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Old 09-25-2018, 07:25 AM   #1
JSD
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Default Twin Turbo setup

Hi,

I'd like to set up a twin turbo on my inline-6 engine. After studied the twin turbo system, I see an unusual turbo setup. While the intake of the conventional parallel system is designed to feed air to the turbo individually, the one I found on a diagram is one turbo is fed by the other. However, the exhaust sides are alike, yet, it won't called a compound or 2-stage turbo set up. Could anyone please tell me the advantages and disadvantages of this setup?

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Old 09-25-2018, 09:21 AM   #2
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Why do you want to go twin turbo? Just for the bling or do you have a certain power curve or HP goal in mind?

Parallel turbos, smaller turbos for fast spool
Compound turbos for high turbo boost pressure
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Old 09-25-2018, 09:26 AM   #3
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Originally Posted by Duder View Post
People are throwing in "sequential" and series/compound turbo systems into this discussion...

Probably worth clarifying some terminology.
  • Twin: two identical turbos in parallel
  • Series: two differently-sized turbos, one feeding the other. The larger turbo is the LP (low pressure) and feeds the smaller turbo (HP) on the compressor side. On the exhaust side, the small turbine feeds the larger one. Sometimes called "compound" setup, but that's actually something else (see below).
  • Sequential: can be parallel or series. Indicates that there is staged control of airflow, i.e. one turbo handles all of the flow at low engine speeds and the other is brought in to help at higher speeds...in sequence. Implies a change over time.
  • Turbocompounding: geared connection between turbine and engine crankshaft. Converts exhaust energy back into mechanical shaft power to the crankshaft of the engine. Like an inverse supercharger.
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Old 09-25-2018, 09:27 AM   #4
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Quote:
Originally Posted by JSD View Post
Hi,

I'd like to set up a twin turbo on my inline-6 engine.
Wow!
Awsome idea!
Can't wait to see the car run!
I subscribe to this thread!
Keep us updated!
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Old 09-25-2018, 09:32 AM   #5
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So, if I'm picturing the picture you've described correctly, it's parallel on the turbine/exhaust side, and sequential on the compressor/intake side?

Could you just show us the pic you're describing?
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Old 09-25-2018, 09:39 AM   #6
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Quote:
Originally Posted by JohnMc View Post
So, if I'm picturing the picture you've described correctly, it's parallel on the turbine/exhaust side, and sequential on the compressor/intake side?

Could you just show us the pic you're describing?
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Old 09-25-2018, 09:50 AM   #7
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Ahhh... My work blocks most pic hosting. It's in the first post already.

I'm not an expert (wait for Duder, he is), but I would tend to suspect that you would need very carefully selected turbos. Since the compressor will be seeing very different conditions. They're both ultimately passing the same CFM, and assuming they're properly specced, raising the boost pressure the same number of PSI, but the second one will probably need to be smaller. Same hotside, though?

Not sure how boost control would work either, but I'd assume you'd run the first compressor at a set psi its output, and the second one at a higher psi on its output.

All in all, I really just think you're going to get differing amounts of backpressure on each set of cylinders, depending on what the two turbos are doing. Which would affect how much air flows into each set of 3 cylinders.

Might work better on a diesel where the a/f mixture isn't critical (at least, not very, lol rolling coal) and you're going for some sky high boost pressures that a single turbo can't do. I.e. tractor pulling type setup?
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Old 09-25-2018, 10:01 AM   #8
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Would the one on the right be for "packaging issues" where there just isn't much room under the hood? That's the only benefit that I can come up with...
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Old 09-25-2018, 10:19 AM   #9
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Quote:
Originally Posted by Benjam83 View Post
Would the one on the right be for "packaging issues" where there just isn't much room under the hood? That's the only benefit that I can come up with...
You could use a small turbo to spool up a big one with that setup
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Old 09-25-2018, 11:45 AM   #10
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So when is someone going to try using the exhaust pressure for turning the crankshaft? Volvo D13 already has a version of this.
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Old 09-25-2018, 11:50 AM   #11
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Quote:
Originally Posted by lummert View Post
So when is someone going to try using the exhaust pressure for turning the crankshaft? Volvo D13 already has a version of this.
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Old 09-25-2018, 07:12 PM   #12
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AFAIK, the compounding setup uses 2 different size of turbo but in this case, parallel system, it uses the same size turbo. A little modification has been done on the intake side. So what’s the reason of this mod? Any advantages/disadvantages?
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Old 09-25-2018, 07:24 PM   #13
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Quote:
Originally Posted by JSD View Post
AFAIK, the compounding setup uses 2 different size of turbo but in this case, parallel system, it uses the same size turbo. A little modification has been done on the intake side. So what’s the reason of this mod? Any advantages/disadvantages?
Do it please!

There is some great ideas here:

http://www.turbobricks.net/forums/showthread.php?t=280

and here

https://forums.tbforums.com/showthread.php?t=344166

and here

http://www.forums.turbobricks.com/sh...ad.php?p=44518

and here

http://forums.turbobricks.com/showthread.php?t=198758

and here

http://www.turbobricks.org/forums/sh...d.php?t=337584

and here

http://forums.tbforums.com/showthread.php?t=8700

All amazing build, working great and it's really simple.

Please keep us updated on your project.

Last edited by Vincent Gagnon; 09-25-2018 at 08:06 PM..
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Old 09-26-2018, 04:26 AM   #14
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This is the planning stage. I need time+knowledge+money. Please be calm.
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Old 09-26-2018, 07:54 AM   #15
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Quote:
Originally Posted by JSD View Post
This is the planning stage. I need time+knowledge+money. Please be calm.
It will never spool
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Old 09-26-2018, 07:58 AM   #16
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Just install Owen Development quad turbo 4 banger.
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Old 09-26-2018, 11:10 AM   #17
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There could be an entire subforum of twin turbo threads.
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Old 09-26-2018, 12:37 PM   #18
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If you have to ask...
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Old 09-28-2018, 10:05 PM   #19
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Quote:
Originally Posted by JohnMc View Post
been doing it for a while look up wright r3350 uses a power recovery turhine they realized in the 30's adding inlet psi wasn't helping but using the exaust side of a turbo and hydraulic coupling to the crank shaft to help turn the crank
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Old 10-03-2018, 08:50 PM   #20
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Single twin scroll turbo? I6 is perfect for it.
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