Which engine?

[mudgudgeon]

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

I'd say try and talk to Graeme at GTurbo, see what he can recommend.
I know he has a history of playing with 12ht

 

[Dougal]

I think you're looking at this backwards.

First question is how fast do you need to drive. Considering you're in a lumpy brick without modern brakes and steering there's a few safety considerations there.
Second is how much power do you need to drive that fast.
Third is what engines will last at that sustained power output.

 

[sodafeld1]

(nice looking lumpy brick)

 

[mudgudgeon]

I think you're looking at this backwards.

First question is how fast do you need to drive. Considering you're in a lumpy brick without modern brakes and steering there's a few safety considerations there.
Second is how much power do you need to drive that fast.
Third is what engines will last at that sustained power output.

Agreed, which is why I'd suggest looking at turbos for the 12ht that improve low end torque.
And, if you're looking to improve the gearbox, look at one with lower 1st & 2nd gear ratio, such as H150
I'm sure a H152F would be nice, once you exceed 110km/hr which I'd imagine would be a terrifying prospect in that rig!
H152 needs an input shaft and bell housing from a H151 to make it work too.

Torque at low rpm is what gets all that weight rolling which is where small truck engines would start to make sense.

 

[rideglobally]

I think you're looking at this backwards.

First question is how fast do you need to drive. Considering you're in a lumpy brick without modern brakes and steering there's a few safety considerations there.
Second is how much power do you need to drive that fast.
Third is what engines will last at that sustained power output.

I have disk brakes on all four.

 

[Nz Nath]

For overlanding I'd be looking to get slightly more go out of the 12ht, and settle for the big girl being a bit sluggish. It's hard to believe any of the toyota motors in contention are going to have a long life when moving along nearly 5ton day in day out running significantly more fuel/torque than stock.

What else did you do to the 12ht besides the gturbo? A fmic, large dump/exhaust, large intake/filter, and fuel maxed out would surely go quite well?

It sounds like money is no object for this vehicle? A medium-rigid truck engine like a 6bt would probably be the only way to get good performance without worrying about the motor handling it long term.

 

[Silveredition]

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

This question wasn’t directed at me, however I thought I would reply as I have semi-recently spent considerable $ on rebuilding my 12ht - with more power / drivability in mind (1988 hj61 - with the main goal of towing my 1.5t boat in hot ambient temps long distances… my goal was to sit on 100km/hr in roughly 45degrees celsius ambient temps over our annual 1500km non-stop (each way) trip - without overheating!! (I am in Western Australia)
I had a full rebuild done (drive in / drive out) by a guy who works closely with Grahame at GTurbo and Brian at PDI, as well as Mick at ADS…
As far as performance mods go, I had the following done:
Alfin pistons
MLS head gasket
GTurbo Green Wheel (22psi and 22:1 afr’s)
PDI front mount
ADS modified injector pump and +30 injectors
Exedy HD clutch
I think (on 33’s) I am currently at 167hp and 530Nm.

My rebuild certainly wasn’t without issues - and maybe a good reason to not add extra complications by getting even more complicated and changing the engine altogether!!

I would also research JHHilux, and Monroe Racing Turbos (I have had nothing to do with either of these companies, but researching options is free, and I haven’t heard anything bad about either of them…)

 

[-MaTTi-]

Yes my fuel is tuned up, Gturbo, 3.5” down pipe, over the top inter cooler with fan, radiator fan, etc..

You would need to get your fuel pump properly tuned, bigger elements etc. It’s quite easily double the power of the 12H-T.

 

[rideglobally]

This question wasn’t directed at me, however I thought I would reply as I have semi-recently spent considerable $ on rebuilding my 12ht - with more power / drivability in mind (1988 hj61 - with the main goal of towing my 1.5t boat in hot ambient temps long distances… my goal was to sit on 100km/hr in roughly 45degrees celsius ambient temps over our annual 1500km non-stop (each way) trip - without overheating!! (I am in Western Australia)
I had a full rebuild done (drive in / drive out) by a guy who works closely with Grahame at GTurbo and Brian at PDI, as well as Mick at ADS…
As far as performance mods go, I had the following done:
Alfin pistons
MLS head gasket
GTurbo Green Wheel (22psi and 22:1 afr’s)
PDI front mount
ADS modified injector pump and +30 injectors
Exedy HD clutch
I think (on 33’s) I am currently at 167hp and 530Nm.

My rebuild certainly wasn’t without issues - and maybe a good reason to not add extra complications by getting even more complicated and changing the engine altogether!!

I would also research JHHilux, and Monroe Racing Turbos (I have had nothing to do with either of these companies, but researching options is free, and I haven’t heard anything bad about either of them…)

Thank you for your response, it is exactly what I am looking for, someone with concrete experience on the 12th. I wish I was in Australia. Btw there is nothing currently wrong with my 12ht. We have done many modifications to the chassis. suspension, brakes, lower gears, etc. Now researching what are my options on the power plant area.

 

[nickolai]

That 40 with a 3208 looked like a ton of work.

