Bores: Any shape you want as long as they're round (?)

[Kenny]

Check these pictures out. This is a 14:1 piston that ran most of last season in a dirt track motor. It was a stock bore/stroke motor pumping out 70 or so horses. The head was torqued to 35 ft-lbs with stock bolts. The area highlighted in red has been making contact across the full width of the ring, the blue area is where it made partial contact, and the yellow highlighted area never made contact with the cylinder wall. Since the top and oil rings are chromed it they would not wear in as well as the second ring, so they were making even less contact. The only saving grace was the sheer ring tension against the cylinder walls. 

[RaptorRandy]

Bring on the torque plates 

[Kenny]

Is that crazy as hell or what? I am on a mission now..... My goal is to be able to take this motor at 70 HP and gain 3 HP with the same bore size and compression with a combination of a super round bore, low tension rings and a trick final finish on the bore.

I have feelers out all over the place looking for the lowest friction/ highest tensile strength sleeve material I can find. I even have some guys working with me on some new "harder than diamond" bore coatings. These guys are wild as hell with their ideas

[Krandall]

Amen on the torque plates.

But a machine shouldn't really bore "out of round" should it? If anything I'd assume it'd just be off angle or something.. (coming from a nooby)


But suprised there isn't a torque plate out there already for the rappy at the same time.

[RaptorRandy]

The cylinders distort when being bored and honed from the heat and when installed and torqued to spec.
You want to simulate a running condition, that's why the use of TQ plates is key to good ring seal, performance and longevity