After 2 decades as an auto mechanic with my own business for 10 of them, (including a decade of prototype work on natural gas and propane alternate fuel installations) I think I have some background into internal combustion. Same went for the next career, that as a heli-fixed wing pilot/AME with experience in I/C and turbine.
From that, I can estimate that glow and gas engines would require different specs in critical areas. First, their combustion qualities would be significantly different, with combustion temps, pressures and timing requirements unique to each. I would feel confident converting a nitro glow to nitro ignition, but not straight gas ignition without replacing the connecting rod lower end to primarily a roller or at least phosphor bronze. Both Saito 91's have the con rod alloy used as a bearing surface to the crank pin and do NOT seem to tolerate adverse conditions. Doubt they would survive the swap.
When running gas, the spark can be externally controlled and mixture leaned accordingly. Unfortunately this usually results in increased combustion temps, (and also NOx, but doubt we will require catalytic convertors at this point). This would seem to be confirmed if the fact the FG series has improved cooling is correct.
Not sure where the term gasoline is "Oilier" than methanol came from. If that were true, you should be able to run a rich mixture without the risk of washing lubricant away from the cylinder wall/ring interface. As with full size aircraft engines, the break in recommendations from Lycoming and Continental specify straight non-AD, (Ashless Dispersant) mineral oil until consumption stabilizes, (meaning the rings have seated) then allow synthetic or semi to be used. Even though not scientifically valid,this has been the standard practice for years. Basically any non-synthetic oil should be fine to allow the rings to seat. The key is to avoid any synthetic component oils until that break in period is complete.
That does not appear to be the case with our methanol/nitro procedures, unless full-synthetic would require longer break in times. As I never ran full synthetic cannot say. Anyone else have some insight?
As for reliability, I repeat that any engine manufacturer that survives and thrives only making 4-strokes speaks for itself. However, I would choose Saito over any other engine I've tried so far. Having said that, there are others with extremely good ratings as well. Not going to start arguments over specifics, but I have had a few makes across my rebuild bench and they would not be worth even a give-away price to me.
Last edited by Cougar429; 08-23-2014 at 10:00 AM.