What exhaust size for diesel performance

[monchochos]

I'm considering a new, less restrictive, exhaust for my 2.8ltr T/D NL pajero to improve power and torque.

Has anyone fitted a 3inch or 2.5inch system? I've had some advice that 3inch may be too big and result in less low down power than a 2.5 inch system. Anyone know if that's true?

If anyone a real world experience with this, please let me know.

[dolphin]

what i have heard is the 2.8 litre is more suited to the 2.5 inch exhaust as opposed to the 3 inch which is more suited to the larger engines. i would be fitting the 2.5 inch myself.

[schnitzel]

i have 2.5 inch free flow on the delica, vast improvement over standard, general consensus on the delica site was unless you have a bigger turbo 3 inch give no benefit aver a 2 and a half inch.

[pajeroman3lt]

I,v only got 2.5tdi but the 2.5'' exhaust on mine works fantastic. Quicker spool up and runs a little higher boost. I say got the free breathing 2.5''. plenty big enough.just my 2c worth.

[monchochos]

Thanks for the input. I did a bit more forum research last night and it seems that going bigger (3") shouldn't have any negative effect on performance compared to 2.5". But the performance increase from 2.5" to 3" would be negligible.

So at the moment it looks like 2.5" is winning.

[Mcreight911]

Mate when I was runing the standard turbo on my 2.8t I had a 2.75 inch exhaust with one muffler . Driving wise it revved easier, most noticeable over 2500rpm, not a lot of gain performance wise but still a gain . A Mate and i made our own 2.5 inch for his 2.8t and it felt no different to myn . Best bang for your buck power mod is a tune. Take it to a diesel specialist or if your confident have a look at the 4m40 tuning section and DIY. Without gettin expensive the exhaust, tune and snorkel is about it for this engine. Attached dyno -before is with exhaust, after is small boost increase and tune.

[yozrock1]

Hi,

The DPF delete pipe on my NS Pajero has been fitted too short(previous owner) and has pulled the rear exhaust forward causing it to move closer on one of the bends to the chassis which it hits.

The local exhaust shop has a cheap fix or spend $380 for a 3 inch system from the dpf delete pipe to the back, It would be a straight through pipe with only 1 straight through muffler.

Has anyone had any experiences/issues or recommendations on this?

I was looking to improve the exhaust but can not afford a full system. I am worried about extra noise or drone it could make? I have also heard that a turbo may suffer if there is less back pressure in the exhaust?

TIA