Piston pin is off center

[doughnut]

The industrial engines we modify for racing have their wrist pins offset 1 mm. These 26 cc, 36 mm bore engines develop over 6 hp at 16,000 rpm and can turn 20,000 rpm. As was pointed out above, piston offset is common in IC engines.

Lohring Miller

Now you have me interested. Model car racing?
BR, Paul

 

[lohring]

I race RC boats. I have modified some 26 cc engines for RC cars. The main difference is the required power band. Boats don't loose much rpm in the corners, but cars throttle a lot. Even with a transmission this takes a broader power band. The pipe design is mostly responsible for this.

Lohring Miller

 

[popnrattle]

Hello, I haven't offset piston pins but I have read racing engine message boards that tout benefits of up to a 1/16" offset. I offset the cylinder in the miniature engines I build 1/4" above crank CL for less piston side load on power stroke. My antique Case tractor(4"x 5-1/2" bore/stroke) has very noticeable cylinder offset. Link below is a good read about offsetting cylinders. Later, RT.

https://www.fev.com/fileadmin/user_...pactonPistonAndPistonRingFrictionBehavior.pdf