Why such low power output

[00quattro00]

Looking at using either a 4jb1t or 4jh1 with a mechanical pump for my landrover 110 but im wondering why they have such a low power out put? Compared to the land rover 2.5tdi and my vw 1.9tdi the seem to be on the gutless side. Do they only run very low boost?

Land rover 200tdi 112hp and 265nm at 1800, 4jh1 120hp and 235nm. My vw 1.9tdi is 130hp 310nm at 1900rpm

[geeves]

4jb1 was designed mid 80s 4jh1 mid 90s Your vw is close to 20 years younger and the steps made through common rail and computer control in that time have completely changed the diesel engine
As a comparison as we are talking Land rover look at the trusty alloy v8 they used to use. In the 3.9 or 4.0 configuration its close to 300hp but its routes go back way further. Most people believe it was sources from Buik but in reallity they got it as war reperations from BMW in the 40s when it produced a massive 30 horsepower

[00quattro00]

The vw diesel design is just as old as the 4jb1, for a 3l 4jh1 engine to make only 245nm is pretty weak. It should be at least 330nm

[geeves]

Whats the vw engine like once its done 600000km? How about a million km. We have documented proof of a 4jb1 in a small truck doing a million km. In the 4x4s we have several touching 500k and going strong

[00quattro00]

Whats the vw engine like once its done 600000km? How about a million km. We have documented proof of a 4jb1 in a small truck doing a million km. In the 4x4s we have several touching 500k and going strong

So far its done 360,000 miles. Hasnt been touched apart from routine maintenance. Uses about 500ml between oil changes. And it still does 5l/100km easily

[geeves]

Is the injection system pre computer? The basic design of diesel engines hasnt changed much but the injection systems have been completly changed. I would love to see a modern common rail system on a 4jb1 Im sure it could double its output but these engines were designed for trucks not cars and despite the low output on paper they still do a great job

[00quattro00]

Its an ecu controlled pump.

Ill take a punt on the 4jh1 and see how it goes with more boost and fuel

[geeves]

There are many things that affect published power outputs. The same engine in different countrys has different outputs because of the way the laws dictate the output must be specified Japan requires all accessorys fitted and those normally running to be running it doesnt have to be attached to a transmission. America requires all accessories running and trans attached. This is why a lot of american cars have woefull power outputs. Mid 80s 305 v8 had less horsepower than your 4jh1 or did it? Europe allows a bare engine to be tested. Then of course one has to ask is VW output related to VW emissions results?
The other thing to consider is that the vw engine was designed for a car The 4j engines are industrial designs adapted first to trucks then 4wds. Car engine typically runs at full load 2% of its life Truck engine runs at full noise maybe 10% of the time but industrial engines are expected to be at rated output 100% of the time.
Out of a 4jb1 we typically up the boost to 15psi from the rated 10 which on its own takes the engine to just under 100kw. The boost compensator allows for extra fuel to this point. Upping the fuel will take you past 100kw and tweaking the timing and plunger size etc can see 120kw and still be reliable.
To see the extremes available look for posts by powertruck and superturbocound. They have done amazing things with these engines. Superturbocompound is into drag racing these diesels