1HD-t vs 12H-T vs TD42TDi for WVO

**Nuddy** · 3rd January 2010, 09:24 AM

Originally Posted by Tim-HJ61

Nuddy,
Before I start, Brian has pulled his 1HD-t apart several times and is very knowledgeable about the internals of the engine. He doesn't make that so clear in his posting, not one to blow his own trumpet.
I'm familiar with Brian's 1HDT and his 12H-T project. I also have been running my 12H-t for 70K on vege without apparent problems.
As background:
These engines are both direct injection factory turbo. The 12H-t started in about 1985 in the Landcruiser 60 series and ceased in 1989 when the 60 series finished.
It is a build up of the 2H engine with similar or same bottom end and different top end. One addition over the 2H bottom end are oil squirters that fire coolish oil onto the bottom of the pistons. They are highly regarded as being powerful, simple and reliable with 500k being the norm. They do however suffer from piston ring groove wear that becomes excessive at 300k and making new pistons with steel ring groove inserts a beneficial upgrade at that time. They keep going for an extra 200k even with the wear, so maybe it's not so much of a problem but it sure looks bad when the ring groove is twice as wide as the ring itself!!
The 1HDT is a build up of, I'm not so clear about this, a 1HZ motor. The 1HZ is the stock diesel for Toyota and has been installed in them for 20 years. Not sure what the 1HZ standard output is.
The 12H-t has an inline injection pump incorporating a separate lift pump that supplies pressurised fuel to the IP.
The injectors are single stage.
It starts when you turn it over and stops via a choking butterfly on the intake. There are no electronics. Simple and effective.
Standard output is 100kw
The 1HD-T produces more in standard form - 120Kw I think.
It has a VE injection pump with integral lift pump and highly complex internals.
It has dual stage injectors that are more complex and expensive to repair/replace/clean.
It has stronger conrods than the 12H-t and revs higher.
It is more modern and appeared in the 80 series Landcruiser in the 1990's.
Being DI, both are eminently suitable for getting more power by increasing fuel and boost, bigger turbo's, intercoolers and the normal go faster adjustments available on diesel engines.
IMHO, purging effectively at the injectors is the most critical thing with a DI. My inline pump is much stronger in standard form than the VE pump and with less internal complexity and can be purged more easily. I need to be less concerned with purging the IP than Brian with his VE pump, but we both need to be concerned with purging our injectors correctly.
You may recall my rather complex setup on my 12H-t which has proved very reliable and suitable for this engine and in part is what Brian is chasing. I utilise the existence of the separate lift pump of the 12H-t, not possible on VE pumps. On purge, I feed the IP with a separate electric fuel pump at high flow and high pressure that purges the IP in 3 seconds (determined by colour of fuel exiting IP). I routinely shut down after a 1 minute purge, which I know ensures the injectors are also clear as I get black smoke on a blip of the accelerator and the diesel rattle comes back.
Easy purging is also critical for Brian as his vehicle is the family hack and gets used for suburban travel. Having an effective one minute purge is much more suited to this use.
Being a more basic IP, there are more adjustments that can be made more easily to increase power. Brian is chasing more power in his 12H-T and will install various go faster bits to bring the 12H-t performance close to his 1HD-T. And besides all of this, he just wants one!
I hope that clarifies.
Tim

Excellent summary thanks Tim.
I remember the outcry from LandCruiser enthusiasts when Toyota changed from the 2H to the 1Hz. Alloy head, overhead camshaft, belt drive camshaft, rotary IP with integral lift pump, compared to the iron head, pushrod OHV, gear drive camshaft (or is it chain - either way very reliable compared to a belt), in line IP, separate lift pump of the highly reliable 2H. The 1Hz has proven quite reliable over the years since but it still can't compare to the mighty 2H except on power output.

The 12H-T being based on the 2H has a good start over the 1Hz based 1HD-t and then has the added advantages listed by Tim, only downside being the less strong conrods. I see higher revving as being a disadvantage. So Brian's planned conversion makes a lot of sense to me.

