aboutENGINES (DVD)

There's a lot to know about model engine operation and adding this DVD to your library means you gain the benefit of learing from an experienced pro. With an approximate run time of 3-hours, topics covered include care, handling, break in, disassembly, tips and tricks, fuel and it's composition, tuning, selecting glow plugs, gasoline versus nitro fuel engines, how to work on Walbro type pump carburetors, etc. Subsections include;

1. aboutENGINES
2. Safety
3. Fuel Make-up
4. Fuel Systems
5. Engine Break-in
6. 2-stroke Break-in
7. 2-stroke Assembly
8. 4-stroke Break-in
9. 4-stroke Assembly
10. Adjusting Valves
11. Gasoline Engines
12. Gasser Assembly
13. Multi-cylinder Engines
14. Walbro Carbs
15. Spark Plugs
16. Fine Tuning

Whether it's how to break in an engine for a model helicopter versus a model airplane, or how to adjust valves on a 4-stroke engine, we have you covered. While you won't quite become an overnight expert just by watching you will be able to handle breaking-in an engine, tuning it for proper power, or selecting a propellor. That, plus you'll be able to make repairs because you'll understand the ins and outs of disassembly. Along with the many little things it otherwise takes a lifetime of experience to gain, you'll be well on your way to being your club's go to guy when the rest are stumped.

Q. Why does some fuel contain castor oil and other is full-synthetic?

A. Fuel with a bit of castor adds protection during a lean run, e.g. engine protection if I make a mistake on the needle valve setting. However, I'm a pretty experienced modeler and this really no longer happens to me. However, experience doesn't protect me from mechanical failure when the little bit of castor oil is like an insurance policy.

Examples of mechanical failure are a pin-hole leak in the line, or a tiny leak at the fuel filter body, or when a line begins splitting where it attaches to the carburetor nipple. Any of these may allow air into the fuel line. In turn this results in a leaner fuel mixture than you set with the needle valve. And if it's lean enough that the oil cooks off instead of lubricating, it'll kill an engine.

Q. Why does castor oil protect metal better?

A. The reason is the castor oil has a higher flash point than the synthetic oil but more importantly, just as it begins burning (and any oil will burn once it gets hot enough) it forms longer chain molecules (this is the reason it stains mufflers with brown spots and splotches). The longer chain molecules make it thicker and thicker just before it flashes off. However, like the synthetic, it too will cook off. Hopefully, however, in becoming thicker it may present enough drag on internal components to slow the engine to a halt before it's damaged. Thus, the film the castor oil makes while ugly often protects an engine. Yes, it becomes a pain in the hind end to subsequently disassemble and clean the engine up but this is better than slagging an engine in my opinion.

Q. Is there a downside to castor oil other than the surface stains on the metal?

A. While the stain on metal surfaces can be tough to remove, it can be by cooking engine parts overnight in anti-freeze. Parts with a cosmetic polishing will need to be polished once again. Moreover, th castor will over time gum some components, which can be a little troublesome at the start of the next flying season after an engine has been stored for the winter. I lubricate my engines before putting them away (Marvel Mystery Oils works well to ameliorate the issue). However, if you didn't run the engine dry and lubricate before putting it away you may discover the carburetor's throttle valve won't turn in the carb-body next spring because it's gummed up by the residual castor oil.

Q. Why does fuel with full-synthetic oil exist?

A. It's because a lot of modelers don't like the staining and gumming castor oil does to metal parts. This is why manufacturer's responded by offering a full synthetic. As long as the engine never runs so lean the oil in the fuel begins flashing off (burning) there's no downside to a full-synthetic and the upside is the engine stays spotless inside and out.

Q. Why does helicopter fuel have higher oil content than model airplane fuel and will it hurt anything to run model airplane fuel in helicopter engines and vice-versa?

