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Joined May 2013
44 Posts
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Joined May 2013
44 Posts
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I personally like to run high octane non ethanol 91-93 in my RC gas engines. The main reason would be to prevent early predetonation during compression due to a hot spot in any carbon deposit that may be present on the cylinder head. The higher octane % will ignite at a higher compression level allowing the cylinder to be closer to its maximum stroke height before ignition hense, making better use of its power. Our model engines don't have sensors to retard timing when lower grade fuels are detected causing engine knock like in our automobile engines. I plan to use 91-93 fuel for break in on my UMS 7cylinder 160cc radial. I will then try some 100LL aviation fuel and record cylinder temperatures to see if they actually do run cooler with the higher octane mix. I would be glad to share my findings with anyone interested.
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Joined Nov 2012
19 Posts
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On all radials is better if you use a fuel pump.
In terms of one day runs good one day bad, one good , one bad sort of say...is not a roller coaster, if engine goes bad will be bad. The internals are the same today, tomorrow and the day after. Metal does not have a mind of it's own. Could be couple things , temperature / humidity,carb setings, the pump may not supply enough or to much fuel. The spark plugs may get oil in them during storage . point is metal is metal it either shines or breaks...LOL |
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This new radial option makes me think I should finish my GeeBee's.
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Joined May 2013
44 Posts
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Joined May 2013
44 Posts
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Today I ran my new UMS radial 7-160 I received from Adrian at CH Ignitions. I put three tanks of fuel through it so far and am impressed. I did a little fine carb tuning and got these results. Prop: Sail - wood 28x12 2blade, Fuel: 91 non ethanol, Oil: Quick Silver Full Synthetic 2cycle mixed 20:1(6.4oz) per gal. ,Idle: 1000, Full throttle 5400. Same results with RC excel fuel pump connected or without. Cylinder temps 164 deg F. Transition was crisp and darn near blew my hat off even though I was slightly out of the main prop wash �� Was able to hand start this beast once I got a couple tanks through it and had the needles adjusted better. It sounded like it would idle all afternoon, and whenever I punched the throttle it roared to life. Midrange was smooth and clean too. Love it!
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Joined May 2013
44 Posts
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Today I ran my new UMS radial 7-160 I received from Adrian at CH Ignitions. I put three tanks of fuel through it so far and am impressed. I did a little fine carb tuning and got these results. Prop: Sail - wood 28x12 2blade, Fuel: 91 non ethanol, Oil: Quick Silver Full Synthetic 2cycle mixed 20:1(6.4oz) per gal. ,Idle: 1000, Full throttle 5400. Same results with RC excel fuel pump connected or without. Cylinder temps 164 deg F. Transition was crisp and darn near blew my hat off even though I was slightly out of the main prop wash 😀 Was able to hand start this beast once I got a couple tanks through it and had the needles adjusted better. It sounded like it would idle all afternoon, and whenever I punched the throttle it roared to life. Midrange was smooth and clean too. Love it!
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Joined May 2013
44 Posts
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