exhaust size for 2.5 turbo diesel

[wildplumdx]

looking at putting a bigger exhaust on my L200 so i was thinking of 3 inch from the turbo to the turbo flow muffler which will be just under the drivers feet area ish then go into 2 and a half inch after the muffler ? or is this too big for a small diesel ?

[tweake]

with exception of variable turbo motors, you can't go to big !

biggest things are cost and noise. depending on power output you may not see much gain with 3" and it will certainly cost more and noise goes up.
however with some of the more gutless engines any gain is good.
2.5" is a good size cost wise and noise wise. with your muffler it will be quiet.

[strx7]

i'd go 2.5. the only thing 3 inch will gain over 2.5inch will be cost and decibals.

[wildplumdx]

yeah but i have heard a guy go 3 inch from the turbo then at the muffler go 2 and a half as by this time the exhaust gases have cooled enough to go bit smaller but i dunno how true it is, as you hear you cant go too big off the back of the turbo ? what about back pressure etc cause i always thought you could go to big ?

[tweake]

can't really lower the back pressure as the turbo is the biggest restriction. back pressure is not really an issue.
some engine can run into problems (especially variable) when the dump pipe is used as a restrictor. putting a big exhaust on can cause turbo rpm to go to high.

3" into muffler and 2.5 out would be ok assuming muffler dampens out the exhaust pulses. not something i've ever tried.

[Sketchy_Racer]

2.5 from the dump will be best. Biggest gain will probably be from making a new dump pipe as they are usually the restrictors.

Going 3" to 2.5" is counter intuitive. As the exhaust gas temperature reduces so does it's flow rate (hence people heat wrapping their headers to keep temps and flow rates high) If you were worried about flow later in the system then going from a 2.5" up to a 3" would be beneficial, but with a 2.5 litre diesel wont be necessary.

A 2.5" with a free flow muffler sounds great, gives a nice turbo whistle.

[lownslow]

Neat good thread! I'm keen to give this a go also on my 2.5DT pajero. Dump pipe looks very restrictive. Anyone know who sells the turbo rear flanges? Or just cut and weld existing cast dump pipe?

Cheers Chris

[ArvinSlayer]

so u cant get a template of your dump flange, then get it laser or cater cut out of 6-8mm steel, then you basically gotta shape the dump pipe and get it welded and checked for leaks. alternatively you can get aftermarket dump pipes, but i think they make em for turbos of more mainstream racing engines, such as the RB, but yes a dump pipe isnt tht much more than that i reckon

Peace

Arvin

[strx7]

so u cant get a template of your dump flange, then get it laser or cater cut out of 6-8mm steel,

I'd reccomend starting with a 10mm thick flange, and once you have welded the pipe to the back of it, make sure you check it for distortion, if it distorts, get it refaced at a machinists.

[wildplumdx]

very interesting its quiet a science isn't it also might look into getting this flange off ebay

http://www.ebay.com/itm/Kinugawa-Turbo- ... 40&vxp=mtr

[wildplumdx]

just wondering its a td04 could you just grab any old td04 with similar specs and wack it on ? http://www.ebay.com/itm/Kinugawa-Upgrad ... 5f&vxp=mtr

[wildplumdx]

also this option http://www.ebay.com/itm/Turbo-Upgrade-C ... 19&vxp=mtr

[ArvinSlayer]

yea thts rite, 10mm ono lol my bad!

Peace

Arvin

[lownslow]

very interesting its quiet a science isn't it also might look into getting this flange off ebay

http://www.ebay.com/itm/Kinugawa-Turbo- ... 40&vxp=mtr

Good find! Kinugawa make good stuff. Will have to get one of these when i get around to doing my zorst.

Whats the deal with increasing boost / putting better turbos on these motors? New to diesel turbo tuning. Dial more fuel? Do these motors/diesels have knock sensors or equivilant auto adjustment of any kind.