Thread: NA pistons and turbo piston differences?

Tim, AFAIK any NA 4BD1 engine manufactured 1988 onward had turbo (Alfin) pistons anyway.


JC

The difference I have read about is in the block where there is access to the oil gallaries for the squirters to cool the underside of the pistons.

Genuine T's have the same compression as NA.

As JC said, late model engines have Alfin (turbo) pistons. These have a steel groove where the top compression ring sits. They also have a very minor difference in the shape of the precombustion bowl in the piston crown.

Plenty of people have turbocharged engines with non-alfin pistons. The only blown piston I have seen was on an NA engine (thread on here somewhere...).

Originally Posted by isuzurover

Genuine T's have the same compression as NA.

As JC said, late model engines have Alfin (turbo) pistons. These have a steel groove where the top compression ring sits. They also have a very minor difference in the shape of the precombustion bowl in the piston crown.

Plenty of people have turbocharged engines with non-alfin pistons. The only blown piston I have seen was on an NA engine (thread on here somewhere...).

Ben made a typo in 2nd paragraph, precombustion should be combustion.

There were some interesting faxes converted to pdf format that were attachments in another recent thread here. They detail the minor changes to the combustion bowl, and the significant changes to the material thickness below the bowl. With oil cooling changes for better piston cooling, the changes were made sometime in 1988.

AFAIK turbo and NA pistons of the same model year are same. I imagine all replacement pistons would be the new design.

I ran 19 pound on my NA engine. Just do it

from memory i think there was a difference in skirt lengths in some models (98mm compared to 102mm ????)
i currently have a NA 390,000klm's 25psi for 8 months then over 30psi for 2weeks then snapped the turbine wheel off (my bad) as most others will agree the NA doesnt need to be modified to achieve great outcomes having said that when time comes for upgrade i will be trying to find a later model factory "T" motor to gain the small changes but thats only due to chasing more than daily drivable power.

also all the articles about upgrading to turbo internals otherwise you will blow the motor to bits is a lie its overated in my opinion.

oh and hey lambrover welcome back to the section haha