Model Boat Mayhem

Dry Dock / Shipyard: Builds & Questions => Pleasure boats, Sports, Race, Power and Leisure Boats: => Topic started by: budlia on March 25, 2008, 08:52:30 PM

Title: Does i.c nitro fuel go off?
Post by: budlia on March 25, 2008, 08:52:30 PM
Just a thought! About to start a new season's boating, two of my seven boats are nitro with very frugal O.S 15 motors.I purchased 1 Gallon of 5% nitro, 20% castor oil 4 years ago! and still got over half a gall left! I give it a good old shake every time I use it, and it seems fine, but I wonder if that little dash of 5% nitro is still there?

Best regards

Bud Lane
Title: Re: Does i.c nitro fuel go off?
Post by: ids987 on March 26, 2008, 12:13:03 PM

Fuel is more likely to lose methanol than it is to lose nitro. Methanol is also hydroscopic (absorbs water / moisture - including from the air), so fuel does go off over time - to some extent. Methanol loss in itself shouldn't be too much of a problem, as you just end up with a slightly higher percentage of oil and nitro. Water absorption can be a problem. It doesn't take much of it in fuel to prevent running completely. Smaller amounts will affect performance, and may - though probably only marginally, increase the risk of corrosion of bearings etc, but should be pretty well minimised by good oiling up regimes. This is not the only source of water / moisture inside the engine, and other fuel elements - mainly nitro, are pretty corrosive, so I would have thought the additional danger from moisture in the fuel would be pretty small - if not negligible.
These are the only factors I know of, and obviously depend on how tight the seal is on the container, as well as how much fuel is left in the container (the more the better), but there may be others - like ageing or breakdown of the component parts of the fuel, so I'll toss the topic back into the air for others to chip in........