Thread: 4BD1T Turbo Sizing and Performance Prediction.

I assume by intake diameter you mean the diameter of the small end of the compressor wheel, which is 50.5mm. the od (large end) is 76.2mm. the turbine side has the wastegate hole so the waste gate on fleabay looks like it should fit. The outlet on the compressor side is only 45mm ID, does that seem a little small?

Originally Posted by jackz

I assume by intake diameter you mean the diameter of the small end of the compressor wheel, which is 50.5mm. the od (large end) is 76.2mm. the turbine side has the wastegate hole so the waste gate on fleabay looks like it should fit. The outlet on the compressor side is only 45mm ID, does that seem a little small?

Okay, so it's a ~45 trim compressor. Now find a T04e 45 trim compressor map and we'll see how it fits.

having trouble finding a T04e map with 45 trim, plenty of T3/45 trim maps. would there be a lot of difference.

Originally Posted by jackz

having trouble finding a T04e map with 45 trim, plenty of T3/45 trim maps. would there be a lot of difference.

Yep, big difference. T3's are usually 60mm compressors.

Here is a T04e 46 trim, that'll probably be it:


Now for the bad news.
It looks too big. Even with ~200kw from our engines you only need ~35 lb/min airflow. This turbo is suitable for up to 45 lb/min.
To get decent low-mid range you need a PR of 2 at ~13 lb/min airflow. That point is off that map to the left in the surge region.
To get decent top end you need a PR of 2.5 at ~20lb/min airflow. Same story, not even on that map.

Oh dear. never mind. Thanks for all your assistance Dougal, guess I'll be hitting Fleabay later.
of the several different turbos listed as being for a 4BD1, are any particular types better or worse than the others?

Originally Posted by jackz

Oh dear. never mind. Thanks for all your assistance Dougal, guess I'll be hitting Fleabay later.
of the several different turbos listed as being for a 4BD1, are any particular types better or worse than the others?

My thoughts at present are the TH04HL-19T is the best of the most commonly available.
This can be bought most economically as a Kinugawa.
Complete turbo here: Turbocharger Kinugawa TD04HL 19T T25 Flange w Kit 200 280HP Fit 1 6 2 5L | eBay

Outlet adapter P/N here (cummins) http://www.4btswaps.com/forum/showth...l=1#post214760

These need a T3-T25 adapter to fit the later Isuzu manifolds. I have a new one piece design for those, just pricing up manufacture now.

With a bit of wet weather got back on the Isuzu I asked the consultants the question but I think they had other things on there mind. Best place for EGT probe? I would rather put in the bend after the turbo instead of pre I would imagine there would be a certain amount of heat loss you would have to allow anybody with experience of either?

Thanks AM

Originally Posted by Ancient Mariner

With a bit of wet weather got back on the Isuzu I asked the consultants the question but I think they had other things on there mind. Best place for EGT probe? I would rather put in the bend after the turbo instead of pre I would imagine there would be a certain amount of heat loss you would have to allow anybody with experience of either?

Thanks AM

Pre turbo is much better for EGT. Post turbo numbers are -200oC +/- 50+ oC, so your numbers are a lot less accurate.