12 ht rebuild information request.

[Fasteddie34]

Hello all,
I have a in great condition that I am looking to swap my 2h (280 K reliable but slow) for a 12ht, that will need a complete rebuild.
I'm yet to strip the 12ht and check its condition, but it runs (smoky and needs attention 450 k). My mate who is a diesel mechanic will be helping me with the rebuild.

Looking for reliability and suitable power to tow my ski boat.

My plans are a complete rebuild and looking for some information if anyone can help me out and have experience in this motors would be appreciated. Please see below list so far.

1. Test & rebuild pump as required - any pump mods worth considereing?
2. rebuild injectors
3. send turbo for rebuild (if rebuild able) and high flowed
- any suggestions of modication to ct26
- if turbo is too far gone, can new ct26 be bought (other than Toyota $$ or china rubbish) or equivalent Garrett
4. rebuild and clean up head for better flow, is it worth to go bigger valves or small potential gains not worth the extra dollars
5. 3.5 dump pipe to 3 inch exhaust with high flow muffler
6. get diesel specialist to tune completer set up
7. maybe air to air intercooler down the track
8. any information on the strongest pistons for these motors that keeps the same or close compression ratios. Research done so far suggest new design of piston with steel lining for top ring to stop piston/ring from flogging our, don't know brand or part number. Can forged pistons be sourced? Looking for possible 1 mm over bore.
9. is it worth investigating bigger nozzles for the oil piston cooling or newer aftermarket pistons handle higher boost 14 - 16 psi
10 what egt are safe for this engine after rebuild less 650 measured after turbo

Any other information on this engine rebuild would be great.

Cheers,

 

[Tim-HJ61]

Welcome aboard.

For a first time poster, you have some pretty detailed questions.

You will find a few threads that have already addressed this issue.

Questions 1 and 2

Rebuild pump if needed. It will be your biggest expense. Normally pumps last around 500k km so at 450k, it might be worth doing. My local injection specialist spent 12 hours rebuild one recently that someone had mucked around with. Cost the owner $2400.

Injectors. Yes, redo with standard tips and get set to correct pressures.

Question 3
https://forum.ih8mud.com/diesel-tec...toyota-ct26-upgrade-13bt-12ht-1hdt-1hdft.html

Question 4
See current thread on this topic of flowing head.

https://forum.ih8mud.com/diesel-tech-24-volts-systems/486249-match-porting-polishing-12th.html

https://forum.ih8mud.com/diesel-tech-24-volts-systems/269939-12h-t-performance-build.html


Question 5.
Good idea.
3" exhaust | landcruiser | Tim Law

Question 6.
same as question 1. Whoever checks your pump will reset it to standard. After that you unwind the max fuel screw until your EGT are less than 650°C pre turbo, 550°C post turbo under full load. With a gbentink turbo and front mount intercooler, this will be never, so just unwind the fuel screw to give max fuel. This is a HIGH RISK activity without correct modifications to cope with extra fuel.

Question 7.
Yes. Do it whilst your engine is out. routing the pipes will be easier.
Turbo and Intercooler | landcruiser | Tim Law
The other thing to do whilst the engine is out is to install an endless air compressor underneath the alternator for a highly effective onboard air system. You won't be able to do this with the engine in the car, much easier to set it all up on a stand.

Question 8.

AFAIK, all aftermarket pistons have the steel ring land inserts. I am not aware of any better piston option for standard use. If you want to highly modify things, see the thread by gbentink as above, https://forum.ih8mud.com/diesel-tech-24-volts-systems/269939-12h-t-performance-build.html and send him a PM.


Question 9.
Probably not. Ones out of a 1hdt fit, but provide so much more flow you may not build oil pressure enough. Standard appear quite adequate.

Question 10.
as per Question 6

I am running 1.4bar = 20 psi without any signs of a problem. Cruises on less than 300°C pre turbo at 100kmh with a 600mm front mount, 3" exhaust and a gbentink CT26 turbo and completely unwound fuel screw.

Prior to these modifications the data I got from one test hill in my local area with an 80kmh speed limit, was that at the top of the hill, I could just hold onto 5th gear, EGT's were 700°C and the engine was working really hard.

Add a fat exhaust, gbentink turbo, front mount intercooler, and yesterday I could accelerate at 80kmh, EGT were never over 400°C and all was very sweet. As per my site, I'm getting 450nm at 1600rpm on a dyno.

The head has not been touched, the pistons are standard, the oil squirters are standard. If you want more performance than this, you're into major modification territory.

Be brave, give it more boost, fuel and an intercooler.

Tim

 

[Fasteddie34]

Tim,

Thanks for the infomation and answer my questions. I found your web site after posting, impresive figures from the 12 ht, considering the new V8 cruiser gets 151 kW & 430 nm @ 1200 and is 4.5 litres with 4 v in standard tune, and yours running on veg oil.

