trhlz1222
Veteran CEG'er
wat exhuast do you recommend with a turbo?
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True duals?
- Thread starter trhlz1222
- Start date
striker2
Official CEG Vendor
3" minimum for a V6
2.5" minimum for a 4 (although 3" is still better)
2.5" minimum for a 4 (although 3" is still better)
trhlz1222
Veteran CEG'er
so if i plan on turboin it just get a regular cat back with 3"?
striker2
Official CEG Vendor
yup. best option
S2Knott
Hard-core CEG'er
so explain to me you truduals setup is it 2" the whole way? how isnt that a restriction? does it open up after the rear y pipe or something?
zorrex
Enjoys the Abuse
Or just get a supercharger...:laugh:
BK4293
Hard-core CEG'er
What did you say Tina?
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zorrex
Enjoys the Abuse
:laugh:
JesusFreak
Hard-core CEG'er
2 2" pipes alows more air then 1 3" pipe?! Where is the lack of logic?
zorrex
Enjoys the Abuse
Well, actually, they would be very close to the same...The cross-sectional area of the 2" pipe = 2 pipes * (1" radius)^2 * pi = 6.28 sq in
The cross-sectional area of a 3" pipe = 1 pipe * (1.5" radius)^2 * pi = 7.07 sq in.
So the ONE 3" pipe WILL allow more air to flow through it than TWO 2" pipes. And in addition, with 2 2" pipes, there will be more friction losses in the 2 2" pipes because there is more surface exposed to the flow of air through the pipe...
:shrug:
don't forget about the amount of air flow, the single 3 inch pipe will receives all of the exhaust flow from both banks where as the tru-duals will only receive half of the total exhaust flow from the engine ...
striker2
Official CEG Vendor
and the smaller diameter pipes will help to keep the velocity of the gas up.
yup thats correct
now Ian since you are currently taking fluid dynamics calculate the thickness of the boundary layer in both situation, a 2" and 3" pipe and that will give you an idea of how much area the pipe really flows
zorrex
Enjoys the Abuse
I'm too lazy, lol. Will there even be a boundary layer?
. I would think the relative roughness of a rusted (over time, it would become rusted) pipe would be too great and there wouldn't actually be a "boundary layer."I'm too lazy, lol. Will there even be a boundary layer?
pretty sure there would be, that the definition of flow in a pipe, the roughness is what will cause the air to be turbulent and seperate from the sureface creating the boundary layer
think of a velocity profile from a pipe cross section, the greatest flow is in the center and it tappers off to the walls of the pipe where the velocity would be zero
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zorrex
Enjoys the Abuse
And Brian, I was comparing the TOTAL area of both setups, that way they can be compared using total flow. But if you are saying that there will be a boundary layer, then that only supports the use of a 3"...More of a total surface area between the 2 2" pipes meaning more non-flowing fluid along the boundary layer...
ok, so by area we know the single 3" pipe can flow more, so lets now look at velocity.
the 3" pipe will have a lower velocity then the 2" pipe, and remember that the smaller pipe has less volume to flow
i can't remember but the boundary layer has to be dependent on the velocity, area, etc
but more then likely the this isn't going to have a big affect in this, but techanically you would need to account for it, as well as all losses from bends in the pipe
zorrex
Enjoys the Abuse
Hmm. You may be right, but I'm still on the fence on this issue. I will work out calculations in the near future. What would be a good estimate for the flow of exhaust from a Duratec at 1k rpm, 2k, etc? I quickly whipped out a lab report I've been working on recently, and the epsilon (roughness value) for new stainless steel is .000084 inches +-50%, and for rusted steel it is .084 inches +-50%. The rusted value is quite high, and I wouldn't expect it to be that high in engine applications. Let me know what you think and I will run through some calculations...
good estimate of exhaust flow, not really sure, I know at idle a duratec MAF reads about .7 #/min on average, and I have seen miine get upwards of 11~14 #/min at high rpm.
as for the epsilon of the pipe I would say go in the middle of the two values as a good average, the inside definately shouldn't rust as much or like the outside of the exhaust
98TredSVT
Veteran CEG'er
Was this over stock exhaust or what setup? Did you already have headers on there? I already have headers and an optimized y pipe, with a borla resonator, what kind of gains could I expect with true duals?