Thread: Query on setting up turbo on NA 4BD1

Can't say that mine blazed smoke out the rear at low revs, there was a little under hard acceleration but that was about the extent of it. If it dose it then look at other problems like haveing your injectors cleaned and having the timing checked. And a new air filter dosen't go astry either.

AFAIK, Isuzu trucks released in Australia with the 4BD1-T, did not have the boost compensator fitted to the injection pump (but some other countries did).

The purpose of the boost compensator is to reduce fuel/smoke when boost pressure is low.

Although there are some differences between the injection pump on the NA and turbo engine, the main ones are calibration (disregarding the boost compensator).

Sounds good to me.

current thought is for a garret GT2560, which I gather mounts to a standard isuzu turbo manifold (westar quoted $230 new).

Should these two bolt straight up?

W

Originally Posted by will@montlaur.com.au

Sounds good to me.

current thought is for a garret GT2560, which I gather mounts to a standard isuzu turbo manifold (westar quoted $230 new).

Should these two bolt straight up?

W

If you pick the right turbo, you'll have very little time off-boost and so the smoke won't be a problem.
I have a JDM engine which has a boost compensator (reduces fueling when there's no boost), I suspect the pumps without boost compensators restrict fuelling based on rpm, this would be the torque plate's influence.

The GT2560 (basically the new version of the old T28) is a good place to start, but I went even smaller on mine (GT2252 is the new equivalent of my T25).

It won't bolt straight up, but I have an adapter design which will make it fit. See this thread http://www.aulro.com/afvb/isuzu-land...o-install.html for pictures, PM me if you'd like a copy of the drawings.

Originally Posted by Dougal

If you pick the right turbo, you'll have very little time off-boost and so the smoke won't be a problem.
I have a JDM engine which has a boost compensator (reduces fueling when there's no boost), I suspect the pumps without boost compensators restrict fuelling based on rpm, this would be the torque plate's influence.

The GT2560 (basically the new version of the old T28) is a good place to start, but I went even smaller on mine (GT2252 is the new equivalent of my T25).

It won't bolt straight up, but I have an adapter design which will make it fit. See this thread http://www.aulro.com/afvb/isuzu-land...o-install.html for pictures, PM me if you'd like a copy of the drawings.

Thanks Dougal,

I'm trying to stick to the 'keep it simple' principal given I'm not doing the work myself, so off the shelf would be preferred.

Am I correct in assuming that any turbo from the GT25 family will mount straight up to a stock turbo manifold? 2nd assumption being GT22 or smaller won't mount straight up?

If that's the case any reduction in turbine size takes me outside the "mount straight up" requirement; ie into the GT22 family. A GT2554 will provide a smaller compressor but I don't see that providing any benefit in making boost at the lowest revs possible. (correct me if I'm wrong here)

I know I'm just fishing for an answer I want to hear but if a GT2560 meets my needs, ie;

a) mounts straight up to a stock manifold
b) wastegated, ball bearing & water cooled
c) quick spool (I'll keep the exhaust as large as possible)

I think I'll probably stick with it. What do you think?

W

Originally Posted by will@montlaur.com.au

Thanks Dougal,

I'm trying to stick to the 'keep it simple' principal given I'm not doing the work myself, so off the shelf would be preferred.

Am I correct in assuming that any turbo from the GT25 family will mount straight up to a stock turbo manifold? 2nd assumption being GT22 or smaller won't mount straight up?

If that's the case any reduction in turbine size takes me outside the "mount straight up" requirement; ie into the GT22 family. A GT2554 will provide a smaller compressor but I don't see that providing any benefit in making boost at the lowest revs possible. (correct me if I'm wrong here)

I know I'm just fishing for an answer I want to hear but if a GT2560 meets my needs, ie;

a) mounts straight up to a stock manifold
b) wastegated, ball bearing & water cooled
c) quick spool (I'll keep the exhaust as large as possible)

I think I'll probably stick with it. What do you think?

W

The factory manifold has a T3 flange. Very few turbos of the correct size have a T3 flange. AFAIK all the turbos you mentioned above have a T2 flange, which is why an adaptor is needed.

The turbo I fitted (in the thread Dougal linked) is the same as a GT2560R except that it has journal bearings. IMHO, you wouldn't want to go smaller than a T25, and it won't help with the flange issue.

Water cooling offers no benefits, and some disadvantages in a diesel. Have a look at the turboglide website for the reasons. Many people (Dougal and myself included, run water cooled turbos with the water lines disconnected/blanked.

If you are paying someone to do the job, the turboglide kit may be a good way to go.

Originally Posted by isuzurover

. Many people (Dougal and myself included, run water cooled turbos with the water lines disconnected/blanked.

If you are paying someone to do the job, the turboglide kit may be a good way to go.

I don;t run the water cooling either

Turboglide will do a full kit for you

Mine smokes off boost and sharp throttle openings in low range, but you don;t need to fuel it up that much

excellent. thanks heaps guys.

I'll give turboglide a call on Monday and see how I go.

cheers

W