Yep, it's a good point and pretty sure they are factory 1HZT pistons, which also has me pondering whether some of the coaster engines imported are actually 1HDT or 1HZT. There were factory 1HZT in Coaster buses outside Australia.
Next was time to do valve clearances, and then I figured, why not just do it properly as I had 330,000klms and at 400,000klms we would typically do a top-end rebuild. So I decided to recondition the head while I was at it. To be honest, it all looked pretty good but in reality I had pitting in the seats and the valve guides were moderately worn which is to be expected at those klms.
After testing, I found the new factory 1HZ clutch was slipping by 17psi and couldn't get it tuned till it was upgraded. Then I got to installing the new clutch and also fitted the reconditioned full-spline kitted R151 box I bought previously with the spare turbo engine. I decided on a 4Terrain Ultimate as provided enough pressure for my setup without breaking the bank. My personal opinion is that they need to be balanced once clamped to the flywheel. Speaking of flywheel, in the pics is a picture of two flywheels. The bigger one is my factory flywheel, the other is one that had been machined on the spare engine. Significantly lighter. I opted to keep my larger one on there for extra rotating mass for torque. I then machined the step another 0.2mm to offer that extra bit of crush force and extend friction plate life.
Test and tune day! Midrange fueling and 20psi of boost yielded me 193HP which I was very surprised at. Still more fuel left and upto 35psi if I wanted. But the poor R151 wouldn't cope I don't think. I adjusted the aneroid pin to offer a bit more fuel down low and at max boost which extended it to a peak of 22psi, but not sure how many more HP as it was post Dyno. So many people dissed me on the 1HZ performance and issues and their faces after they saw the Dyno sheet. I am heavy as, loades to 3220kg and this setup rockets me along nicely.
Now that I could cruise at 100kph loaded up to 3220kg I decided to add a Kings hardshell roof top tent. Such a great addition. Fuel does get impacted a bit, I think around 14-15L/100 driving economy style, but if I want to jet everywhere, that turbo and 12mm pump system can chug down 20L/100 if the heavy foot wanted to. Unloaded with not roof tent has me at 12L/100 which I am happy with.
Cheers Phil. Can't agree more, ay. I miss the sound of the 80's and 90's eras of the TD42, RD28, 12HT, 1HDT's rumbling around. Now it's like you're a crim if you have a loud vehicle. Out where I live it's still "Cruiser Country" and I am lucky to still hear the VDJ's and 1H engines (and some TD42's) rumbling around the place. But I just love it. The louder the better.
Always good to see the effort people put in to making their 4WD special, turning it into their ultimate rig. I am a Toyota fanboy, especially Cruisers, but I still appreciate other makes and how people make them into what they're after for their situations. And if my old 80 sounded and went half as good as your 105, I'd have been a very happy fella. Look forward to seeing what else you do to it. Enjoy it mate and keep up the good work