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Engine basics => Engine set up tips => Topic started by: Peter in Fairfax, VA on March 30, 2022, 08:37:35 AM
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Much appreciate a recent discussion of head/piston clearances as it relates to performance and fuel.
For my Brodak 40, which I and others note could use another 500 RPM, I'm considering running 25 or 30% nitro. We'll see how that works out.
For my LA and SF 46 engines, 5% nitro is fine, though I ran too much oil one season, resulting in so much varnish the engine squeaked. While the crock pot / antifreeze method recovered it, I will run 15% synth / 5% castor 2022.
Peter
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30% nitro seems extreme and expensive. The later B40's came with a larger intake bore and muffler exit. The first B40's came with a higher compression head. Maybe combine the two for a little more power.
Motorman 8)
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Much appreciate a recent discussion of head/piston clearances as it relates to performance and fuel.
For my Brodak 40, which I and others note could use another 500 RPM,
Peter
What plane and how heavy is it? The Brodak 40 is a very popular engine people use in the club I belong too. We use 10 nitro 22% oil fuel, APC prop 11.5x4. This set up will pull a 50oz Vector with ease using 59’ .015 lines doing 5.0 to 5.1 lap times, with a box stock engine. If you have one of the very first Brodak 40s, they had a liner timing issue and had less power than the newer version.
Al
Al
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It's a Vector about 43 oz on 60' lines.
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I think Al and Motorman are right. The muffler exit was very small, and I recall drilling it out. Maybe I have the one with the bad timing.
Peter