Which engine?

[rideglobally]

Have you turned up the fuel on the 12HT or is it stock?

Yes my fuel is tuned up, Gturbo, 3.5” down pipe, over the top inter cooler with fan, radiator fan, etc.. My 12ht has done me well over the years. For sure it has not left me stranded. And seems to be doing great pulling this amount of weight with the gear reduction. Except for the long waits when i am in remote areas i have not had much issue finding parts for it. What I am doing here is just trying to understand my options, keeping the 12th is one of those option. Thx

 

[rideglobally]

Or, just be satisfied with what you have and take the slow road. You are over-landing and in no rush. Soak it in as you go. Isn’t that the purpose of overlanding, slowing it down, no deadlines, get there when we get there? You can keep $ in the bank. My take is you’re pissing your money away staying simple Toyota. It’s a 45, I get it but let’s be realistic it’s an RV as well. Get some Barry White playing.

Yes keeping what i have is definitely an option. Please see my reply to @Dougal. I am slow when i am in the US and the EU but honestly in Africa, Mexico we are there flowing with the locals. Yes we do soak it in when we travel, I do need to get some Barry White great idea. Thank you.

 

[rideglobally]

Thank you, I have learned a lot and this is a lot to digest. The last comments from @Dougal, @ceylonfj40nut, @sodafeld1, @Nikolai also made me think that maybe what i should also be thinking is how to upgrade my 12ht. My Gturbo is the first generation Gturbo maybe replace it with a new one, I know there is a company in Australia who has done something to the injectors that i cannot recall at this moment Etc… thank you again

 

[David*BJ70]

It has bottom end bearing issues that need to be fixed if it has not.

Well the BEB will be changes as the engine is out

But also the worst option. You can’t fix the BEB issue - only keep replacing them. It’s an inherent design floor from the piston pulses. And it’s most gutless stock with the least power potential

Really ? So every 1HDT are weak and still weak because of the BEB even if the BEB have been change with newly design OEM part ? Regardless of the year and regardless of what Landcruiser it come from ? That new to me. Never heard that.

 

[suzuguru]

You may want to go with a Toyota out of a bigger truck like a Hino. I'm not familiar with those engines, so I can't give you any recommendations along those lines. However, of the ones you mentioned, I would say the 1HD-FT. That would give you a little more power, but still the reliability of a mechanical pump. Still... I think you're going to need more power than it will offer, with that kind of weight.

 

[Hulsty]

Why not go the other way, 15BFT or 15BFT, engines designed for high weight applications, used in Dyna and other small Toyota trucks and busses. They are an evolution of the 3B that lived in 40 series engine bays.

 

[Silveredition]

GTurbo, ADS (or JH Hilux) modified injector pump, mls head gasket, +30 (or +50?) injectors, and slightly smaller diameter tyres and you will have close to 200hp and 600Nm at the wheels out of your 12ht….
That is good, reliable power and torque out of a simple engine!

 

[wedgetail]

Well the BEB will be changes as the engine is out


Really ? So every 1HDT are weak and still weak because of the BEB even if the BEB have been change with newly design OEM part ? Regardless of the year and regardless of what Landcruiser it come from ? That new to me. Never heard that.

The problem isn’t the bearings themselves - the same ones were used in 1HZs of the same period (even more of them as 1HZ sales were far higher) and 1HZs are not known for the issue - I’d warrant there was an order of magnitude more I6 diesel cruisers sold here than Canada. As I mention above - the problem is inherent in the piston/combustion pulses and harmonics creating premature BEB wear regardless of what bearings are used

 

[sodafeld1]

 

[bcsteel]

I’ve lost track of your build. Has your 12ht been upgraded with later style Alfin pistons? If so then maybe some tweaks like you mentioned above is all that’s needed.

Remy at wink turbo has built some 12ht’s that make some power too. Maybe worth a chat. I’ve heard the support isn’t always there. That said I have one of his turbos in my truck (also 12ht) and he has always responded promptly to my tuning questions.

 

[SNLC]

1HDFTE + H152.

