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Parts, Technical

How to Convert your 1HZ to 1HDT

Toyota 1HZ is an indirect injection, which means they have a pre combustion chamber in the cylinder head. The injector injects directly into the pre combustion chamber (this is why it is common for 1HZ cylinder heads to be cracked.)

Toyota 1HDT is direct injection, which means the injector squirts directly in the bowl, if the piston is shown below and an explosion occurs in the piston bowl, preventing the cylinder head from getting hot and reduces the cylinder head from cracking.

Unfortunately 1HDT  and 1HZ heads are not interchangeable, without changing the complete fuel system, pistons and con rods. You can only use on both engines are the block and the crankshaft.

What you can do is use 1HDT conrods, as they are stronger and use the 1HZT pistons, and upgrade to a better stronger 1HZ turbo.

In the direct injection 1HDT , the combustion happens in the piston.

Noordeman 1hz 1hdt 1 1

In the indirect injection 1HZ, combustion happens in the combustion chamber in the cylinder head.

The 1HDT injectors have protruding nozzles and  1HZ injectors are flat, they are different also as pictured.


Noordeman 1HZ injectors 300x201 1

1HDT Injectors Noordeman 300x198 1

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