Hi!
Well I have said lots of stuff about what I am going to do etc. Well here I am going to tell you about what I have helped a mate do, so I am still "0" on the doing something lately for myself lol (except if you count transplanting a 2006 1HDFTE into a 2000 LX470)
A long time ago now I discovered that the wall thickness on the 12HT was far greater than later model Toyota diesels. As an example, there is 16mm between cylinders on std bore 12HT whereas 1HZ/DT/FT/FTE has 11mm between the cylinders.
I had a block bored out and wall thickness checked - all good for boring to 95mm - 1mm oversize for the 1HDT.
Then I checked the combustion bowl position for the 1HDT. It was not quite right for the 12HT, however with the increase in capacity, the small amount of machining neccesary to have it correct meant that the compression ratio was still excellent and near std, if not the same (I cant recall, but it was fine).
A custom head gasket was made locally.
3B exhaust seats and valves were fitted
A nice side benefit of larger diameter piston
Now the other reason the 1HDT piston (edit, I did say 12HT in error before) was chosen was due to its design and the fact that the compression height was ~ 6mm less than the 12HT, allowing a longer stroke crank to be used.
A local company claimed that they had been welding up and offset grinding cranks for 20 years without fault for drag racing (street cars). Anyway, we did this. The engine ran ever so sweety with 114mm stroke (up from 102mm) until the crank broke on #6 big end.
So there is a small market there for someone wanting to make up some custom cranks. I would do it except I spend all my time building turbos for people at the moment - when not working full time on day job!
Anyway, no other damage to engine, so I had 2 sets of rods made in the USA out of forged 4340. The design is actually taken from aftermarket Duramax rod good for over 100hp/ea and are lighter than the factory rod funnily enough!
The engine has been built and installed with std stroke 102mm and 95mm bore (4.35L) and OMG is still not running right (injection system). The injection pump has been rebuild twice - the first company totally stuffed it, fixed it (kind of) and then another company rebuilt it again! Cost a FORTUNE just to get back to a stock pump. It is acting really weird but anyway, in 2 weeks should be all good!
Mechanically it sounds sweet as!
The engine is in a JDM 1990 HDJ81. It runs a A442F along with 1HDT A442F torque converter (NOT the A440F) by using the bell housing from a 12HT A440F. Minor mods and all good. Has extreme stage 2 valve body from wholesale autos.
Here is a photo of the rods also posted in an old thread that I have decided today needs to not have any more comments from me on.
Well I have said lots of stuff about what I am going to do etc. Well here I am going to tell you about what I have helped a mate do, so I am still "0" on the doing something lately for myself lol (except if you count transplanting a 2006 1HDFTE into a 2000 LX470)
A long time ago now I discovered that the wall thickness on the 12HT was far greater than later model Toyota diesels. As an example, there is 16mm between cylinders on std bore 12HT whereas 1HZ/DT/FT/FTE has 11mm between the cylinders.
I had a block bored out and wall thickness checked - all good for boring to 95mm - 1mm oversize for the 1HDT.
Then I checked the combustion bowl position for the 1HDT. It was not quite right for the 12HT, however with the increase in capacity, the small amount of machining neccesary to have it correct meant that the compression ratio was still excellent and near std, if not the same (I cant recall, but it was fine).
A custom head gasket was made locally.
3B exhaust seats and valves were fitted
A nice side benefit of larger diameter piston Now the other reason the 1HDT piston (edit, I did say 12HT in error before) was chosen was due to its design and the fact that the compression height was ~ 6mm less than the 12HT, allowing a longer stroke crank to be used.
A local company claimed that they had been welding up and offset grinding cranks for 20 years without fault for drag racing (street cars). Anyway, we did this. The engine ran ever so sweety with 114mm stroke (up from 102mm) until the crank broke on #6 big end.
So there is a small market there for someone wanting to make up some custom cranks. I would do it except I spend all my time building turbos for people at the moment - when not working full time on day job!
Anyway, no other damage to engine, so I had 2 sets of rods made in the USA out of forged 4340. The design is actually taken from aftermarket Duramax rod good for over 100hp/ea and are lighter than the factory rod funnily enough!
The engine has been built and installed with std stroke 102mm and 95mm bore (4.35L) and OMG is still not running right (injection system). The injection pump has been rebuild twice - the first company totally stuffed it, fixed it (kind of) and then another company rebuilt it again! Cost a FORTUNE just to get back to a stock pump. It is acting really weird but anyway, in 2 weeks should be all good!
Mechanically it sounds sweet as!
The engine is in a JDM 1990 HDJ81. It runs a A442F along with 1HDT A442F torque converter (NOT the A440F) by using the bell housing from a 12HT A440F. Minor mods and all good. Has extreme stage 2 valve body from wholesale autos.
Here is a photo of the rods also posted in an old thread that I have decided today needs to not have any more comments from me on.
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