Thread: does anyone have any info on injector pumps for 4BD1

Originally Posted by isuzurover

The army bought a batch of new perenties in the early 90's, so would be interesting to know what they have - Dave???

The later model NPR trucks do seem to rev better.

getting the cam profile will prove interesting... I'll dig through the deeper level stuff for you but I think it will just provide a part number for a stock replacement cam for either the turbo or the NA

Originally Posted by Blknight.aus

getting the cam profile will prove interesting... I'll dig through the deeper level stuff for you but I think it will just provide a part number for a stock replacement cam for either the turbo or the NA

Surely you can do better Dave - remove the radiator hoses from 1 new and 1 old perentie, then find a couple of grunts stupid enough to drive them - like last time...

Voila - a couple of cams to compare!!!

they are pefectly capable of generating enough work for me without me goading them into the ludicrously stupid...


besides there is a reason I am in the defence force...


Im lazy remember...

for instance tomorrow I have to go sleep under a tree for about 6 hours to wait my turn to chuck 23 or 43 bullets downrange (depends on if I decide to take the first lot seriously or If I want a yipee shoot)

Originally Posted by isuzurover

Larns - Sorry if I came across as rude, wasn't intended. It was late at night and I was doing some annoying work... I haven't seen any cam PN's that you have posted???

Those cam specs were from my (genuine) manual. Although I was tired I am sure they are as printed (but will check tonight). Can anyone else confirm? I am not such an anorak that I always have it in front of me.

Btw - for the record, I have driven both genuine and aftermarket 4BD1Ts. IME a properly set up aftermarket conversion drives as well or better. There is a lot of room for improvement over the original design. e.g:
Intercooling
Better intake and exhaust routing/flow (as John said - better manifold(s)).
etc.

Mate, appoligy accepted.(I know I can't spell)

I saw the time on your post, and it was late.

I agree about the aftermarket turbo'd engines, as I've driven alot of the 4BD1-T's with the non-gated turbo and they leave much to be desired, like mine, but one thing they do do better is idle and are smoother through the rev range.

I havn't posted the Pt No's but here they are for all that are interested

Cam N/A engine-5125110810
Injector tip N/A- 8941548640

Cam Turbo - 8970145731
Injector tip T-5153110200

I have ordered the different tips and they are on my engine, they made a differance in the 800-1500rpm range, much less soot under acceleration.
the cam are both available through Isuzu but are very exy.

The information that I posted was taken from the source that I stated in the post.

I'm not surprised by small changes over different years. Also I am not surprised by mis-prints in documentation.

In the case of a slow revving diesel like the 4BD1/4BD1-T, it is quite logical to use the same camshaft for the N/A and turbo versions. With high revving petrol engine, then there is a lot to be gained by reducing the valve overlap when a turbo is fitted.

The angles quoted for valve opening and closing have been interpreted incorrectly to get the duration.

It was not made clear that the angle for inlet opening is BTDC, for inlet closing it is ABDC, so duration is greater than 180* (not less). For exhaust valve opening it is BBDC and closing is ATDC.

Thanks for the information about changes to camshaft and injectors in the later engines.

Originally Posted by Bush65

The angles quoted for valve opening and closing have been interpreted incorrectly to get the duration.

It was not made clear that the angle for inlet opening is BTDC, for inlet closing it is ABDC, so duration is greater than 180* (not less). For exhaust valve opening it is BBDC and closing is ATDC.

Thanks John - was just about to post the same - I missed that in my first post.

To add to what I posted previously, the NA camshaft changed in '86/'87 and the T camshaft changed in '88/'89. But they BOTH changed from spec A to Spec B in my previous post.

This would suggest that they originally designed the cam to improve the NA model, then tried it on the turbo???

Lars - according to my info on Nozzles - ALL T's had an opening pressure of 185 kg/cm2. NA models had injectors with the same opening pressure until '86/'87, when it changed to 220 kg/cm2. Maybe for emissions reasons??? At the same time, the pressure adjustment changed from screw-adjusted to shim-adjusted.

Do you know the opening pressures of the two nozzle PN's you posted?

I have a box here with my old 4BD1T (86 JDM engine) injector nozzles. Anyone got some NA nozzles to dig out and take photos of?

One last bit of info from the manual - pump timing settings:

EARLY CAM
13 / 10 deg (NA/T)

LATE CAM
16 / 15 deg (NA/T)