Turbo for 12HDT Engine

Yes that is correct...I had a HJ61 and I am pretty sure it was the 12HT (not 12HDT).

I bought this engine from a friend of mine and he says its 12HDT and came with original HJ61 SUV and told me i can find this in Australia. I pretty sure its 12HT. I assume there is no 12HDT engine? I just love the roar of this engine.

I have contacted GTurbo and All Four X 4 Spares. I am worried if 3rd party turbo power exceeds than the original specs it might damage engine as this engine was rebuilt with sleeves and nor via ovesrize boring.

I have also heard about garrett, kkk and Holset but unsure if these are OK for 12HDT /12HT

How is high powered 3rd party turbo for rock crawling? Does it ever get unstable?

I am taking it that you have a 12h-t.

I was not aware you could put a sleeve inside a 12h-t bore. Never heard of that before, but that's not to say it's not done. These engines usually last a very long time - 500,000km plus and then only need a small rebore and new Alfin pistons with a steel ring land insert. There is a design problem with the original 12h-t pistons in that the top ring tends to bash a groove in the top ring guide and eventually bits break off and bounce around on top of the piston, causing all sorts of nastiness.

This generally starts to be evident at 300,000km and can be fixed by renewing pistons at that time and a light honing. Then drive another 600,000km without problems.

Is it possible you have not been given the correct information. For example, you were told it was a 12HDT - never heard of that one before.

Regarding strength of the engine. There is no problem. I could explain all this in detail as to why there is no problem, but at the end of the day, you're either going to believe me or not. I guess I need to explain myself a little:

Potential problems with high boost.
Head Gasket:
There is a LOT of clearance between the pistons, water and oil galleries on a 12H-t. I have been running 19 to 20 psi boost for a couple of years with not a problem. The thing is that it is not at that boost for very long unless you are towing a very heavy load up a very long hill. With the GTurbo and other mods I have made, I never run out of power unless the load is exceptional. I'm talking overtaking roadtrains at 120kmh towing a 1.5t camper up a hill. The thing that kills these diesels is heat, not high boost. You control the heat and before any mods you MUST install a pyrometer or EGT gauge, Exhaust Gas Temperature pre the turbo so you get a reasonable measurement of the temperatures inside the combustion chamber. If you exceed 750°C for too long, that is bad. Comfortable levels are below 600°C.

With the G Turbo, given it's capacity to flow vast amounts of air and burn all the fuel my IP can pump in, I rarely exceed 450°C, and under the passing road train conditions described above it might get to 600°C.

Anyway, boost and therefore the heat you produce, is controlled by your right foot.

The second aspect of high boost people worry about is the bottom end. The 12h-t has oil squirters onto the bottom of the pistons to keep them cool. I have never known of any problems with a standard 12h-t and the bottom end, no matter what boost.

So - there is no problem with high boost and a 12h-t. By high boost I mean in the vicinity of 20psi. Creeping up to 25psi and 30psi increases the realms of risk and is not something I am prepared to do. Others might and find no problems. I suggest you will need significant IP modifications in order to give you enough fuel to justify those levels of air flow. I have unscrewed my IP fuel screw to its maximum and find 19psi a happy setting. Besides, by boost gauge only goes to 15psi!!

Moving onto your question "How is high powered 3rd party turbo for rock crawling? Does it ever get unstable?"

Unstable?? Not sure what you mean. It's not going to fall off.
Rock crawling typically requires very low speed, both on the ground and for the engine. You don't load the engine up very much with low gearing and low speed, so the turbo won't boost very much. Turbo's come into their own on the highway, towing, sand dunes and general acceleration around town. Low speed along beaches were the engine is loaded up dragging the car through sand is also nice to have more power. But not for rock crawling. If you're talking about building a vehicle for off road competition rock crawling, then you're on the wrong forum and need to go to IH8MUD or Outer Limits and get the high tech expertise that is pretty thin on this site.


When looking for a turbo, another option is a cheap version from China via ebay. Some people have found these to be useful for them, and they might be okay. I have also heard of poor fitting control and bits of swarfing and other debris left inside the internals which was only going to cause problems.

