I am planning to build my internals, and my tuner from Manila, Philippines just emailed me and told me to get:

Pistons: JE 81.00mm (no more 81.50) remember flat head; only with the valve's pokets


I want to ask the boost gurus out there............and for opinions:
1.) What is the advantage or disadvantage of getting 81mm instead of 81.5mm?
2.) what is the meaning of having a "valve's pocket" in a piston? advantages/disadvantages in a piston of a boosted car?
3.) in regards to strengthen the cylinder........is putting ductile sleeves the solution or is something else?

thanks!

 

The 81 and 81.5 mm measurements are bore size of the piston/cylinder wall. The larger the size, the more displacement you get... I think 81.5 is close to a 1.9 total displacement on a 1.8L motor.

The pockets you refer to are prolly the valve reliefs, menat to give extra space for clearance on the top of the piston. They look like someone took a large coin and pushed in the 4 corners on the piston.

Higher compression pistons are typcially domed and have deeper valve reliefs, but for lower compression turbo pistons you want to go with a flat or dished piston (which also have shallow valve reliefs). A dished piston, like Je's dished turbo piston is designed to promote proper mixture and aid in flame peopagation under boost.

X2

 

Flat top pistons which is around 10:1 compression.

 

so.....81.00mm remember flat head; only with the valve's pokets (recommended by my tuner) ............is the best piston to boost my turbocharged b16?

what is his logic for having valve pockets on a flat headed piston for increasing the boost?

also, to build a bottom end................do I need to get a new set of cylinder? or getting "sleeves" will make my bottom end stronger? are these (cylinder and sleeves) not related?