll turbine housing on the HTA 35r. Which is why Ted mentioned the T4 housings.
Basically a twin scroll T4 35r, with better midrange and quicker spool, due to the HTA wheel and the twin scroll design.
The .78 a/r T3 housing your mentioning uses a divided housing. Generally when you go to a twin scroll setup, you need to use larger than normal turbine housings. Personally I believe that housing is too small for a 3082/3065. I still think it would be become a restriction on a 3076 if you were trying to max it out. Although according to TedB, it works very, very well.
The 3065, 3082, and HKS 3037, are all the same turbo, just different names.
So I'm thinking about doing a twin scroll T4 flanged manifold, with a .85 a/r T4 twin scroll turbine housing on the HTA 35r. Which is why Ted mentioned the T4 housings.
Basically a twin scroll T4 35r, with better midrange and quicker spool, due to the HTA wheel and the twin scroll design.
The .78 a/r T3 housing your mentioning uses a divided housing. Generally when you go to a twin scroll setup, you need to use larger than normal turbine housings. Personally I believe that housing is too small for a 3082/3065. I still think it would be become a restriction on a 3076 if you were trying to max it out. Although according to TedB, it works very, very well.
The 3065, 3082, and HKS 3037, are all the same turbo, just different names.
Last edited by deadbeatrec; Apr 24, 2007 at 08:01 AM.
