Twin-scroll skeptics...
A simple thing that so many vendors cannot seem to wrap there heads around.
Ron/Geoff, thank you for carrying out this discussion in front of us, it's a shame to see vendors and or tuners/fabricators unable to carry out civil conversation when disagreeing with each other. Posting this discussion up for us all to see opens all our eyes to more possibilities on either end of the spectrum
Scorke
I see alot of people mention the stock turbo and why its twin scroll...
Honestly when i saw it i thought it was to correct the unequal lengths inherent to the cast manifold. So that the unequal pressure beween runners would not effect overall perfomance. I have seen first hand on the effects of unequal length Manifolds...the pressure difference between the short and long runners has been over 350C EGT difference! Exhaust valves on the short side also were trashed after 300 hours of flight time. So In car terms thats 13500 miles if you average 45MPH.
I think the same can be said about most of the TS set-ups. The separation would also help mask problems found in the unequal lengths or in the large turbo realm..the extremely long runners.
So with that being said if a "Single Scroll" (i have always called Twin Scrolls Divided housings...but Twin Scroll is more catchy huh)...If the Manifold was tuned correctly and "The Pulses" reached the Turbine at regular intervals then the turbo would spool Just as good right?
Another thing Not mentioned alot in the Twin Scroll threads is that...Is there a noticeable restriction in the Exhaust gasses....Restriction would be very noticable by the Hot Spots on the manifold. You dont need to be a Engineer to know that if your manifold is running Hot..say alot hotter then normal, then Cracking will be more predominate...or in some cases i have seen...actuall Burn through. Yes the Manifold has Alot of restriction and thin walled.
From test we have done with Aircraft Manifolds we found that Exhaust gasses will travel with the pulses. These Pulse waves that has been mentioned Alot Travel at about the the speed of sound....why do you think open headers are so loud. These pulses will pull the Hot gases down the pipe..Hotter the gas the faster it moves. But you all know that..its basic Fluid Dynamics stuff. I just wanted to throw that out there in case some people didnt know.
So some of you know that Shearer Backs his manifolds with a life time warranty for the orginal owner.
Honestly when i saw it i thought it was to correct the unequal lengths inherent to the cast manifold. So that the unequal pressure beween runners would not effect overall perfomance. I have seen first hand on the effects of unequal length Manifolds...the pressure difference between the short and long runners has been over 350C EGT difference! Exhaust valves on the short side also were trashed after 300 hours of flight time. So In car terms thats 13500 miles if you average 45MPH.
I think the same can be said about most of the TS set-ups. The separation would also help mask problems found in the unequal lengths or in the large turbo realm..the extremely long runners.
So with that being said if a "Single Scroll" (i have always called Twin Scrolls Divided housings...but Twin Scroll is more catchy huh)...If the Manifold was tuned correctly and "The Pulses" reached the Turbine at regular intervals then the turbo would spool Just as good right?
Another thing Not mentioned alot in the Twin Scroll threads is that...Is there a noticeable restriction in the Exhaust gasses....Restriction would be very noticable by the Hot Spots on the manifold. You dont need to be a Engineer to know that if your manifold is running Hot..say alot hotter then normal, then Cracking will be more predominate...or in some cases i have seen...actuall Burn through. Yes the Manifold has Alot of restriction and thin walled.
From test we have done with Aircraft Manifolds we found that Exhaust gasses will travel with the pulses. These Pulse waves that has been mentioned Alot Travel at about the the speed of sound....why do you think open headers are so loud. These pulses will pull the Hot gases down the pipe..Hotter the gas the faster it moves. But you all know that..its basic Fluid Dynamics stuff. I just wanted to throw that out there in case some people didnt know.
So some of you know that Shearer Backs his manifolds with a life time warranty for the orginal owner.
Last edited by BiFfMaN; May 15, 2008 at 09:08 AM.
