Getting back to gas to glow. I've looked, (only briefly I will admit) to find any reference to compression ratio when going from gas to glow. My understanding is that increasing compression ratio without altering port timing can yield good results.

From, http://www.oneillbrothersracing.com/...ption/dome.htm

We have their product, a "dome", a bolt on insert head that's available with the following ratios.

This is a removable dome for the CY 27cc and 29cc head kit motors.

11:1 Dome- 87 octane or higher
12:1 Dome- 89 octane or higher
13:1 Dome - 92 octane or higher
14:1 Dome - 95 octane or higher
15:1 Dome - 105 octane or higher
16:1 Dome - 112 octane or higher
17:1 Dome - 116 octane or higher
18:1 Dome - 120 octane / alcohol
19:1 Dome - Alcohol



It appears that any gas to glow conversion would benefit from increased compression ratio. And octane rating affects optimum compression ratio. Wonder if this might shed light on some of the experiences related on this thread.

Comments?