Twin-scroll skeptics...
#152
Evolved Member
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Just a GT4202 setup that put down 800 WHP and would spin all 4 when boost hit in 3rd gear at under 5000 RPM, does that count?
I'm not going for 600+ HP though. The question I have is compared to a better spooling smaller turbo that is capable of 400-450 WHP, is there really any benefit to a TS setup for a more race oriented setup? I literally could care less about going over 450 WHP, so the argument of getting a larger turbo to spool like a smaller single scroll is a moot point.
The smaller turbo is already going to spool very well in the single scroll setup. Yes, I agree, it will spool faster in a proper TS setup below 5k RPM. But is that faster response really worth it considering transient response above 5K is going to be nearly identical?
Once the engine speed gets ~1000 or so RPM higher than the boost threshold, it seems like the difference in response is pretty minimal. Below that area though, yes, TS has definite benefits and I do not question the benefits on a street car.
I'm not going for 600+ HP though. The question I have is compared to a better spooling smaller turbo that is capable of 400-450 WHP, is there really any benefit to a TS setup for a more race oriented setup? I literally could care less about going over 450 WHP, so the argument of getting a larger turbo to spool like a smaller single scroll is a moot point.
The smaller turbo is already going to spool very well in the single scroll setup. Yes, I agree, it will spool faster in a proper TS setup below 5k RPM. But is that faster response really worth it considering transient response above 5K is going to be nearly identical?
Once the engine speed gets ~1000 or so RPM higher than the boost threshold, it seems like the difference in response is pretty minimal. Below that area though, yes, TS has definite benefits and I do not question the benefits on a street car.
Scorke
#153
Evolved Member
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Efficiency being higher on a larger turbo is not always right as smaller compressors can easily produce high efficiency along with lower turbine demand from reduced rotating weight and aerodynamic drag. Case in point, the GT3076R maps out to 74% efficiency accross almost the entire engine operating range I'd be looking for. The GT3582R is off the map for much of the rev range and finally comes up to 72% efficiency by 6500 RPM. Bigger is not better in this case.
I just don't agree with it being a one size fits all solution like its being pushed.
If it was superior in all ways, you'd see it being used in all forms of racing almost exclusively, but it's not. Almost every top level racing organization allowing turbocharging is dominated by single scroll turbo setups.
Last edited by 03whitegsr; Mar 23, 2010 at 02:40 PM.
#155
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iTrader: (18)
Huh? How about I drove the car without a divided manifold and it spooled almost 1000 RPM later and was a complete dog? I'm well aware of the benefits of twin scroll when the car has terrible spool. That's not my concern though. My point is, on a setup that already has great power and response, is there any benefit. Efficiency being higher on a larger turbo is not always right as smaller compressors can easily produce high efficiency along with lower turbine demand from reduced rotating weight and aerodynamic drag.
I just don't agree with it being a one size fits all solution like its being pushed.
If it was superior in all ways, you'd see it being used in all forms of racing almost exclusively, but it's not. Almost every top level racing organization allowing turbocharging is dominated by single scroll turbo setups.
I just don't agree with it being a one size fits all solution like its being pushed.
If it was superior in all ways, you'd see it being used in all forms of racing almost exclusively, but it's not. Almost every top level racing organization allowing turbocharging is dominated by single scroll turbo setups.
It's not being pushed as a one size fits all solution, people are just saying that a properly designed and sized twin scroll setup seems to offer more power throughout the rev range than a similarly sized single scroll one.
When you reference other top level racing organizations allowing turbocharging which ones are you specifically talking about?
Scorke
#156
Evolved Member
iTrader: (8)
If the smaller turbo is more efficient on the compressor and turbine (which on the turbo I am interested in, it is more efficient on both accounts) how is it not using the exhaust gases more efficiently? Yes, it's subjective and that was my point, that's all.
CART/IRL, Lemans, WRC, TurboF1 all seem to have used single scroll setups at their pinnacle. Many WRC teams were using twin scroll setups until Garrett produced the TR30, which is a single scroll turbo similar in size to a GT30. The TR30 was also used in IRL and Lemans. I believe it has been replaced with a next generation of turbo though, but it's still a single scroll arrangement.
CART/IRL, Lemans, WRC, TurboF1 all seem to have used single scroll setups at their pinnacle. Many WRC teams were using twin scroll setups until Garrett produced the TR30, which is a single scroll turbo similar in size to a GT30. The TR30 was also used in IRL and Lemans. I believe it has been replaced with a next generation of turbo though, but it's still a single scroll arrangement.
#157
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What HP do you think a TS GT4088 will max out at? When will it run out of breathe on a 2.3. Would there be a certain Psi that once it goes by it won't be making any more power?
#160
EvoM Guru
iTrader: (6)
Actually, the pinnacle of turbo F1 saw BMW's turbo motor using a twinscroll setup to deliver up to 900bhp/L. The Zakspeed engine used TS as well. The V6 engines were twin turbocharged, so they ostensibly didn't/couldn't use TS.
Last edited by Ted B; Mar 23, 2010 at 04:56 PM.
#162
EvoM Guru
iTrader: (6)
Here are a few clear photos from these amazing turbo F1 engines:
BMW F1
The twin ducts from the TS manifold to a single WG are apparent:
Zakspeed
Same arrangement as the BMW engine:
These TS setups were delivering 1000+bhp with 4-5+ bars (60-75 psi) of boost and 11-12k rpm with 1.5L. That's impressive even by today's standards.
BMW F1
The twin ducts from the TS manifold to a single WG are apparent:
Zakspeed
Same arrangement as the BMW engine:
These TS setups were delivering 1000+bhp with 4-5+ bars (60-75 psi) of boost and 11-12k rpm with 1.5L. That's impressive even by today's standards.
#163
Account Disabled
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I'm interested in a 50-55lb/min sized turbo for my next setup and have been very on the fence of which direction I would go.
I like the simplicity and low weight of the single scroll single wastegate setup. Also, not buying a second wastegate gives a little extra coin to invest in other areas. I'd be pretty willing to drop that money into thin wall 321 on the header with slip joints and the Tial housing to absolutely minimize weight and I would still feel fairly comfortable with it on a street car that sees less then 5k miles a year.
I like the simplicity and low weight of the single scroll single wastegate setup. Also, not buying a second wastegate gives a little extra coin to invest in other areas. I'd be pretty willing to drop that money into thin wall 321 on the header with slip joints and the Tial housing to absolutely minimize weight and I would still feel fairly comfortable with it on a street car that sees less then 5k miles a year.
#164
Evolved Member
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That is what I've been considering too, a thin wall manifold with FP HTA Green. Still pretty light weight, compact and simple. Probably total weight very similar to the Tial housing GT30 and MV-S setup. Done with a modified 2-port actuator it should provide pretty solid boost control with a good range of boost levels.
Just very spendy on the turbo, but without buying the wastegate, helps offset the price.
Does BW have internal wastegate housings that flow well?
Just very spendy on the turbo, but without buying the wastegate, helps offset the price.
Does BW have internal wastegate housings that flow well?
#165
Account Disabled
iTrader: (7)
yes, but i dont know how well the wastegate would flow, or how well the internal would fit an evo.
Last edited by Geoff Raicer; Mar 24, 2010 at 11:22 PM.