1hdt pistons (1 Viewer)

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Hi all

Iam rebuilding my 1hdt motor it is out of 1990 hdj80.i have priced the rebuild kits and found there are 2 different kits. One for 1990-1992 and one for 1992 onwards. Done a bit of research and I think the early ones crack pistons. I know the combustion hole in the piston is larger in the newer one but can I convert to the newer pistons.
Any help would be great.
 
I dont see why you couldnt,but if you are sourcing your kit from a reputable seller,they would know for sure.
Engines Australia are fairly knowlegable on these kinds of things

I think someone removed the head on a 1HD T and found both types of pistons being used in the one engine,so they obviously fit.
 
I know the combustion hole in the piston is larger in the newer one but can I convert to the newer pistons.
Any help would be great.

If the chamber in the newer pistons is actually greater in volume, it WILL lower your compression ratio if all other dimensions are equal between pistons.... this may not be critical or cause any problems though......
 
I dont see why you couldnt,but if you are sourcing your kit from a reputable seller,they would know for sure.
Engines Australia are fairly knowlegable on these kinds of things

I think someone removed the head on a 1HD T and found both types of pistons being used in the one engine,so they obviously fit.

I have contacted engines Australia and all they can tell me is the combustion size is different. I need to be sure that by using the newer pistons I am not going blow the engine or have white or black smoke problems.
 
I have contacted engines Australia and all they can tell me is the combustion size is different. I need to be sure that by using the newer pistons I am not going blow the engine or have white or black smoke problems.

Try contacting simonliew,I think he did a bit of research into this
https://forum.ih8mud.com/member.php?u=4650

Or try contacting Matt at the Perth branch of Engines Australia,he is a bit more proactive on things like this
Their site is down at the moment so I dont have a link for the Perth branch.
 
Tried Perth no luck. Anyone with any other idea's.all I can find out is the pistons changed to bigger combustion chamber. Increased by 3mm. Injectors are the same, pump is different but that is because of the problems the early pumps had.
 
There is a rumour that Toyota modified the piston to reduce the BEB cavitation problem. It stands to reason that the newer pistons will be better. I'd be surprised if the chambers are actaully larger (maybe in diameter but with reduced depth) but if they are and cold weather starting wasn't a problem, I'd prefer the lower compression and would turn up the boost.
 
This is some info I sent simonliew that I got from engines australia. I didnt think about the depth

If your pistons have holes that are 39.1mm it will be a 7/92 or earlier
If the holes are 42.4mm,it will be a 8/92 or later.
Got that info from Engines Australia.

It could be for beb reasons or maybe it burns the fuel more evenly.
 
Just thought I would bump this thread up with my experience (or lack thereof) as this is the only thread I could find discussing the difference between the early model and later model 1hd-t pistons on any landcruiser forum.

I rebuilt my 06/1992 1hd-t earlier this year, could source liquid forged aftermarket pistons for the post 08/92 models but could only get standard aftermarkets for the earlier model. Ended up going with the later model ones and so far so good. (2500kms only so far) Power seems fine, economy is better than it was before rebuild.

So they definitely do work in the earlier models, as far as longevity goes, well who knows. I will be sure to update if I do have any issues.

Cheers
Dan
 
Yes you can run them (newer series pistons) however you should run different washers under your injectors for optimum performance (thinner I think but check). I find the engines with the newer pistons are better; less smoke, more power after tuning.

Recently I was trying to tune a 1HDT and the smoke was terrible. 25:1 wouldn't clear it, clearly there was a combustion issue. The issue was the washers. In this case the engine builder left a few cylinders with the old washers in, so some had the injector sitting up too high. Idled beautifully, sounded great to the point that I said "this sounds like a good one, you can expect a great result" and it was the opposite, really terrible. Anyway got it all fixed and now it's really nice.
 
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The 2 different pistons are to match the 2 different injector models. You can use either piston solong as its matched with the correct injector/and the injector is used with the correct washer. Otherwise like Graeme has said the injection fouls.
 
Just for laughs. Can Anyone see the problem here?

2 of them where like this from an engine that was rebuild 6 months earlier. Amungst alot of other issues.

IMG_4920.JPG
 
Yes you can run them (newer series pistons) however you should run different washers under your injectors for optimum performance (thinner I think but check). I find the engines with the newer pistons are better; less smoke, more power after tuning.

Recently I was trying to tune a 1HDT and the smoke was terrible. 25:1 wouldn't clear it, clearly there was a combustion issue. The issue was the washers. In this case the engine builder left a few cylinders with the old washers in, so some had the injector sitting up too high. Idled beautifully, sounded great to the point that I said "this sounds like a good one, you can expect a great result" and it was the opposite, really terrible. Anyway got it all fixed and now it's really nice.

That is good news Graeme, you will be seeing this one soon too! (I'm Dan that used to live down the road in Padbury btw).

I was actually a bit worried about the smoke I am getting on take off, it isn't too bad at all but I am only running standard fueling at the moment, was worried what it will be like when I up the fuel (or should I say send it to you) I am definitely running the thicker washers for the earlier models. I actually have a full set of the thinner ones in my spares box so will swap them over on the weekend.

So just to confirm all you did was change the washers over on the older injectors ? I am hoping I don't have to change over the injectors to the later ones, these ones were only reco'd a couple of years ago.
 
Hi,i rebuilt 2 1hdt for customers about 3 years ago,they were both 92's,got the parts from engine Australia and they couldn't tell me if i can use the later pistons so i stuck with the earlier pistons.
I have a 92 hdj and my wife's truck is a 93,I'm running gturbo and 20 psi boost ,intercooler and 3" exhaust,and my wife's 93 only have aftermarket exhaust that came with the truck from Japan,and I'm surprise how much power the 93 truck have with no mods......
 
Hi, it's a quite old post but it was the only one about this issue that I found. I rebuild my 1991 1HDT with post 8/92 pistons (larger hole), and now I have to much smoke namely at low rpm. I've tested with the two types of washers (previous and post 92), and now I'm running with the later ones (thicker). I rebuild the turbo and injectors and still no luck. In this post someone referred that the injectors are different, and in fact the part-numbers are different (23600-17010, 23600-17032), nevertheless according with the catalog all the internal parts are exactly the same. Any help? Thanks
 
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