Glowgeek

Onward with the 82 mods! Compression ratio is now 11.75 to 1. No peak rpm increase from the previous 10.5 to 1 CR but on the other hand no losses either. There is however a very noticeable increase in throttle response from midrange rpm to peak rpm, just as there was with the previous CR increase. 1750 idle rpm is very smooth and reliable.

I think with the latest CR increase the engine may be on the cusp of over compressing using 15% nitro content where further increases may bring on unwanted effects eg detonation and an unpredictable hsn.

I recently picked up a pnuematic pencil grinder so the next mod will be a little mild porting of the intake and exhaust runners. Currently there are no short turn radii on this engine, just sharp 90° bends which should be fairly easy to relieve. I may also take time to grind reliefs into the valve stems behind the caps as well. Undercutting.

Notes:

1. Raising the compression ratio beyond 10:1 requires removal of material from the bottom of the cylinder for case clearance.

2. Raising the compression ratio to 10.5:1 requires all mods in note #1 as well as shortening the pushrod tubes.

3. Raising the compression ratio to 11.75:1 requires all the mods in note #2 & #3 and may be reaching close to max because the quench zone is reduced to .018". Raising CR beyond 11.75:1 may require remachining the combustion chamber quench zone or piston top as well as bottom tapping the cylinder mounting holes in the case.