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  #21  
Old 09-14-2022, 11:07 PM
dbier99 dbier99 is offline
 
Join Date: Aug 2022
Location: Wisconsin
Posts: 57
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Quote:
Originally Posted by Sam Buchanan View Post
I pull mixture to where rpm is ~10 lower than full rich and that has proved over the past 23 years to be a pretty good economy setting.
Did you mean 100 RPM lower or do you actually just tweak the mixture a little bit until the RPM needle nudges down ever so slightly to represent a 10 RPM drop?

Quote:
Originally Posted by Sam Buchanan View Post
But this thread has drifted far away from the original poster's inquiry.
Sorry everyone - I didn't mean to hijack the thread - but really appreciate the input and patience with my being in the early stage of the learning curve!

Last edited by dbier99 : 09-14-2022 at 11:31 PM.
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  #22  
Old 09-14-2022, 11:28 PM
dbier99 dbier99 is offline
 
Join Date: Aug 2022
Location: Wisconsin
Posts: 57
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Quote:
Originally Posted by tgmillso View Post
Hi Dave. I'm not giving up that easily.
Thanks Tom - I appreciate your persistence. I will try your suggestion of setting MP to 22 (should I dial down RPM to 2200 or leave it at 2400?) and then experiment with leaning the mixture while watching the CHT readings.

Quote:
Originally Posted by tgmillso View Post
On the AVGAS side of things, the lead bromide biproduct of combustion is a salt and is the primary contributor to corrosion in aircraft engines. You are doing yourself a disservice running it. ...(using Mogas is) way better for your engine and way significantly cheaper. You can mix mogas with existing AVGAS, with no changes needed.
Good to hear! But I have what may be a stupid question - if my fairly common 180HP Lycoming 0-360 A1A engine can run ethanol free 93 octane Mogas, then why has the transition to a leadfree aviation alternative been such a long drawn out process? Couldn't many engines like mine just have switched to 93 octane Mogas versus waiting for some special lead-free alternative aviation fuel to be developed? What am I missing?
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  #23  
Old 09-15-2022, 12:09 AM
Robert Sailor Robert Sailor is offline
 
Join Date: Nov 2018
Location: Nanaimo BC Canada
Posts: 174
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Yup it works fine in your engine, Iím sure there is probably an STC for it however it doesnít work so fine in a higher compression engine
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  #24  
Old 09-15-2022, 12:16 AM
tgmillso tgmillso is offline
 
Join Date: Nov 2012
Location: Launceston, Tasmania, Australia
Posts: 857
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Hi Dave. The whole unleaded avgas debacle has been because they have been trying to find a one-size-fits-all solution so they only have to use one fuel type per airport. It's been the 20% of aircraft equipped with high compression engines and turbochargers that has held the show up, not the standard compression engines like yours. You could have been running 93AKI mogas for years, and some airports here in Australia have 93AKI on tap for that reason, but they also have to stock 100LL for the rest of the fleet. This has all now been solved with the G100UL, but it's sure been a long ride to get here.

Tom.
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  #25  
Old 09-15-2022, 12:17 AM
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Untainted123 Untainted123 is offline
 
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Location: Azle, TX
Posts: 194
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Quote:
Originally Posted by dbier99 View Post
Thanks Tom - I appreciate your persistence. I will try your suggestion of setting MP to 22 (should I dial down RPM to 2200 or leave it at 2400?) and then experiment with leaning the mixture while watching the CHT readings.


Good to hear! But I have what may be a stupid question - if my fairly common 180HP Lycoming 0-360 A1A engine can run ethanol free 93 octane Mogas, then why has the transition to a leadfree aviation alternative been such a long drawn out process? Couldn't many engines like mine just have switched to 93 octane Mogas versus waiting for some special lead-free alternative aviation fuel to be developed? What am I missing?
You should use the AirPower app mentioned or the Lycoming chart to figure out whatever MP/rpm combination is comfortable (vibration, noise, flicker etc) that gives the desired power setting. For example 22/2400rpm may be 65% power, or 26/1900rpm might also be 65% power, but 1900rpm may be very smooth or very vibraty. Just also note that many props have an rpm range that they recommend not running for a prolonged time at. Many Hartzells itís 2000rpm - 2250rpm, which means most people ending basically with a few rpm options, but much more flexibility with MAP settings.