Newbie
Joined: Sep 2006
Posts: 1
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From: Reading, UK
Hi,
Not a regular poster on here but I am intruiged by the ongoing debate about twin-scroll. I have a European car (not sold in the US) which is a 2.4 (2446cc) and I tried a GT3582R twin scroll back to back with a GT3082R single volute and the latter made more power (+60BHP approx) with a lot less lag. Both run on a twin scroll T3 manifold and single Tial 44mm wastegate (join of the divided wastegate pipes was at the face of the wastegate. The reason was the 0.78A/R was way too small for my application, particularly my 2.4 motor. So I can imagine that for a 2.3 or 2.4 stroker Evo that the twin scroll T3 housing is definitely NOT the way to go. Unlike comparing other cars I did this on the same dyno with everything else staying the same aside from the fuelling and minor changes to the ignition.
The divider is also quite wide for the application as I understand it.
Not a regular poster on here but I am intruiged by the ongoing debate about twin-scroll. I have a European car (not sold in the US) which is a 2.4 (2446cc) and I tried a GT3582R twin scroll back to back with a GT3082R single volute and the latter made more power (+60BHP approx) with a lot less lag. Both run on a twin scroll T3 manifold and single Tial 44mm wastegate (join of the divided wastegate pipes was at the face of the wastegate. The reason was the 0.78A/R was way too small for my application, particularly my 2.4 motor. So I can imagine that for a 2.3 or 2.4 stroker Evo that the twin scroll T3 housing is definitely NOT the way to go. Unlike comparing other cars I did this on the same dyno with everything else staying the same aside from the fuelling and minor changes to the ignition.
The divider is also quite wide for the application as I understand it.
Now I try to look at some of the HARD numbers out there and realize whos having the best performance gains......most power......fastest E.T.'s and none of them have twinscroll. You ask a guy like David Buschur and he doesn't sound like he'll ever do twinscroll. Along with Sean Ivey....he told me that he's not a big fan of the TwinScroll. Then you talk to Geoff and he seems to think the opposite, he thinks in due time that alot more shops will start to use TwinScroll. It's a tough call. I just try to educate myself the best that I can and make a decision from there.
Sean
Even for a 2.0L EVO, a .78 A/R TS T3 is too small for a GT35R. Increasing the displacement by 20% only exacerbates the situation.
A true test on any car of similar displacement, same turbos, same primary size, yada yada. Hell, use the same divided manifold and swap out the turbine housings. Datalogging backpressure, boost, throttle, rpm, a/f, timing, turbine shaft speed, etc... would be some excellent information to act as a selling point towards your product.
I have heard of some good reviews of the response of your 35r TS set-ups. Some of those gains comes directly from the fact that you are using ~.240" smaller diameter primaries from everyone else. But I have not heard of any of these set-ups being turned up yet to see where they max out.
I have heard of some good reviews of the response of your 35r TS set-ups. Some of those gains comes directly from the fact that you are using ~.240" smaller diameter primaries from everyone else. But I have not heard of any of these set-ups being turned up yet to see where they max out.
I've actually been preparing such a test for the last few months to be performed at the Skunk2 facility on the engine dyno. Then road tested in our shop car. We will be comparing 4 different manifolds and 3 different turbine housings using the GT3076R on the EVO engine.
I would also like to add that with the current single scroll FTW GT3076R kit thats on our shop8 right now, we were datalogging 28psi @ 4k at this weekends Super Lap Battle.
Ken
Newbie
Joined: Jan 2006
Posts: 76
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From: nyc
I see alot of people mention the stock turbo and why its twin scroll...
Honestly when i saw it i thought it was to correct the unequal lengths inherent to the cast manifold. So that the unequal pressure beween runners would not effect overall perfomance. I have seen first hand on the effects of unequal length Manifolds...the pressure difference between the short and long runners has been over 350C EGT difference! Exhaust valves on the short side also were trashed after 300 hours of flight time. So In car terms thats 13500 miles if you average 45MPH.
I think the same can be said about most of the TS set-ups. The separation would also help mask problems found in the unequal lengths or in the large turbo realm..the extremely long runners.
So with that being said if a "Single Scroll" (i have always called Twin Scrolls Divided housings...but Twin Scroll is more catchy huh)...If the Manifold was tuned correctly and "The Pulses" reached the Turbine at regular intervals then the turbo would spool Just as good right?