Strip the FTE down to only what is needed.

Cheers

 

[rideglobally]

GTurbo, ADS (or JH Hilux) modified injector pump, mls head gasket, +30 (or +50?) injectors, and slightly smaller diameter tyres and you will have close to 200hp and 600Nm at the wheels out of your 12ht….
That is good, reliable power and torque out of a simple engine!

Thx at one point I was looking into this route, but the communication with ADS injection was difficult at that time. I was in Slovenia blew my head gasket, I was gonna switch to the MLS but i got mix review on the MLS gasket, so i just went OEM, also it was difficult to get them in Slovenia. I am heading South in the Africa, when i get to South Africa i am thinking of getting some work done. It would be great to hear from members who have experience with this set up on their 12th. Meanwhile i will look at the ADS injection fb. Thx

 

[rideglobally]

I’ve lost track of your build. Has your 12ht been upgraded with later style Alfin pistons? If so then maybe some tweaks like you mentioned above is all that’s needed.

Remy at wink turbo has built some 12ht’s that make some power too. Maybe worth a chat. I’ve heard the support isn’t always there. That said I have one of his turbos in my truck (also 12ht) and he has always responded promptly to my tuning questions.

I have not done the Alfin piston. I have the first generation Gturbo and i have not have any issue with it I think I will stay with that. But i will look into the Alfin pistons i have not heard of them. thx

 

[AussieHJCruza]

Some folks may think I am full of bs but I met an engine builder recently with over 6000 builds under his belt. He reckons he can get more from a hz with a custom turned up pump and turbo from a hz than what is possible from a hd, probably hd-t. He prefers the hz over the hd. MS engine reconditioners on facebook in Melbourne, Oz. Really nice fella, loves sharing his knowledge, shall die with a spanner in his hand.

On the other hand, there are some super duper injectors for the hd which can deliver 400hp or something, as wedgie pointed out. Aussiehjcruza on here loves his hd. Maybe he shall chime in. But , personally I reckon electronic injection would always be more finicky upon fuel. Let alone ecu's and stuff..

From what I know of the difference of the hz it is more suited for the locations you travel. It is well known a hz would get a million kms, but have not heard of the hd getting a million kms.?

My two bob for toyota engines for you..lots would say cummins 6bt, it is pretty legendary.

I'm a fan of the DI engines, I've had too many challenges keeping a turbo 1HZ cool to recommend it.
A 1HDFTE is a simple electronically controlled engine, don't be scared off by the EFI.

The only limitation would be the difficulties fitting a H15# into a 40 series without significant floor modification.

 

[rideglobally]

I'm a fan of the DI engines, I've had too many challenges keeping a turbo 1HZ cool to recommend it.
A 1HDFTE is a simple electronically controlled engine, don't be scared off by the EFI.

The only limitation would be the difficulties fitting a H15# into a 40 series without significant floor modification.

How much modification is needed to connect a H55 transmission to 1hdfte?thx

 

[AussieHJCruza]

How much modification is needed to connect a H55 transmission to 1hdfte?thx

None with the bellhousing etc. From a HZJ75, you will probably need the 75s flywheel and a clutch to suit as well.

I would go easy on the power up mods to the fte though and don't pull hard in 5th gear.

 

[mudgudgeon]

For simplicity 1hd-t or 1hd-ft.
For maximum power and torque 1hd-fte
For best bang for buck, keep the 12ht.

For power to match the weight you're hauling, look outside the box you've selected.
I think the suggestion of Hino engine is an interesting one. Or Isuzu small truck engine.
Lots of Japanese low speed 4 cylinder small truck engines that will make loads more torque than any of the I6 Toyota engines listed. But you'd be travelling uncharted territory for these as an engine swap candidate.

The difference in power from 1hdt vs 1hdft is gonna be mostly down to pump and injector upgrades.
At higher RPM the 24 valve head will start to make a difference with improved air flow. At lower RPM the 12 valve HDT may have an advantage with greater velocity through the ports.
Replace BEB in a hd-t so you know their history, then do oil sample analysis after 100k km. I personally would not be scared of using a 1hd-t because of the BEB issue. Huge numbers of these engines running around with original bearings in them.

