Should I bother with a divided merge?

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RJK3

RJK3

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I'll be running twin S366's, T4 divided housings. Is it worth dividing the merge to the turbo flange? 4-2 / 2. Or should I just go 4 - 1?
It'll be mostly street driven with a few spirited track days thrown in from time to time.
73' Duster
408
727
3:23
 
RJK3 said:
I'll be running twin S366's, T4 divided housings. Is it worth dividing the merge to the turbo flange? 4-2 / 2. Or should I just go 4 - 1?
It'll be mostly street driven with a few spirited track days thrown in from time to time.
73' Duster
408
727
3:23
Click to expand...
It will make the turbo spool sooner if you run each bank separate thats what the twin scroll turbo is designed for.
 
I'm running the same setup. I ran from my header to turbo with 2.5 inch and ran 1.75 from waste gate. It spools pretty good and runs great. You will like this setup.
 
I'm thinking I'm going to run 1 and 5 , 3 and 7(driver side) then 2 and 4 , 6 and 8(pass side) into separate 2 inch pipes that merge into each side of the divided flanges. So two cylinders to each half of the flanges.
If anyone wants to chime in on the cylinder combinations, that'd be great. I've talked myself into and out of that particular order a couple of times...lol trying to keep the best exhaust pulse sequence in mind.
Thanks for the input guys!
 
I think you will be just fine if you send the drivers side to one side of the merger and the passenger side to the other side of the merger.
 
I'm running twins. 2 S366 Borg Warner's with T4 divided housings, so one turbo for each bank and 2 inlets per turbo.
 
Then it would be smart (since you're fabricating this up) to align all the exhaust pulses as best as possible. You don't want to end up with 5&7 merged into the same hole. Then there's pipe length to ponder :BangHead:

Good luck and add pics when you're done!
 
Don't even get me started on header length....lol.
1 and 5 will "merge" into their own 2" pipe, as well as 3 and 7 to its own 2" pipe. So basically two 2" "logs" per bank, merged to the divided flanges.
Edited, because I'm a rude dinner partner....
 
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RJK3 said:
Don't even get me started on header length....lol.
1 and 5 will "merge" into their own 2" pipe, as well as 3 and 5 to its own 2" pipe. So basically two 2" "logs" per bank, merged to the divided flanges.
Click to expand...

are you going to cap cylinder 7 ?
:poke:
 
Dahhh! Sorry....lol. I'm actually at dinner with the wife, she's giving me the stink eye! I was rushed!
You know what I meant!
 
RJK3 said:
I'm running twins. 2 S366 Borg Warner's with T4 divided housings, so one turbo for each bank and 2 inlets per turbo.
Click to expand...
I guess I should have read better, if your running twins then the way your planning on running would work.
 
I'd just go 4-1 and let the Turbine draw from all 4 cylinders.
It don't agree that the design intent of most divided turbines is that 1 side only see 2 pulses per cycle.
 
lol, yeah, they somehow take offence to it if we take em out on a date and spend some talking to other people on the phone
 
myduster360 said:
I'd just go 4-1 and let the Turbine draw from all 4 cylinders.
It don't agree that the design intent of most divided turbines is that 1 side only see 2 pulses per cycle.
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Wouldn't 4 pulses, equally spaced,divided to each half of the merge be the intent of the divided housings? It's fairly common on the ricer crap.
The S366's are a little on the largish side, size wise, with the .91 AR. Just trying to optimize spool characteristics.
 
RJK3 said:
Wouldn't 4 pulses, equally spaced,divided to each half of the merge be the intent of the divided housings? It's fairly common on the ricer crap.
Click to expand...

I would say the true design intent is to evenly split and accelerate the total available gas flow so that the turbine nozzle sees a near constant mass flow. Pulsed flow to a turbine just results in pulsed acceleration of the turbine.

i just don't see how alternating one half of the turbine nozzle getting a pulse and then the other half is really what the turbine wants. It just seems it would work best on a constant pressure manifold
 
Since the cylinders are already separated by the time they get to the collector, I'm skeptical that keeping them separated for a few more inches before reaching the turbo flange will make a perceptible difference in spool.

Regardless, what I do know for sure is if you don't merge 4 into 1, to prevent boost creep or leaning out the other 2 cylinders when the WG opens, you'll probably need a Wastegate on each pair of tubes, so 2 WG per turbo. 1 WG per turbo seems more simple.
 
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Or this
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