Data on internal vs external WG
Mar 6, 2017, 06:07 PM
#16
EvoM Guru
iTrader: (1)
Originally Posted by 03whitegsr
Not really.
There is a certain amount of "mechanical advantage" to any given wastegate system that the valve has in relationship to the EBP and boost pressure. Change that mechanical advantage and it will change the boost pressure.
Case in point, put a stiffer wastegate spring in an external and that same 90% duty cycle will increase the boost pressure without affecting the backpressure at all.
Evo8cy, I'm curious about the setups you speak of. Got pictures.
Honestly, the issues I speak of have less to do with it working and more to do with long term reliability and just general manufacturability. To fully maintain the benefits of a TS turbo, you have to keep the passages divided all the way to the face of the wastegate valve. Doing that, you have one piece of steel that divides the two flow paths being exposed to the full exhaust flow. Usually it means the functional temperature limits of the material are exceeded. There is also usually a high differential temperature between that divider and the outer wall tubing.
The divider ends up cracking and buckling, from what I've seen. Once it does that, boost response usually goes to hell.
There is a certain amount of "mechanical advantage" to any given wastegate system that the valve has in relationship to the EBP and boost pressure. Change that mechanical advantage and it will change the boost pressure.
Case in point, put a stiffer wastegate spring in an external and that same 90% duty cycle will increase the boost pressure without affecting the backpressure at all.
Evo8cy, I'm curious about the setups you speak of. Got pictures.
Honestly, the issues I speak of have less to do with it working and more to do with long term reliability and just general manufacturability. To fully maintain the benefits of a TS turbo, you have to keep the passages divided all the way to the face of the wastegate valve. Doing that, you have one piece of steel that divides the two flow paths being exposed to the full exhaust flow. Usually it means the functional temperature limits of the material are exceeded. There is also usually a high differential temperature between that divider and the outer wall tubing.
The divider ends up cracking and buckling, from what I've seen. Once it does that, boost response usually goes to hell.
Mar 6, 2017, 10:42 PM
#17
It is critical to performance to maintain exhaust pulse separation between the two volutes of the twin-scroll turbine housing. Therefore, a divider wall must go all the way up to the wastegate valve surface if a single valve is used to cover both wastegate ports. If there is a gap between the divider wall and the valve surface, it will allow cross-talk between the two volutes and reduce performance.
I have personally performed testing on a large commercial vehicle diesel inline-6 engine in an engine cell. The cylinders were paired 3 and 3 to each volute of the twin-scroll turbine housing. This is exactly what BMW does on their N55 3.0L inline-6 engine.
Each volute of the turbine housing was instrumented with extremely high frequency pressure transducers to measure the exhaust pressure on a crank angle basis. Allowing cross-talk between the two volutes of the twin-scroll turbine housing by having a gap between the divider wall and wastegate flapper resulted in measurable pressure differences and transient performance differences. Another team did similar testing on a 4-cylinder gasoline engine with internally gated twin-scroll housing and had similar results. I even made a GT-Power model representing my diesel engine test and the results correlated with what I saw on the engine.
There's a reason why all internally wastegate gated twin-scroll turbine housings use a divider wall between the two wastegate paths from each volute all the way to the flapper valve.
Mar 6, 2017, 11:44 PM
#18
Account Disabled
All the vendors want the customers to think that externals are better so they can make more money.
Externals were around first, the internal came along in about 1974 as an upgrade.
Internals are always the best, they are easy to modify to make better and at no expense.
With a twin scroll turbo, as said above, if you want to go external, you'll need 2 of them.
If you want to upgrade your internal, it's the merge after the WG that you need to concentrate on. In particular the join angle and the pipe diameter.
Externals were around first, the internal came along in about 1974 as an upgrade.
Internals are always the best, they are easy to modify to make better and at no expense.
With a twin scroll turbo, as said above, if you want to go external, you'll need 2 of them.
If you want to upgrade your internal, it's the merge after the WG that you need to concentrate on. In particular the join angle and the pipe diameter.
