Therefore, heat-cycling (break-in) can be described as the process of heating and cooling the engine from its normal operating
temperature, at WOT (wide open throttle), to ambient temperature – time after time – until it holds a peaked setting. Break-in
(heat cycling) SHOULD NOT be considered the “wearing-in” of the internal parts as many manufacturers would like you to
believe. Our heat cycling method only relieves the internal stresses of the metal parts that occur during the manufacturing
process.
Here’s how to perform the job correctly:
1.
Decide on a fuel (nitro and oil content). Your Fantom engine is designed to run best with at least 20% nitro, but no more than
30% nitro content. If you like a more “drivable” engine, choose 20%; if you like a lot of horsepower choose 30%. As previously
mentioned, most people choose 30% nitro with .21-.27 size engines. Whichever type you choose, use the same fuel for
break-in and everyday operation – for the life of the engine. Don’t indulge
in the “fuel of the day” game – it only hastens
the day when you will need a new piston and cylinder-sleeve set. Here’s why:
Increased nitromethane content in the fuel causes combustion chamber temperatures to rise. This is normal since nitro is
the primary power-producing ingredient in the fuel’s chemistry. As the temperature increases, so does the expansion of the
piston and cylinder-sleeve. As described previously, the chrome-plated sleeve is engineered to expand more than the
aluminum alloy piston – as controlled by the cooling ability of the cylinder head fins. With higher nitro content fuels (e.g.,
30%), the piston to cylinder-sleeve running-fit (clearance) is a bit larger than with lower nitro fuel blends, because of higher
combustion chamber temperatures produced with higher nitro content. Therefore, if you start by using 30% nitro fuel at the
beginning of your engine’s life – with its tight pinch fit when cold – It will produce the best possible WOT performance
characteristics if you continue to use the same fuel for the life of the piston and sleeve. If you change fuel – reduce the nitro
content to say 20% - the engine will run good, but a bit of the pinch will wear away from the top of the piston because lower
cylinder temperatures equate to less expansion of the cylinder-sleeve. If you then decide to switch back to the higher nitro
fuel, the elevated temperature and expansion will produce greater piston clearance (due to its previous wear using 20%); the
elevated quantities of blow-by combustion gas will cause the engine to lose power.
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