Isuzu 4H Series Introduction

[MadTripper]

Since there isn't a specific area for the newer engines, I posted this here. I'll cite reference where I can. Most of the following information was pulled from the following thread:
http://forum.ih8mud.com/diesel-tech-...4he1-swap.html

Manual with specs here:
http://lilaw.info/images/Manuals/LG4H-WE-9691.pdf

Also some pictures and info here (I revisited this and you need to register to view the post):
http://www.aulro.com/afvb/isuzu-land...onversion.html

Thanks to member astr for digging the info up. Please let me know if there should be corrections or if you have additions.

4HE1-TC Basic specifications:
Cylinders: 4
Injection: direct
Injection pump: Bosch inline type with automatic timer
Displacement: 4.75L (289.75 cu in)
Bore: 110mm (4.33 in)
Stroke: 125mm (4.92)
Valves: 2 per cylinder
Inlet manifold ?
Exhaust: RHS (drivers perspective).
Weight: Approx. 365Kg (803lbs)
Dimensions: 833.3H X 699.8W X 1181L (the length may be incorrect. Member astr has measured 30" from fan mount on water pump to tail which is nearly identical to the 4BDx series)
32.8"H x 27.6"W x 46.5"L
Bellhousings: ?
Starting aids: ?
Electrical: 12v in US market
Turbochargers: Garret GT226?
Alternator: 12v (US market)
AC Compressor: ?


Power output:
Automatic -175 hp (130.6 KW) @ 2700 rpm
Manual - 142 hp (106 KW) @ 2800 rpm
Torque output:
Automatic - 347 ft-lb (470.5 nm) @ 2000 rpm
Manual - 275 ft-lb (372.0 nm) @1300 rpm

Boost: ?

[Dougal]

I've split this 4HE1 introduction to a new thread for information on these and other Isuzu 4H series engines.

[astr]

Unlike the 4B series, the 4H is turned around – the gear train that drives the cam, IP, oil pump and PS pump is located between the 4th cylinder and the flywheel.. As a result, there is no access to the flywheel from the front of the engine, so Isuzu chose to use a rear mounted starter that mounts on the left side of the engine above the transmission. This has some significant implications when trying to swap this engine into a conventional truck – the starter is going to conflict with the body sheet metal.

Unlike the 4BD Series, the 4H have gear-driven overhead cams. The 4HE1 has two valves per cylinder; the 4HK1 has four valves per cylinder. The 4HE1 has an in-line injection pump similar to the 4BD Series while the 4HK1 has an electronically-controlled fuel rail injection system. The truck version of the 4HE1 with automatic was rated at 175 hp while the 4HK1 was rated at 195 and latter 205 hp. (Automatic versions). For some reason, Isuzu always derates their engines when fitted with manual transmissions. The 4HE1 came primarily fitted with Aisin AW450-43LE 4-speed automatic transmissions (4th was O.D.) The early 195 hp versions of the 4HK1 also were fitted with the AW450 transmissions while the latter 205 hp versions came with the Aisin A465 6-speed automatics. The A465 is the same transmission as the AS68RC used in the newer 3500 and larger series Dodge trucks.

The bottom end on the 4H Series consists of a single casting sort of resembling a ladder so there is no way to pull an individual crankshaft bearing cap; the whole bottom end must be removed as an assembly. Isuzu claims that this design results in a much more rigid bottom end.

There is NO interchangeability between the truck 4BD and the truck 4H Series with respect to transmissions. The 4H series were and still are available in marine and industrial versions so SAE-type bell housings are available.

[Dougal]

Apparently there are industrial 4H series engines with front mounted starters. If anyone has information on these, please post it up.

[astr]

Apparently there are industrial 4H series engines with front mounted starters. If anyone has information on these, please post it up.

There is a discussion on industrial versions of these engine here along with some pictures: http://www.4btswaps.com/forum/showthread.php?t=9184

[DieselSchlepper]

I've never heard of a japanese manufacturer derating the engine on a standard shift. Why do you think. How do they do it - cam changes?

[Dougal]

I've never heard of a japanese manufacturer derating the engine on a standard shift. Why do you think. How do they do it - cam changes?

Derating is really easy, they just dial back the maximum fuel delivery a little. It's quite common on diesel cars now to see the torque curve has been chopped to give a flat maximum torque to prolong drivetrain life.

[4btoy4me]

Does anyone offer a "tuning box" or any other performance increase for the 4hk? Driving an NPR, it feels like they 'derate' the engine in 1st and 2nd gear. It could be my imagination but a few of my friends thought the same thing. Being a 5.2l 16 valve engine, there has to be more potential.