Mar 7, 2017, 09:14 AM
#19
This seems to be missing the boost curve for one of the runs though? I'm guessing the external is likely higher on boost across the RPM range?
Don't get me wrong though, externals are absolutely better. I hate internals. Pick one or two of these traits for any given internal gate:
Transient boost spikes
Drop boost with engine speed
Blow open limiting peak boost
Boost creep
As for only needing one external gate on a twin scroll setup...good luck.
I'm not saying it's impossible, but I've seen nothing but poor results trying to do it and the few tests that have tried both, back to back in fair tests, have shown the dual gate setups are better.
Don't get me wrong though, externals are absolutely better. I hate internals. Pick one or two of these traits for any given internal gate:
Transient boost spikes
Drop boost with engine speed
Blow open limiting peak boost
Boost creep
As for only needing one external gate on a twin scroll setup...good luck.
I'm not saying it's impossible, but I've seen nothing but poor results trying to do it and the few tests that have tried both, back to back in fair tests, have shown the dual gate setups are better.
Mar 7, 2017, 02:59 PM
#20
Evolved Member
This is an incorrect statement.
It is critical to performance to maintain exhaust pulse separation between the two volutes of the twin-scroll turbine housing. Therefore, a divider wall must go all the way up to the wastegate valve surface if a single valve is used to cover both wastegate ports. If there is a gap between the divider wall and the valve surface, it will allow cross-talk between the two volutes and reduce performance.
I have personally performed testing on a large commercial vehicle diesel inline-6 engine in an engine cell. The cylinders were paired 3 and 3 to each volute of the twin-scroll turbine housing. This is exactly what BMW does on their N55 3.0L inline-6 engine.
Each volute of the turbine housing was instrumented with extremely high frequency pressure transducers to measure the exhaust pressure on a crank angle basis. Allowing cross-talk between the two volutes of the twin-scroll turbine housing by having a gap between the divider wall and wastegate flapper resulted in measurable pressure differences and transient performance differences. Another team did similar testing on a 4-cylinder gasoline engine with internally gated twin-scroll housing and had similar results. I even made a GT-Power model representing my diesel engine test and the results correlated with what I saw on the engine.
There's a reason why all internally wastegate gated twin-scroll turbine housings use a divider wall between the two wastegate paths from each volute all the way to the flapper valve.
It is critical to performance to maintain exhaust pulse separation between the two volutes of the twin-scroll turbine housing. Therefore, a divider wall must go all the way up to the wastegate valve surface if a single valve is used to cover both wastegate ports. If there is a gap between the divider wall and the valve surface, it will allow cross-talk between the two volutes and reduce performance.
I have personally performed testing on a large commercial vehicle diesel inline-6 engine in an engine cell. The cylinders were paired 3 and 3 to each volute of the twin-scroll turbine housing. This is exactly what BMW does on their N55 3.0L inline-6 engine.
Each volute of the turbine housing was instrumented with extremely high frequency pressure transducers to measure the exhaust pressure on a crank angle basis. Allowing cross-talk between the two volutes of the twin-scroll turbine housing by having a gap between the divider wall and wastegate flapper resulted in measurable pressure differences and transient performance differences. Another team did similar testing on a 4-cylinder gasoline engine with internally gated twin-scroll housing and had similar results. I even made a GT-Power model representing my diesel engine test and the results correlated with what I saw on the engine.
There's a reason why all internally wastegate gated twin-scroll turbine housings use a divider wall between the two wastegate paths from each volute all the way to the flapper valve.
My statement is not incorrect. If you do not want to agree with it that's your choice, but the statement is far and beyond correct. What you say exists only in theory. In practice and reality using a short diameter non divided pipe, has no effect whatsoever, and this is what seperates those who read something or done a couple of tests in a certain way, and think that's the way to do things when in applicable reality it is not as such and those who test and re-test every single parameter on a setup, constantly changing setups to make sure what they have created in theory, exists in applied action as well. I will give you just the example of my personal car, on which in the 14years I own her, I have changed 8 different turbo setups, and 5 times engine setups. I do not know what your findings were or the teams that you say you have read about have found, but I go by what my personal experience says, and my testing which has been done roughly throughout the last 20 years on twin scroll vs single scroll setups either being involved in some one else's project or in one of my own has shown me that there is no effect whatsoever if you add a single short length pipe from either the merge collector or the divider itself up to the face of the gate. Absolutely none whatsoever!
