Nitro? We Don’t Need Nitro! (Part 2)
This is to follow up on the(again)situation of Sig Manufacturing not being able to get nitro to mix fuel. I have now flown in, and ‘trophied’, in two contests using zero nitro fuel that I mixed with methanol, from the local go-cart/motorcycle speed shop, and Klotz synthetic oil from Sig. (18% oil content).
My Stalker engines actually run better on ‘no-nitro’, as the break into 2 cycle is not as abrupt. On my .40’s, I removed .016 thousandths of head shims and have the same power as on 5% nitro fuel. On my Stalker .66 I have not changed anything, and I finished 5th in Expert PAMPA at Brodak’s. (26 entries). At the NATS, if hotter, I may remove a shim or two.
You can compensate for lower, or zero, nitro in several ways:
(1) Increase compression as indicated above. Removing .010 to .020 thousandths of head shims seems a good place to start.
(2) Run a slightly larger venturi to allow more air(oxygen) into the engine. What nitro provides is oxygen…it is ‘chemical supercharging’
(3) Run a little more prop pitch.
(4) A combination of the above.
An unexpected benefit of running no-nitro, is fuel economy. Since the only oxygen source is the atmosphere, much less volume of fuel is needed to achieve the proper combustion mixture. In real terms, that means that I am burning 3.0 ounces of fuel where I used 4.0 ounces of 5% nitro fuel. Some of you scoff and say “That is not enough fuel!” well, if the engine is making power, and is cooling adequately, exactly what would be the benefit of running more fuel through it? Anyhow, the Europeans have been running them this way for years.
At Brodak’s I also talked briefly with Kaz Minato’s friend (sorry, I did not write down his name) who runs a Super Tigre .60 on 0% nitro with no problems.
In a way, we’ve become ‘addicted’ or at least ‘dependent’ on nitro methane. There is a long, long history of it being in commercial model fuels. In stunt, where we can run virtually any size engine, nitro really is not a requirement…it’s a crutch. It is handy to change nitro levels through the day as the temperature changes, and I have done that for years. But it is not the only way to go. In my Stalkers, I just don’t see ever using any nitro anymore.
Oh, Sig can provide their ‘FAI’ fuel. It is zero nitro, 20% oil, half Castor, half Klotz synthetic. I sell it for $20.00 a gallon.
Tom Dixon
06/21/2018