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Any performance increase from tdi exhausts?


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er, just by sticking the exhaust out the side will not do a thing, apart from cover people in exhaust when driving down the street.. however removing the first silencer box for a straight through tube will increase the power a little. and it sounds a little better.

don't remove all the silencers from the exhaust because the turbo does require some back pressure or it will go bang eventually (if there is no back pressure at all).

a mod my mate is looking at is removing all the silencers and installing a cherry bomb, which should stop the turbo going bang.

I was curious if theres an increase in performance that you can feel if i were to stick the exhaust out the body to the side of the rf like i see some competition rigs do? I've seen em on devon4x4's ride.
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Bruce, there are no perfomance benefits from routing the exhaust through the bodywork, unless you remove silencers or increase the bore of the pipework, even then performance gains are likely to be minimal. People mostly do it on competion trucks because it reduces the risk of exhaust damage

Lars, yes the 2.5na exhaust is smaller bore so will likely restrict the engine somewhat, best to replace with a proper tdi system, or make a custom system of your own using 2.5inch pipe

Lewis :)

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I would also be interested to know why a lack of back pressure would cause a turbo to go pop as I had heard that back pressure was the enemy of a turbo.

On my disco I removed the back box and brought the tail pipe out the side (to stop it hitting things offroad) and I found that it made absolutely no difference to the performance.

I have heard that making a 3" system can improve performance but have yet to have had the funds and time to try this.


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my tdi i removed the rear box and brought the exhaust out a different route no fuel or bhp difference noticed

td5 (chipped) removed centre silence and replaced with straight through pipe, a hell of a difference in pickup, a bit louder and 1 mpg increase on average. It doesnt seem to have this affect on non chipped td5s though.

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I agree with Mr Pigster to a point

A few weeks ago - I took the advice in the tech section on the cat removal - (was planned for a while) I have just put a new defender middle box on and ran the tailpipe just to the left of the tow hook on the back.

the whole system is now 60mm

if you can (legally) remove the cat

It did make one hell of a difference in my case

the turbo really spins freer and earlier & makes it much easier to drive (I have a disco transfer box on 265/75`s)

previously i had a side entry exhaust based "system" - because the box on it had a smaller exit diameter on the pipe - always throwing soot up the side of the vehicle

up to now the bigger diameter system has really reduced the soot levels

I initially was going to go down the road of sourcing a "Vortex" exhaust but despite a few e-mails didnt get a reply & am now happy i went with a more conventional (cheeper) solusion

To Conclude, the vehicle was trailed at the weekend it was good for fording door-bottom height (incl a fitted 3 inch lift on the suspension) moreimportantly the power lowerdown has given it a snap lowerdown in the powerband and generally easier to dealwith.

happy trails


PS on the theme of back pressure & its advantages: dont speak too loud or someone will start to market a "Hiclone" for the exhaust system


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And related (sorry for hijacking :) ) as I am going to convert from 2,5 n/a to 200 Tdi... Will the original exhaust system strangle the new engine so I'd better get one for a 200Tdi Defender?

Don't try to fit a 200Tdi system all the mountings/hangers are totally different, use a TD system, LR used to do a retro fit kit for 2.5n\a diesl to 200TDi which used the existing main sections of exhaust with a new downpipe to connect to.

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Thanks for your concern, Ralph ;) But these have already been changed to some softer kind that don't transfer noise and vibrations like the standard ones. Made quite a difference regarding noises and rumble in the almost empty hardtop. :rolleyes:

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