Also for those that believe that twin scroll housings and setups own a huge difference in transient response, boost threshold, spool time and full boost rpm point in relation to single scroll, well I have news for you, they do not. I have seen and built single scroll setups that have better characteristics than their twin scroll equivalent.
As for bmw or any other car manufacturer, many use twin scroll setups, but in many cases where a twin scroll setup model should have had the advantage in performance to a single scroll model of the same category of another company, it does not. Most automotive manufacturers use single scroll setups in most of their turbo models, i,e Honda in their new Type R turbocharged engine, or Audi, Seat, Fiat and VW, Toyota in their diesels and trucks.
Marios
Last edited by Evo8cy; Mar 7, 2017 at 03:28 PM. Reason: typo
Mar 7, 2017, 03:05 PM
#21
EvoM Guru
iTrader: (1)
Yeah like your FP red that spooled at 2800rpms....
And yes, of course you know better than MHI, BMW, VAG, etc...
And yes, of course you know better than MHI, BMW, VAG, etc...
Mar 7, 2017, 05:09 PM
#22
Marios, not attacking you but you have laid out some big claims there. Please provide some backup to your claim about single scroll turbos being having the same boost threshold, transient response, etc. as their twin scroll variants. It's really hard for us to believe everything you say without solid evidence being shown here.
Mar 7, 2017, 10:23 PM
#23
Actually, it is. Every OEM turbo manufacturer has tested this. Every automotive company has tested this. Other engineering houses such as Ricardo and FEV has done extensive testing on it.
There is a lot of added cost in going with a twin-scroll setup due to the extra complexity of the castings. Do you really think every automotive engine manufacturer would spend that extra money if it didn't provide significant performance benefits in spool-up and transient response? I guess Ferrari must be wrong in using twin scroll turbos on the 488. I guess McLaren must be wrong using twin-scroll turbos on the new 720S. I guess BMW must be wrong using twin-scroll on the M5/M6. Audi must not know what they are doing on their new S4/S5. Mitsubishi must be idiots for using twin-scroll on the Evo. Subaru must be stupid for using it on the WRX. Ford must be stupid for using it on the Focus RS. They must all be stupid because they are spending extra money on something that does not provide performance benefits. Notice that twin-scroll is only used on high performance variants of a car because it does cost more money.
There is a lot of added cost in going with a twin-scroll setup due to the extra complexity of the castings. Do you really think every automotive engine manufacturer would spend that extra money if it didn't provide significant performance benefits in spool-up and transient response? I guess Ferrari must be wrong in using twin scroll turbos on the 488. I guess McLaren must be wrong using twin-scroll turbos on the new 720S. I guess BMW must be wrong using twin-scroll on the M5/M6. Audi must not know what they are doing on their new S4/S5. Mitsubishi must be idiots for using twin-scroll on the Evo. Subaru must be stupid for using it on the WRX. Ford must be stupid for using it on the Focus RS. They must all be stupid because they are spending extra money on something that does not provide performance benefits. Notice that twin-scroll is only used on high performance variants of a car because it does cost more money.
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Mar 8, 2017, 12:30 AM
#24
EvoM Guru
iTrader: (1)
Originally Posted by Evo8cy
Listen *****, my fp red would kick your ***, and yes it did spool as I said it did.
As for the car manufacturers read what I write morron. I said that Audi , Honda, Seat, VW , Fiat, Toyota, use single scroll setups and not twin scroll ones, and yes they do know more than me on the matter.
Next time do not read my posts since you do not like them, do not create personal attacks calling i.e a liar on anything, as I do not give a **** if you believe that there are not people out there that can do a lot more than you can do, I seem to be one of them.