Another thing Not mentioned alot in the Twin Scroll threads is that...Is there a noticeable restriction in the Exhaust gasses....Restriction would be very noticable by the Hot Spots on the manifold. You dont need to be a Engineer to know that if your manifold is running Hot..say alot hotter then normal, then Cracking will be more predominate...or in some cases i have seen...actuall Burn through. Yes the Manifold has Alot of restriction and thin walled.
From test we have done with Aircraft Manifolds we found that Exhaust gasses will travel with the pulses. These Pulse waves that has been mentioned Alot Travel at about the the speed of sound....why do you think open headers are so loud. These pulses will pull the Hot gases down the pipe..Hotter the gas the faster it moves. But you all know that..its basic Fluid Dynamics stuff. I just wanted to throw that out there in case some people didnt know.
So some of you know that Shearer Backs his manifolds with a life time warranty for the orginal owner.
Honestly when i saw it i thought it was to correct the unequal lengths inherent to the cast manifold. So that the unequal pressure beween runners would not effect overall perfomance. I have seen first hand on the effects of unequal length Manifolds...the pressure difference between the short and long runners has been over 350C EGT difference! Exhaust valves on the short side also were trashed after 300 hours of flight time. So In car terms thats 13500 miles if you average 45MPH.
I think the same can be said about most of the TS set-ups. The separation would also help mask problems found in the unequal lengths or in the large turbo realm..the extremely long runners.
So with that being said if a "Single Scroll" (i have always called Twin Scrolls Divided housings...but Twin Scroll is more catchy huh)...If the Manifold was tuned correctly and "The Pulses" reached the Turbine at regular intervals then the turbo would spool Just as good right?
Another thing Not mentioned alot in the Twin Scroll threads is that...Is there a noticeable restriction in the Exhaust gasses....Restriction would be very noticable by the Hot Spots on the manifold. You dont need to be a Engineer to know that if your manifold is running Hot..say alot hotter then normal, then Cracking will be more predominate...or in some cases i have seen...actuall Burn through. Yes the Manifold has Alot of restriction and thin walled.
From test we have done with Aircraft Manifolds we found that Exhaust gasses will travel with the pulses. These Pulse waves that has been mentioned Alot Travel at about the the speed of sound....why do you think open headers are so loud. These pulses will pull the Hot gases down the pipe..Hotter the gas the faster it moves. But you all know that..its basic Fluid Dynamics stuff. I just wanted to throw that out there in case some people didnt know.
So some of you know that Shearer Backs his manifolds with a life time warranty for the orginal owner.
Newbie
Joined: Jan 2006
Posts: 76
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From: nyc
However the thing that really bothers me about all of this is the info I'm reading here where it's said that the (TS) doesn't make topend power no matter how big the TS turbine hsing(A/R) is T4 or T3 divided.
Therefore I'm still stuck trying to figure out if it's worth it going TS if I want topend power.
Seems like having a single scroll hsing and some lag will be inevitable for the topend power I want ,even though I wanted the pwr spread over the rpm range instead of the car being peaky.
I was hoping that going with a divided T3 and a 1.0 something A/R or divided T4 and 70+ or even 80 to 90+ A/R would give me the best of both worlds.
Evolving Member
Joined: Jun 2004
Posts: 371
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From: Australia
My 2c .
Twin scrolling has its place but it can be a little lame if the overall package wasn't designed to work together .
I think those 0.78 A/R GT32 turbine housings have their uses but note that they don't turn up on larger Garrett spec-ed turbos than their GT3267 and GT3271 . I don't see any point in going larger than a 56T GT3076R at most in these turbine housings .
I have a problem with GT3582R's and their native Garrett petrol spec GT turbine housings . I am highly suspicious that these are really just GT3076R housings re-profiled the suit the larger 68mm (vs 60mm) GT turbine .
