different style of twins

01CumminsSport

01CumminsSport

CapeCodDieselPerformance
Joined
Aug 8, 2008
Messages
559
Im about to build a set of twins for my truck. i currently have a 2.8 charger mounted up top where the small turbo would go in a twins kit, im thinking about putting the small turbo down below that one and having the exhaust go into the big guy first then through the little one and out through the exhaust, ill be using a 50mm gate between the two turbos to control boost just as if the small turbo was bolted directly to the manifold.

Give me what you think is a pro or con for this setup.

for me i think it will spool quicker because the exhaust will be hitting the large turbo first and there will be way less piping going between the chargers on the hot and cold side. Ill post up some pics of how the truck is now and what it will look like when it is done
 
set
 
Might as well just stay with a single. No reason to have a smaller turbo at all.
 
Well I started towing my girlfriends horse trailer through the mountains up here in the north east and when it's 90 degrees out with a single 69mm it gets a little tricky not to give the horses cancer lol.

So it's time to put a 64 under an 80 to make it tow a little better
 
01CumminsSport said:
Im about to build a set of twins for my truck. i currently have a 2.8 charger mounted up top where the small turbo would go in a twins kit, im thinking about putting the small turbo down below that one and having the exhaust go into the big guy first then through the little one and out through the exhaust, ill be using a 50mm gate between the two turbos to control boost just as if the small turbo was bolted directly to the manifold.

Give me what you think is a pro or con for this setup.

for me i think it will spool quicker because the exhaust will be hitting the large turbo first and there will be way less piping going between the chargers on the hot and cold side. Ill post up some pics of how the truck is now and what it will look like when it is done
Click to expand...

:badidea:
 
Con- not going to work with expanding gasses going from big to small.

Pro- we all get to laugh at your creation and it's ensuing failure.
 
With the gasses expanding as they go from the big turbo wouldnt that help spool the little one better. And there is going to be a 50mm external gate between the big and small turbo to take care of the extra drive pressure.
 
Not a chance.


The only way it would remotely work is if it was set up as a loosely defined sequential setup. Even then the fact that you're moving the smaller turbine further from the engine would reduce it's responsiveness.
 
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The reason the small turbo comes first is because it gets first dibs at the exhaust gas energy. If you have the big turbo first, it will remove kinetic energy from the exhaust gases leaving even less energy for the small turbo making it spool like a turd.
 
BigErk77 said:
The reason the small turbo comes first is because it gets first dibs at the exhaust gas energy. If you have the big turbo first, it will remove kinetic energy from the exhaust gases leaving even less energy for the small turbo making it spool like a turd.
Click to expand...

Bingo.

Big before small = 2 free wheeling hunks of worthless metal
 
Turbines work on (among other things) pressure differentials. The big turbo provides relatively little restriction to the flow of exhaust. The little turbo provides a much larger restriction. So instead of having a free flowing exhaust after the big turbo, you now have a bottle neck, which will back up the pressure behind it. If the pressure on the inlet of the big turbine is close to or equal to that of the discharge pressure, there is little or no pressure differential, and no work is done. The little turbo will be doing all the work.

If you look at any multistage centrifugal compressor or any turbine, it always goes from small to big (or big to small for compressors, as they are essentially the opposite of a turbine) because of that reason. Low volume, high pressure gas expands through the blades to become a high volume, low pressure gas.
 
Specs on the turbos are 64/73 t4 .90 and an s480/96 t6 1.32 or a s480/92 t4 1.23
I was thinking about gating both of them and running the t4 1.23 on the 480 to get real quick spoiling twins.
 
It would work, but it would spool really really slow, choke at about 2500 rpm, and it would only make about half as much air flow as your current single by itself.
 
i see this being a huge fail thread. Why wouldnt you just run the 64 by itself and save all this work just to make it worse that it already is.
 
Why dont you just use those two turbos in a convetional compound setup? They would work well.
 
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