Compound turbo setups.

[smoked240]

Alright guys school me on compound setups! I've researched it all and have seen the few setups people have done. I've even checked out our quadtrac case at work with compound turbos:2f2f:

My only concern is finding the right turbo to match. My engine is Rb25 with rb26 internals and a precision 6266. Supporting mods up to 800hp but capping it roughly around 500 until I add a metal head gasket.

Thanks and I'm sorry if this was the wrong section. Carry on.

[KAT-PWR]

Do you have an unlimited budget?
-find someone to work the details for you

Are you a professional fabricator?
-figure out what's necessary

Neither?
-Don't bother and do a simple nitrous/turbo set up.

[smoked240]

Do you have an unlimited budget?
-find someone to work the details for you

Are you a professional fabricator?
-figure out what's necessary

Neither?
-Don't bother and do a simple nitrous/turbo set up.

Yes and yes. I guess I only have a machinist degree but I've been doing it all myself for 14 years now.

Everything will be done by me, I'm just hung up on a proper turbo to match with my 6266.

[derass]

Read up on diesel truck forums.

[smoked240]

Read up on diesel truck forums.

Yup! Ripped through a couple forums on compound diesels.

[2muchboost]

Dodge Cummins forums will be the best source of evidence. Found a nice article on a build thread for DSM's here http://www.dsmtuners.com/threads/my-compound-turbo-set-up.336541/

Might want to reach out to people like Full Race for turbo matching or someone with a few years of turbo technology expertise.

[Def]

There's no point in a compound setup on a spark ignition engine. You're too octane limited to make use of the stupid high boost pressures that'd create.

[R3b]

Im so glad this came up. I was thinking similar idea with compound boost recently but with a super charger. Stumbled across HKS super GT. Figured if, there is a way to mount it by the intake side with an excessive intake to free up some room and work out a bracket/pulley system it should be a killersetup for a ka. Just have your turbo, then have the cold pipe link right up into the supercharger. The cool thing about the hks it has a bypass valve so you could have whatever boost at low rpms hit then shut it down once the turbo is hitting boost and have that take over completly.

https://image.nengun.com/catalogue/1024x768/nengun-1263-01-hks-gt_supercharger.jpg

The issue if you mount it up is do you feed the supercharge into the turbo or feed the turbo into the supercharger. I havent done crazy research but something like the lancia delta would work out great if you can bolt up the hks.
http://www.ecv1.com/images/presentazione-2.jpg

[tb13]

Compound turbo setups are sweet, you can get that sweet top end that a big turbo gives you and keep good response with a rich low end/mid range.

A guy here in AZ, Jon, who owns a shop called Future Fabrication built a sweet compound setup on his 1jz S13 a while back. It fucking ripped, I don't think it was ever dyno tuned, but on the track it proved it was able to throw down. The setup was super simple, modified stock manifold with an external waste gate, stock CT15 turbo and a big ass turbo set on top using a simple "up-pipe" from the stock turbo's outlet. The big turbo stuck out the hood, but it was awesome proof of concept.

http://i.imgur.com/kTCvTmMh.jpg
http://i.imgur.com/25OpkvXh.jpg

[PoorMans180SX]

Alright guys school me on compound setups! I've researched it all and have seen the few setups people have done. I've even checked out our quadtrac case at work with compound turbos:2f2f:

My only concern is finding the right turbo to match. My engine is Rb25 with rb26 internals and a precision 6266. Supporting mods up to 800hp but capping it roughly around 500 until I add a metal head gasket.

Thanks and I'm sorry if this was the wrong section. Carry on.

1. Ditch the 6266 and get a 6466. No point in running a smaller less capable turbo that spools roughly the same as a better one in a compound setup. Run at least a 1.15 turbine housing.

I've helped build two compound setups that were both on a successful drag car that continues to run mid nine seconds.

2. A common mistake is to run too small of a low pressure turbo (small), and to run too small of a turbine housing on the high pressure turbo (big).

3. I'd recommend running something like a V-band GTX2860 for the low pressure turbo, with the primary wastegate venting to atmosphere.

4. 800hp in a compound setup is a LOT of torque for an RB25. You're going to break things, even with RB26 internals. Better build that thing to the hilt, and hope you have a proper oiling system if you're wanting that much power.

