I figure the beginner forum is a good place to ask the stupid questions. I don't want to get flamed in the specialty forums.

Is there any benefit to running fuel chilled, say below 32 degrees? If you can prevent condensation around the tank, wouldn't the cooler fuel burn better and reduce crank temps (avoiding premature wear).

Does it matter with higher % nitro fuels?

Here's another one: Does the nitromethane component evaporate?

answer to first question is yes. answer to second question all engines run fine on 10 to 15 percent. if you go any higher in nitro content your wasting your money. answer to third question is yes.

Reduce wear by keeping the fuel cool - perhaps - but it's a moot point, I have been using a sleeved TT42 GP for 12 years and it is running great!

The lifespan of an engine can easilly exceesd 10 years IF you use a good fuel (with caster oil) and keep the RPMs within tolerances. (tune for peak and then back off 500 RPM)

As to the amount of Nitro in the fuel - check the manufacturer's recommendations... they make them to run on X% nitro for their market... If you get a European engine it could require 0% nitro.

From my experiance 5% works just fine, 10% is also OK - passed that you are just burning up your money.

IMHO

Actually that is a very good question. You know , we had this nasty 2300 thread and a guy in there tested one engine rpms with different plugs. Why don't you test an engine with cool and room temp fuels and see whatkind of rpms you get. May be useful knowledge. Generall, you get better performance incool conditions. I flew in Alaska for 3 years. In the winter time, the performance planning would (in theory) allow the helicopter to carry a couple thousand more lbs than its gross weight!

You generally get better power from cool AIR. Its denser, so each engine stroke has more O2 to react with. The fuel, however is different. I think, ( im not certain), but I think the fuel will react better if it is warmer. Generally speaking, heat is a catalyst in most chemical reactions.
Nitro methane is a long carbon chain molecule with an oxygen on the end of it. The purpose of the nitro meth is to use that loosely attached O2 . Its the same principal as nitrous oxide. Essentially, you are simpley adding more O2. Thats the best I can remember of chemistry that I had 25 years ago. I'm no expert.

These questions are not stupid.
Cooler fuel will not add anything to the performance of a glow engine.
Thermal energy that a ounce of glow fuel can hold is very low.
What benefit it will have is that if you cool your jug and keep it cool will prevent evaporation of the volatiles in the fuel.
Just as stated above, nitro add oxygen to the combustion process. It also increases consumption because more fuel is needed to offset the nitro added. Nitro tends to give better idle at lower percentages. For normal sport flying it is not needed.

My recommendation is that if you have an airbleed carb, find a nitro percentage that works for you then stick with it. If you have a engine that you can adjust the idle mixture, then just use what is available and adjust the engine for it.

Keep your fuel cool and out of the sun light and you should be fine.

What matters is the fuel to air ratio coming into the engine. So colder or warmer fuel doesn't matter, but may need needle adjustment. On the other hand, I fly diesels some, and I think diesel fuel expands and contracts a lot more with temperature changes than glow fuel does. I have had to put diesel fuel on ice on a really hot day to be able to get enough fuel in the tank to get the length run I wanted.

I am going to have to agree with pilotfighter on this one
As a performance car nut I have found that cooling the air makes the difference. Now I would not sujest ice packs for your 2 stroke but a velocity stack that increases your intake air speed will cool your air. Just yesturday I was running in my Saito 4 Stroke and was thinking about this very topic. If your not familiar with the Saito its carb is located in the back of the engine and has a 1 1/2 inch or so long chrome intake runner. After a short while of running I noticed condensation on the intake runner. It was about 95 Deg and very humid. Well couriosity won the day so I touched it. I know some one is saying don't touch a running engine but hey I set my beer down first. Anyway that intake runner was COLD. Looks like a good thing to me.

I believe the intake pipe on a four stroke gets cold because of the alcohol in the fuel. It evaporates some on it's way up, and evaporation is a cooling process. Not sure because I really haven't studied it (although I have observed it a lot). However, speeding up airflow will not cool the air. It produces more friction between the molecules, which would actually act to warm the air up further. Velocity stacks are useful for a couple of reasons. First, they allow less of the fuel to be wasted by being blown out of the carb. You can attach an air filter to one, and even further increase this advantage. Secondly, they help keep the prop blast from sucking fuel out of the carb through venturri effect. They can also help promote more positive airflow into the carb..........

