Kevin's Compound Sequential Twin Turbo Design
08-26-2014, 03:07 AM
#12
0.0 BAR
Join Date: Aug 2014
Posts: 1
I believe he is referring to the fact that your cold side is sequential, not compound, therefore you are sequentially turbo charging your engine in a somewhat Frankenstein way.
Compounding means that you are multiplying or incrementing the boost from one turbo by using another.
The cold side is looking a lot like a Subaru TT setup now, the advantage the Subaru setup has is that when in twin turbo mode the turbos are in parallel.
In other notes:
Running two turbos in series on the hot side will create an imbalance in the system, turbo 1 will always have a different dynamic to turbo 2, therefore the boost output of both will always be different. How will you control this?
Second wastegate location is in the reverse direction to flow, might as well remove it.
As mentioned, 2 Blow off valves are not needed.
Probably some other things I have missed. Your work looks good, just the theory may be a little lacking.
Compounding means that you are multiplying or incrementing the boost from one turbo by using another.
The cold side is looking a lot like a Subaru TT setup now, the advantage the Subaru setup has is that when in twin turbo mode the turbos are in parallel.
In other notes:
Running two turbos in series on the hot side will create an imbalance in the system, turbo 1 will always have a different dynamic to turbo 2, therefore the boost output of both will always be different. How will you control this?
Second wastegate location is in the reverse direction to flow, might as well remove it.
As mentioned, 2 Blow off valves are not needed.
Probably some other things I have missed. Your work looks good, just the theory may be a little lacking.
Last edited by GorGasm; 08-26-2014 at 03:14 AM.
08-26-2014, 03:56 AM
#13
0.0 BAR
Thread Starter
Join Date: May 2013
Posts: 24
I prefer the words original or unique rather than Frankenstein. 
Once the setup is at max boost, the turbos are running parallel, just different in size so they will be flowing different volumes of air. Both will flow the same boost pressure once the pressure paths are joined.
There are two wastegates, one to control each turbo. The main boost control is the second turbos wastegate as that controls the big turbo. The first wastegate is only accurately controlled up to the point that the turbo flows are joined and then is just under control of the manifold boost pressure. As long as one turbo doesn't have enough flow to overpower the other one, it should work fine. If one does, then I'll need to control the turbo wastegates more directly to stop that, for example by referencing turbo speed using a speed sensor.
The second wastegate flow path is not ideal, but it will still bleed off pressure which will allow it to control the second bigger turbo as the second wastegate is much larger than it needs to be.
As mentioned, my two blow off valves are quite small so I need both of them.
Once the setup is at max boost, the turbos are running parallel, just different in size so they will be flowing different volumes of air. Both will flow the same boost pressure once the pressure paths are joined.
There are two wastegates, one to control each turbo. The main boost control is the second turbos wastegate as that controls the big turbo. The first wastegate is only accurately controlled up to the point that the turbo flows are joined and then is just under control of the manifold boost pressure. As long as one turbo doesn't have enough flow to overpower the other one, it should work fine. If one does, then I'll need to control the turbo wastegates more directly to stop that, for example by referencing turbo speed using a speed sensor.
The second wastegate flow path is not ideal, but it will still bleed off pressure which will allow it to control the second bigger turbo as the second wastegate is much larger than it needs to be.
As mentioned, my two blow off valves are quite small so I need both of them.
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