There's no point in a compound setup on a spark ignition engine. You're too octane limited to make use of the stupid high boost pressures that'd create.

While I generally agree with you in that modern technology can overcome the classic "tons of lag and tons of top end power" turbocharger dilemma, there is a place for compound. If you can fabricate, you can create an engine with a fantastic powerband with two super cheap turbochargers. Especially with E85.

Compound turbo setups are sweet, you can get that sweet top end that a big turbo gives you and keep good response with a rich low end/mid range.

A guy here in AZ, Jon, who owns a shop called Future Fabrication built a sweet compound setup on his 1jz S13 a while back. It fucking ripped, I don't think it was ever dyno tuned, but on the track it proved it was able to throw down. The setup was super simple, modified stock manifold with an external waste gate, stock CT15 turbo and a big ass turbo set on top using a simple "up-pipe" from the stock turbo's outlet. The big turbo stuck out the hood, but it was awesome proof of concept.



Yes, Jon had an RB25 compound setup before that, but it met an early end.

[tb13]

Yes, Jon had an RB25 compound setup before that, but it met an early end.

I heard about that setup, but never saw it. From what I was told the RB setup wasn't nearly as capable as the JZ setup he built later.

[smoked240]

1. Ditch the 6266 and get a 6466. No point in running a smaller less capable turbo that spools roughly the same as a better one in a compound setup. Run at least a 1.15 turbine housing.

I've helped build two compound setups that were both on a successful drag car that continues to run mid nine seconds.

2. A common mistake is to run too small of a low pressure turbo (small), and to run too small of a turbine housing on the high pressure turbo (big).

3. I'd recommend running something like a V-band GTX2860 for the low pressure turbo, with the primary wastegate venting to atmosphere.

4. 800hp in a compound setup is a LOT of torque for an RB25. You're going to break things, even with RB26 internals. Better build that thing to the hilt, and hope you have a proper oiling system if you're wanting that much power.



While I generally agree with you in that modern technology can overcome the classic "tons of lag and tons of top end power" turbocharger dilemma, there is a place for compound. If you can fabricate, you can create an engine with a fantastic powerband with two super cheap turbochargers. Especially with E85.



Yes, Jon had an RB25 compound setup before that, but it met an early end.


A lot of great info thanks for the help! I'm not going to push more than 600 to the wheels if that, I would like the car driveable heh. I'm kinda stuck with the 6266.
I'm also tuned on e85 using aem series2.

I'm not looking for crazy power. A streetable setup is what I'm shooting for.

Keep up the info!

[derass]

3. I'd recommend running something like a V-band GTX2860 for the low pressure turbo, with the primary wastegate venting to atmosphere.

Wouldn't that energy be used better in spooling the high pressure turbo?

[ThePaddy]

http://www.supraforums.com.au/forum/topic/75200-kevins-compound-sequential-twin-turbo-design/page-7

[PoorMans180SX]

Wouldn't that energy be used better in spooling the high pressure turbo?

I hold onto some different theories than most people. There aren't many guys doing R&D on such setups, so there's still a lot of theories floating around, especially about boost control and back pressure control. I'd love to do some testing of my own if I can ever get the capital around to build such a monstrosity.

This is hands down the best thread on the internet I have found, but it still leaves a lot of questions unanswered.

http://www.yellowbullet.com/forum/showthread.php?t=216811&page=75

[PoorMans180SX]

A lot of great info thanks for the help! I'm not going to push more than 600 to the wheels if that, I would like the car driveable heh. I'm kinda stuck with the 6266.
I'm also tuned on e85 using aem series2.

I'm not looking for crazy power. A streetable setup is what I'm shooting for.

Keep up the info!

That's good. I'm not a huge fan of AEM series 2, since it doesn't seem to have the failsafes and control that the latest systems do, but it should work overall.

I'd say do some serious reading, develop your own theory, and run with it! Just keep in mind backpressure and heat are probably your two biggest enemies.

[tb13]

I hold onto some different theories than most people. There aren't many guys doing R&D on such setups, so there's still a lot of theories floating around, especially about boost control and back pressure control. I'd love to do some testing of my own if I can ever get the capital around to build such a monstrosity.

