turbo inlet top turbo for twins

DTanklage

DTanklage

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just wondering if having a 4" inlet on the top turbo is a good thing or a bad thing when you do twins?

if the tube coming up from the bottom charger is 3" why not mill the snout off the top turbo and make it 3" also?

in a typical twin set up the air would 'slow down' as the tubing went from 3 to 4 but is that a good thing or not?

on one hand i can see it maybe making it easier for the top turbo to 'grab' air but on the other it seems like it would flow better if it were 3" all the way thru (or 3.5 or what ever your tube is)

karl already pointed out that doing something like this makes it a lot harder to swap different turbos in n out but what else do you guys think about the idea??????

i am considering milling mine off and welding 3" on and then filling it in with epoxy to form a perfect taper (same concept as a race cover) to direct the flow from the bottom charger right down the throat of the top, without the dia enlarging first

for a single i think the 4" inlet is great

has anyone tried doin this?

do you think it would be a noticable difference?

thanks, don
 
probably minimal gains for a lot of work, but it would be good to have a real-world example to know exactly what the difference would be
 
it would be a lot of work to try it and even more work to try both

could even hinder performance - i dont see how tho

it just does not seem right having the tube flare out before entering the top charger

usually everything is a trade off but i dont think this mod will be

think it will decrease spool time and increase power

see it like the grid heater - it probably aint worth much but if you want it right you gotta get that thing outta there

karl aint gonna like this but i want mine to be a straight shot
 
Use 4" pipe instead.

If you make it a 3" you will lose your map enhancer wich IMO would be worth more air flow having it then what you MAY gain out of making it all 3".
 
if we use 4" pipe it will affect spool tho correct? (increase spool time)

and it still has to get crammed thru a 2.5" hole

have already decided to go with 3" tubing there

only question now is flare it out to 4" or make the turbo 3"


kinda like using a -12 line feeding one inlet on a p-pump

the i.d. of the fitting it is connected to is only .370


*why would it lose the map enhancer? isnt that the groove the cut into the compressor housing down below the leading edge of the fins?
 
and it still has to get crammed thru a 2.5" hole
Click to expand...

Dont forget the velocity profile of the air flowing through the pipe
h1012v3_40_1.jpg
 
There will be a higher flow velocity toward the center of the tubing, so that profile of flow will be very close to the inlet dia. of the 2nd compressor stage.... i guess im saying that the flow probably will not be that different at the inlet of the 2nd stage with the 3" or the 4" simply because of the opening shape. The only bad thing I can think of is if the 4" provides some added turbulence near that transition area - but then again most anyone with twins is making great power so it doesnt seem to be an issue

{wishy/washy response}
 
Hurley said:
i guess im saying that the flow probably will not be that different at the inlet of the 2nd stage with the 3" or the 4" simply because of the opening shape.


The only bad thing I can think of is if the 4" provides some added turbulence near that transition area...
Click to expand...

the shape of the top housing inlet? (i change that)


thats exactly what i am getting at, the turbulence that is created by going from 3 to 4". if i wasnt gonna fill in the opening shape and make it a funnel (like a race cover) it might not matter but i do fill that in


really want to try this - both ways
 
Boost pressure has a tendency to mask poor flow/turbulence issues in my experience. Look at the heads/intakes on these motors for a prime example. IMHO, the big turbo compressor/housing will be more of a restriction prior to it making boost pressure and the restriction/turbulence created by having the 4" inlet on the small turbo will be negligible once the big turbo is making boost.

That's the way I look at it anyway. I'm interested in your findings if you do try it both ways...
 
thats what i am talking about doin

but why use a 4" inlet when the tubing connecting the two is 3" ?
 
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