If you read the thread at the IH8MUD forum I gave in my first reply to your question, you will find that what people appreciate about the GTurbo over the other options is that it is a direct bolt up replacement for your standard turbo, and to the outside observer it remains looking standard. What Graeme has been able to achieve however, is boost that comes on much lower than other options and maintains stable boost all the way to the maximum revs for each engine it is designed for.

By fitting a smaller turbine housing, on the exhaust side, it is possible for any turbo to give you boost at lower revs and increase drivability with more low down power. But then the challenge is to maintain that efficiency through the rev range and this is where smaller turbines by themselves come unstuck as a solution. Hence manufacturers built variable vane turbos that provide a good solution across the rev range. But a 12h-t cannot be fitted with a VV turbo without special modifications.

What Graeme has done is designed both the turbine and compressor to match the engine in a much better way than the standard turbo, and from what others across the world are saying, better than any of the other aftermarket options. And he continues to develop these turbos so they provide greater efficiency. One component of efficiency is to ensure the compressor wheel is designed to still 'grip' the air at high speed and boost. Poor design just creates poor air flow, extra heat and limited air flow.

So, sure, you can buy a turbo from Garrett, KKK and Holset but it really needs to be properly matched to your engine, both the exhaust and the compressor side. You will be spending a lot of money whichever way you go, unless it's an ebay version from China which used to be around $400 last time I looked.

Boost on a 12h-t standard is 7psi. They are lame at that setting, absolutely lame. Mine has been dynoed to measure 50% increase in torque and at at least 200 rpm lower than standard. It's been like this for a couple of years and I expect it will continue for many more to come. The EGT are remaining remarkably cool, indicating low load on the engine, the oil stays remarkably clean, indicating highly efficient burning, I get good fuel economy, enjoys heaps of power and it's all thoroughly enjoyable. Especially when I take on friends on hills, or drive around them on the road - all by a little wheel pumping a bit of air!!!

I trust this adds clarity for you.

Tim

Tim, thanks for a very interesting and informative post!

I am running my 12HT with the stock turbo at ~10psi thanks to a 3" exhaust and a little extra fuel and I do a fair bit of towing up to 2 tons. I currently get EGTs of ~500-550*C post-turbo when working hard uphill.

I was wondering if I could drop this somewhat by increasing the boost to ~15psi via modifying the wastegate mechanism without increasing the fuel anymore. Do you think this would work?
I don't really want to fit an intercooler as I simply have no space in the 75.

12ht75,

Happy to give you my thoughts - any mods from standard are at your own risk.

Several people have commented that my own site of http://www.peoplehelp.com.au/landcruiser/ is useful as it contains stories of all my own mods to my 12ht and a few other things.

First off it's a pity your EGT is installed post turbo and not pre turbo. It's rather odd that all the commercial installers will put them post turbo and all the home users want them pre turbo so we can get a better gauge of actual combustion chamber temperatures, without the cooling influence of the turbo. If I recall, 150°C difference is regarded as pretty much what you lose across the turbo, so given you are running to 550°C post turbo, this is VERY high and really on the limit of safe operation over an extended period.

My first thought is you need to reduce your fuel a little until you can get the EGT under a bit of control. As you say, an alternative is to increase boost, but pay particular attention to your EGT, it needs to be lower on those long hills. You can run up to 15psi with the standard turbo, probably closer to 16-18psi if you really wanted to, but that'd be the limit before they start losing efficiency. Try 15psi and see what difference that makes. The CT26 may not blow enough air to burn all the fuel you are putting in, which helps to increase EGT, so if increasing boost to 12psi doesn't help, reduce your fuel a little. Do those adjustments quarter turn at a time. A little can make a big difference.

Do you get any black smoke under those towing conditions?

Do not modify the waste gate mechanism to gain boost. Purchase a standard ball and spring waste gate controller from Ebay and install that so it gives you more control.

You could try a front mount IC in your 75 or what about a water to air?

Tim

Thanks for the reply Tim.

Firstly, apologies to the OP for the thread hijack - we should take this to PMs but I can't see an option for that on this forum.

Re the EGTs and black smoke:
The fuel was 'set by eye' long before I got an EGT gauge ie wind it up until it just starts to smoke so yes I get a little black smoke when working hard, barely enough to notice in the slipstream. (Might be more obvious from a following vehicle though!)

