better tow vehicle? HDJ-80 or turbo'ed HZJ-80?

[drexx]

24Jul2005 (UTC +8)

Need a bit of guidance here... what a better tow vehicle for a tow weight of 3,500kg (7,700lb but with trailer brakes) ??? A Safari turbo'ed HZJ-80 with the H150F tranny or an HDJ-80 with Safari intercooler and H155F tranny?

Which has potentially more power and can last longer? Do note that the 1992 HDJ-80 currently has no intercooler for its turbo.

The 1HD-T engine has a lot of similarities with the 1HZ, but it's said to have piston skirt cooling while the 1HZ does not. The 1HZ does have higher compression ratings though so that's better for engine braking. The HZJ-80's H150F has lower gearing than that of the HDJ-80's HDJ-80, so that's better for pulling power.


I ask because I want to know this before I commit to restoring my 1992 HZJ-80 to its former glory, and at the same time an acquaintance is selling a nice HDJ-80 to me (and if that happens I need to sell the HZJ-80).

[Stone]

My guess would be the 1HD-T engine will outlast a 1HZ and can be cranked up to produce more power than a 1HZ in a turboed scenario. Of course, this is strictly just guesswork.

[HZJ60 Guy]

Where is WayneO when we need him? I cant believe that the 1HZ "doesnt" have piston skirt cooling!!! It must.

[rick_d]

the two 1995 HZ's I have seen both had piston skirt systems. I call BS.

as for tow (sustained) I might think about the 'less expensive' HZ turbo vs a 1HD-T. Max power will make the optimal engine work less...

[Stone]

Just wondering what the effects are of boosting an indirect injected engine versus a direct injected one? Wouldn't TDI be the way to go in terms of power and longevity?

[Greg_B]

I was going to say the HZ has piston skirt cooling as well...

We gotta get more people from oz on this here board...they have walked this path a lot longer then most of us here have.

It's the old DI vs IDI argument, and some of it depends how much you are going to stress the 1HZ. It already is a higher compression engine then the 1HD-T, and you will reach the point of diminishing returns when trying to pump large volumn through the precups. DI allows more tuning safetly I think, but what the upper end of safe tuning is for the 1HZ is I've no idea.

If you are going moderate, use the 3B VS 13BT datum...many have turbo'd the venerable 3B with moderate boost, and the engines are still pumping happily...I would not hesitate to do the same with a 1HZ like Tom is going to do (you're going moderate and intercooled...right Tom?)

Read post #21 http://forum.ih8mud.com/diesel-tech-24-volts-systems/52949-boost-pressure-where-set.html

Would there be anyone from the 80's cool list that might help (lots of Oz listers there who speak from experience I believe).

gb

[HZJ60 Guy]

Yes Im going to turbo and intercool my HZ.

Checkout this Australian forum board.

Outer Limits (Oz forum)

They talk about the HZ all the time.

TB

[crushers]

neither, get a 7.3 powersmoke and do the towing right...
the longer wheelbase, larger brakes and wider stance makes for a much more comfortable tow...
that being said i would go wiht the HDT as it is turn key...
as for longevity of the HDT vs the !HZ i will go even steven...
the 1HZ will put out more power than the HDT when tweaked since it has high compression to begin with...
cheers

[bigbrowndog]

http://www.axtturbo.com.au/IHZ.html
This link shows a power & torque graph. cheers.

[neowulf]

my 1991 hzj80 1hz has piston skirt cooling and i curently run on a safari turbo and intercooler system with the recomended boost compensator, everything is adjusted by ear exept the boost i run it on 1,2 bar and have done it the last year, i have no smoke build up and it is more powerful than a original 1hdt verson.(hdj80)

i run on a 5spd manual gearbox so i don't get an rpm issue as you would with an automatic gearbox

the heaviest loads i drag with me is around 2000kg and i hardly notise it (sometimes i actualy forget about it but i remember it when i start braking, especialy in the winter time)

btw the 1hdt engines have a reputation of getting a bearing rupture when they are tangled with.(se the 80scool website)

if i had to make that desicion i would go for the one with lowest km/miles on the meter, i belive you can get more power with the one with original turbo if you IC it and get some diesel tuning parts.

btw. i'm locking for another hzj80 and if you deside on the hdj80 im interested in buing the leftovers i have to import it in any case sinse they are extremly rear here.

[beanz2]

There must be good reasons Toyota reduced the compression ratio on the 1HDT as compared to the 1HZ. We may never know exactly why, but I'm sure they could have kept the same compression as a 1HZ if they wanted to. There has to be some good reasons the 1HDT gets a few different parts from the 1HZ that makes it more suitable for a turbo application. If I had the choice, I would go for a factory turbo than an aftermarket.

True, the H150 has a lower first than an H151 but in the 80 series it comes with a 25mm smaller clutch than the H151, another factor in longevity. I know someone will jump in and say, I've run the smaller clutch for xxxxxxx kms and I've had no abnormal wear, etc. Like the above, the factory knows better to put a larger clutch behind the turbo engine (with the exception of EU market 80 series for ? reasons).

Please explain the big end bearing issue, I don't see how the 1HZ has superiority when the two engines share the same part numbers. I am aware of the delamination issues.

Dave

[Exiled]

I've read about the same bearing issues on aftermarket-turbo'd 1HZ engines on Aussie magazines. I knew that the part numbers were the same for both engines, so the failure must be turbo-related.

I'm with Wayne, if you're going to tow that size trailer on a regular basis, get a real tow rig, either Cruiser choice will be a compromise at best.

[roscoFJ73]

One of the aussie 4wd mags did a test on the accelration between the OEM turbo and a AXT fitted to a landcruiser.

From memory the OEM turbo had more low down torque and faster acceleration in the low ranges.
The OEM was also reported to be smoother.

The AXT had better attributes at higher rpm.

I think both used the same 1HD (F)T

[Tapage]

I think the same as others here .. is more reliable a factory turbo engine .. than other with non turbo desing .. in spite of 2 are Toyota engines, with very close specs ..

More than that if you can buy a intercooler for 1HD-T engine, maybe you can handle and produce much more power than 1HZ only with turbo.

[beanz2]

I am with David. Any aftermarket turbo kit manufacturer would aim to outdo the factory turbo, therefore their 1HZ output figures would of course be better than the 1HDT. One thing they would be hard pressed to match is the built-in factory reliability.

Go for the HDJ80, Drexx.

Dave

[crushers]

yep, Dave, especially the "built in factory reliability" of the BEB...
;^)

[Tapage]

Originally Posted by beanz2

I am with David. Any aftermarket turbo kit manufacturer would aim to outdo the factory turbo, therefore their 1HZ output figures would of course be better than the 1HDT. One thing they would be hard pressed to match is the built-in factory reliability.

Go for the HDJ80, Drexx.

Dave

good point .. there are many ingenieers working hard to desing a aftermaket turbo system, with the maximun reliability, but in a non-factory turbo engine.