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Discussion Starter #1
Hey guys i think im getting a custom exhaust done. I was thinking about getting it split into dual but im not sure if it will lose too much back pressure with dual exhaust...i have a 1.8T so i think it might lose a little bit of back pressure but wasnt sure. Also if getting a dual exhaust isnt gonna be a bad thing i was wondering if they have any valences that have 2 slots cut out, or if i would have to just buy a rear bumper or what. If there are some rear bumpers that would work without buying a whole body kit let me know. thanks guys
 

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Dual exhaust would provide no performance gains over a standard turbo-back on a 1.8T since it's an inline engine. You gotta have a V-configuration engine like a V-8 in order to create a dual exhaust that actually helps increase performance. Also, it would be very difficult (and not to mention expensive) to fabricate a dual exhaust for our MKIV's because the passenger side exhaust piping will have to be routed away from the gas tank and spare tire which are in the way. Plus think of the added weight! If you aren't 100% concerned about performance, and have got the money, anything can be done.

You need to balance the amount of exhaust gases your engine will output with the diameter of your exhaust system. If you take a huge exhaust and put it on a small 4-cylinder, the flow of exhaust gases will be very poor. They will whirl around inside the huge piping and will obstruct flow out of the engine. This is where the rumor about a need for "backpressure" comes from. You need a big enough exhaust to be able to flow all the gases out, but not too big where the rate of flow becomes slow enough to hold everything up.
Having a turbo on the engine creates enough "backpressure" that you don't have to worry about the flow on the other side of it. The larger, the better (up to a point where you will notice diminishing gains from going to larger piping).

With a non-turbo engine though, you definitely don't want a huge exhaust. 2.5" (I think) is good for VR6's, but anything bigger (without additional motor work) will probably cause a power loss. That's why I always laugh when I see 1.6 liter Honda's with 4" exhaust tips....

Think of an engine as an air pump. Now, for conceptual purposes, replace air with water (they are both fluids anyway).
If you have a small pump (like ours), you want a tube that is big enough to not present a restriction on flow. But, if you put in too big a pipe, the volume of water inside the pipe becomes too large and the pump again is overloaded.
If you put a big waterwheel (turbo) between the pump and the tube, then it doesn't matter because the wheel is the main restriction and the tube's size becomes less important.

[ January 06, 2004: Message edited by: Josh Fryauff ]

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Very nicely put, Josh.

If you wanted to run a split muffler, you could run an R32 Rear bumper (VW dealers are starting to get the parts in the computer now...) and make it split exit if you want. Some manufacturer has to make one aftermarket if you would rather have that instead, I just don't know of any.

Oh yeah...the R32 has true dual exhaust! The only production Mk4 to have it. Its sweet.
 

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<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by Josh Fryauff:
Dual exhaust would provide no performance gains over a standard turbo-back on a 1.8T since it's...... <HR></BLOCKQUOTE>

almost exactly what i was gonna say. exept for the water pump/line thing. very nice.

i remember when i had my civic w/ a 2.5" pipe and a 4" tip, fartin around everywhere
 

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<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by big dub:
[QB

i remember when i had my civic w/ a 2.5" pipe and a 4" tip, fartin around everywhere
[/QB]<HR></BLOCKQUOTE>

We forgive you. Everyone makes mistakes
Remus makes a dual out for the 1.8t golf/gti look into it
 

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<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by BlueRabbit0886:
wow josh, you really know your stuff about turbos and the related stuff...

im always learning stuff on vwf...i love it
<HR></BLOCKQUOTE>

agreed! good job josh


[ January 08, 2004: Message edited by: 1point8T ]
 

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Discussion Starter #8
thanks josh for the info...there was a whole buttload of it...and it was all important...i love u guys lol...but yea i was kinda thinking about going for the r32 bumper dual exhaust look but im more worried about performance then look and if its not going to help much doing it that way ill just run a nice turbo back system...thanks again guys for the info.
 
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