what is the purpose of the holes on the oem pistons

[Dale002]

What is the purpose of the two half dollar size holes on the oem piston?

 

[Dale002]

Re: what is the purpose of the holes on the oem pistons

Help!!!!! Anyone?

 

[rodbolt]

Re: what is the purpose of the holes on the oem pistons

it can double as a piggy bank depening on who built it, horsepower and year model.

 

[ewbish]

Re: what is the purpose of the holes on the oem pistons

Those act as ports for the fuel/air charge-hence the proper term for a 2-stroke engine: Piston Port Engine.

Changes to the size, location of those ports will dynamically change how your 2-stroke makes power.


Putting your piston in backwards will also dynamically change how your 2-stroke makes power;-)

Here is a typical 2-stroke:

 

[Dale002]

Re: what is the purpose of the holes on the oem pistons

I contacted wiseco because the replacement pistons I bought from them did not have this holes. They said that this holes are to make the piston lighter. Does this make any sense to anyone?

 

[rodbolt]

Re: what is the purpose of the holes on the oem pistons

yep, chysler,US marine and merc never made that block with boost ports.
no sense in dragging the extra weight,

while the above video is cute it shows a basic design theory, part looper part crossflow.
are we dealing with OEM or Wiesco ?

 

[ewbish]

Re: what is the purpose of the holes on the oem pistons

I contacted wiseco because the replacement pistons I bought from them did not have this holes. They said that this holes are to make the piston lighter. Does this make any sense to anyone?

Put the OEM piston in the block, run it from BDC to TDC, and mark anywhere those "holes" match a port in the block. Make sure you put it in the right way. If the holes don't line up with any openings in the block, then they are for weight reduction. Now put in the Wiseco piston, make sure it's in the right way (generally Wiseco puts an arrow on the front of the piston that usually should point to the exhaust side). Run the Wiseco from BDC to TDC, if you can see your marks from before through a cutout in the skirt or whatever, should be good to go, or if they didn't cover/uncover anything, you are OK. Also, most of Wiseco's products are forged aluminum and made much lighter than OEM pistons-may be why it has no holes.

Eric

 

[ewbish]

Re: what is the purpose of the holes on the oem pistons

yep, chysler,US marine and merc never made that block with boost ports.
no sense in dragging the extra weight,

while the above video is cute it shows a basic design theory, part looper part crossflow.
are we dealing with OEM or Wiesco ?

All it was meant to show--couldn't find a marine specific animation, or a inline animation. It effectively illustrates the basic concept of a 2-stroke. It's really irrelevant from strictly a functional aspect whether or not the intake is on the side of the cylinder or straight into the bottom, it does, however, change the performance characteristics.