Single Turbo Twin Scroll Single 4 port MAC vs two 3 port MAC

Mar 14, 2017
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Minot, ND
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2010 135i
So I have been doing some reading about this on other platforms for the past couple weeks after seeing @[email protected] mention the topic. But for single turbo twin scroll owners that are running two wastegates, is anyone running two 3 port MAC solenoids vs one 4 port. It seems like there would be no significant advantages to run two three ports vs one 4 port when it comes to the topic of low and high boost target accuracy but I’m looking for someone already running this setup versus theory. Also, a question for Terry, are users able to run one solenoid to the rear harness and one to the front as long as they stay bank specific? I apologize in advance if this information is available. I’ve been digging and haven’t found it anywhere.
 
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[email protected]

Sergeant
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Jan 23, 2017
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I've never played with a 4port, but the 3port is generally good for 2.5x WG spring pressure or higher. The lower the back pressure the higher over WG spring you can go.

On the N54 the banks merge before the throttle body using a common boost sensor so both banks wind up running the same WGDC. On the S63TU for example there are 2 TMAP sensors and we run separate control PIDs and WGDC for each side of the engine.
 
Mar 14, 2017
418
346
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Minot, ND
Ride
2010 135i
That makes total sense. So the two separate solenoids won’t have any effect from bank specific AFR changes? My plan was to run a three port to each wastegate.
 

[email protected]

Sergeant
Platinum Vendor
Jan 23, 2017
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I don't see the need for two solenoids since each solenoid will have the same duty cycle. But, sometimes when you try new things, you find something that works better. Go for it. :)

I don't foresee any AFR issues.
 
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Mar 14, 2017
418
346
0
Minot, ND
Ride
2010 135i
My goal for testing is finding which setup has the best boost accuracy at low boost and high boost using one three port solenoid, two solenoids, or a 4 port solenoid. The 4 port with the gates ran in parallel was recommended to me by a few tuners. I’ll mot likely do my own testing to see which setup achieves the best results. I’ll tune first with a single 3 port ran in parallel and log, then try the other two setups on the same tune and log again. I’ll post results in their own thread.
 

doublespaces

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Oct 18, 2016
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Terry should abandon n54tech and make this his default fourm for BMS. :blush:

I'm more than happy to consider carving out vendor specific sections where they self moderate. Its been on my mind anyway. If you don't like their rules, you just don't go in there.
 

Milan

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With both of my ST 335's that I had, the 3 port never worked as well as Terry seemed to suggest it would. I brought up the 4 port thing before since that's the standard on all the other platforms but it fell on deaf ears.