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Author Topic: 2.25 or 2.5 exhaust ?  (Read 2203 times)

April 04, 2009, 07:48:26 am

1outof5

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2.25 or 2.5 exhaust ?
« on: April 04, 2009, 07:48:26 am »
Wondering what your thoughts are on this subject.

The car: caddy (MK1 Golf pickup) with a 1.6 TD (RA engine, pump, injectors and gearbox) with FMIC and Garrett T2
Future: Giles pump, boost 15 - 18 max
Usage: daily to work and fun and loads to the dump (redoing my house) maybe some towing

why the question? I want to stay as discret as possible, one just for the "surprise" effect on others when I open the throtle  :lol: the other (maybe the first reason) avoid getting stoped by the police because of the "chimney" sized exhaust (and then they will start digging and realise the none standard engine - illegal here).

I know the bigger exhaust size at the turbo outlet is good for the EGTs (so more potential fuel  8) ) and for least back pressure but 2.5 is big.

Is it possible to start of with 2.5 then go down to 2.25 further down the line? How soon down the line would it be possible? Wouldn't this diameter reduction actualy help to accelerate the gas to exit?

Thoughts?
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Reply #1April 04, 2009, 09:28:14 am

hamradio

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2.25 or 2.5 exhaust ?
« Reply #1 on: April 04, 2009, 09:28:14 am »
If you're trying to look stock, 2.25" would be better.  Not sure about having a 2.5" dp-2.25" exhaust...in the world of saab ng900's and 9000's (turbo, of course), people will run a 3" dp to a even a stock exhaust and see considerable gains there; I don't think 2.5" to 2.25" would be a *that* big of a deal.
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Reply #2April 04, 2009, 09:45:23 am

Dirtrag2

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2.25 or 2.5 exhaust ?
« Reply #2 on: April 04, 2009, 09:45:23 am »
why not 2.5" to dual 2" not too big to look at and still lots of flow  :twisted:
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...Darcy
'97 Jetta 1.9TD ( dirtrag2 )
'88 Fox Wagon ( projekt Dirtrag 3 )
Reply #3April 04, 2009, 10:56:41 am

theman53

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    Holmes County Ohio - North Central Ohio
2.25 or 2.5 exhaust ?
« Reply #3 on: April 04, 2009, 10:56:41 am »
It would be similar to a ranger of that year if you had either 2.25 or 2.5. I would go with 2.5 and the last 12" or so put a 2.25 tip on it if your really concerned.
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Reply #4April 04, 2009, 12:34:53 pm

RabbitJockey

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2.25 or 2.5 exhaust ?
« Reply #4 on: April 04, 2009, 12:34:53 pm »
you can't modify your engine in france?
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01 Jetta TDI 100% stock daily
81 Rabbit:TDI-M ported head, Frank06 cam, PD intake, hybrid T3 turbo, Renault intercooler, Syl20 11mm pump, light weight fw, and yellow California Clutch clutch kit
Reply #5April 04, 2009, 02:49:55 pm

1outof5

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2.25 or 2.5 exhaust ?
« Reply #5 on: April 04, 2009, 02:49:55 pm »
Quote from: "Trev0rbr"
you can't modify your engine in france?


nope !

in theory you can't change the color of your car ...

"older" cars have a technical control every 2 years, commercial vehicules (like my pickup) also have polution check every year. Cars have to stay standard.

Now they open the hood to check that VN corresponds to the paperwork and note oil leaks and such. If you "know" a "friendly" inspector ...

If you change anything you have to take your car to a special technical center that go through the whole car and you must provide an official autorisation from the manufacturor (is this cas VW) that accepts the modifications if not they must request a "crash test" ...
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Reply #6April 04, 2009, 03:00:05 pm

RabbitJockey

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2.25 or 2.5 exhaust ?
« Reply #6 on: April 04, 2009, 03:00:05 pm »
wow i will never live in france.
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01 Jetta TDI 100% stock daily
81 Rabbit:TDI-M ported head, Frank06 cam, PD intake, hybrid T3 turbo, Renault intercooler, Syl20 11mm pump, light weight fw, and yellow California Clutch clutch kit
Reply #7April 05, 2009, 10:25:29 am

Baixo

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2.25 or 2.5 exhaust ?
« Reply #7 on: April 05, 2009, 10:25:29 am »
what is better between 2.25 or 2.5? 3" lol

when you make your exhuast keep the old one. design a nice flange or coupler so that when its time for inspection you can easily put in the old exhuast....


being a caddy there is tons of room, so i would go 3"
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