Have sent PM to gbentink for info and costing on his turbo mod.

With the 12ht im looking forward to be able to over take cars with the 60 and not be the one holding up trafffic, and get back to 2/3 gear for the hills.

Cheers,

 

[Mountain Goat]

Tim,

"Question 6.
same as question 1. Whoever checks your pump will reset it to standard. After that you unwind the max fuel screw until your EGT are less than 650°C pre turbo, 550°C post turbo under full load. With a gbentink turbo and front mount intercooler, this will be never, so just unwind the fuel screw to give max fuel. This is a HIGH RISK activity without correct modifications to cope with extra fuel."

Just curious why you feel this is a high risk tweek.

 

[Tim-HJ61]

This is a HIGH RISK activity without correct modifications to cope with extra fuel."

Just curious why you feel this is a high risk tweek.

It's a reasonable rider for people who might just read and act on one paragraph in a whole story. If they leave everything else standard, and the only mod they do is unwind the fuel screw, they will overfuel the engine and create too high EGT - which they will not know about because they have not fitted a pyrometer. Then when they melt things they'll come back and say - 'well you told me to'.

It has to be done as part of a package of a number of other things.

In my mind, I've got the complete package now. But I started like most people, with a standard setup.

First I added a pyrometer to read the EGT
Then I added a boost adjuster to control the opening of the waste gate and allow higher boost dialled up by an adjustable bleed valve.
I increased boost to a 'scary' 10 - 14 psi, can't recall.
Then I smiled.
Then I installed the 3" exhaust to get me better flow.
Then I unwound the fuel screw one turn.
Then I smiled more.
Then I unwound it a bit more.
And I smiled more.
In a long drag up a sanddune, my EGT were 700°C. Doing that too much for too long is not the best, and without an EGT I would have been ignorant of the risk.

Then I installed the gbentink CT26 upgraded turbo and boost set to 20psi.
And I smiled a great deal.
And I unwound the fuel screw completely to give maximum fuel. As it turns out, I'd already maxxed out fuel flow with my previous adjustments but hadn't realised it, so I didn't smile any bigger after this adjustment. Besides, my jaw was getting tired

At this point it was dynoed and measured to have 450nm at 1600rpm and around the same up to 2200rpm IIRC.

The latest and most likely last to complete the package was to install the front mount intercooler. Looking back from where I started, this difference is substantial, and I've not actually modded anything substantial in the engine or the fuel system apart from the turbo. All the mods have been about getting the most fuel and air into the engine, a standard engine, and plenty of extra grunt is available simply by adjusting boost and fuel with a standard turbo - WITH CAUTION.

I'm a cautious old bloke. One step at a time has got me here.

Tim

 

[Mountain Goat]

Thanks Tim.

I believe I already have to appropriate safty measures in place. However, being generally ignorant of automotive technology I regularly second guess myself.

I ordered one of Graeme's turbos last week. Looking forward to smiling.

 

[Fasteddie34]

Mountain Goat,

Please post some feed back and info when you get your Grameme's turbo fitted and soughted.

Was wanting to refresh this thread t see if anyone else could lend some imput to tuning these 12 ht motors.

 

[rideglobally]

i also got a Graeme turbo which i will be installing on my newly rebuild 12ht this coming wednesday....... i hope to be smiling. will let you know

Mountain Goat,

Please post some feed back and info when you get your Grameme's turbo fitted and soughted.

Was wanting to refresh this thread t see if anyone else could lend some imput to tuning these 12 ht motors.

 

[Tim-HJ61]

What other info do you want??

Was what I posted earlier, and others have added to, inadequate, or not able to be understood?

Tim

 

[Fasteddie34]

tim,

Thank you for all your infomation, and answering my questions, much appreciated. I was just posting to see if anyone else has experience with tuning these motors or other considerations i might consider for my rebuild, eg turbo specs (other than Graeme turbo), intercooling wta or ata Specific set up, for Hj60's and pump mods and settings, etc.

Once i get started in the next month (saving for parts), and finished the motor build i will posts my results with dyno results and fuel consumption to document my experience.

Cheers.

 

[rideglobally]

smiling

so far i have done 4,000 miles on my new rebuild 12ht with the Graeme turbo, it has been all smile all the way. i have stopped analyzing the performance cause it was giving me a headache, i know for sure this engine has a lot more guts. we have cross the continental divide i believe 4 times some at over 10,000 feet. mostly on third gear and sometime i dropped to second gear. i have also been babying the engine cause it is newly rebuild running the EGT at no more than 900 degree Fahrenheit. i have everything Tim has except my intercooler is top mounted which i did not install for this trip cause i wanted to see what the engine does without it. also i have not turn the fuel screw all the way out i have only turn it out one turn, when i get back home and install my intercooler i may get enough guts to turn it a couple more turn.

maybe the other difference with Tim's engine is that mine was match ported, 3.5 inch down pipe and balance during rebuild.

this coming weekend i will start the last leg of my trip, about 1,400 miles. i want to push my engine a bit. my question is this what would be a good egt to cruise all day long and what should i expect the water temperature of the engine to go to? i notice that the water temp was going up at 900 degree fahrenheit.

how are you doing on your rebuild?

