Engine Family Comparison: 1HZ, 1HZ-T, 1HD-T, 1HD-FT (1 Viewer)

Will Van

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I am thinking about converting my 1977 FJ40 to diesel. I have Crushers swap kit with engine mounts, radiator bracket, fan shroud, and trans mount for the H55. The kit works with any 1H series engine.

I thought this would be a good opportunity to compare and contrast the various advantages and disadvantages of this series of engine, specifically related to engine swaps for trucks in USA. Yes, all of this information is available within the site, or with a quick google search, but I would like to consolidate it into one place with a digestible format. Contributions and opinions welcome.

I have deliberately excluded the FTE because it is electronic, and the focus of this thread is on mechanical IPs.

Let's get started.


1HZ Engine
1-HZ-Engine.jpg


Engine code1HZ
LayoutStraight-6, vertical
Fuel typeDiesel
Production1990 to Present
Displacement4.2L, 4,164 cc (254.1 cu in)
Injection pumpMechanical
Power adderNone
Horsepower net129 HP at 3,800 rpm
133 HP at 4,000 rpm
Torque output206 ft·lb at 2,200 rpm
210 ft·lb at 2,200 rpm

Pros:
  • Exceptionally Simple
  • Still in Production
  • Relative availability in USA for Engines and Replacement Parts
  • "Short" A/C Clutch
  • H55F Bellhousing and Input Shaft Available
  • Valve Adjustment???

Cons:
  • Underpowered (Same or worse power/torqe figures compared to 2F)
 

Will Van

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1HZ-T
1-HZ-Turbo-Engine.jpg


Pros:
  • More power than NA 1HZ
  • Still Relatively Simple
  • Relatively Cost Effective
  • Could be swapped in "Stages" - 1HZ first, then turbo
Cons:
  • Non-factory turbo engine
  • Questionable reliability
  • Added complexity of adding turbo to non-turbo block
  • Issues with head cooling???
  • Can get expensive quickly - Better off just splurging for 1HD-T???
 
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Will Van

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1HD-T
1-HDT-ENgine.jpg


Engine code1HD-T
LayoutStraight-6, vertical
Fuel typeDiesel
Production1988-1995
Displacement4.2L, 4,164 cc (254.1 cu in)
Injection pumpMechanical
Power adderToyota CT26
Horsepower net162 HP at 3,600 rpm
165 HP at 3,600 rpm
Torque output266 ft·lb at 1,800 rpm
268 ft·lb at 2,000 rpm

Pros:
  • Factory Turbocharged
  • More headroom for power upgrades
  • Conventional Glowplugs
  • “Short” common A/C compressor
Cons:
  • BEB Issues
 
Last edited:

Will Van

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1HD-FT
1-HDFT-Engine.jpg


Engine code1HD-FT
LayoutStraight-6, vertical
Fuel typeDiesel
Production
Displacement4.2L, 4,164 cc (254.1 cu in)
Injection pumpMechanical
Power adderToyota CT26
Horsepower net167 HP at 3,600 rpm
Torque output280 ft·lb at 2,500 rpm

Pros:
  • Highest factory power/torque figures out of the box
  • 24 valves
  • Most Sophisticated Toyota Mechanical Diesel
  • Lots of Headroom for more power/torque

Cons:
  • Limited Availability
  • Expensive
  • Added Complexity
  • Challenging Valve Adjustment
  • "Long" A/C Clutch - Limited Availability
  • Switch to Glow Screen instead of conventional Glow Plugs
 
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HDT! Naturally aspirated HZ 2nd.
1HZ-T
  • Relatively Cost Effective --> Not if done correctly. You will need to rebuild motor with HDT bits, add intercooler and oil cooler plus all of the associated turbo parts. Add $$$$ to engine price if you're not a fabricator
Cons:
  • Overheating due to lack of coolant flow through head
 
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GTSSportCoupe

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My advise:

If you want turbo, stick with the direct injection motors. And if you want to build for a lot of power, stick with the 24 valve versions.