If you're thinking of keeping the 12ht, it could pay to look into other turbo options, try and get the most low end boost you can for maximum torque from idle upwards.

My experience with a 12ht was as a 18-20 year old, in a hj60 with modified turbo.
It was a lot of fun, but peaky power delivery. I think you'd get a flatter torque curve from any of the 1hd-t** series engines.

I would absolutely choose H151 over H55F gear box. The gears in the H151 box are massive in comparison. The H55F is a modified 4 speed core. 5th gear is tacked on St the back of the box in the reverse gear housing and has known issues with 5th gear failures, and output shaft failure.
H151 was a completely new heavy duty gearbox, designed and built as a 5 speed.

For a heavy beast, another option is use a H150F gearbox, and install a H151F input shaft into it so you have the heavy duty input shaft, but lower ratios in 1st and 2nd gear.
The downfall of the H151F, it's 1st gear ratio is a bit too high. I think this would be a disadvantage in your heavy beastie particularly in off-road situations where you need to be able to crawl up a steep incline.

 

[wedgetail]

None with the bellhousing etc. From a HZJ75, you will probably need the 75s flywheel and a clutch to suit as well.

I would go easy on the power up mods to the fte though and don't pull hard in 5th gear.

You can get a 300mm pressure plate to suit the H55 easily. Agreed on taking it easy with the power though

 

[mudgudgeon]

1HZ had the advantage of higher static compression. With a turbo, they make loads of torque from 1200rpm upward.

They can be built with stronger aftermarket turbo pistons, and 1hdt rods and wrist pins. Then the head still remains a weakness if you can't keep them cool.
To do all that, you're in full rebuild territory with a bunch of new parts. Bang for buck is gonna evaporate fast.

For a situation where is constantly pulling a heavy load, I'd skip the 1hz

 

[rideglobally]

For simplicity 1hd-t or 1hd-ft.
For maximum power and torque 1hd-fte
For best bang for buck, keep the 12ht.

For power to match the weight you're hauling, look outside the box you've selected.
I think the suggestion of Hino engine is an interesting one. Or Isuzu small truck engine.
Lots of Japanese low speed 4 cylinder small truck engines that will make loads more torque than any of the I6 Toyota engines listed. But you'd be travelling uncharted territory for these as an engine swap candidate.

The difference in power from 1hdt vs 1hdft is gonna be mostly down to pump and injector upgrades.
At higher RPM the 24 valve head will start to make a difference with improved air flow. At lower RPM the 12 valve HDT may have an advantage with greater velocity through the ports.
Replace BEB in a hd-t so you know their history, then do oil sample analysis after 100k km. I personally would not be scared of using a 1hd-t because of the BEB issue. Huge numbers of these engines running around with original bearings in them.

If you're thinking of keeping the 12ht, it could pay to look into other turbo options, try and get the most low end boost you can for maximum torque from idle upwards.

My experience with a 12ht was as a 18-20 year old, in a hj60 with modified turbo.
It was a lot of fun, but peaky power delivery. I think you'd get a flatter torque curve from any of the 1hd-t** series engines.

I would absolutely choose H151 over H55F gear box. The gears in the H151 box are massive in comparison. The H55F is a modified 4 speed core. 5th gear is tacked on St the back of the box in the reverse gear housing and has known issues with 5th gear failures, and output shaft failure.
H151 was a completely new heavy duty gearbox, designed and built as a 5 speed.

For a heavy beast, another option is use a H150F gearbox, and install a H151F input shaft into it so you have the heavy duty input shaft, but lower ratios in 1st and 2nd gear.
The downfall of the H151F, it's 1st gear ratio is a bit too high. I think this would be a disadvantage in your heavy beastie particularly in off-road situations where you need to be able to crawl up a steep incline.

What would you do to the 12ht? What turbo would you recommend? Currently if i keep the 12ht i am thinking ADS injection, MLS head gasket and Gturbo. Anything else? Thank you