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The higher octane of methanol will allow a more aggressive timing advance setting closer to the 36* ideal timing advance for a high output 4-stroke internal combustion engine. Methanol on spark ignition will allow a much higher CR @ these aggressive spark advance setting allowing even more HP increase over a gasoline engine of similar design/displacement. My 12.7:1 (estimated) compression ratio FA180HC CDI makes 17% more HP than my standard CR FA180 running glow ignition W/the same 15% Cool Power glow fuel. In fact, it makes nearly the same HP (97%) as a glow ignition FA220 & & makes 13% more HP than the CDI/gasoline vesion of the FA220 (FG36) even though the displacement is 18% less. AS far as your results/ What was the spark advance curve in the RCEXL system? Did you do various advance settings observing power gains/losses for various degrees of timing advance settings? C&H uses a ring that secures to the existing prop hub W/set screws. It can be readily advanced/retarded in small increments . I have done testing from 28* BTDC to 36* BTDC. Most engines W/CDI/methanol ran @ higher WOT RPM W/advance setting in the 34-36* BTDC range compared to the 28* BTDC initial setting.. Idle performance is not substantially affected as the built in retardation of spark @ idle speeds is still sufficient for good idle performanmce. The prop hub installed magnet of the RCEXL system lacks a locating pin like the OEM Saito system. This lack of a solid locating device frequently results in the shifting of timing on the initial start-up. This often degrades performance.The scew applied timing ring of the C&H CDI does not suffer from this problem as the prop hub driving the propeller is not removed/shifted for the initial installation. Quote:
I would say that testing W/various ignition advance setting (hard to do W/RCXEL's inferior prop hub magnet system) & gaining consistant 5%-6% gains in power, 22%-23% fuel economy, ease of hand starting & @ least 300 RPM lower reliable idle speed in EVERY CASE W/6 different Saito engines would be difinative information. Quote:
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Well saying that spark ignition is "less reliable" sounds an awful lot like saing that glow is "more reliable". |
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The Netherlands
Joined Nov 2009
1,448 Posts
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Power loss due gasoline conversion has NOTHING to do with octane number or even with burning dynamics.
It has everything to do with the respective stoichiometric ratio of both fuels, and their respective caloric values: Gasoline has a two times higher caloric value by weight (even slightly more than two times) but in the same amount of air, you can burn roughly 2.5 times more methanol (by weight). Therefore, the total chemically stored energy that is admitted at every cycle, is, as you mentioned, approximately 15% higher when using Methanol as fuel. Timing, ignition requirements or burning characteristics don't have anything to do with that standard power difference. You can take for example take a small two stroke petrol engine, and fuel it with methanol. Adjust the needles but don't touch the ignition, and you will see that power gain.... Has nothing to do with agressive timing.... Brgds, Bert |
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I was able to gain 200 RPM W/a 15 X 4 prop on my FA91 CDI/methanol conversion by advancing the timing from 28* to 36* W/no other changes. Almost all of my testing has yelded similar power gain W/more agressive ignition timing. More ignition timing advance will make more HP as will higher CR. Modern 3rd gen Chryler Hemis can run 14:1 CR on E-85 while 93 octane pump gas starts running into detonation issues @ the 11:1 range. Even with the same energy content in the fuel, compressing it into a smaller chamber before ignition will extract more power as long as the octane is high enough to prevent detonation @ a given advance value for the ignition. Lower CR, loose power. Retard the timing, loose power. The increase in power is 2 fold when ignition timing factors are considered, 3 fold when timing as well as CR factors are considered. More power from methanol due to higher volunm (by weight) of fuel being buned thus more power. 15% buy your calculations. But, my tests show 22% gains when running CDI/methanol W/an additional 8* ignition timing over the Saito FG versions of the same engines. Furthermore, using my high compression FA180HC as an example, the increase in power over an FG30 should be about 34% if the FG30 does indeed drop 15% HP over the glow FA180 as other Saito gas engines seem to suffer.. Standard FA180 2.91HP (according to my tests/calculations) less 15% = 2.53HP My FA180HC CDI = 3.38HP using the same tests/calculations as above. FA180HC 3.38/2.53 = 1.34 34% more HP. 15% more power due to the metahol fuel. 6% more HP compounding that 15% by more aggressive ignition timing. 17% more HP compounding that 15% by more aggresive ignition timing & an increase in CR from 9.56:1 to 12.67:1. It all adds up. |
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Joined Jun 2011
713 Posts
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USA, IN, Commiskey
Joined Oct 2007
130 Posts
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I sent Adrian of C&H an email telling him what I wanted to do. He sent me an email asking him to call and we could talk about it. After discussing it he said he had never made a unit for a helicopter using the engine I want to use. So I am going to send him a couple different engines, an OS 50 hyper, and a YS 50 regulated helicopter engine for him to work with and he said he would see what he can come up with. This is the first time I have had a manufacturer do anything like this for me. If this works it will cut the cost of flying helicopters by about 50%. I am so stoked.
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Joined May 2010
2 Posts
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Hi Guys,
This Is Adrian AKA CH Ignitions. I will try my best to help any and each of you I can. I have lot of work and I am ...One guy at the moment+ Wife that is a real great help. On the site all say on order as everything is build as ordered. A Helicopter engine request I did not had but will give it a shoot. I know it will but is the 85gr weight that you have to add to the heli. Any and every engine can be converted is just a matter to find the best solution . I am also going to have real soon for public custom curves. I will be able to make the curves per customer specifications. CDI systems for radial engines , 3 cyl first then 5,7,9. Thanks for testing and support Adrian |
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USA, IN, Commiskey
Joined Oct 2007
130 Posts
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Hi Adrian
I got the engines ready to send in the morning. The weight will not be an issue. The power to weight on these 3D helicopters is just crazy. You will have them in a few days. I can't believe you found this thread. that just shows you are one dedicated man. It may not work but I think I found the right person to help me find out. Adrian, thanks again.
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Going from the much higher nitro content of heli fuel to pure methanol will further decrease the fuel requirements. I think that the 85g weight penalty for CDI will be offset by a smaller fuelm load requirement. 3oz less fuel will just about make uo for rhe weight of the CDI. |
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The Netherlands
Joined Nov 2009
1,448 Posts
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Anyway, that is not how reliability assessments are made. That would be: parts present combined with their respective mean faillure rate. Personally, I think glowplugs in general show a significantly higher faillure rate than the combined chain of battery, sensor, electronics and sparkplug. Brgds, Bert |
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