Personally I think they really need T4 flanged turbine housings (preferably TS) like the diesel spec GT35 turbochargers ie GT3571/GT3576/GT3582 . The diesel spec GT35 turbine is dimensionally the same (68mm 84T) though the material and blade for is a bit different .
If I had the need for all a "GT35R" could give then that F135R would be a good turbo to research .
I'm not sure if Geoff's point about larger (higher pumping capacity)
compressors reducing turbine efficiency got across . The higher workload the turbine has the greater the slip losses through its blades becomes .
I'm sure the HTA compressor wheels have their place and it would be interesting to compare the GT30R based one with say Garretts HKS spec GT3040R/GT3082R , the HKS spec Garrett GT3040R had a larger 82mm GT40 compressor of the same family as the GT3582R's but in 50 rather than 56 comp trim . It also used the 0.70 A/R T04S comp cover .
As far as smaller OEM spec turbos go Mitsy made lots of Evo 4-9's and Subaru have TS versions of some EJ powered cars as well .
What they seemed to gain from TS was high torque at low (use it every day for Mr/Mrs/Miss) type engine revs which is what makes a good all round std road car .
Diesels are are another example of high torque over a lowish but acceptable rev range for the application .
Like someone else here I think we can learn a LOT about TS and TORQUE from the diesel engine manufacturers , the fact that small car sized turbo diesel engines are exploding ATM means they must be doing something right . When these engines get into the 1800-3000cc range their turbochargers will be something to keep an eye on .
I have no experience with TS turbo exhaust manifolds but I reckon somewhere between the pipes having enough sufficient size to pass the gas through to low restriction TS housings and turbines there is a message .
The old make her a bit big just for luck doesn't hold water with me . The right gas velocity and absolute minimum restriction for the column of gas holds the secrets .
A .
Twin scrolling has its place but it can be a little lame if the overall package wasn't designed to work together .
I think those 0.78 A/R GT32 turbine housings have their uses but note that they don't turn up on larger Garrett spec-ed turbos than their GT3267 and GT3271 . I don't see any point in going larger than a 56T GT3076R at most in these turbine housings .
I have a problem with GT3582R's and their native Garrett petrol spec GT turbine housings . I am highly suspicious that these are really just GT3076R housings re-profiled the suit the larger 68mm (vs 60mm) GT turbine .
Personally I think they really need T4 flanged turbine housings (preferably TS) like the diesel spec GT35 turbochargers ie GT3571/GT3576/GT3582 . The diesel spec GT35 turbine is dimensionally the same (68mm 84T) though the material and blade for is a bit different .
If I had the need for all a "GT35R" could give then that F135R would be a good turbo to research .
I'm not sure if Geoff's point about larger (higher pumping capacity)
compressors reducing turbine efficiency got across . The higher workload the turbine has the greater the slip losses through its blades becomes .
I'm sure the HTA compressor wheels have their place and it would be interesting to compare the GT30R based one with say Garretts HKS spec GT3040R/GT3082R , the HKS spec Garrett GT3040R had a larger 82mm GT40 compressor of the same family as the GT3582R's but in 50 rather than 56 comp trim . It also used the 0.70 A/R T04S comp cover .
As far as smaller OEM spec turbos go Mitsy made lots of Evo 4-9's and Subaru have TS versions of some EJ powered cars as well .
What they seemed to gain from TS was high torque at low (use it every day for Mr/Mrs/Miss) type engine revs which is what makes a good all round std road car .
Diesels are are another example of high torque over a lowish but acceptable rev range for the application .
Like someone else here I think we can learn a LOT about TS and TORQUE from the diesel engine manufacturers , the fact that small car sized turbo diesel engines are exploding ATM means they must be doing something right . When these engines get into the 1800-3000cc range their turbochargers will be something to keep an eye on .
I have no experience with TS turbo exhaust manifolds but I reckon somewhere between the pipes having enough sufficient size to pass the gas through to low restriction TS housings and turbines there is a message .
The old make her a bit big just for luck doesn't hold water with me . The right gas velocity and absolute minimum restriction for the column of gas holds the secrets .
A .
Last edited by discopotato03; May 22, 2009 at 06:52 PM.