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Building Tips and technical articles. => 1/2 A building. => Topic started by: Bill Little on June 05, 2007, 09:41:50 AM

Title: Cox Fuel for .020 Pee Wee, .049 Babe Bee, .010 TD
Post by: Bill Little on June 05, 2007, 09:41:50 AM

Hi Guys,

I have a gallon of Coopers 20% nitro fuel.  It's great fuel, but it is around 20% all synthetic oil.  I have plenty of Bakers Castor Oil from Sig.

What I need help on is I want to "mix some" of this for my Cox engines.

Please give me a good ratio for mixing a quart of this to use in these engines until I can actually get some 1/2 A fuel.  (which could be some time from now!)

TIA!

Title: Re: Cox Fuel for .020 Pee Wee, .049 Babe Bee, .010 TD
Post by: Larry Renger on June 05, 2007, 02:12:38 PM

Ideal 1/2A fuel depends on for which engine type.  For Norvel and APC you probably can run what you have with no problem.  C*x, Cub, and other steel liner/piston engines need some Castor oil to survive.

You really can't get there from here, for the steel engines, as the oil content is already high.  The best you can do is add about 5% Castor, and put up with poor "gas mileage" due to the diluted "go juice" components.  Your engines should sure run cool with that much oil carrying away heat.

I use (supposedly) 15% Nitro, 11/11% fuel in about everything but Foxes.  The question, though is "what is the actual Nitro content?"  It seems the way various manufacturers buy their supplies and combine components differ radically.  I recently bought some "quality" fuel from an independant supplier, and although it was nominally my usual mix, it was way too much nitro for the way my engines are tuned.  This guy's mix is honest.  Apparently my usual big-box store fuel is way overrated.  I suspect that my actual Nitro needs are 10% or less.

C*x and especially Cub engines love nitro!  The Cubs are really low compression, so a hot plug and high nitro make them come alive.