I repeat, learn to respect what I or other have to offer or say on here or the next time you imply or say anything dimishing or impolite I will hunt you down on every thread that you post, *****.
Marios
As for the car manufacturers read what I write morron. I said that Audi , Honda, Seat, VW , Fiat, Toyota, use single scroll setups and not twin scroll ones, and yes they do know more than me on the matter.
Next time do not read my posts since you do not like them, do not create personal attacks calling i.e a liar on anything, as I do not give a **** if you believe that there are not people out there that can do a lot more than you can do, I seem to be one of them.
I repeat, learn to respect what I or other have to offer or say on here or the next time you imply or say anything dimishing or impolite I will hunt you down on every thread that you post, *****.
Marios
Also, you still have yet to post ANY data logs or a single shred of proof that your Red reached a full 30psi+ boost threshold at 2800rpms. Because we all know it didnt. A stock 9, or even 8! Turbo spool that fast. But you claim you made a turbo that is around 20% larger spool faster than stock.
Your red setup would have walked all over mine? Are you sure? My car is tuned by the guys who tune the record holding Evo X in the 1/4 and 1/2 mile (using a twin scroll turbo), and the record holding 1/2 mile Evo 8 (also using a twin scroll turbo LAWLZ). And one of the fastest GTR's on the planet.
The power numbers in my sig, have survived the rigorous test of time attack format competition. 1-2 hot laps at a time, with a cool down lap in between, on the STOCK short block, for 25-30 minute sessions. Could we make more power? Sure. Would it survive 2 consecutive hot laps on a 3 mile road course? Probably not.
Some of your posts are spot on. Some of what you post is so ridiculously far out in left field and incorrect, it's laughable.
Mar 8, 2017, 12:49 PM
#25
Evolved Member
BMWs in line 6 in single turbo form is also twin scroll as is most if not all of the BMW/PSA turbo 4's including the most powerfull 1.6 turbo from peugeot 308 gti, which has 270 hp and is on full boost at something like 2000 rpm..
to get back to original topic, I think the threat name is not really correct as this is a comparison of IWG vs EWG WITH EXTERNAL DUMP.. which is important difference.. on some turbos, like MHI you can run external dump even with stock IWG...
Mar 9, 2017, 07:13 AM
#26
Evolved Member
Honda's new type r 2018 turbo setup is single scroll.
Vw eos, gti, passat diesel, many other models, single scroll.
Mitsubishi's shogun, warrior, pajero, carisma diesel and many others, single scroll.
Toyota hilux, land cruiser, corolla diesel, starlet, glanza many others single scroll.
Mazda gtx, gtr, rx7, mazda 3 mps 2017, diesel models all single scroll.
Fiat models, single scroll.
Porche panamera 2016 model single scroll.
Lambo models single scroll.
Marios
Vw eos, gti, passat diesel, many other models, single scroll.
Mitsubishi's shogun, warrior, pajero, carisma diesel and many others, single scroll.
Toyota hilux, land cruiser, corolla diesel, starlet, glanza many others single scroll.
Mazda gtx, gtr, rx7, mazda 3 mps 2017, diesel models all single scroll.
Fiat models, single scroll.
Porche panamera 2016 model single scroll.
Lambo models single scroll.
Marios
Mar 9, 2017, 07:36 AM
#28
EvoM Guru
iTrader: (1)
LOL
http://blog.caranddriver.com/porsche...win-turbo-v-8/
As for single scroll on the RX7, that a wankel engine, completely different design. I also don't really care what diesel vehicles use, they are not a part of this conversation.
The brand new VW/VAG four cylinders are no longer a twin scroll turbo, but hose also have a the exhaust "manifold" integrated into the cylinder. So, again, that's a completely different set of design paramaters. All the previous 2.0t/1.8t had a twin scroll K03 or K04.
