Thread: 3" exhaust on td5

Mike, there appears to be plenty of TD5's and Tdi's (and lots of other 4wd diesels) running around with 3" systems and we don't seem to hear of massive turbo failures ?

Maybe the length/pressure drop of a 110/130 system vs the predominance of 90's in the UK makes a difference ?
I'm guessing Lara had the wick turned up pretty well too, probably much more than, say a customers ECU in terms of fuel ?

When I built my 3" system all those years ago (and it feels like another lifetime now) I tried to source 2.75" tube and bends and it was going to cost roughly double in materials over using 3" parts, so it was a no-brainer for me at the time.

Do I suffer from overspeeding the little T250 ?
Dunno, analogue gauges aren't the best for recording something like that, and I'll probably jinx myself saying this, but it's still pumping away and the car is about to clock 300,000km.

Originally Posted by noogie

Are you happy with the set up you have now?

There is always room for improvement and the list of things you can do is virtually endless but at some stage money can be spent on other things.
But to answer your question, yes VERY HAPPY.

A VNT (after the remap) was a massive improvement in drivability.
No EGR is a given
There are a few airbox mods that all help.
Boostbox is a must for remap and vnt.
Uprated MAF (or 2 channel boost box) as airflow was peaking out cutting fuelling.
And on and on and on..............

Don't know if there is much to be gained with a 3 inch exhaust. it is after all only a 2.5 litre engine but as long as there is something to be gained any avenue is worth trying, it's only money

As I said earlier, the straight through exhaust created a terrible drone that I was glad to get rid of and no noticeable difference when I put a high flow muffler back in it.

Cheers,
Paul.

Originally Posted by uninformed

are we talking mandrel bent or crush bent?

I always talk Mandrel bends....

Originally Posted by isuzurover

Do we have to do this all again??? (it usually ends in someone having a tanty and going away for a while???)

Noboody is arguing that turbos cannot overspeed. What is being debated is that fitting a 3" pipe will cause any detrimental effects (and/or overspeed).

You cannot provide any proof of overspeed. Conversely, there are plenty of TD5s driving around quite happily with 3" exhausts and have been doing so for many years...

If fitting a 3" pipe to a 110 / 130 causes overspeed, then a 90 TD5 should overspeed with a 2.5" exhaust...

As for the suppliers. A 2.5" exhaust is cheaper to make, easier to squeeze in, lighter and smaller for shipping, etc... BUT - those on the market are no cheaper than 3" systems



Looks like these guys got it horribly wrong. Exhaust too short, too large, must produce no power and overspeed like crazy...

You like to post up examples like this to justify your replies but what relation is there between a drag car that drives in a straight line for 400mtrs and a road vehicle that has to do everything from towing a boat to picking the kids up from school?.The post is about exhaust size and fitting a 3'' exhaust means fitting a muffler which adds a restriction so you gain nothing over a 2.5'' system which doesn't,like everything on a road vehicle compromise is the key to get the best overall result between performance and comfort. Pat

Originally Posted by harro

There is always room for improvement and the list of things you can do is virtually endless but at some stage money can be spent on other things.
But to answer your question, yes VERY HAPPY.

A VNT (after the remap) was a massive improvement in drivability.
No EGR is a given
There are a few airbox mods that all help.
Boostbox is a must for remap and vnt.
Uprated MAF (or 2 channel boost box) as airflow was peaking out cutting fuelling.
And on and on and on..............

Don't know if there is much to be gained with a 3 inch exhaust. it is after all only a 2.5 litre engine but as long as there is something to be gained any avenue is worth trying, it's only money

As I said earlier, the straight through exhaust created a terrible drone that I was glad to get rid of and no noticeable difference when I put a high flow muffler back in it.

Cheers,
Paul.

Thanks Paul

Ill go with the high flow muffler I think.
Where did you have it mounted? At the end of pipe?

Originally Posted by PAT303

You like to post up examples like this to justify your replies but what relation is there between a drag car that drives in a straight line for 400mtrs and a road vehicle that has to do everything from towing a boat to picking the kids up from school?.The post is about exhaust size and fitting a 3'' exhaust means fitting a muffler which adds a restriction so you gain nothing over a 2.5'' system which doesn't,like everything on a road vehicle compromise is the key to get the best overall result between performance and comfort. Pat

Pat am I reading correctly that you mean a 2.5" system with no muffler what so ever?

If so, who runs this on a road going vehicle?

BTW I have a Taipan Xp Vortex muffler......it changes the laws of physics!

Originally Posted by noogie

Thanks Paul

Ill go with the high flow muffler I think.
Where did you have it mounted? At the end of pipe?

I had it put in roughly where the original one was.
Which is about the middle IIRC.

Cheers,
Paul.

Originally Posted by uninformed

Pat am I reading correctly that you mean a 2.5" system with no muffler what so ever?

If so, who runs this on a road going vehicle?

BTW I have a Taipan Xp Vortex muffler......it changes the laws of physics!

Just a resignator,my Tdi hasn't had a muffler for 10 years and it never came up once in three Blue slip inspections. Pat