My Nissan TD42TDi is an old school engine like the 2H, having iron head, pushrod, gear drive camshaft and does not like high revs (unlike my RD28T). It misses out on the inline IP and separate lift pump but has the further advantage (for WVO) over the 12H-T of being IDI.
I don't know the factory output of the nissan in kw but we did run mine on the dyno and got 80 hp at the rear wheels. Then we fitted a 3" mandrel bent exhaust (with muffler) and a boost controller, upped the max boost from 9 to 12 psi and increased the fuel setting to match and back on the same dyno got 130 hp at the rear wheels.

Conclusion:
For a Toyota - get a 12H-T.
For a Nissan- get a TD42TDi.
Having said that, my RD28T is running very nicely so far on WVO. 260,000 km at conversion and now up to 315,000 km.

**Tim-HJ61** · 5th January 2010, 09:58 PM

There is a little group of us in Perth developing more power with our 12h-t and these build ups are being covered on other forums as they are not really related to vege oil.

I agree with Nuddy's assessment of the Nissan motor, and for vege use it is probably a better proposition than the 12H-t in some ways given the IDI head. They also come with intercoolers which is a real bonus.

However I have proven that with good management the 12H-t direct injection is a fine base for vege, and being DI, the extra power that can be unleashed over the Indirect Injection engines make the 12H-t a lot of fun to play with. Running on vege means I can use that power quite happily and not be at all concerned about the cost of the extra fuel I might use.

Tim

**Nuddy** · 7th January 2010, 12:24 PM

Originally Posted by Tim-HJ61

However I have proven that with good management the 12H-t direct injection is a fine base for vege, and being DI, the extra power that can be unleashed over the Indirect Injection engines make the 12H-t a lot of fun to play with.
Tim

Certainly Tim has proven the suitability of the 12H-t with good management.
I would love to see some evidence, or at least a reasoned logical argument on how or why extra power can be unleashed from a direct injection engine compared with a indirect injection engine, with all other factors being equal.
According to the Patrol4x4 forum it seems that Andy from Deisel Tec in Melbourne has been able to extract remarkable specific power figures from the IDI TD42 engine.
I have been under the impression that the only advantage of DI was the lower cost of manufacture. Sure modern engines are usually DI (because they are cheaper to make that way) and they usually are more powerful and economical (due to other technological advances) than the older designs which are IDI but I don't think it is the DI that is responsible for the improvement but rather other factors involved in the engine design that make the difference.
I am more than happy to be educated on the subject and to have my opinion that the DI = more power thing is all marketing hype.

**Tim-HJ61** · 12th January 2010, 05:28 PM

Nuddy, Your posting got me thinking about the general variables we face when doing a conversion.

I put a set of criteria together that has been added to the Sticky at the top of the forum on 'Vehicle's converted'. It may need improvement but I thought was a helpful starting point - what do you think?

Are their other broad parameters that would be useful in these comparison exercises?

Tim

**Nuddy** · 17th January 2010, 02:42 PM

Well done Tim. I think you have pretty much nailed it.
Could just add the Nissan SD22 and SD33 to category 1.
Some say the SD33 is one of the best ever.

**RODEONICK** · 27th January 2010, 08:48 PM

hi guys my 2 cents. For veg why not a 2H with aftermaket turbo and exhaust or even just an exhaust? They are great engines ( no disagree ments im sure) The 12 ht is rarer and parts are rather ridiculous at times and the direct injection spoils the gains for veg use. And why not a 1hdt over the 12ht more power, cheaper spares smoother running and just as proven. Im not dissing the 12ht however it isn't the only choice out there or worth considering.

Now nissan
I have thought until recntly that ild get a 2005 td42 patrol with the cut and shut dual cab mod when the rodeo finally dies...... But i drove a work mates recently and was astonded as to how slow it was to pick up in power it honestly doesn't feel turboed. my old mans 1hd-t 1990 model crusier would tear it a new A-hole IMHO. so why I think that IDI has something to do with it. Nuddys power up for relatively low cost is bloody marvelous IMHO so if that is normal il'd reconsider the patrol again otherwise ill have to stick with the dao and buy another when she dies.

Ps the sd33 is the most gutless engine ive ever know known except the 3L of course ( and yes im counting the om617).

cheers guys
Nick..

