NPS300 engine

I would visit the closest Isuzu truck centre and talk to the foreman of the workshop or a mechanic who has been working on them for years. That way you will find out the features, common faults and strengths of each engine you are interested in.
I suspect most of them use the unit injector and High Energy injector actuation of pressured oil to operate the injectors. This is different to CRD systems.
Edit.
It seems from Ron’s post below that Isuzu hasn’t used the unit injectors in these engine. I was unsure as the the exact injection.

Had 2000 4HG1 non-turbo engine. She chugged along and reliable as. The biggest issue was the gearing and noise in the cab, as it was doing around 2700 rpm from memory at 95kph, which was about top speed. That was on standard 16” tyres 235 85 16. It needed bigger tyres or the gearing changed. A 6th gear would have helped. Instead, I changed to an Iveco Daily and don’t regret it a bit.

FSH00 - The Isuzu nomenclature is reasonably simple, the engine series runs alphabetically.
However, the individual engine model range is mind-boggling and confusing.

So, you have the 4H family of engines, with E being the earlier version, F the next version, and G the version after that.
If the nomenclature has -T in it, it's turbocharged. The -TC series are turbocharged and intercooled.

When the Zexel electronic pump is fitted, it appears X is sometimes used in the model number.
XN denotes turbocharged and intercooled with the Zexel pump.

The power ratings are varied quite a bit, according to model fitment.
The 4x4 models usually get a slight power and torque boost over the 2WD models.
I have outlined some of the engine models specs below. These specs (particularly those related to compression ratio, power and torque), are not "hard and fast".
You need to acquire the particular workshop manual for the vehicle you purchase, to get precise engine specs.

I can find no specs on the 4HE1, this engine and its 6 cylinder brother, the 6HE1 were introduced around 1992 and the 4HE1 doesn't ever appear to have been fitted to the 300 series Isuzu's. But I may be wrong.

Below are some typical Isuzu engine specs. The Isuzu engines are particularly robust, they have no weaknesses or faults worth mentioning.


4HE1-T

Type: 4 cylinder, 4 stroke, overhead camshaft, direct injection diesel, turbocharged.
Bore x Stroke: 110 mm x 125 mm
Displacement: 4752 cc
Compression Ratio: 18.5:1
Power: 103 kW @ 2900 RPM
Torque: 363 Nm @ 1800 RPM

Bosch ‘A’ type fuel injection pump with ‘RLD’ all-speed governor.
Quick-start glow plug cold starting aid.

4HE1-TC

Type: 4 cylinder, 4 stroke, overhead camshaft, direct injection diesel, turbocharged and intercooled.
Bore x Stroke: 110 mm x 125 mm
Displacement: 4752 cc
Compression Ratio: 17.3:1
Power: 130 kW @ 2700 RPM
Torque: 470 Nm @ 2000 RPM

Bosch ‘A’ type fuel injection pump with ‘RLD’ all-speed governor.
Quick-start glow plug cold starting aid.

4HE1-XN

Type: 4 cylinder, 4 stroke, single overhead camshaft, direct injection diesel, turbocharged and intercooled.
Bore x Stroke: 110 mm x 125 mm
Displacement: 4751 cc
Compression Ratio: 17.3:1
Power: 109 kW @ 2800 RPM
Torque: 400 Nm @ 1200-1400 RPM

Zexel MI-TICS mechanically integrated in-line injection pump, with Bosch 4 hole injectors

4HF1

Type: 4 cylinder, 4 stroke, overhead camshaft, direct injection diesel.
Bore x Stroke: 112 mm x 110 mm
Displacement: 4334 cc
Compression Ratio: 19.0:1
Power: 85 kW @ 3200 RPM
Torque: 285 Nm @ 1800 RPM

Bosch ‘A’ type fuel injection pump with ‘RLD’ all-speed governor.
Quick-start glow plug cold starting aid.

4HF1-II

Type: 4 cylinder, 4 stroke, overhead camshaft, direct injection diesel.
Bore x Stroke: 112 mm x 110 mm
Displacement: 4334 cc
Compression Ratio: 19.0:1
Power: 76 kW @ 3000 RPM
Torque: 242 Nm @ 2000 RPM

Zexel MI-TICS mechanically integrated in-line injection pump, with Bosch 4 hole injectors

4HG1

Type: 4 cylinder, 4 stroke, overhead camshaft, direct injection diesel.
Bore x Stroke: 115 mm x 110 mm
Displacement: 4570 cc
Compression Ratio: 19.0:1
Power: 85 kW @ 3200 RPM
Torque: 291 Nm @ 1600 RPM

Bosch ‘A’ type fuel injection pump with ‘RLD’ all-speed governor.
Quick-start glow plug cold starting aid.

4HG1

Type: 4 cylinder, 4 stroke, overhead camshaft, direct injection diesel.
Bore x Stroke: 115 mm x 110 mm
Displacement: 4570 cc
Compression Ratio: 19.0:1
Power: 85 kW @ 3200 RPM
Torque: 291 Nm @ 1600 RPM

Zexel MI-TICS mechanically integrated in-line injection pump, with Bosch 4 hole injectors


All of the earlier Isuzu engines are fitted with the Bosch mechanical injection (up until the late 1990's).
With the advent of tighter emissions regulations from the late 1990's, Isuzu started to fit the Zexel electronic injection pump.
So you can have some of the engines above fitted with Bosch mechanical injection, or Zexel electronic injection, depending on the year of production.

The MI-TICS on the Zexel pump stands for Mechanical Injection, and Timing and Injection rate Control System.
The Zexel pump is a modified Bosch-style in-line injection pump with electronics added, that control the quantity and timing of the injection process, and which electronics also contain self-diagnostic and backup abilities.

The 4HK1-series engines from 2008 onwards are fitted with fully electronic, common-rail fuel injection.

Cheers, Ron.

Thank you all for your input it is much appreciated.

Ron n, I don't know where you found that info but certainly glad you did, that is exactly the info I was looking for, thanks for the reply.

Pete.

I've had several as work trucks over the years & the earlier ones do like to drink & if you fit the larger wheels they are gut less & drink heaps more
Remember to change to the springs & fit super singles etc or you will feel the painted lines on the road & all the other problems you get with duals on the ass

My present camper is a NPS300 4x4 but the 5.2ltr 2014model & is so much more economical & more power & has just finished a quick lap of oz