Thread: Exhaust size 2.5 or 3 inch?

The 2-1/2 would be fine for the n/a. The turbo definatly benifits from the 3", and it sounds cooool

Originally Posted by Larns

The 2-1/2 would be fine for the n/a. The turbo definatly benifits from the 3", and it sounds cooool

^^^^x2

i run 2.5" exhaust on ute no problems...except you cant hear a thing...

ok I'll bite... why not 3.5 or 4 inch doameter then? any benefits/downside in even less back pressure than 3 inch exhausts provide (4BD1-T)??

Originally Posted by EchiDna

ok I'll bite... why not 3.5 or 4 inch doameter then? any benefits/downside in even less back pressure than 3 inch exhausts provide (4BD1-T)??

The mob i got my car tuned at said 2 1/2 was big enough for a 4bd1t. They said that the landcruisers 1hz turbo diesels also made more power with a 2 1/2, than a 3. Dont ask me why though, i always thought the less back preassure, the better. I run a 3 inch all the way from the dump, but my muffler shuts it up heaps.

Andy

thanks all for the replies.

peter

G'day again Pete,
I ran a 3inch exit just in front of the rear left wheel, but it was too noisey with the pax window down, so extended as per standard exhaust, out the rear end. Now much quieter, in fact less noise than the old 2.25!. This fact alone makes the three inch the go, but it's also giving better economy, and the turbo is more free reving, so less lag from a standing start. These engines were designed for trucks and the exhaust manifold flange easily copes with 3inch.........

Had a chat with an old school exhaust bloke. He said 2 1/2 with no muffler on a turbo 4bd1T is fine. he said unless your chasing a 10th of a second around Mount Panorama in a touring car 3" might benefit.


Justin