2.5" Dump pipe for 4JB1T

[lucasks82]

I own a 91 Rodeo 2.8L with the 4JB1T engine, it goes great and never misses a beat but I would like the turbo to spool up a bit faster and get the benefits of a little more low down power and torque and hopefully increased fuel efficiency.

I have found out on this forum that a 2.5" straight through exhaust is the way to go but my problem is I cant find a 2.5" dump pipe to suit my engine and turbo. On ebay and an online store you can get one for the 98 model and onwards but not the earlier models

Would anybody have a used one they do not need any more?

Should I ask around at the wreckers?

Does anybody know who can fabricate one?

Any help or advice would be much appreciated

[geeves]

Dump pipe is good for the last few horsepower but a big bore without the dump pipe still gives quite usable improvement as does a high flow air filter and snorkel.
If the 98 one you saw quotes your engine it should work but be aware there are 2 different oil filter settups on that engine so you might have to play with that to fit

[lucasks82]

Thanks Geeves, I have some more questions

1. What do you mean by "big bore" do you mean a big exhaust? I do want to get a 2.5" exhaust.

2. I have a unifilter - is that "high flow"

3. So a snorkel will help? I have seen them on ebay, are the cheap ones ok?

4. So with the oil filter, can I change its orientation to make the dump pipe fit? Mine is upright, is it different with the 98 model?

Thanks for your help

[geeves]

standard exhaust is 2 inch anything bigger is big bore
Unifilter is good as long as its cleaned correctly
Snorkels help some cars more than others. You always get cold air which is good but also replace a fair bit of the intake plumbing and on some cars thats a huge improvement
Changing the oil filter location means changing the housing it connects to. Is your filter on a slant or straight up and down? Which filter is it
I dont know when Holden started putting the later belt drive engine in the Rodeo or when they changed to the 4jh1

[isuzurob]

91-97 4jb1 engines in rodeo were the same a 4jb1 mu so oil filter points upwards, 97-01 4jb1 the oil filter faces down like the 3.1 4jg2 mu/bighorn, end of 01 they went to 4jh1 with top mount intercooler, as above can change oil filter housing and piping, or get a cutstom system made for you truck, they normally fit alot better

[lucasks82]

ok thanks for the info.

are the cheap snorkels ok or should I fork out for a decent one? What brands do you suggest?

the filter is straight up and down. Its a Z178A oil filter

my car has the 4JB1T engine.

[geeves]

there isnt much technical difference between comercial snorkels but the likes of airflow and safari have spent more research dollars on making them easy to fit right and mounts etc. Typical story with the cheapys is "Once I got the thing in it was fine"

[Downhillnz]

In regards to the dump pipe. I would suggest going to a 3.1 oil filter set up. I wish I had before I made my first dump pipe.

[lucasks82]

Is that off a 3.1L Jackaroo?

How does that help?

[geeves]

The angled filter allows more room and better angles. Also with the straight up and down version you are already limited in room to do filter changes and the dump pipe will take half of that