This is hands down the best thread on the internet I have found, but it still leaves a lot of questions unanswered.

http://www.yellowbullet.com/forum/showthread.php?t=216811&page=75

That setup is really cool, looking at pictured below this wastegate placement is interesting.

Although I have zero real world experience building crazy setups like that one, I think I understand why his setup works so well. I think most would expect a wastegate between the first and second turbo, like he is running, to send exhaust gases around the first turbo to the second once a certain boost pressure is achieved. This keep the first turbo from seeing insanely high shaft speeds and helps spool of the second larger turbo.

His second wastegate placement got me thinking though. I think most would expect a second wastegate before the second turbo venting to atmosphere, but with a motor seeing very high boost that would never work due to the limitations of flow through and around the smaller turbo. An engine seeing 40+psi of boost at high rpm is going to have an incredible amount of energy flowing through the exhaust, more than enough to spool a pair of turbos and keep them spinning. Having a second wastegate before both turbos allows for some of this excess energy to be bled off in the high rpm that would more than likely overwhelm the small turbo and wastegate between turbos. It also keeps back pressure low and the exhaust gases flowing smoothly through both turbos.

Correct me if I am wrong though, I would love to learn more about setups like that one. I really like the idea of using a pair of well sized turbos to keep great response, setup some wastegates and forget about it instead of trying to spool a massive turbo using something like Nitrous and extra tuning.

[feito]

Wouldn't that energy be used better in spooling the high pressure turbo?
I guess by primary he's referring to the WG that controls the pressure on the bigger turbo? because if you go to the link he provided, you can see that the WG that controls/bypasses the smaller turbo DOES re-circulate back into the bigger turbo, and it does make sence.

http://i116.photobucket.com/albums/o23/kjewer1/RWD%20pics/RWD%202015/4_zpsu09hk1on.jpg


http://i116.photobucket.com/albums/o23/kjewer1/RWD%20pics/RWD%202015/20160615_1534222_zpsmwo0vyjb.jpg

This seems like one of those things that in theory sounds pretty simple and easy to do, but in reality is really complex.
Im thinking finding the right way to control the smaller turbo WG is one of the hardest things.
Question: does the boost from the bigger turbo (once it starts pumping) force the compressor wheel from the smaller turbo to spin faster even if (the smaller turbo's) wasgate is open?

[PoorMans180SX]

Wouldn't that energy be used better in spooling the high pressure turbo?

Sorry for the confusion here, I can see now what I was saying was not clear. When using a single-scroll low-pressure turbo, you can put both of the wastegates before it. The "primary" gate would then be the one that is controlling overall pressure the engine sees.

That setup is really cool, looking at pictured below this wastegate placement is interesting.

Although I have zero real world experience building crazy setups like that one, I think I understand why his setup works so well. I think most would expect a wastegate between the first and second turbo, like he is running, to send exhaust gases around the first turbo to the second once a certain boost pressure is achieved. This keep the first turbo from seeing insanely high shaft speeds and helps spool of the second larger turbo.

His second wastegate placement got me thinking though. I think most would expect a second wastegate before the second turbo venting to atmosphere, but with a motor seeing very high boost that would never work due to the limitations of flow through and around the smaller turbo. An engine seeing 40+psi of boost at high rpm is going to have an incredible amount of energy flowing through the exhaust, more than enough to spool a pair of turbos and keep them spinning. Having a second wastegate before both turbos allows for some of this excess energy to be bled off in the high rpm that would more than likely overwhelm the small turbo and wastegate between turbos. It also keeps back pressure low and the exhaust gases flowing smoothly through both turbos.

Correct me if I am wrong though, I would love to learn more about setups like that one. I really like the idea of using a pair of well sized turbos to keep great response, setup some wastegates and forget about it instead of trying to spool a massive turbo using something like Nitrous and extra tuning.

What you're saying is correct, but also depends on setup and boost control strategy a bit. Having a wastegate between the two turbos does work, but seems a little less efficient to me. If you were to use a twin-scroll low-pressure turbo, having both wastegates before the low-pressure turbo isn't really possible though.


Question: does the boost from the bigger turbo (once it starts pumping) force the compressor wheel from the smaller turbo to spin faster even if (the smaller turbo's) wasgate is open?

