1HZ-T Question

Submitted: Tuesday, Feb 09, 2021 at 13:26
ThreadID: 141055 Views:4461 Replies:3 FollowUps:2
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Hi all, quick question
Using genuine 1HDT pistons and turbo conrods in build, but using new genuine 1HZ head. Been advised that maybe compression might be a bit low because of pistons and head both having compression chambers, seems to make sence, any real world experience would be appreciated. On another note i just left shop and the motor has been fired up and is running, just a bit more plumbing to be done and then off for dyno to get fuel componsator and pump tuned in.
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Reply By: Chop 1961 - Tuesday, Feb 09, 2021 at 13:27

Tuesday, Feb 09, 2021 at 13:27
My bad. Forgot to mention the car is an 80 series with the 1HZ
AnswerID: 635010

Follow Up By: axle - Tuesday, Feb 09, 2021 at 13:48

Tuesday, Feb 09, 2021 at 13:48
Hi Chop.

What does the engine builder think?.......Sounds like he's been around toyota engines a bit.

Cheers Axle.

FollowupID: 912461

Reply By: Member - John - Tuesday, Feb 09, 2021 at 16:55

Tuesday, Feb 09, 2021 at 16:55
Chop, probably a tad late to ask the question if it has just been fired up..............
John and Jan

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AnswerID: 635012

Follow Up By: Chop 1961 - Tuesday, Feb 09, 2021 at 17:31

Tuesday, Feb 09, 2021 at 17:31
Fair dinkum. If it does or does not it may help the next bloke in his decisions...
FollowupID: 912468

Reply By: RMD - Tuesday, Feb 09, 2021 at 20:03

Tuesday, Feb 09, 2021 at 20:03
G'day Chop
I understand there is two sizes of inserts for the head, a 42mm and a 44mm. I presume the head fitted with the 42mm insert is for turbo. It still has a swirl chamber but it would be smaller than the flatter top piston uses for natural aspiration 1HZ. Since you mentioned quite high boost, it would seem to be to compensate for a lower than designed compression ratio. For example, a direct inj engine uses less comp ratio but that is varied by boost level / throttle using the turbo to create more air in each charge and results in higher comp than static. The figure of boost you gave seems higher than a 16:1 CRD diesel or infact higher than the 7to8 Psi of a 12ht direct inj engine. Perhaps ensure you can begin low with boost and only use what you require so no excessive cylinder pressures or temps are created. The boost compensator simply holds/slows the pump rack from opening so fuel injection amount doesn't go above what can be burnt at that moment of acceleration.
AnswerID: 635014

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