by loucrane » Wed Dec 10, 2008 10:57 pm
Ch/ss,
Thanks again for the reminder about the disappearance of white gas. We do need to be reminded as needed...
As to glo fuels in spark engines, consider - again, I may have said this elsewhere in this site -
Methanol will burn well at a much greater range of fuel/air ratios than gasoline, or apparently, naphtha (Colemans).
Methanol produces less heat, at ideal fuel/air ratio, than gasoline (~20,000 BTU/lb for gasoline; ~11,000 for methanol). These two thoughts explain why we get so much more time per fluid ounce from gasoline- (or for diesels, kerosene-) based fuels.
Oil is what we need to keep the engines from chewing themselves apart. A 3:1 mix of gasoline (or kerosene) to oil, that runs twice as long as a 3:1 methanol to oil blend, passes half as much oil through the working parts in the same length of time.
A methanol-based fuel can run richer, yet still well. Methanol chills considerably when it is vaporized; gasoline and kerosene do not. So, we get more oil through the engine, and a bonus in cooling it, too.
We need a bigger tank to get the same time from a methanol-based fuel as from a gasoline or kerosene-based fuel. That allows a "broader" needle setting, too, as methanol fuels can run richer, successfully.
We may not get the beautiful hot oil smell from a methanol/castor fuel blend, but if it starts more reliably, holds setting better, and both cools and oils the working bits better, how hard a trade-off is that?
BTW, I've been unable to find Harley-Davidson oil above SAE 60, but racing shops should be able to locate the SAE 70 Kendall racing oil.
I would NOT recommend using heavier weight greases - they are brewed for an entirely different set of working conditions and temperatures. The main thing they must do is support extreme sliding pressures at lower rates of motion, and at much lower heat conditions.
Castor mixes well with both gasoline and methanol. Petroleum oils give us that great aroma, but they don't mix well, if at all, with methanol.
What are we shootng at? - Fragrance, accompanied by cranky, undependable starting, setting and durability, or -
-sound, frequent reliable and consistent performance?
(The bark of a spark engine is a reward in itself...)
So, I think FAI fuel of 25% oil, balance methanol, should be a great alternative to 25% petroleum oil, balance pump unleaded. The engines we can use in SAM FF and RC-assist FF events, as well as in control-line Old Time Spark events, must be from the spark era, or approved replicas of those engines. Replicas are not cheap. Originals are rare and fragile. To protect them - and our wallets - the no, or low, nitro glo fuels seem a wise choice.