After installing the pyro, I didn't bother changing the fuel as I have read in various places that a 550*C post-turbo temp (equating to ~700*C pre-turbo) was OK. However it would be nice to lower this a little and at the same time get rid of all the smoke and run a clean exhaust without losing the power level I have now, hence my thoughts of raising the boost without raising fuel any further, rather than just reducing fuel.

Re modifying the wastegate, I was going to try disconnecting the actuating rod to start with then maybe play around with adding a stronger spring - you don't seem to think that is a good idea? Long term I will get a proper ball & spring controller.

I have looked at your site and am currently reading through the IH8MUD thread you linked earlier, very useful info in both, long-long term I wouldn't mind a GTurbo too!

How about in the short term you wind that fuel screw in a bit.

I'm certainly not comfortable with 700 preturbo for anything more than a brief spike. And black haze under full power means too much fuel. I agree more boost will likely help that, but how about knocking the fuel back a quarter turn first.

Once you sort out your mechanism for increasing boost, start with increasing boost and wind more fuel in later. Boost won't kill your motor, over fueling will.

You could see what difference extra boost makes by disconnecting the waste gate actuator and going for a drive. The CT26 will boost to over 20 psi but not be very efficient at those levels. Do not run for long with your WG disconnected, just enough to see the impact on the haze and the EGT.

Thanks Tim, I will try a run without the wastegate connected first, then I think I will do what you suggest and reduce the fuel a bit - I just checked on my EGT gauge which stores the min and max readings, and the highest it has been is 589*C (which would have only been for a brief time).

I will leave it at that for now until I get time to play around with the car (it is not a daily driver).

BTW, do you have any recommendations for a boost controller? A couple I have googled are the original Turbotech one and the Turbosmart boost tee. Thanks.

The original Turbosmart is cheap and easy to operate. Quite suitable too. I ran one for years until I found the waste gate Graeme supplied with my new Grunter was set to the pressure I wanted anyway, so no need for a controller anymore.

If you are going to run high boosts over 20psi with a GTurbo, then their upgraded model helps lessen the surging that can be a problem with the standard unit under high boost conditions. But for normal use, the standard one is fine.

Tim

12ht75

I spoke to Graeme today. He recommended not pushing your engine too hard when running without the waste gate connected. Nothing more than 2200rpm as it is likely to overspeed the compressor wheel on the standard CT26 that is fitted to the 12H-T. It may fly apart! This would be a bad thing.

He has built his compressor wheels to be thicker in the centre, and therefore stronger and be able to manage much higher speed and boost.

He also agreed with my observation to you that 550°C post turbo is okay for a short time only, and should not be held for a long time when towing.

With my complete installation of a 3" exhaust, intercooler, GTurbo Grunter stage 1, and IP turned up to full, I can confidently run at foot to the floor throttle up a hill towing a load at 2500rpm in 5th gear and watch the EGT slowly rise from 300°C at 100kmh on cruise to 600°C preturbo and not much more.

The volume of air that little compressor wheel is pumping at these speeds is phenomenal and I am sure I'd be getting restrictions through the air box and filter element which are next in line for reworking.

Regards

Tim

Thanks for the alert on the compressor speed Tim, it may be a while before I get an opportunity to do any testing but I will keep this in mind.

Your pre-turbo figure of 600°C would equate to ~450°C post turbo I assume?

How does your clutch handle the boost you are running, do you have a heavy duty clutch? Mine is slipping a bit when cold, usually OK when warm but it is pretty old.

Backtracking a little to your previous followup, you mentioned an upgraded model of the Turbosmart boost controller, is it this one?

http://www.turbosmart.com.au/product/boost-tee

or did you mean the Turbotech V2?

http://www.turbotechperformance.com.au/epages/tutu2750.sf/en_AU/?ObjectPath=/Shops/tutu2750/Products/MBCV2

Thank you.

Graeme has advised me he findshttp://www.turbosmart.com.au/product/boost-tee okay.

My first one was http://www.turbotechperformance.com.au/epages/tutu2750.sf/en_AU/?ObjectPath=/Shops/tutu2750/Products/MBCORIG.

