Tuning your Gas Engine made easy....
08-25-2015, 05:15 AM
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Tuning your Gas Engine made easy....
I just want to say that this worked very well for me tuning my Evolution 15GX2. I give the credit to Mark Fuess who posted this on the Flying Giants website some time ago.
Before you begin your tune up, reset your needles to factory settings to start from ground zero.
It's best to set the top end first. Start your engine, let it warm up. Transition to full throttle. Adjust the HIGHEND NEEDLE to peak RPM. Then, SLOWLY throttle back until the engine begins to FOUR STROKE. At the point, adjust (lean) the LOWEND needle until the FOUR STROKING stops. Pull the throttle down more until it FOUR STROKES again and repeat this until you reach full IDLE. NOW, transition up rapidly. IF it sags or bogs, open the LOWEND needle SLIGHTLY until the sagging is gone...revisit the top end HS needle and re-peak it since you made adjustments to the low end. YOU"RE DONE!
One big MISTAKE people make (when they tune up a gasser) is to peak the engine then back off the needle to richen it up slightly just like a glow fuel engine. DO NOT DO THAT! Once your carb is properly tuned to peak it will maintain the CORRECT air to fuel balance. Richening it up only causes the engine to run wet and inefficient. IF you are not sure if you have a good tune, look inside your muffler or pull your spark plug. It'll tell you real quick. If it's black & wet its time to re-do your tune.
Before you begin your tune up, reset your needles to factory settings to start from ground zero.
It's best to set the top end first. Start your engine, let it warm up. Transition to full throttle. Adjust the HIGHEND NEEDLE to peak RPM. Then, SLOWLY throttle back until the engine begins to FOUR STROKE. At the point, adjust (lean) the LOWEND needle until the FOUR STROKING stops. Pull the throttle down more until it FOUR STROKES again and repeat this until you reach full IDLE. NOW, transition up rapidly. IF it sags or bogs, open the LOWEND needle SLIGHTLY until the sagging is gone...revisit the top end HS needle and re-peak it since you made adjustments to the low end. YOU"RE DONE!
One big MISTAKE people make (when they tune up a gasser) is to peak the engine then back off the needle to richen it up slightly just like a glow fuel engine. DO NOT DO THAT! Once your carb is properly tuned to peak it will maintain the CORRECT air to fuel balance. Richening it up only causes the engine to run wet and inefficient. IF you are not sure if you have a good tune, look inside your muffler or pull your spark plug. It'll tell you real quick. If it's black & wet its time to re-do your tune.
08-26-2015, 01:44 PM
#6
I love it when in the movies or the news they say something like "There was thousands of gallons of AVIATION gasoline involved in the mishap!"; as if the Avgas is more volatile and "hotter". In truth, it burns slower than automotive gas and is somewhat less likely to blow up. If it does blow up, it won't have any more power, and neither will your engine unless the compression ratio is reset to need higher octane fuel.
AV8TOR
08-27-2015, 10:54 AM
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That is true only if you do nothing to your engine to take advantage of the higher octane Avgas. If you increase the compression and increase the timing you will get more out of your engine. That is why AC use Avgas and not 87 octane.
10-27-2015, 06:54 PM
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I met a guy a the field the other day that tells me he has been using 110LL Avgas for years. But he did mention his timing is set at 34BTC and not 28 or 30 like most motors. He also uses red line oil and he fly's about 300 days a year.The motor he was using was a DLE111 and a DA 120., the day that I met him.
10-28-2015, 06:14 AM
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This is correct. Unless you are running high compression and the manual calls for it there is no benefit even to premium 93 octane, much less avgas. Some articles claim that the higher the octane the lower the BTU content, I believe this is not really true but the real reason is that higher octane burns slower... so your power output will suffer if you are not timed to take advantage of it.
In fact most of the light private planes that run avgas today in lycomings and continentals dont even need the 100 octane (holdover from the high perfomance blends of WWII). The main reason they keep using it is the need for the leaded formulation and the fact that its the only thing avalable at most civil airports. There are companies tha tconvert light aircraft engines to run on pump gas. the EPA has been trying to phase out 100LL for years....
The ethanol issue is way overblown. Avgas does store longer because it is better refined and has a more consistent vapor pressure and less additives. The storage life is only really a factor however if you are keeping your gas longer than a year befure using it.
Also avgas has lead which is a neurotoxin and you will be breathing that. Its up to you to decide if you are concerned over the health impacts.
Guys in the heli community have proved that hobby engines are very tolerant of a range of octanes and can even run on Coleman camper fuel (55 octane naptha) with a small loss of power.
Bottom line is you are free to run the 100LL if you want but about the only real impact it has is a hole in your wallet.
Last edited by jharkin; 10-28-2015 at 06:21 AM.
Thanks for the tuning tip.
10-28-2015, 11:51 AM
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This is correct. Unless you are running high compression and the manual calls for it there is no benefit even to premium 93 octane, much less avgas. Some articles claim that the higher the octane the lower the BTU content, I believe this is not really true but the real reason is that higher octane burns slower... so your power output will suffer if you are not timed to take advantage of it.
In fact most of the light private planes that run avgas today in lycomings and continentals dont even need the 100 octane (holdover from the high perfomance blends of WWII). The main reason they keep using it is the need for the leaded formulation and the fact that its the only thing avalable at most civil airports. There are companies tha tconvert light aircraft engines to run on pump gas. the EPA has been trying to phase out 100LL for years....
The ethanol issue is way overblown. Avgas does store longer because it is better refined and has a more consistent vapor pressure and less additives. The storage life is only really a factor however if you are keeping your gas longer than a year befure using it.
Also avgas has lead which is a neurotoxin and you will be breathing that. Its up to you to decide if you are concerned over the health impacts.
Guys in the heli community have proved that hobby engines are very tolerant of a range of octanes and can even run on Coleman camper fuel (55 octane naptha) with a small loss of power.
Bottom line is you are free to run the 100LL if you want but about the only real impact it has is a hole in your wallet.
In fact most of the light private planes that run avgas today in lycomings and continentals dont even need the 100 octane (holdover from the high perfomance blends of WWII). The main reason they keep using it is the need for the leaded formulation and the fact that its the only thing avalable at most civil airports. There are companies tha tconvert light aircraft engines to run on pump gas. the EPA has been trying to phase out 100LL for years....
The ethanol issue is way overblown. Avgas does store longer because it is better refined and has a more consistent vapor pressure and less additives. The storage life is only really a factor however if you are keeping your gas longer than a year befure using it.
Also avgas has lead which is a neurotoxin and you will be breathing that. Its up to you to decide if you are concerned over the health impacts.
Guys in the heli community have proved that hobby engines are very tolerant of a range of octanes and can even run on Coleman camper fuel (55 octane naptha) with a small loss of power.
Bottom line is you are free to run the 100LL if you want but about the only real impact it has is a hole in your wallet.
Yep, I ran coleman camper fuel for 10 years in my heli gasser with Zenoah motors with no problems. Years ago we called it white gas.
10-28-2015, 03:58 PM
#14
Want a real good gas, go to Puregas.com & read all the benefits of using it. It is a very good storage fuel also. Capt,n
http://pure-gas.org/
http://pure-gas.org/about
http://pure-gas.org/
http://pure-gas.org/about
Last edited by captinjohn; 11-01-2015 at 07:21 AM. Reason: add data