A. Helicopter fuel often has 23% oil content and model airplane fuel may be as high as 20% but as low as 20%. However, fine differences, e.g. 17% vs. 18% oil content doesn't mean squat in the real world. Remember, the oil in the fuel doesn't burn (or isn't supposed to). However, it will burn during a lean run when it's no longer lubricating but instead is burning up - just like the alcohol in the fuel. This is bad, very bad because then it's not doing its job of lubricating and cooling the metal. However, in and of itself, lower oil content won't hurt a thing - except - if you run the engine too lean. This is when you face a greater likelihood of ruining the engine. As for significantly lower oil content, e.g. 17% vs. 23% . . . not 17% vs. 18% which is really a rather inconsequential difference in the real world is usually a matter of the intent of the fuel. Higher oil content is usually found in fuel expressly for model helicopters because manufacturer's opt for thinner oil and increased nitro to make more power.

However, usually, the reason why some fuel has 23% versus 17%, in some cases is because it's the manufacturer's choice of oil itself. For example, a popular brand of fuel is Cool Power. They first popularized the high oil content fuel for helicopters. In their case, they were using a thinner oil and made up for the difference in lubrication qualities (versus thicker oil) by just using more of it. This, of course, resulted in a power loss so they made up for it by adding more nitro. Power loss? Yes because what burns to make power is the alcohol, not the oil. Remember, the oil is part of a total loss oil system. It just flows through the engine whilst lubricating and cooling the parts . . . but the oil really doesn't burn. Anyway, this is where using 30% nitro first became popular.

Q. What happens with adding nitro to make more power?

A. Basically, the more oil in the fuel the less power it can make because you've reduced the alcohol content. Alcohol is what actually combusts (what burns) to make the explosion within the combustion chamber to drive the piston on the power stroke. Oil is added to lubricate and cool. More oil lubricates better but you have to recover the power somehow. The 'somehow' is the added nitro, which bonds with oxygen molecules in the air and this is what allows more fuel to burn within the combustion chamber. After all, alcohol won't burn without oxygen, remember? Added nitro results in more oxygen in the liquid fuel and this added oxygen allows a richer mixture, which means more alcohol to make more power to compensate for the added oil (as a percentage) and thus, make more power. Think of the nitro as chemical supercharging, which lets you run the engine richer yet still burn the alcohol completely thus making more power.

Q. What's too little oil?

A. As a practical matter, I have run engines with as little as 12% oil content. However, while this gives you almost no margin for error, the engine will run happily enough 'and' make great power. Why? It's because there's more alcohol burning within the combustion chamber (instead of oil flowing through for cooling purposes). But there's really no margin whatsoever for a mistake in fuel mixture. Understand?

Q. I've seen fuel marked FAI in model shops and been told it has no nitro at all. Why is this?

A. FAI fuel is 80/20, or 80% alcohol and 20% oil. This came about because in the rest of the world nitro is very, very expensive. With a slight modification to the engine ( higher compression ratio) they run just fine on no-nitro fuel. However, just a little bit of nitro makes engines easier to start and handle because they idle better. This is what nitro really does for model airplane engine.

Q. What about using FAI, or low nitro fuel in model helicopters?

A. European engines are generally manufactured for no-nitro operation. American and Oriental sourced engines are designed with lower compression ratios for using nitro in the fuel. Personally, I have flown many, many model helicopter flights with 5% nitro fuel (with Japanese engines). Why? it's because I don't give a darn about 3D-flight which needs as much horsepower as you can throw at the rotor blades. Basically, this means I never need the ultimate in horsepower making ability from my engine because my flying style is principally big air maneuvers (with lots of slow hovering maneuvers thrown in to replicate scale like flight). This flying style simply doesn't need as much horsepower as the power sapping maneuvers like a rainbow or tick-tock that constitute what's called 3D.

Added to which, I'm an old hot rodder and thus, when I feel the need for more horsepower I prefer to install a bigger engine. In normal operation I don't pay any penalty because I can throttle back but when there's a need for more power, there's really no substitute for cubic inches. This is why I simply opt for a much bigger engine in many of my models for when I want more horsepower. Basically, a big engine loafing is - in my opinion - better than a small one screaming its guts out to make horsepower.

Q. You seem to prefer fuel with castor oil included, why is this?

A. Yes, I do prefer my fuel with a little bit of castor oil in it. This, in part for the insurance value despite my being very experienced. Basically, I accept it will stain my engine and muffler and gum up the insides and the carburetor over time. Why? Simply because I especially LOVE how it smells when I catch a whiff of exhaust. For me it's an essential part of the modeling experience.