1HD-T vs HZJ (turbo?)

[OGBeno]

Yup.

 

[AussieHJCruza]

I've never met a turbo IDI engine (1HZ, 2H etc) that didn't battle with heat when working hard.

1HD-T isn't without its issues which have already been mentioned, but will make decent power reliably and without a battle keeping it cool.

Look for an MY93 truck or newer with a 1HD-T - 12mm fuel lines to resolve a surging issue with the earlier trucks, different pistons which hold up much better with more boost/fuel, the earlier engines are more prone to cracking pistons.

 

[Eurasiaoverland]

Maybe worth explaining DI vs. IDI in diesels, as it's not quite the same as in petrol engines.

With a DI diesel, the piston has a cup-like comustion chamber in its crown and the cylinder head is a flat surface with only the valve ports (and glow plugs on a 1HD-T).

With an IDI engine the piston crown is effectively flat, and combustion occurs, or at least starts, in a pre-combustion chamber which is a hardened steel semi-hollow cylinder in the head. This is less thermally efficient than the above DI system leaing to the following:
- a higher compression ratio is needed to achieve a similar efficiency (e.g 22:1 vs 18:1) -> more heat in the head
- combustion starts in the head -> more heat in the head
- there is less space in the head for metal and coolant passages, which makes it weaker, and means the head has a comparatively lower heat capacity ~ more heat in the head per unit of metal.

There are absolutely zero advantages from an engineering perspective to IDI. People will tell you 'oh but the direct injection fuel pump runs a higher pressure' - true, but using the exact same technology (in engines like the 1HD-T). The only reason the 1HZ is still made is for sale in less eceonomically developed countries where there are no emissions regulations, so Toyota can still supply the same old technology. Same with the 5L.

 

[AussieHJCruza]

Maybe worth explaining DI vs. IDI in diesels, as it's not quite the same as in petrol engines.

With a DI diesel, the piston has a cup-like comustion chamber in its crown and the cylinder head is a flat surface with only the valve ports (and glow plugs on a 1HD-T).

With an IDI engine the piston crown is effectively flat, and combustion occurs, or at least starts, in a pre-combustion chamber which is a hardened steel semi-hollow cylinder in the head. This is less thermally efficient than the above DI system leaing to the following:
- a higher compression ratio is needed to achieve a similar efficiency (e.g 22:1 vs 18:1) -> more heat in the head
- combustion starts in the head -> more heat in the head
- there is less space in the head for metal and coolant passages, which makes it weaker, and means the head has a comparatively lower heat capacity ~ more heat in the head per unit of metal.

There are absolutely zero advantages from an engineering perspective to IDI. People will tell you 'oh but the direct injection fuel pump runs a higher pressure' - true, but using the exact same technology (in engines like the 1HD-T). The only reason the 1HZ is still made is for sale in less eceonomically developed countries where there are no emissions regulations, so Toyota can still supply the same old technology. Same with the 5L.

The one thing IDI does better is deal with rubbish fuel as compared to a DI engine.

 

[Eurasiaoverland]

The one thing IDI does better is deal with rubbish fuel as compared to a DI engine.

Is this something you can explain, or just observation? To me, lower cetane fuels would be more suited to the lower compression engine, though I suspect the IDI would be more tolerant of premature ignition.

 

[AussieHJCruza]

Is this something you can explain, or just observation? To me, lower cetane fuels would be more suited to the lower compression engine, though I suspect the IDI would be more tolerant of premature ignition.

More observation than anything else, but the IDI engines do run lower injection pressure and a simpler injector which I guess means the internal tolerances of the pump and injectors are not as tight so contamination has less of a negative effect.

I assume that, given the way the IDI injects into a pre-chamber the spray pattern is much less critical to reasonable combustion so that fuels like WVO that have a different viscosity to diesel which might change the spray pattern, doesn't matter.

Lots of assumptions and observations, and poorly written but maybe it makes sense

 

[Eurasiaoverland]

More observation than anything else, but the IDI engines do run lower injection pressure and a simpler injector which I guess means the internal tolerances of the pump and injectors are not as tight so contamination has less of a negative effect.

I assume that, given the way the IDI injects into a pre-chamber the spray pattern is much less critical to reasonable combustion so that fuels like WVO that have a different viscosity to diesel which might change the spray pattern, doesn't matter.

