Offroad-Express

Had a brief chat to my local nissan parts guy as well as Sibainmud a few weekends back and it got me thinking.

I'd like to raise the boost on my Terrano - the engine / turbo / exhaust is factory and feels quite underpowered. From what I've heard / read on the forums it should handle a few extra pounds without reliability problems.

Given there's a 14psi relief valve and I'm not planning a new exhaust (yet); I'd think I'd like to run it at or just a tad under 14psi.

Just a few questions:
1) Will I need to raise the fuel flow when I increase the boost?
2) How do I make sure the air / fuel mix is right - is this where I need an EGT gauge to monitor the exhaust temp?
3) From searching the forums; it sounds like more air = lower temps and more fuel = higher temp? Is this right; seems to be the opposite rule to a petrol engine?

I'd be happy to post a 'how to' thread once done given this topic comes up every now and then.

Search here first. All the questions have been covered multiple times.

Cheers,

more importantly....your first mod to a TD27 should be to make it a TDI27.

secondly remove the EGR system that is clogging up the intake.

then modify the air fuel ratio's

Read loads and loads of threads on this site (and others) but being completely new to diesels I wanted to confirm my understanding.

Most threads talk about running roughly 20psi; I'm looking at running a lot less than that and if point (3) is right I'm wondering whether I need to muck around with fuel mix / EGT gauges.

Will look into removing EGR (sounds like a pointless system from what I've read so far).

By TDI I presume you're referring to an intercooler - could be something I look into down the track but as most of the driving is at speed it shouldn't be an issue for now.

you could always look into making a good cold air intake for it.

intercoolers are pretty good things to have, even at speed.

top mount ones are better for speed, water cooled ones are better for slow speeds.

my whole setup cost $120, out of an old subaru legacy, its a water to air one, so no need for a scoop, front mounted radiator, and water pump.

the only part that needs to be modified is the intake for the intercooler part, just needs the elbow rotated a little. im sure there are other ways to go, but this will do for me anyway.

if you would like pics, im half way through installing it.

i have owned both the pre facelift and now have the facelifted ecu controlled intercooled TDI27 mistral the power differences are massive even by factory standards. much more torque and acceleration.

Terrano Tim wrote:1) Will I need to raise the fuel flow when I increase the boost?
2) How do I make sure the air / fuel mix is right - is this where I need an EGT gauge to monitor the exhaust temp?
3) From searching the forums; it sounds like more air = lower temps and more fuel = higher temp? Is this right; seems to be the opposite rule to a petrol engine?

1- no. but its the fuel thats gives power increase..

2- Yea. install EGT, but it measures temp, not air/fuel mix. thats a petrol tuning idea.

3- Yeap. forget petrol rich/lean idea. think temperature.
More fuel will raise EGT
More cool airflow (boost, exhaust, waterspray etc) will help lower EGT.

You're on the right track. Do a bit more searching for likes of 'EGT' and 'diesel tuning', theres lots of info both on this forum, and what google will dig up

Nath

Do the egt. Anything much over 700 deg sustained temp will kill your turbo and cast exhaust manifold etc. It's a damage prevention gauge.
You're pretty much right with your basic understanding of the mixture thing, close enough to get it running harder without breaking it anyway.
Intercooler is a great idea too.
How far do you wanna go?

Dirtydog wrote:my whole setup cost $120, out of an old subaru legacy, its a water to air one, so no need for a scoop, front mounted radiator, and water pump.
if you would like pics, im half way through installing it.

Pics would be great - if it only cost $120 it sounds like a viable option (I was envisaging a big job with lots of cutting & rerouting – not really my thing). A front mount would be appealing as I want to keep the Terrano as close to factory looking as possible (so no scoops etc).

DEATH_INC wrote:Do the egt. Anything much over 700 deg sustained temp will kill your turbo and cast exhaust manifold etc. It's a damage prevention gauge.
Intercooler is a great idea too.

slide wrote:2- Yea. install EGT, but it measures temp, not air/fuel mix. thats a petrol tuning idea.

3- Yeap. forget petrol rich/lean idea. think temperature.
More fuel will raise EGT
More cool airflow (boost, exhaust, waterspray etc) will help lower EGT.

You're on the right track. Do a bit more searching for likes of 'EGT' and 'diesel tuning', theres lots of info both on this forum, and what google will dig up

Thanks – that’s the advice I was after. I’ll purchase a gauge over the next few weeks and plumb it in before mucking around with fuel / boost. Interesting learning curve as I've only ever had petrol motors.

DEATH_INC wrote:How far do you wanna go?

The Terrano is mostly to get me to work and back through traffic so it doesn’t need to be a speed-sleigh of doom.
But it just to be constantly working at its limits just to get it moving and as soon as I get on mud or sand with the tyres down everything’s exacerbated that much more.

I think I’ll look at doing things in stages and assess after each (1 & 2 a must, 3’s a maybe):
Stage 1) EGT Gauge & boost / fuel increase. Possible boost gauge.
Stage 2) Remove EGR.
Stage 3) Intercooler.

It’s also an auto (hence buying for work) and from what I’ve read that’s where the weakness will be. Probably another reason not to overdo the power.

Terrano Tim wrote: Stage 1) EGT Gauge & boost / fuel increase. Possible boost gauge.
Stage 2) Remove EGR.
Stage 3) Intercooler.

Just a suggestion, do EGR removal first. Make a fitting on blanking plate on exhaust manifold to insert sensor for EGT. (maybe buy gauge 1st so know what fitting)
Its a bitch to access, but works quite well. Not exactly central to all cylinders, but is plenty good enough
,Nath

slide wrote:

Terrano Tim wrote: Stage 1) EGT Gauge & boost / fuel increase. Possible boost gauge.
Stage 2) Remove EGR.
Stage 3) Intercooler.

Just a suggestion, do EGR removal first. Make a fitting on blanking plate on exhaust manifold to insert sensor for EGT. (maybe buy gauge 1st so know what fitting)
Its a bitch to access, but works quite well. Not exactly central to all cylinders, but is plenty good enough
,Nath

Great advice Nath. That's where my egt is

My recommendation would be this order;

1) EGR removal
2) Fit EGT gauge
3) 2.5 inch dump pipe and exhaust system
4) Boost controller
5) Fit intercooler
6) Play with fuel
7) Try and keep up with me

1,2&3 can be done all at the same time to make access easy and cost effective


Cheers,