Off the top of my head I'd have to say that warmer fuel would actually produce more power because one of the things that methanol does when it passes through the carb is to begin to evaporate. Methanol has the fortunate ability to take a lot of heat out of the air as it evaporates (it's latent heat of evaporation is extremely high compared to other fuels). This cooled air takes up less volume allowing even more air to get into the crankcase so you end up with a greater mass of air. On top of all this, our engines rely quite a bit of the cooling affect of the evaporating methanol to the point where, if you run the engine rich enough, there's no need for any external cooling from the propellor.

Nitro doesn't cool anywhere near as well from evaporation as methanol does but because you can feed comparatively huge amounts (by volume) of nitro in this makes up for it.

As for the crankshaft, they always run cold because of the fuel and airflow inside them so they're self cooling. With a plain bearing engine you should be able to touch the crankcase under the bearing area and it'll feel quite cool even at max revs. If it feels warm or hot then it's too tight and is generating heat from friction so it needs more running in.

Interesting... I think you are part right here. Alcohol and other similar chemicals are cool to the touch and have a cooling effect on what they touch. Anything with a reletively low flash point shares this property. I would bet you are right and this is what is causing my condensation and super cool intake runner. But if faster moving air is warmer then why would anyone use a fan?

People use fans because moving air will evaporate sweat off of our skins more efficiently than still air. Once again, evaporation is an endothermic process--leaving it's surroundings cooler. This is why we sweat--to keep our bodies cool. However, sweating when the humidity is much over 90 to 95 % is relatively ineffective because the ATM is unable to absorb much of the sweat off of your body, so it never evaporates, and therefore never cools you down. This is why we have developed heat indexes--the temperature that it feels like to the body--regardless of the actual kinetic energy in the air. With higher RH, less sweat is evaporated, and the body continues to heat up--dangerous situation. 110 degrees in 50% or less humidity is much safer than 98 degrees in 90% humidity, from a health standpoint because the body is simply unable to cool itself.
Sorry for the rambling....

Have you ever put a fan behind something hot--like a fire? It will simply blow hot air. This is how central heaters in homes operate. If moving air caused it to cool off, then central heaters wouldn't work.
Now, having said all of that, the velocity reached in the venturri's of our little engines makes for a negligible amount of heat increase. And, whatever increase there is is WAY offset by the cooling effect of the alcohol evaporating on it's way up the pipe. The cold air in the pipe (because of the evaporation) is what cools the pipe to below the dew point of the surrounding air. The higher the humidity outside, the more condensation you'll see on the pipe. Good observations, though. I really like the point about setting your beer down first--safety first, always!

Methanol has a specific heat of .6 BTU per pound, thus to raise the temperature of a pound of methanol from 60 degrees F to 149 degrees F (methanol's boiling point) requires 53.4 BTU of heat.

On the other hand, methanol's latent heat of vaporization is 506 BTU per lb at 60 degrees F. That means that one pound of methanol takes away 506 BTU of heat just by turning into a vapor.

It's methanol's vaporization that does the lion's share of the fuel related cooling. Chilling the fuel only makes your engine harder to start for all practical purposes.

If you want to experience for yourself what "latent heat of vaporization" is, wet a t-shirt with HOT water and put it on. Now stand in front of a powerful fan and feel how cold that shirt gets as the wind starts evaporating that water.

Thanks for the explaination... that does make sense as a fan is more efective if you are wet be it sweat or just out of the shower. So to cool the air in my little engine what can we do? Can you get Liquid oxygen in the small CO2 size cartridges? Pretty sure that would burn a hole in the piston.

Now I know why jugs of omega are not a full as they use to be, Seems like they're getting lower and lower.

I think the idea for this came from drag racing. Some racers use cool cans filled with ice on there cars to cool the fuel. Cool fuel gives you a denser air/fuel mixture. Meaning you can cram more of it into the combustion chamber giving you more power. It can make a diffrence in a 500ci engine but i don't think it would have a noticable effect on a small r/c engine.

Randy