How Much Nitro?

[yogorilla]

I have been given a nearly complete Precedent trainer by a friend who has lost interest. The engine is a .40 size 2 stroke which is yet to be run in, what percentage nitro fuel should I get for this? Thanks.

[fhhuber506771]

You should be able to use any fuel with 5% to 25% nitro in a typical .40 engine. Unless you have a compeling reason to do otherwise, I would use the 10% nitro "sport" fuel. This will typically have 16% to 18% oil and the balance will be nitromethane. It doesn't realy matter a lot if it has castor , synthetic or a mix for the oil.

Castor oil protects better from overly lean engine runs and is needed if you have a cast iron piston liner. Most modern engines have "ABC" or "ABN" piston/cylinder systems and are OK without castor oil as long as you don't overly lean the engine.

Proper "break-in is essential.. don't overheat an engine durring the first gallon of fuel (especially with a chrome or nickle plated cylinder) as you can severely damage the engine. (ABC or ABN you can cause the plating to peel)

[abenn]

Most newbies at our site come with 5% nitro with castor oil, as supplied by our l.h.s. We find with most engines that they run more smoothly and consistently with 10% nitro, so that's what we recommend after they've used up their first gallon.

Personally I stick with synthetic oil because it makes less mess and is compatible with my 4-strokes as well as my 2-strokes (castor can gum-up the valves on a 4-stroke) but, as fhhuber506771 says, some engines require castor.

[DaveSawers]

I would use the 10% nitro "sport" fuel. This will typically have 16% to 18% oil and the balance will be nitromethane.

"Nitro is nitromethane". The rest of the fuel is methanol.

Nitromethane is the expensive part of glow fuel. The cost goes up in direct proportion to the amount of nitro. 5% is plenty for most engines of .40 size. 10% works fine too. More than that is just a waste of money. Just like putting high octane gasoline in a truck.

[fhhuber506771]

:p oops.. I got typng faster than i was thinkihg... :P I meant Alcohol for the ballance ...

(I do that sometimes)

[Munkey]

Use 10% or 5% nitro anymore is a waste of money and wears your engine like acid. I used to use no nitro at all at one point, 25 austrailian for 5 litres (bout 1 and a quarter gallons) that fuel they used standard for the nationals. Castor is bad news though it will run like a dream until u find carbonisation and gumming in ur engine. Took me all day to clean out the engine (.46la) use synthetic fuel. Runs a bit hotter but if ur tuning is right (ask someone for help) it will run practically the same. And remember if the fuel is cheap it is cheap for a reason. Good Luck

[clipclop]

My recomendation for a beginner would be 10% nitro fuel with castor as the oil .
Why?
Well 10% nitro will make the motor easier to tune.
Castor , as 1 lean run is the difference between a good motor and a paperweight.
Use castor till you become familiar with tuneing your motor , generally if the motor is gumming up from lacures created from the castor your motor is running hot. From either overloaded when not properly run in or being run lean or over coweled (in the case of an enclosed instalation).
Stewart
For an explanation of oils read this http://staff.dstc.edu.au/chernich/ron/faq/index.html#qa5

[robert harik]

What clipclop said, One good lean run with synthetic oil and its all over.
The castor gives you a little room for mistakes until you now your engine.
It does save money to run 0% nitro, on fuel cost, engine wear and plugs, but can make the engine much harder to start especialy in cold weather.

[blizzardwarrior]

most engines have a recomended fuel to use with them, howeveri find that powermaster (15% nitro and 18% castor oil) works very well in all of my engines, and is only 15 bucks for a good amount of it.

[blizzardwarrior]

Use 10% or 5% nitro anymore is a waste of money and wears your engine like acid. I used to use no nitro at all at one point, 25 austrailian for 5 litres (bout 1 and a quarter gallons) that fuel they used standard for the nationals. Castor is bad news though it will run like a dream until u find carbonisation and gumming in ur engine. Took me all day to clean out the engine (.46la) use synthetic fuel. Runs a bit hotter but if ur tuning is right (ask someone for help) it will run practically the same. And remember if the fuel is cheap it is cheap for a reason. Good Luck

MOST engines recomend not to use 100% synthetic oil, it dramtically reduce performance and it isnt good for the engine. If you use the correct amount of castor oil in the first place it will work fine.

[Munkey]

I Used pure synthetic with my first plane although i got help on how to properly tune my engines and also if an engine is runnning dangerously lean, you can hear it and it lacks power so you just land it after the first circuit then it doesnt get hot enough or run long enough to do too much damage. Also there isnt much of a lack of power if you buy good quality fuel (i got very close to prop hanging a aeroflyte hustler with standard gear and a 46 la).
0% is a bit harder to start but i thought it was ok because i had an electric starter. Also if you do lean an engine and cease it its not too bad with the popular engines because you can buy a new piston and liner pretty cheap from most hobby stores.

[fhhuber506771]

some engines you can run pure synthetic oil and be fine.

Some engines (especially older cast iron sleeve types) NEED at least 50% of the oil to be castor.


I use mostly all synthetic NOW... but I just got a new-old -stock (NOS) Royal .25 which requires castor oil because of its piston's material. 2% castor content will be adequate to protect this one. (so I'll just add 3 oz castor to a gallon of all-synthetic fuel) and using the least castor acceptable to the engine is good for reducing the brown discoloration and guming problems you get with 100% castor lubrication.

[blizzardwarrior]

I think almost all experienced flyers would agree, 100% synthetic oil is bad for your engine. Their is not a single engine i know of that recomends using synthetic oils. Castor oil is much more effective. It will make your engines last logner, and run cooler.

[blizzardwarrior]

I think almost all experienced flyers would agree, 100% synthetic oil is bad for your engine. Their is not a single engine i know of that recomends using synthetic oils. Castor oil is much more effective. It will make your engines last longer, and run cooler.

[ivanc]

I think almost all experienced flyers would agree, 100% synthetic oil is bad for your engine. Their is not a single engine i know of that recomends using synthetic oils. Castor oil is much more effective. It will make your engines last longer, and run cooler.This is not exactly true - there're engines for which the manufacturers recommend even 100% synthetic oil. One example is OS FS70II and FS91II - according to the manual, page 11, Fuel section (http://www.osengines.com/manuals/fs-70s-ii-91s-ii-p-manual.pdf), quote: The FS-70S2, FS-91S2 and FS-91S2-P should be operated on a methanol based fuel containing not less than 18% castor-oil, or a top quality synthetic lubricant (or a mixture of both), plus a small percentage (5-15%) of nitromethane for improved flexibility and power. The carburettor is adjusted at the factory for a fuel containing 20% lubricant and 10% nitromethane.

As you can see the manufacturer recommends castor OR synthetic OR mixture of both - so 100% synthetic is OK according to the manual.

I use a mixture of both as IMO that's the best solution - you get the advantages of both oils.