The mitsu pajero used a "highly efficient" twin scroll turbo...
http://www.mitsubishi-motors.com/en/...ajeromini.html
Its appearance spells the end of the 4.8-liter V-8 engines currently offered in the Panamera and the Cayenne, but fret not. We’ve had some experience with this new engine, and we can attest that it delivers everything expected of a true Porsche engine, especially high-end performance. Force-fed by two twin-scroll turbochargers, it’s rated at 550 horsepower which is available at 5750 rpm, and 568 lb-ft of torque from 1960 to 4500 rpm—redline is 6800 rpm. That puts it virtually on the level of the previous Panamera Turbo S with its 4.8-liter turbo.
http://blog.caranddriver.com/porsche...win-turbo-v-8/
As for single scroll on the RX7, that a wankel engine, completely different design. I also don't really care what diesel vehicles use, they are not a part of this conversation.
The brand new VW/VAG four cylinders are no longer a twin scroll turbo, but hose also have a the exhaust "manifold" integrated into the cylinder. So, again, that's a completely different set of design paramaters. All the previous 2.0t/1.8t had a twin scroll K03 or K04.
The mitsu pajero used a "highly efficient" twin scroll turbo...
http://www.mitsubishi-motors.com/en/...ajeromini.html
Mar 9, 2017, 07:44 AM
#29
Evolved Member
So my mistake was that I did not know that the newer panamera petrol model is using twin scroll turbos, lol. Are you serious?
The 3.0L V6 turbodiesel model uses single scroll.
The latest petrol turbo pajero model comes with two types of turbo, single and twin. All the diesel models ones come with single scroll turbo.
Honda's new type r engine and many others use single scroll ones.
Does the fact that the majority of the vehicles out there including supercars do still use single scroll setups tell you something?
Whos says that this discussion should be dictated by you in terms of what is included or not, or even worse what you care about or not.
When talking about turbos everything is included related to them.
Marios
The 3.0L V6 turbodiesel model uses single scroll.
The latest petrol turbo pajero model comes with two types of turbo, single and twin. All the diesel models ones come with single scroll turbo.
Honda's new type r engine and many others use single scroll ones.
Does the fact that the majority of the vehicles out there including supercars do still use single scroll setups tell you something?
Whos says that this discussion should be dictated by you in terms of what is included or not, or even worse what you care about or not.
When talking about turbos everything is included related to them.
Marios
Last edited by Evo8cy; Mar 9, 2017 at 07:55 AM. Reason: typo
Mar 9, 2017, 07:58 AM
#30
EvoM Guru
iTrader: (1)
Your mistake? You specifically said the 2016 panamera, and I fould that you were wrong...LOL
None of the current Lamborghini's comes with factory turbo's...lol
So my mistake was that I did not know that the newer panamera model is using twin scroll turbos, lol. Are you serious?
The latest petrol turbo pajero model comes with two types of turbo, single and twin. All the diesel models ones come with single scroll turbo.
Honda's new type r engine and many others use single scroll ones.
Does the fact that the majority of the vehicles out there including supercars do still use single scroll setups tell you something?
Whos says that this discussion should be dictated by you in terms of what is included or not, or even worse what you care about or not.
When talking about turbos everything is included related to them.
Marios
The latest petrol turbo pajero model comes with two types of turbo, single and twin. All the diesel models ones come with single scroll turbo.
Honda's new type r engine and many others use single scroll ones.
Does the fact that the majority of the vehicles out there including supercars do still use single scroll setups tell you something?
Whos says that this discussion should be dictated by you in terms of what is included or not, or even worse what you care about or not.
When talking about turbos everything is included related to them.
Marios
No, we're discussing gasoline piston engines, that have an exhaust manifold not integrated with the head. You change to a rotary, and the needs of the system change. Same goes for diesel, and the newer cars that have the exhaust manifold integrated into the head. But even some of those cars, like the Focus RS, use a twin scroll turbo.
Great, the new type R uses a single scroll turbo, Honda also claims they used the Vtec system (variable valve timing/duration/lift) to overcome the lag associated with a single scroll. They LITERALLY admitted single scroll introduces more lag, but they used another design parameter to get around it...LOL
And most supercars come with twin scroll. The McLarens and Ferraris being most notable.
This is simply funny.