Had another look at this over the weekend - its on a 105 chassis

 

[PIP]

I know a guy with a twin turbo version of the 3208 in an old Chevy Suburban 4x4. He's been driving it for about 30 years and loves it. My BIL has an 1160 in a Firetruck he converted to haul his antique vehicles cross country. The 1160 is not very impressive. Cat still supports them though. Something to be said for that.

 

[rideglobally]

For overlanding I'd be looking to get slightly more go out of the 12ht, and settle for the big girl being a bit sluggish. It's hard to believe any of the toyota motors in contention are going to have a long life when moving along nearly 5ton day in day out running significantly more fuel/torque than stock.

What else did you do to the 12ht besides the gturbo? A fmic, large dump/exhaust, large intake/filter, and fuel maxed out would surely go quite well?

It sounds like money is no object for this vehicle? A medium-rigid truck engine like a 6bt would probably be the only way to get good performance without worrying about the motor handling it long term.

Our rig has gone through a lot of modifications to carrying the 10,000 pound weight. It is regeared lower, air bags, reinforced chassis, custom made lift springs, dish brakes on all four, drive shaft etc. I have done all the things you mention on the 12ht.

Our rig is actively overlanding on the current set up not once has she left us stranded on the side of the road. We been all over the US including Alaska, Mexico, 2023 we are overlanding Africa north to south. I want to address the power plant issue in the future. I am on research stage I appreciate all the input.

I would like to stay Toyota but you are not the first to suggest the 6bt, I will look into it. It would be great to hear from someone who has done a 6bt conversion on a 45 series. Thx

 

[chapel gate]

i dont see the weight of this rig as an issue. whats the combined weight of a 1HZ powered coaster bus with 30 passengers?

1HDT/FT/FTE powered land cruisers are often bought as towing rigs in the uk for there ability to lug 3.5 tonnes around all day everyday.

a intercooled, G turbod, correctly tuned one of the above would give the OP a worthwhile and usable increase in output IMO.

 

[nickolai]

i dont see the weight of this rig as an issue. whats the combined weight of a 1HZ powered coaster bus with 30 passengers?

1HDT/FT/FTE powered land cruisers are often bought as towing rigs in the uk for there ability to lug 3.5 tonnes around all day everyday.

a intercooled, G turbod, correctly tuned one of the above would give the OP a worthwhile and usable increase in output IMO.

Agree, all sort of huge heavy stuff gets towed by 80s and 100s in NZ, boats, caravans, containers, all sorts.

 

[sodafeld1]

Can't help to say that 40 series is just the coolest toyota body ever made. They won't make them with bolt on panels like that a gain. Very enticing with a 3.5t pull, engine and gear box.

 

[chapel gate]

Agree, all sort of huge heavy stuff gets towed by 80s and 100s in NZ, boats, caravans, containers, all sorts.

indeed.

the OP has wisely lowered the gearing.
i have a 5 tonne 4 cylinder turbo intercooled 140 BHP unimog u140 that will carry 4 tonnes.

my dad has a 65 BHP zetor tractor that will pull your house down.

i have 27 speed mountain bike that will lug 16 stone up any hill with next to zero HP...

 

[PIP]

I would like to stay Toyota but you are not the first to suggest the 6bt, I will look into it. It would be great to hear from someone who has done a 6bt conversion on a 45 series. Thx

I've done these types of builds with 70's pickup trucks. The recipe I have found nets the best ratio of smiles to dollars is purpose built 12 valve Cummins, Proper air/air intercooler and radiator, ZF6, 2011+ Superduty chassis with wheelbase corrected and pro level fabrication to support body correctly.

A low mile Superduty chassis with large capacity diesel fuel system, ZF6, NP271, drivelines, huge brakes, excellent steering, etc can typically be found under $5k. Add a couple thousand for lockers. A pro-build turnkey 12 valve that will deliver the upper echelon of economy, power and reliability is around $15k.

Integrating it correctly with the vehicle is the tricky part. You want to end up with the ultimate overlanding land missile, not a hack and stuff special.

If you have the resources to pull that off for a proper (value added) end result that is the way I would go. If a build of that scope is not on the table I would stay Toyota and stay within the limitations of the Toyota powerplant.

 

[rideglobally]

indeed.

the OP has wisely lowered the gearing.
i have a 5 tonne 4 cylinder turbo intercooled 140 BHP unimog u140 that will carry 4 tonnes.

my dad has a 65 BHP zetor tractor that will pull your house down.

i have 27 speed mountain bike that will lug 16 stone up any hill with next to zero HP...

Thank you, in Croatia google map have gotten us lost on a lumber jack road and ended up on top of a mountain. Did not need High 4 just 4x4. We are also equipped with ARB lockers on all 4. We are not fast on the highway because of low gearing.

 

[sodafeld1]

Can't help pointing out, it seems hard to find examples of hdfte longevity over 400k kms. The pump seems to fail.

Like the story of the hare and tortoise.

I believe the 6bt has a better longevity.

 

[rideglobally]

For those of you that has been pointing me towards the cummins 6bt here is something interesting I found the cumming R28 on a 45 series Landcruiser here is a link about the engine it has 161 HP and 310 foot pound of torque. what do you think? It is quite than a 6bt and I think it only weight 300 pounds.