anybody happen to know the specs on the pistons for the 250? skirt size, ring thickness, pin thickness? also what does anyone know what the diameter of the valves are? I'm probably just chasing my tail trying to find this information. but wanted to see if anyone knew before I go out and buy a new piston for comparison.

 

I have read that the piston material is Hypereutectic. Not the best material for adding big power as it is more brittle the a forged piston. But if you avoid pinging than it is not as much of an issue.

I was disappointed that the Lexus repair manuals don't include the engine internals data, specs etc... I am curious about these details as well. It has got to be listed in some of the documentation somewhere.

 

I don't have any info for you, but I am curious why you need to know.

 

Pins are:
Mark Diameter

A 21.997 to 22.000 mm (0.8660 to 0.8661 in.)

B 22.000 to 22.003 mm (0.8661 to 0.8663 in.)

C 22.003 to 22.006 mm (0.8663 to 0.8664 in.)


Piston size is:

82.976 to 82.986 mm (3.2668 to 3.2672 in.)

There is nothing else in the service manual to assist you in determining piston dimensions. They don't even give ring thickness, they just tell you to measure the piston grooves with a new set of rings and measure for clearance.