Nitro content vs. run time

How does the % nitro content affect run time? Does run time increase with increasing nitro content, or decrease?

Would just like to add a few seconds run time to those set ups that love to run out of fuel during the last maneuver.

Cheers,

More nitro = less run time for a given volume of fuel of the same oil content. If you want a longer run go to less nitro.
Nils

Warren, if you are having problems with enough run time, at the expense of a slight decrease in power, an old trick is to add a small amount of gasoline to your fuel. Gasoline will run about 4 times as long as alcohol, so adding about 5% gasoline will add about 15% to your run time. (Don't get carried away. This is not "if a little works, adding a lot more works better".)

If you do try this, I wouldn't spike a whole gallon of fuel. Mix up a couple of tankfulls and try it. If it is not compatible with your fuel or if it does strange things to your engine run, then that is all that you have wasted. (Adding 2% gasoline should add 6% to your run time. If you are getting 5 minutes now, that should add another 15 seconds.)

If you try it, let us know your results. (Disclaimer: Your results may vary...oh, you know the drill.)

Leonard Neumann

Will the gasoline attack the (glo) fuel line? I know the R/C guys have to use special fuel line for their gas engines. Maybe it's such a small amount it doesn't matter?
Nils

Another way is to add a head gasket.005 will give you about 20 seconds....OR...An Airfilter Green will add about 20 sec....Black about 15 Sec...OR add alittle White Gas to your fuel NO MORE THAN 4OZ TO A GALLON. All are proven and work.
I have a OS-46 LA that I needed more time...Added a .005 head gasket and Green airfilter.......I got an extra Min.
Fuel I was using SIG 5%n 20% castor.
Scott (not out of gas)Riese

Leonard --

Your response is the greatest one I have ever seen to prove what geeks we are! That you would have tried this, and proved it true should make you worry a little. First off, it has little practical value. Second, it proves that we are all not really modelers, but frustrated science fair entrants. I love it!

I have always thought that you could put less fuel in a too-big tank, but not more fuel in a too-little tank. Learn something new every day.

Jim Thomerson

PS Another thing you might try is running diesel fuel instead of glow fuel. It may in fact work.

Warren --

All the above makes perfect sense. It is not just models, but all internal combustion engines. Choosing a fuel for any engine is a choice between power and milage. Methanol has fewer BTUs per ounce than gasoline or auto diesel fuel. Nitro is a poor fuel (BTUs per ounce) in and of itself.

We get power by adding oxygen, one way or another (bigger valves, port timing, nitro, etc.) Methanol is a great fuel because it cools the air, concentrating the oxygen. Back in the days of flathead Ford powered midgets running on pure methanol, you could sometimes see frost on the intake manifold! That is, the latent heat of vaporization (may not be the correct technical term, but you get the point)is high with methanol.

Nitromethane and nitrobenzene are unstable fuels that release oxygen when they burn, hence the power increase, even though the BTUs per ounce are low. Since they take up volume, they decrease mileage.

Gasoline has higher BTUs per ounce, increases mileage, and decreases power.

If I got this wrong somewhere, one of the experts will correct me. But I believe it is conceptually correct.

Saw Jim T response about trying diesel fuel and had to throw this in. Years ago We had a Thor< remember those> and of course it would'nt run with gas and ignition. The solution we used was to put a glow pkug in and run it with the 50-50 mix of gas and oil. only problem was of course you couldn't take the battery off or the motor would quit. We tried the diesel thing to I know that we had to use an igniter to get it going and it did run. But as i remember it wasn't too satisfactory. Time fogs the memory might have ti try this again