Thread: td5 exhaust what size?

No bigger than 2.75"...and if your engine is stock, 2.5 in, mandrel bend, with hi flow cat, and mufflers.

Not 3"!!!!

Originally Posted by Hamish71

No bigger than 2.75"...and if your engine is stock, 2.5 in, mandrel bend, with hi flow cat, and mufflers.

Not 3"!!!!

Same!!!!!!!!!!!!!!!!

Allan

mine has a 2.5" mandrel bent stainless with decat and no silencers..... it sounds a treat and goes really well

In general - bigger the better for performance.

There are reports that the turbo can overspeed if you fit a 3" exhaust. However there are several people on here who have 3" exhausts and the turbos have not failed...

Originally Posted by isuzurover

In general - bigger the better for performance.

There are reports that the turbo can overspeed if you fit a 3" exhaust. However there are several people on here who have 3" exhausts and the turbos have not failed...

Bigger = Better = Wrong

With turbo diesels 10% larger than exhaust turbine exit is optimum.

Hence why LR fitted a 2.5" exhaust factory.

Just free flow it with a better silencer etc.

Originally Posted by Tombie

Bigger = Better = Wrong

With turbo diesels 10% larger than exhaust turbine exit is optimum.

Hence why LR fitted a 2.5" exhaust factory.

Just free flow it with a better silencer etc.

Not this crap again...

Optimum based on what??? Price vs performance maybe, but that is all...

On a TD (or TP engine), reducing back pressure will increase power. The "optimum" for performance is something like this:



Which has orders of magnitude less back pressure than any diameter full length exhaust you care to fit.

Overspeeding on a tuned td5 is very possible.

I've tested this 1st hand and seen the issues - although we didn't destroy the turbo thankfully.

3" pipes are the choice of tuned 4200cc Nissan diesels with increased boost etc. A 2500cc rover doesn't even come close even tuned to 20psi and 200kw.

Here's what donaldsons say:

Originally Posted by Tombie

Overspeeding on a tuned td5 is very possible.

I've tested this 1st hand and seen the issues - although we didn't destroy the turbo thankfully.

3" pipes are the choice of tuned 4200cc Nissan diesels with increased boost etc. A 2500cc rover doesn't even come close even tuned to 20psi and 200kw.

Here's what donaldsons say:

My original post said:

In general - bigger the better for performance.

There are reports that the turbo can overspeed if you fit a 3" exhaust. However there are several people on here who have 3" exhausts [forgot to add on TD5s] and the turbos have not failed...

Both of those statements are correct.

Don't Td5s have a redline of 5500 rpm and a max boost of 22 psi in stock form?

Even assuming the same volumetric efficiency, a stock TD5 will flow MORE AIR at redline than a stock 4BD1T, and slightly less than a stock TD42.



I am sure we both agree that the best compromise is a 2.5" or 2.75" on a TD5, however it is by no means the "optimum" for performance - if that is your priority.



EDIT : Those I can find with a 3" exhaust after a quick search:

Clarkie has a 3" mandrel bent exhaust - the turbo seems to be holding up fine:
http://www.aulro.com/afvb/90-110-130...-defender.html

Benny_IIA also had one on his TD5 110 ute (I think it is now sold?).

George130

Originally Posted by George130

Mine was already changed when I bought it. 3 inch system all the way with only a rear muffler. I beleive it should be better but have no idea.

Redback

Originally Posted by Redback

...I've fitted a 75mm mandel bend to mine...

Baz.

Micka

Originally Posted by Micka

Mine loves the 3" Mandrel

I finally heard how it sounds from outside when my old man took it out the other day...I almost got hard ops:

Best thing I have done is the Bruce Davis Chip upgrade and the 3" zorst.

Micka

Probably plenty more as well. No blown turbos amongst those with 3" exhausts.

and what do we find here:

Originally Posted by tombraider

Hear Hear!!!!!! Love my 3" system...
Nothing like the whistle of the turbo from the rear of the vehicle at idle
And such a sweet, sweet sound as she revs up. :!:

Cheers
Mike

Originally Posted by tombraider

...

Driveline:
TD5 with 'Total Rover Tech' intercooler and Bruce Davis ECU upgrade
3" mandrel bent exhaust from turbo housing with (for legality) 1 straight through muffler (straight through - hint )

Tombraider

As I posted in another thread:

Originally Posted by isuzurover

To go from a 2.5" to a 3" exhaust, we are talking about a 30% reduction in gas velocity, and a corresponding reduction in pressure drop (back pressure).

The TD5 is fitted to 90, 110, 130 and discos. If they all have 2.5" exhausts (of varying lengths), there would probably be a 30% difference in back pressure between a 90 and 130 exhaust (if not more).

I would be surprised if they are set up so close to the limit that a reduction in DP of that order can overspeed the turbo...