Lots of assumptions and observations, and poorly written but maybe it makes sense

Not at all, makes sense. A good point which I had overlooked. I think the pre-combustion chamber will tolerate a lot of bad fuels and poor atomisation, rather than hot-spotting on the DI piston which is a known issue, though I think more with the higher pressured common rail diesels than engines like the 1HD-T or 14B.

I was going to say probably not an issue in the US, but reading about the fuel there it seems the quality standards are very low compared to Europe.

I've certainly run all manner of rubbish through my IDI 2L engine and never noticed any change in running.

 

[mudgudgeon]

As @Cruisers and Co says, I've had both engines in my FJ60. When first converted I went with a 1HZ-T. No intercooler, boost was max at 10 psi. I spent many years and $$$ trying to make that engine run cool, and it just wouldn't. I explored every aspect of timing and tuning (yes, it was boost compensated). I even added data-logging digital gages for EGT's, boost, water temp, and AFR's so I KNEW what was going on (yeah, I'm an engineer) and track the results to any changes in tune. Summertime driving on flat highways at 65-70 mph near sea level, boost around 7 psi, and my water temps would get up there. Add any kind of gradient to that and they would spiral out of control. The only way to deal with that was to go to third gear and reduce speed to keep boost under 4 psi. I eventually added a top mount WTAIC hoping that would solve the problem, and it did not. Zero difference. I was always fighting EGT's as well, no matter how it was tuned - my right foot would often be tethered to the EGT gage. Whenever I drove it I felt like I was piloting a plane - I could never take my eyes off the gages, day or night. And I drove all over the Western U.S., from California to Colorado and from Montana to Arizona. The only time I could "use" the full capacity of the engine was in the dead of winter. Also, I'm never towing anything. I'm just a "heavy" 60 series, built for either the Rubicon or long road trips.

I finally gave up and got a 1HD-T that @OGBeno recommended and helped me source. I ditched the TMWAIC and ran it. What a difference. No more overheating (same radiator). EGT's were now not running wildly away from me anytime I was on a grade and under boost. I still had to watch them, however, just nothing like before. Water temp was "meh" all the time, fully back to normal. I decided to up the boost to 14 psi and see how it did (and added more fuel). More power and a little more aggressive at getting the EGT's up there, but still no overheating, even on steep grades in the summer time (95F) under high boost (had to back off some for EGT's) and full aircon (water temps max at 205F). At this time I'd moved to northwest Nevada, so the truck was now running at elevation, something that always had further exacerbated the problems with the 1HZ-T. I drove the truck out to Colorado for some spa treatment with @Cruisers and Co and Johnny designed and fabbed up a large FMIC. On the drive back to Nevada I noticed that my EGT's no longer needed to be watched as they never eclipsed 1100F (pre-turbo), now matter how hard I pushed up the grades, and I had more power. When I got home I went through a careful tuning, pushed boost up to around 18 psi (I switched turbos to a Munro full billet high flow), and added more fuel accordingly. Still no overheating issues AT ALL (same as before, summer day at 95F, pulling the grade up to Lake Tahoe at full boost this time, aircon on full blast, water temps <205F!) and still no EGT issues. After lots of research and lots of discussions I think it all comes down to the ability to get heat out of the head in the IDI 1HZ vs the DI 1HD-T. Since this conversion I've made several more laps around the western U.S., in the hot summertime, with the aircon blasting away, and zero issues for water temps or EGT's. Based on these experiences I could never recommend turboing a 1HZ. Get yourself a 1HD-T with a proper tune for your boost, and the biggest FMIC you can fit in the grill, and run it. PFA.

View attachment 3818116

Good summary.

Did you ever run the 1hz at higher boost?

14psi boost vs 7psi with the same fuel settings, and your AFR changes.

A bit of an oversimplification, but the amount of fuel being burnt controls the power output.
Increase air density and intake volume with a turbo that's running efficiently and not heating the air excessively, and you have lower combustion temps, less heat in the head, a greater cool air charge to cool pistons, valves, head, cylinder walls etc with every cycle and the overall heat stress on the system can be reduced.

The same is true with the 1hd-t, ft, fte.