Any ball and spring type boost controller has the potential to flutter at high boost. I was able to reconfigure the boost lines so this was not a problem for mine.

Instead of the little hose going straight from the turbo into the waste gate actuator, I ran the line from the turbo across to the back of the injection pump governor. This way the IP saw the pressure from the turbo as it spooled up and the IP could apply more fuel, more quickly. Bear in mind, I have a large front mount intercooler that had the potential to create some lag.

And to supply the waste gate actuator, I took a line I created off the inlet manifold. This way the waste gate was triggered by the actual pressure AT the manifold, taking into account any pressure drop or time lag caused by filling the intercooler.

In reality, the GTurbo spools up so fast, (there is a short video of it on my website), there is really only parts of seconds involved in all these things, but each little adjustment makes a small difference and improves the driving experience.

Tim

Hi Tim, not sure if you are still watching this thread but I finally got time to play with my wastegate settings on a quiet bit of road.

Firstly I disconnected the wastegate completely and went for a run, being mindful of Graeme's advice to stay below 2200rpm, and that was rather difficult since as soon as the revs hit around 1800 it hit a powerband like a 2 stroke motocross bike, the boost shot up past the 15psi limit of the gauge like in your video.

So I made myself a temporary ball and spring boost controller from some brass fittings and a ball bearing I had lying around and did a few more runs limiting the boost to 12psi but still getting the sudden increase at ~1800rpm. EGTs seemed lower, not exceeding 360*C but I was unable to put it under sustained load as the road was flat.

All the above was accompanied by severe clutch slip however, so a new HD clutch is the first step. Are you using a heavy duty clutch? If so, which one or do you know of a proven good one?

All this sounds good.

Well done for making your own ball and spring controller. You know there is a small hole in the commercial ones that let the pressure bleed off from the actuator when the ball is closed. This allows the actuator to close and not hold the pressure inside the actuator.

I believe I have an Exedy clutch. Sounds like you need a new one!! Check the condition of the flywheel too. Mine had been skimmed so much by the previous owner that the pressure plate didn't bolt up properly. A new one was in order and has worked fine.

I 'think' the regular heavy duty clutch is rated at 600nm, which will be fine for you. My engine was rated at 450nm prior to fitting the intercooler, so it's probably around 490nm now. Clutch holds fine. The vacuum assisted clutch manages the extra foot pressure required for a HD pressure plate.

Pleased you had a chance to experience the powerband. :-) Your standard turbo will be okay to 15psi and as you have experienced, and the performance is just dandy! What happens with a GTurbo is that you get more power, earlier, and it holds right through to whatever revs you run to with no loss of boost. And you can run to 20psi safely for the turbo and the engine. One of the limits in the standard turbo is the bearing, the GTurbo has a 360° thrust bearing so is much more able to take high boost long term.

Being a passenger in Graeme's own Lexus with a 1HDFTE that pushes 600nm in a five speed auto is an experience that leaves one awestruck. To feel the torque lifting that heavy body and getting it to speed with great rapidity that leaves V8 utes gasping is something to behold. But that's another story......

Tim

Hi Tim, I did remember the hole to bleed off pressure, I used a 1/16" drill, the smallest I had. The home made controller works OK but I will order a 'proper' one long term.

Interesting info about the GTurbo thrust bearing, thanks. I will keep my boost to below 15 psi. I would love a GTurbo in order to get the boost coming in earlier, but for now I will save up for a new HD clutch first so that I can at least make use of the extra boost on the std turbo. I think I will need a new flywheel too as I know mine has been machined quite a bit previously.

I can imagine Graeme's Lexus goes well with that torque, I would imagine that vehicles like the V8 TD Range Rover with similar torque and an 8 speed auto would go well too but the thing is that now with a GTurbo and intercooler on an old cruiser, anyone can have that performance too for a lot less money!

EXACTLY!!! :-)

Oh, you want cheap?

Go to Ebay and type "turbocharger 12h-t" into the search. You will find plenty of options around $300 for a brand new turbo, delivered to your door.

Alternatively, try Gumtree for a second hand one. You might find someone who is removing their standard one to fit up a GTurbo and want to really start enjoying their vehicle. You're likely to find people will sell you a second hand one for a price you might find attractive.

Tim