TECH: Back-pressure and Exhuast sizing.......

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toysrus
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Post by toysrus »

Upon further reading, this is getting more complicated by the minute.....

Essentially, design the exhaust system around the physical parameters i.e. size/noise and try to incorporate a few tricks along the way... :roll:
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Post by CussCuss »

toysrus wrote:Upon further reading, this is getting more complicated by the minute.....

Essentially, design the exhaust system around the physical parameters i.e. size/noise and try to incorporate a few tricks along the way... :roll:
ummm, duh.

If you want to have a look what the best exhaust system is go look at a drag or track car. Then try to get as close to that as possible with whatever compromises you need to make (length/noise)

someone once said 'garret make great mufflers'
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mrb1
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Post by mrb1 »

toysrus wrote:Upon further reading, this is getting more complicated by the minute.....
Wisdom is painful.
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Post by coop1er »

Time to dumb it down a shade:
toysrus wrote:
The TC06 Exhuast Housing only requires a 2 1/4" Exhuast pipe size to mate up fine.....

Now the question is related to back-pressure and how we know it robs power, but the fact of the matter is that this 'back-pressure' is going to be pre-determined by the 06 Exhuast Housing itself, so in those terms, why would someone want a 3" exhuast diameter when the 06 Housing outlet only dictates 2 1/4" ??
Because as has been said before, you want the largest possible differential
in pressures before and after the turbo. Now even a straight open ended
piece of exhaust pipe can have a measureable pressure inside it. Also
there is usually an ugly restriction built into an exhaust called a muffler.
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Post by Junkers »

After going so far indeepth into this, is the gain going to be worth while? :wink:

I've always had a simplistic view that if you want performance go 3", if you want something tolerable on the road go for 2.5".
In my opinion with turbo cars, bigger exhuasts can't hurt, you want to try and get it to 'freeflow' as much as possible, isn't that the idea behind massive dump pipes anyhow?
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Post by toysrus »

mrb1 wrote:Remember also that the exhaust is pulsed flow.
Correct, but doesn't the Turbine wheel technically null these pulses out ?
Computer games don't affect kids I mean if PacMan affected us as kids, we'd all be running around in darkened rooms, munching magic pills and listening to repetitive electronic music :D
toysrus
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Post by toysrus »

coop1er wrote:Time to dumb it down a shade:
toysrus wrote:
The TC06 Exhuast Housing only requires a 2 1/4" Exhuast pipe size to mate up fine.....

Now the question is related to back-pressure and how we know it robs power, but the fact of the matter is that this 'back-pressure' is going to be pre-determined by the 06 Exhuast Housing itself, so in those terms, why would someone want a 3" exhuast diameter when the 06 Housing outlet only dictates 2 1/4" ??
Because as has been said before, you want the largest possible differential
in pressures before and after the turbo. Now even a straight open ended
piece of exhaust pipe can have a measureable pressure inside it. Also
there is usually an ugly restriction built into an exhaust called a muffler.
Now, I think what you ae talking about is an 'expansion chamber'.......this is very very time & $$$ consuming and should be the last thing done after developing the Engine/Turbo combination.

I believe there is a point at where the angle of deviation is too great that it impacts on the pressure, when changing the cross-sectional area of flow such that I've read figures of 6 and 20 degrees maximum when creating a venturi like shape to reduce the velocity of the exhaust gases....
Computer games don't affect kids I mean if PacMan affected us as kids, we'd all be running around in darkened rooms, munching magic pills and listening to repetitive electronic music :D
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Post by coop1er »

:o

Hey a109, you are looking into it too deep. Sometimes you need to just
step back and let common sense guide your decisions.
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mrb1
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Post by mrb1 »

toysrus wrote:
mrb1 wrote:Remember also that the exhaust is pulsed flow.
Correct, but doesn't the Turbine wheel technically null these pulses out ?
Well yes pretty much.
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SIR GSR
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Post by SIR GSR »

Easy solution....3" from the turbo. 1 single 8" straight thru muffler, 3" tip. Not too restrictive, not too loud. Works for me.
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toysrus
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Post by toysrus »

coop1er wrote::o

Hey a109, you are looking into it too deep. Sometimes you need to just
step back and let common sense guide your decisions.
Aww, but that's too easy :D

What I would like is to have a quiet exhuast when at the lights, I can silently rip it up to 140k's on the clock and the officer would be none the wiser :twisted:

aka most AMG Mercerdes' :wink:
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Post by Abalistic »

Take it from the engine's point of view, after the exhaust has gone through the turbo, and the energy from it has been used up, there is no further use for it. You could just dump it straight out the side.
But the cops would have a problem with that.
A 2 1/2 inch exhaust flows about 400 Hp max. 3 inch exhaust will allow a lot more, but at the expense of noise.
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toysrus
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Post by toysrus »

mrb1, have you measured the Turbine dimensions on the TD06-19c because I suspect that it would running the 06H wheel in the 12cm^2 Housing.....

As coop1er, stated, creating the biggest pressure difference within the physical limitations but factoring in the volume change in exhuast temp, allowing a smaller muffler (hence noise) and running a twin dump pipe should do the trick :P

I might play around with expansion chambers later on when there is nothing more I can do :twisted:
Computer games don't affect kids I mean if PacMan affected us as kids, we'd all be running around in darkened rooms, munching magic pills and listening to repetitive electronic music :D
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Post by mrb1 »

toysrus wrote:mrb1, have you measured the Turbine dimensions on the TD06-19c because I suspect that it would running the 06H wheel in the 12cm^2 Housing.....
Definitely TD06 which is the same size as TC06.
toysrus
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Post by toysrus »

Mark, have you ever measured the EGTs at the Dump-pipe and exhuast tip ?.....to get an idea on the change in temperature hence volume :P
Computer games don't affect kids I mean if PacMan affected us as kids, we'd all be running around in darkened rooms, munching magic pills and listening to repetitive electronic music :D
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