In Australia 1HZ powered cruisers fetch more money than petrol. 1hd-t more than 1hz. 1hd-ft, stupid amounts more than 1hd-t.

 

[MountNGoat]

Good summary.

Did you ever run the 1hz at higher boost?

14psi boost vs 7psi with the same fuel settings, and your AFR changes.

A bit of an oversimplification, but the amount of fuel being burnt controls the power output.
Increase air density and intake volume with a turbo that's running efficiently and not heating the air excessively, and you have lower combustion temps, less heat in the head, a greater cool air charge to cool pistons, valves, head, cylinder walls etc with every cycle and the overall heat stress on the system can be reduced.

The same is true with the 1hd-t, ft, fte.

In Australia 1HZ powered cruisers fetch more money than petrol. 1hd-t more than 1hz. 1hd-ft, stupid amounts more than 1hd-t.

Everything I’d been told is don’t go over ~10 psi with a 1HZ-T for longevity. Both US and Aussie forums. I understand the turbo efficiency angle and was set up properly. I did turn up boost 2psi and that made things worse, so backed off.

 

[AussieHJCruza]

Everything I’d been told is don’t go over ~10 psi with a 1HZ-T for longevity. Both US and Aussie forums. I understand the turbo efficiency angle and was set up properly. I did turn up boost 2psi and that made things worse, so backed off.

You should be more concerned about pre-turbo EGT than the number on the boost gauge. Don't run a 1HZ over 1200f.

Higher boost with same fuel = leaner = cooler combustion on a diesel. You're better off with a fast spooling and efficient turbo and 15 psi of boost than 10psi with a turbo that was designed in the 1990s.

Boost doesn't kill diesels. High EGT does.

 

[MountNGoat]

You should be more concerned about pre-turbo EGT than the number on the boost gauge. Don't run a 1HZ over 1200f.

Higher boost with same fuel = leaner = cooler combustion on a diesel. You're better off with a fast spooling and efficient turbo and 15 psi of boost than 10psi with a turbo that was designed in the 1990s.

Boost doesn't kill diesels. High EGT does.

Maybe you missed it, but EGT’s were my main concern. Pre-turbo, like I said. Never over 1200F.

 

[AussieHJCruza]

Maybe you missed it, but EGT’s were my main concern. Pre-turbo, like I said. Never over 1200F.

Yes, sorry I did miss that.

From my experience, the water temperature nearly follows the EGT gauge on an IDI engine, much less so on a DI.

 

[sodafeld1]

Excellent descriptions and explanations here! Especially how the head of an idi is going to run hotter, thanks euro. It is more ammo for the against turbo idi party. Not meant to be.
From my cheap 'A' perspective my na 2h is that it is cheap to maintain, set and forget cast timing cogs. Injector service is a fraction of the price for example. I go slow and heavy , but always get there, never overheat, even towing 2t uphill in oz summer.
From info here, hdt or hdfte hands down if you want faster and no overheating.

 

[Eurasiaoverland]

Excellent descriptions and explanations here! Especially how the head of an idi is going to run hotter, thanks euro. It is more ammo for the against turbo idi party. Not meant to be.
From my cheap 'A' perspective my na 2h is that it is cheap to maintain, set and forget cast timing cogs. Injector service is a fraction of the price for example. I go slow and heavy , but always get there, never overheat, even towing 2t uphill in oz summer.
From info here, hdt or hdfte hands down if you want faster and no overheating.

Absolutely nothing wrong with a normally aspirated IDI engine IMO, though the pre-combustion chamber cracking is annoying, I travelled for years in my 2L... slowly. The 567,000 km 3B which came in my BJ60 had good power, didn't smoke at all and would have been kept in service were it not for some moron 'mechanic' who used a DI head gasket, which I think allowed the pre-combustion chambers to slowly come loose and ultimately wear into the cylinder block.

 

[sodafeld1]

yes precups coming loose is a nightmare concept a few here have had the blues from. It shall be my main concern when I fire up and count the miles..

I don't trust many mechanics either. I worked with a good indie mechanic for a bit but trying to run a business and do a good job was always a conflict for him. Another side of it is, mechanics are usually treated like crap unless the customer has worked on cars themselves and can truly appreciate a good job. Which is rare as hen's teeth and getting more rare progressively. Over 20 million cars registered in oz, virtually everyone has at least one! haha.