 

[Tim-HJ61]

this coming weekend i will start the last leg of my trip, about 1,400 miles. i want to push my engine a bit. my question is this what would be a good egt to cruise all day long and what should i expect the water temperature of the engine to go to? i notice that the water temp was going up at 900 degree fahrenheit.

Hi Amado,

Pleased to hear you are still trucking with a smile.

If I recall, 600°C 1100°F is a fair maximum temperature. Now I have the intercooler, I never see these temperatures any more. Bear in mind, I live in a very flat place and don't tow heavy loads, so it is hard for me to load up the engine and turbo in the same way as you would travelling over the proper mountains you have.

What I do notice is that the water temperature does rise when the motor is under high load for a few minutes. But it does not keep rising, and this is the important thing.

You will notice the 'normal' running temperature of your engine with your gauge showing 'normal'. I imagine that this is showing the temperature is being managed by the thermostat and engine temperature kept at optimum (82°C 180°F) . When the engine is under load, I imagine the thermostat opens up wide and the cooling system is needing to work at it's full capacity. I notice the coolant gauge rising at this point, but no more than the upper end of the normal range on the OEM gauge.

The only time I would be concerned is if the temperature kept on rising above this point as it would show the cooling system was not coping with the demand on it.

It will be good to get your intercooler reconnected so you can reduce those EGT's a bit and get that lovely motor working hard


Fasteddie34
One of the reasons Graeme's turbos have been popular is that no one else has been able to produce the same results in a bolt on unit.
Pump mods are limited to
main fuel screw,
off boost fuel screw, and
aneroid spring adjustment which allows the pump to react to boost faster. Unless you want to race the vehicle, I do not know of any other mods to the pump that are common. I do not know of any alternate IP with greater capacity that will fit these engines.

Front mount or top mount are matters of personal choice IMHO. Both have advantages. I know that my front mount was awkward to fit up and covers over the full width of the radiator. I have not had this setup through a summer yet, so cannot say what impact it will have on my cooling system. I do know that with a 600mm intercooler across the front, that under regular running, the housing is cool from about 60% of the way across, so it has heaps of spare cooling capacity. I'll be posting some temperature drop figures across the intercooler from my data logger when I get some new pickups for it.

Tim

 

[rideglobally]

hi Tim, also remember Nulla is heavier that normal, it currently weight about 7000 pounds (picture below). my OEM gauge is currently not working, i am trying to get my isopro gauge working again before i go on the last leg of my trip. when i am cruising at 900 fahrenheit egt, my water temp is 190 fahrenheit.

 

[gbentink]

QUOTE "my water temp is 190 fahrenheit"

Hi Global Rider

190F is only 88 deg C

Not even close to hot (relative to radiators)

So great to hear it is running so well. I would call it all run in now. I look forward to an even bigger smile once the intercooler is fitted and the fuel screw is wound out or removed.

Your rig makes me want to give up work and go on a holiday!!!

Note: On std pumps the max fuel screw can be removed in all the testing that I have done on all but one pump, where it appeared to be able to pump copies amounts of fuel in (heaps of balck smoke) and most certainly couldnt be wound out fully - lucky owner, people usually pay alot for that !

 

[Fasteddie34]

12 ht rebuild

Well, I have pulled the motor, strip the pump and injectors and they should be finished this week their rebuild this week. Then willl strip the motor on the weekend and off to the machine shop, then to assemble.
Thanks for the information and feed back on Graeme's turbo, think i will have to consider this mod for the build.

Tim on your exhaust have you also fitted a hi flow muffler or just straight through ?

Can you confrim were your pryo sender is in the manifold just trying to work out best location ?

Cheers, for the information.

 

[Tim-HJ61]

Well, I have pulled the motor, strip the pump and injectors and they should be finished this week their rebuild this week. Then willl strip the motor on the weekend and off to the machine shop, then to assemble.
Thanks for the information and feed back on Graeme's turbo, think i will have to consider this mod for the build.

Tim on your exhaust have you also fitted a hi flow muffler or just straight through ?

Can you confrim were your pryo sender is in the manifold just trying to work out best location ?

Cheers, for the information.

My exhaust has a straight through hot dog muffler. EGT is pre turbo.. Photos and write up on my website as per link from earlier posting.

Tim