No. The low-pressure turbo simply operates at whatever pressure ratio that the high-pressure turbo dictates, the lowest possible being 1:1. This means that the turbo spins fast enough to simply bypass the airflow from the high-pressure side, at least with any boost control strategy I can envision. This may or may not be the best way to do this in a gasoline engine.
You can do some math to figure out where on the map the low-pressure turbo is operating if the inlet pressure is above atmospheric, and Kevin Jewer (the guy with the setup pictured) does a decent job explaining the math in the yellow bullet thread, but I'm not convinced that his theories are right. He does have the most extensive pressure and temperature data logging setup of anyone with a compound setup I know though. Again, I would love to build such a setup with some serious temperature and pressure datalogging and run various boost control strategies to see how efficiency and power output are affected.

[smoked240]

Sorry for the confusion here, I can see now what I was saying was not clear. When using a single-scroll low-pressure turbo, you can put both of the wastegates before it. The "primary" gate would then be the one that is controlling overall pressure the engine sees.



What you're saying is correct, but also depends on setup and boost control strategy a bit. Having a wastegate between the two turbos does work, but seems a little less efficient to me. If you were to use a twin-scroll low-pressure turbo, having both wastegates before the low-pressure turbo isn't really possible though.



No. The low-pressure turbo simply operates at whatever pressure ratio that the high-pressure turbo dictates, the lowest possible being 1:1. This means that the turbo spins fast enough to simply bypass the airflow from the high-pressure side, at least with any boost control strategy I can envision. This may or may not be the best way to do this in a gasoline engine.
You can do some math to figure out where on the map the low-pressure turbo is operating if the inlet pressure is above atmospheric, and Kevin Jewer (the guy with the setup pictured) does a decent job explaining the math in the yellow bullet thread, but I'm not convinced that his theories are right. He does have the most extensive pressure and temperature data logging setup of anyone with a compound setup I know though. Again, I would love to build such a setup with some serious temperature and pressure datalogging and run various boost control strategies to see how efficiency and power output are affected.



Lots of great info as usual! I'll be starting the build this winter on the compound setup.

[tb13]

What you're saying is correct, but also depends on setup and boost control strategy a bit. Having a wastegate between the two turbos does work, but seems a little less efficient to me. If you were to use a twin-scroll low-pressure turbo, having both wastegates before the low-pressure turbo isn't really possible though.


I think displacement and target power levels would make a big difference in how you would setup your waste gates. If you were on a small displacment 4cyl platform only shooting for 500whp you might be able to get away with only a single waste gate before your primary, small, turbo. When you step up to a inline 6 I just don't think it would be feasible to try and force all of the exhaust gasses through the primary turbo and still hope to have solid exhaust flow and low back pressure.

Would a properly sized primary turbo being twin scroll really make that much of a difference? I feel like it would be difficult to justify a twin scroll primary turbo on a setup that wasn't built to make 1kwhp+ on a 4cly application. Even then, properly sizing the turbos would probably keep a good balance of response to overall power output.

Also, wouldn't diverting gasses around the smaller turbo help maintain the energy that is otherwise lost when it flows through that smaller turbo? That energy would only be wasted once the smaller turbo has made its target boost. Sending it directly to the secondary turbo would allow for better overall response.

Don't know why I really care, but this stuff is really interesting to me...

[PoorMans180SX]

I think displacement and target power levels would make a big difference in how you would setup your waste gates. If you were on a small displacment 4cyl platform only shooting for 500whp you might be able to get away with only a single waste gate before your primary, small, turbo. When you step up to a inline 6 I just don't think it would be feasible to try and force all of the exhaust gasses through the primary turbo and still hope to have solid exhaust flow and low back pressure.

Would a properly sized primary turbo being twin scroll really make that much of a difference? I feel like it would be difficult to justify a twin scroll primary turbo on a setup that wasn't built to make 1kwhp+ on a 4cly application. Even then, properly sizing the turbos would probably keep a good balance of response to overall power output.

Also, wouldn't diverting gasses around the smaller turbo help maintain the energy that is otherwise lost when it flows through that smaller turbo? That energy would only be wasted once the smaller turbo has made its target boost. Sending it directly to the secondary turbo would allow for better overall response.

Don't know why I really care, but this stuff is really interesting to me...

