Any point in going from a 2inch turbo outlet to a 3 inch exhaust for the rest of it? (1 Viewer)

[Fantastika]

Im working on fitting a D5 2052 to my 2LT, the exhaust outlet is 57mm, about 2inches, is there any point in increasing the diameter after if the turbo itself is limited to that size?

 

[TheBussman]

Yes bigger is better. There are many factory turbos with tiny outlets and large diameter pipes for the rest of the system. One example: dodge/cummins truck is about 2.5" turbo outlet and then runs a 3.5" exhaust system.

 

[mudgudgeon]

I used 4" pipe on two different 4.2 litre Landcruiser turbo diesels for the first couple of feet of dump pipe.
Changed back to 3" pipe for the rest of the system, and a couple of big mufflers

You want zero back pressure at the turbo to let the turbo spool.
Bigger dump pipe seems to help this.

I think 3" is too big for a full system on a 2lt.
I used to regularly see a young guy driving a turbo diesel Hilux with 3" exhaust on it.
It was LOUD and not in a good way! Sounded like dog****!

 

[Fantastika]

I used 4" pipe on two different 4.2 litre Landcruiser turbo diesels for the first couple of feet of dump pipe.
Changed back to 3" pipe for the rest of the system, and a couple of big mufflers

You want zero back pressure at the turbo to let the turbo spool.
Bigger dump pipe seems to help this.

I think 3" is too big for a full system on a 2lt.
I used to regularly see a young guy driving a turbo diesel Hilux with 3" exhaust on it.
It was LOUD and not in a good way! Sounded like dog****!

I guess following what Volvo did on the original car would be a good start then, as the D5 makes about 180hp, obviously different engine and its commonrail. Ill look at making a 2.5inch exhaust then

 

[Dougal]

Yes but you need a smooth conical transition. It may be easier to do it in two steps. 2 - 2.5in. 2.5-3in.

But I also think 2.5" is heaps for a 2LT.

 

[Fantastika]

Yes but you need a smooth conical transition. It may be easier to do it in two steps. 2 - 2.5in. 2.5-3in.

But I also think 2.5" is heaps for a 2LT.

Gonna go with 2.5 then, now working out all the bends and mounts etc

 

[TLEXAS]

Yes but you need a smooth conical transition. It may be easier to do it in two steps. 2 - 2.5in. 2.5-3in.

But I also think 2.5" is heaps for a 2LT.

I am considering going 3.5" or 4"on my 1HDFTE when I upgrade to the Titanium Gturbo and +70 injectors. Is it worth going the whole hog from dump pipe to rear pipe or just say dump pipe to the muffler? When does the bigger is better equation fall over?

 

[TheBussman]

I am considering going 3.5" or 4"on my 1HDFTE when I upgrade to the Titanium Gturbo and +70 injectors. Is it worth going the whole hog from dump pipe to rear pipe or just say dump pipe to the muffler? When does the bigger is better equation fall over?

"it depends" as always, how many bends do you have? How tight is the radius of the bends? are you going to have side exit or full length? I'm sure somebody could do a 3d flow model of a system and give you data to make a decision. 4" is going to be very difficult to fit, 3" is hard enough. As mentioned earlier larger pipes are louder too.

 

[Dougal]

I am considering going 3.5" or 4"on my 1HDFTE when I upgrade to the Titanium Gturbo and +70 injectors. Is it worth going the whole hog from dump pipe to rear pipe or just say dump pipe to the muffler? When does the bigger is better equation fall over?

I think you'll be fine with 3". The flow difference to 3.5" isn't worth the hassle. Getting a 4" system to fit will be a huge PITA and is overkill.

 

[mudgudgeon]

3" is tight in a few places.
4" i don't think would even be possible without a body lift. Even then, getting past the transfer case, and rear diff area would be very difficult

 

[Fantastika]

3" is tight in a few places.
4" i don't think would even be possible without a body lift. Even then, getting past the transfer case, and rear diff area would be very difficult

Ive got a volvo truck wtih a 14L engine and that doesnt even have 4inch pipe, 3" is most definitely fine

 

[AussieHJCruza]

You can get a 3.5" dump pipe in easily enough, but you'll definitely struggle further back to keep at 3.5". Beaudesert's HDJ80 exhaust is 3.5" for the first few hundred Mm and tapers into 3" if you're looking for something off the shelf.