**Nuddy** · 4th February 2010, 11:14 AM

Originally Posted by RODEONICK

hi guys my 2 cents. For veg why not a 2H with aftermaket turbo and exhaust or even just an exhaust? They are great engines ( no disagree ments im sure) The 12 ht is rarer and parts are rather ridiculous at times and the direct injection spoils the gains for veg use. And why not a 1hdt over the 12ht more power, cheaper spares smoother running and just as proven. Im not dissing the 12ht however it isn't the only choice out there or worth considering.

Now nissan
I have thought until recntly that ild get a 2005 td42 patrol with the cut and shut dual cab mod when the rodeo finally dies...... But i drove a work mates recently and was astonded as to how slow it was to pick up in power it honestly doesn't feel turboed. my old mans 1hd-t 1990 model crusier would tear it a new A-hole IMHO. so why I think that IDI has something to do with it. Nuddys power up for relatively low cost is bloody marvelous IMHO so if that is normal il'd reconsider the patrol again otherwise ill have to stick with the dao and buy another when she dies.

Ps the sd33 is the most gutless engine ive ever know known except the 3L of course ( and yes im counting the om617).

cheers guys
Nick..

G'day Nick,
Pity we didn't catch up on my recent 2 week holiday at Lake Tabourie.
You could've had a drive of the GU - maybe next year. yes the power up is normal, I have spoken to a few TD42TDi owners who have had the same result.
As a bio man (or are you considering coming over to the 'dark side'?) and a Toyota man why go Nissan? Landcruiser 105 series (beam axle front) - dual cabbed - should be perfect for bio use.
Then again why switch from the Rodeo? A person with your skills (witness the 300D) should be able to keep the mighty Isuzu going forever.

**BrianW** · 12th February 2010, 10:58 PM

Hi

A couple of things. I doubt that being IDI is going to be a power deficiency issue as they can really go hard. When my options for the 80 are 1HZ or 1HDT they can both produce similar power, but I have hard on good authority that the coolant flow through the head makes them marginal at best for dissipating the head when run under constant load. There is insufficient coolant flow around the exhaust as results in the head cracking. There are many reports of this with some towing speed determine by coolant temps. For short load duration there would be no issue. Basically 1HZ was off the list and with the benefits of the 12HT becoming apparent to me I made the decision.

I have seen a boosted 2H (on the internet) and that also produced amazing torque and power.

There were several changes to the Nissan TD42 and the later ones made less power and were internally weaker (so had a reduced power potential). Some people who "upgraded" wished they knew that before switching.

I think the 1HZ has a cast iron head like the 2H, but other differences accepted.

When I had my 1HDT injectors getting repaired, I mentioned the 12HT pump to the guy and he didn't think much of them. The problem was that in the last 20 years he had only re-calibrated the pumps and all were fine, they just don't need to be repaired. These pumps have engine oil lubricating them whereas the VE style pumps are lubricated by the fuel. The 1HDT injectors are double spring and due to the complexity he would not even allow his third year apprentice to set them. Cost $120 each to clean and reset with new tips so they can get expensive.

I hope the conrods are not too much weaker in the 12HT since I am planning on having more than double the torque of the standard 1HDT. The 12HT rods are longer and have more mass. After balancing, as insurance I have sent them for crack testing, cryogenic treatment and shot peening which will make them stronger than factory.

I am keen to see the engine change come to fruition and find out if it is everything I hope it to be. I can then also mark it off my To Do list.

All the best
Brian

**RODEONICK** · 13th February 2010, 07:49 PM

Sounds Wicked brian please show us some piccys this is what i live for powerfull diesels that surprise people with economy as well as torque..

**BrianW** · 13th February 2010, 09:08 PM

Hi Nick, I hope to have the engine mainly assembled in the last couple of weeks in March and then I will start on the engine conversion, which is a long list as I need a custom torque converter and engine mounts. All items are on the opposite side (A/C, alternator, exhaust, fuel system). Once these things are taken care of I still have to make adapters to mount the new turbo and set up the intercooler pipework and find out how I should route my exhaust system.

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