Honestly, if you're looking for 500whp out of your 4-cyl you're probably better off with a 7163 efr IMHO. Compounds are better suited for big power and good response. I guess I've just never seen a setup with a tiny turbo that seemed like it could justify it's complexity. Everything is a compromise though, so it's possible there's a 5-600whp setup out there that works extremely well.

Twin-scroll makes a big difference, regardless of compound or not. Whether it's "worth it" or not is up to the person building the system. I've seen a system built with an OEM Evo 9 turbo. Was it convoluted? Yes. Did it respond ridiculously quickly? Also yes. The GenII GTX's do seem like they would be a nice turbo to run if you were set on running something that small, provided you can get enough exhaust around the turbine.

Oh, and you'll definitely want a wastegate that diverts gasses back into the transfer pipe, that's necessary to keep the low-pressure turbo's speed down.

[tb13]

Honestly, if you're looking for 500whp out of your 4-cyl you're probably better off with a 7163 efr IMHO. Compounds are better suited for big power and good response. I guess I've just never seen a setup with a tiny turbo that seemed like it could justify it's complexity. Everything is a compromise though, so it's possible there's a 5-600whp setup out there that works extremely well.

Twin-scroll makes a big difference, regardless of compound or not. Whether it's "worth it" or not is up to the person building the system. I've seen a system built with an OEM Evo 9 turbo. Was it convoluted? Yes. Did it respond ridiculously quickly? Also yes. The GenII GTX's do seem like they would be a nice turbo to run if you were set on running something that small, provided you can get enough exhaust around the turbine.

Oh, and you'll definitely want a wastegate that diverts gasses back into the transfer pipe, that's necessary to keep the low-pressure turbo's speed down.

A agree, something like an EFR7163 on a well designed twin scroll manifold is probably the best way to make 500whp on a 4cyl motor.

If you were to build a 4cyl setup for 5-600whp, running something like a GTX2560R paired with a larger turbo capable of 500whp you could create a basically lag-less 500whp setup. With a setup like this you could probably even get away with using a holset or some other cheap journal bearing turbo to make the setup more cost efficient too. Run the internal waste gate on the small turbo along with a single 44mm gate, venting to atmosphere, at the manifold to control boost. Would probably make for a killer street setup on ethanol.

For big power and great response, I wonder what could be done using an EFR primary with an airweks secondary. I think they make their twin scroll internal WG T4 housing for the 7064, use that for your primary turbo and an Airwerks secondary. larger, turbo. Would give awesome response with potential to make 1kwhp without a crazy elaborate wastegate setup. Simply use the internal gate on the EFR to bypass to the Airwerks then have a conventional twin waste gate setup on the manifold to further control boost once both turbos have spooled.

The sky is really the limit, wish I had the cash to setup something on the SR I am building right now...

[5280VertDET]

http://www.suprastore.com/spquspva.html

Speaking of twin scroll, this are rather popular in the JZ world.

[PoorMans180SX]

The sky is really the limit, wish I had the cash to setup something on the SR I am building right now...

Indeed my friend. Another good rule of thumb is to size the larger turbo bigger than you think you need.

http://www.suprastore.com/spquspva.html

Speaking of twin scroll, this are rather popular in the JZ world.

Streetfighter had a 2jz swapped Z31, and his compound turbo setup used one of these. He even offered it as a kit to Supra guys for a while.

http://i63.photobucket.com/albums/h128/OK85ZX/Branson%20Z%20Fest%202010/IMG_0309.jpg

[smoked240]

Edit: the ihi turbo won't work. It's an RHF5B.

[midnightreaction]

this is way more effort than it's worth. unless you're fabricating everything yourself, and getting the parts for free then a much simpler setup will be more efficient.

[LibertyMKIII]

I had seen this quite a bit on the 5.9 Cummins motors. They seemed to all use massive s4xx series BW turbos. From what I observed it helps mid range at the expense of high end up. Between the expense of 2 to 3 of everything. Room in the engine bay for placement this is not something to do on a budget....
I think a twin scroll turbo with a quick spool valve might be the best compromise.

Sent from my XT1575 using Tapatalk

[Motary]

http://www.rotaryeng.net/Scania-turbo-compound.jpg

^Compound turbo

Flamesuit on

[RB2.5]

Use a 25 shot on the compressor wheel of a 8374 and it a day. This stuff looks cool, but sounds like it won't work for most people.