There are some wizards here but they have the right customer market to charge fairly for a good job, so don't have to compromise. Does not happen everywhere. But still no one does as good as job as yourself.

 

[mudgudgeon]

Everything I’d been told is don’t go over ~10 psi with a 1HZ-T for longevity. Both US and Aussie forums. I understand the turbo efficiency angle and was set up properly. I did turn up boost 2psi and that made things worse, so backed off.

Fair enough.
Its an old school mentality from the days when mechanics were adapting small petrol engines turbos onto these engines. And winding up the fuel without a good understanding of diesel tuning.
So many 1HZs for a small turbo, fuel around up until smoke was barely tolerable, and call it good. No EGT gauge.

I started messing with mine around 2007, and the only diesel performance tuning info I could find on the net that wasn't from an Aussie business selling turbo kits was from VW enthusiasts.

Then after a while, here.

The Cummins crowd took quite a while to started shifting away from the "roll coal" mentality.
Banks Power did a lot to change that.

 

[The Machinist]

1. A stock 1HD-T-equipped Land Cruiser (HDJ)
2. A high-quality aftermarket turbo setup on a 1HZ (HZJ)
3. A stock 1HZ Land Cruiser (HZJ)

Here’s my situation: I’m looking for a reliable, off-road-capable vehicle that can handle long overlanding trips, occasional towing, and still be easy to maintain and repair if something goes wrong. I’ll likely be in remote areas where simplicity matters, but I’m also not opposed to having a bit of extra power to make highway driving and steep climbs less of a slog.

As much as I love my 1HZ, it is not the best engine choice for road trips in the US. As everyone else has already mentioned, they just don't have a ton of power stock and with a turbo you will be regularly watching gauges to keep temps safe at highway speeds. (especially at altitude) As much as I hate to say it, an "LS" swap is by far the best option for what you are looking to do.


Running a modernish turbo and slightly higher boost, mine seems to be pretty happy. I spent a few weeks tuning it with various boost and fuel combinations; stock fueling and 4-6psi resulted in higher EGT's; the sweet spot I found was 9-12psi with a slight increase in fuel. The extra fuel brought the boost up more quickly which made a big difference in EGT's. Water temps stay low until I'm into a long grade at highway speeds and everything starts to heatsoak.
My exhaust is too small and I don't have an intercooler so take this as you will. Those will be my next two upgrades.

 

[iliketrucks]

There are absolutely zero advantages from an engineering perspective to IDI.

I have a hard time believing this when companies like Toyota, Isuzu, and Mercedes found it worthwhile to produce both types of engines at the same time.

That being said, if anyone wants to trade a 1HD-FT for my turbo 3B, I'm in!

 

[sodafeld1]

Perhaps idi advantages would be for unreliable fuel quality, cheaper injector service, generally more simple, lack of electronics. Suiting either remote or economically challenged regions. So not really from an engineering or manufacturer's perspective, besides old tech with the casting molds already in possession. An engineer would be focused on efficiency and emissions not necessarily longevity or they don't sell more and more, always encouraging the upgrade. They don't consider the mechanic , that's for sure.

We use to have an old 1956 massey diesel tractor on the farm, probably last another 50 years at least. My! that thing could be abused but still worked. Mob in Oz sends these old idi tractors to extremely poor parts in africa, at least they can fix them.
Unsure if idi tractors are still made? Lots of Oz farmers complaining they can't fix the new tractors.
My 2 cents..

 

[KiwiDingo]

There are absolutely zero advantages from an engineering perspective to IDI.

I guess that depends on what you consider to be an advantage....

Indirect injection diesel engines by their design are so much smoother and quieter, have a broader range of torque, continue to make power right up till redline easier, can achieve much faster engine rpm and have so much more idle/off boost torque with their much higher compression ratio which is awesome for off road use. IDI does have its draw backs though and the fuel economy/engine efficiency, emissions and cooling issues ended up being prioritised which lead to DI taking over in certain countries with higher emissions and consumer demands. That being said and what many don't realise is that DI produces a lot more NOx then IDI which is why EGR/SCR is so common and also as a side effect DPF due to NOx and soot having an inverse relationship to each other. When you make a change in the combustion process to reduce NOx you unfortunately increase soot/particulate matter, hence DPF now needed.