MOGAS gas is a whole other discussion. Yes, your engine can easily run it, but that doesnít mean the overall plane is setup to run it, depending on fuel pump, fuel line routing, and several other things. While I share Tomís enthusiasm for getting rid of lead in the gas, for most of us, itís simply not available on any type of XC flying (so you end up burning 100ll anyway), and the hassle and cost of transporting it to the hangar for local flights dampens the benefits. In my area, the cost delta between high octane mogas and 100ll is very small, such that if you have to buy any special equipment for transporting or storing it, it basically becomes the same price as 100ll (the lead free benefits notwithstanding).

If you do want to play with mogas, and you donít have much experience with it, I suggest you approach it very cautiously, and do test flights in a controlled setting until you verify your plane will work with it. Having fuel issues is no fun.
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  #26  
Old 09-15-2022, 07:26 AM
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Sam Buchanan Sam Buchanan is offline
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Quote:
Originally Posted by dbier99 View Post
Did you mean 100 RPM lower or do you actually just tweak the mixture a little bit until the RPM needle nudges down ever so slightly to represent a 10 RPM drop?
I have a digital tach so can see a 10 rpm drop.
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  #27  
Old 09-15-2022, 07:53 AM
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Dan 57 Dan 57 is offline
 
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Quote:
Most likely you will never achieve true LOP with your carbed engine
Sam, with all due respect, this is not entirely true. My ship, sporting dual electronic ignition, and a carb, is easily leaned to where the engine noticeably looses power, well lean of peak. And still runs smoothly. Even more so since I changed to Iridium plugs...
The -8 I occasionally fly has the same engine but injected, and standard mags, but is almost impossible to set LOP.

Electronic ignition is the major factor permitting LOP operation.
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  #28  
Old 09-15-2022, 08:41 AM
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Sam Buchanan Sam Buchanan is offline
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Quote:
Originally Posted by Dan 57 View Post
Sam, with all due respect, this is not entirely true. My ship, sporting dual electronic ignition, and a carb, is easily leaned to where the engine noticeably looses power, well lean of peak. And still runs smoothly. Even more so since I changed to Iridium plugs...
The -8 I occasionally fly has the same engine but injected, and standard mags, but is almost impossible to set LOP.

Electronic ignition is the major factor permitting LOP operation.
I said "most likely" which means it may not be entirely true.

But I think as a general rule a carbed engine is not going to achieve the same degree of balanced LOP as one with calibrated injectors.

Glad to see you are pleased with the performance of your engine.
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Last edited by Sam Buchanan : 09-15-2022 at 08:50 AM.
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  #29  
Old 09-15-2022, 12:10 PM
BoydBirchler BoydBirchler is offline
 
Join Date: Jul 2020
Location: Indianapolis
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I run my o-360, which has been converted to an IO, at nearer to WOT (wide open throttle) than most here are suggesting.

When it was carbureted I ran 26 inches and just pulled the red knob until the RPM came down to 2350, on the then fixed pitch Sensenich. That gave me around 7.5 GPH with CHT's of 320F or less. Up high, where you can not get 26 inches, I ran WOT; also with good results.

When converted to fuel injection and a CS prop all this has become easier.
The engine has always had one electronic and one magneto for ignition. I am confident EI will ignite a LOP mixture much easier, smoother and further LOP the a magneto.

PS: 14.8 times the fuel flow gives the HP number when LOP.

7.5GPH x 14.8=111HP or about 62% on my 180HP engine.
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  #30  
Old 09-16-2022, 02:43 PM
dbier99 dbier99 is offline
 
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Thanks everyone - I have a lot to review and try!
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