A normally aspirated 1PZ or 1HZ will be lightest, and should still move a 40 just fine. Lighter weight will maintain the F/R balance of the vehicle. Lack of turbo keeps things simple and cheaper. The high compression of the IDI engines gives a nicer torque feeling right off the line.
 

Will Van

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HDT! Naturally aspirated HZ 2nd.
My advise:

If you want turbo, stick with the direct injection motors. And if you want to build for a lot of power, stick with the 24 valve versions.

A normally aspirated 1PZ or 1HZ will be lightest, and should still move a 40 just fine. Lighter weight will maintain the F/R balance of the vehicle. Lack of turbo keeps things simple and cheaper. The high compression of the IDI engines gives a nicer torque feeling right off the line.

Thank you for your input! Although the 1HZ has the lowest barrier to entry, I think I will ultimately be happier with a 1HD-T or 1HD-FT.
 
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Saw a kd-ftv swapped into a GMC Jimmy down in Costa Rica. We wheeled with it and what a great little motor: lightweight, turbo, intercooler and parts availability. If our 3B ever gave up the ghost, that's the route I would explore.
Not sure I'd be happy with a HD in a 40? Maybe in a 45.
 
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Will Van

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Saw a kd-ftv swapped into a GMC Jimmy down in Costa Rica. We wheeled with it and what a great little motor: lightweight, turbo, intercooler and parts availability. If our 3B ever gave up the ghost, that's the direction I would explore.

Great intel. I really like the 12HT too. Because cam timing gears and plug-and-play engine mounts.

But for the purposes of this discussion, I’m trying to limit feedback to the motor family mentioned.
 

Will Van

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Can anyone explain the change is how the valves are adjusted on the 1HZ and 1HD-T vs the 1HD-FT? Is one easier than the other?
 

AussieHJCruza

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I thought it was 1990 to 1994 that had the issues. But I’m certainly no expert.

My understanding is it’s best to replace them no matter what motor/year.
The pistons and injector washers changed in 11/92, and I think the fuel pump was different + 12mm fuel lines rather than 10mm, and possibly some other changes.
Graeme from Gturbo told me the later 1HDT is better for an engine to power up due to these differences, I gather the pistons are 'stronger' as I've heard of the early ones cracking under higher boost applications.

The BEB thing did seem to become less common with the updated engine, although in my opinion, for a $60 set of bearings from Taiho and ~4 hours labour, it's cheap insurance.
 
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80 Series 1HD-FT
I have deliberately excluded the FTE because it is electronic, and the focus of this thread is on mechanical IPs.
I would urge you to reconsider this as an option. Over here in Aus you can pick up FTE engines much cheaper than the rarer FT engines and guys are swapping out the electric FTE injector pump for mechanical versions which basically give you a FT engine but with all the extra goodies that come with the slightly more modern FTE internals with the different head cooling/porting and camshaft profile duration and lift which seems to give them an edge over the standard FT.
 

AussieHJCruza

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I would urge you to reconsider this as an option. Over here in Aus you can pick up FTE engines much cheaper than the rarer FT engines and guys are swapping out the electric FTE injector pump for mechanical versions which basically give you a FT engine but with all the extra goodies that come with the slightly more modern FTE internals with the different head cooling/porting and camshaft profile duration and lift which seems to give them an edge over the standard FT.
An FTE is a relatively simple EFI engine anyway, I wouldn't let electrical put you off keeping it EFI
 
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80 Series 1HD-FT
An FTE is a relatively simple EFI engine anyway, I wouldn't let electrical put you off keeping it EFI
Yes I know it's not that complex but I still see a post nearly every month on a group i'm in with guys stranded out bush with FTE electrical issues they can't fix and asking for help with fault codes etc. I lot of guys don't want this and besides there's also guys out there myself included who prefer to do their own tuning and unless you have all the fancy software it can't be done easily at home compared to a mechanical injector pump system. There's no denying though that the FTE's pump far exceeds the mechanical version in both fuel delivery volumes/higher pressures and probably even more importantly the ability to have full timing control till redline which is where mechanical suffers.
 

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