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chaztuna(at)adelphia.net
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 Posted: Mon Jul 03, 2006 5:44 pm Post subject: Fwd: MOGAS Use With FI Engines was Fuel Injected |
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| Quote: | Subject: MOGAS Use With FI Engines
There was some discussion several weeks back re use of MOGAS with fuel injected engines. I expect to be finished with the fuselage by the end of the year and am considering various engine options. I called Superior on Monday and was told that their XP360 fuel injected engines with 7.2/1 or 8.5/1 pistons will run very happily on MOGAS, 87 octane (non-ethanol) and 91 octane(non-ethanol) respectively. However, the 200 HP version (FI of course) of that engine does require 100LL avgas. The 7.2/1 version is not terribly popular and it does cost an extra $100.
I'm leaning toward the 8.5/1 version with the fuel injection.
Dan Bergeron
Chicopee, MA
RV-7A N307TB (reserved)
(Turned the canoe over on 6/25 and am moving out smartly.) |
Dan,
I was one of the listers in on that discussion. I called the EAA and spoke to a woman regarding their STCs. They only attempted to obtain STCs for low compression (7.2 to 1) engines. They made no effort to obtain auto fuel STCs for 8.5 to 1 or higher compression engines. I reported this to the list on June 13th. I called Peterson Aviation that same day, but their technical expert was out of town.
I called back and spoke to him on June 29th at length. He was quite helpful. He stated that Peterson had attempted to obtain STCs for 91 octane (minimum) auto fuel for various fuel injected engines. They had success with a number of aircraft with Continental engines/fuel injection. Every Lycoming based aircraft failed. These tests were done over 20 years ago, and they have never revisited this issue since.
He told me that the testing was done to "worst case scenario". At that time, the Reid Vapor Pressure of aircraft fuel was no higher than 6.5 (lower is better). Common auto fuel could range from 7 to 15. The highest Reid Vapor Pressure numbers were "winter blend" fuels designed to aid in vaporization of fuel in the northern US and Canada, where temperatures can drop to -20 F and below. The engine/airframe combination had to pass all the tests using "worst case" fuel (ie 14-15 Reid Vapor pressure)
Due to various "clean air" enactments, auto fuel Reid Vapor Pressures have dropped considerably in the intervening 20 years. This requirement is related to keeping the fuel in the tank of your car from evaporating out into the atmosphere. That is why you have sealed gas tank caps and a charcoal recovery cannister on cars since about 1981.
He stated that in California, any premium auto fuel without ethanol in it, is practically aviation grade, as California specifies a Reid Vapor Pressure of 7. Please note that once ethanol gets introduced into auto fuel, all bets are off. He stated that the biggest problem would be incurred by aircraft owners in States which see cold winter temperatures. During these months, they may be restricted to 100LL, as the local auto fuel's Reid Vapor Pressure may be to high to allow safe operation with a winter fuel blend.
All the hype about problems with fuel system gaskets and seals relates to parts produced over 20 years ago. Most fuel injection servos now in use have been overhauled with materials which are compatible with auto fuel. A simple way to tell is to look at the color of the diaphragms on your Bendix (now Precision Airmotive) servo. If the diaphragms are orange, you've got the late model, compatible materials. If you see black, stick with 100LL or get the servo and fuel distributor overhauled. He stated that in my home state of Florida, I could expect the Reid Vapor Pressure of local fuels to be 8.5 or below.
His opinion was that for "optimum" operation & safety of Lycoming fuel injected engines, a vapor return system should be installed. This should not be confused with the vapor system marketed by Airflow Performance. API's system consists of a manually controlled valve, which the pilot opens prior to a hot restart of his engine. Once this valve is opened, the electric boost pump in engaged. This clears out the overheated fuel sitting in the system, firewall forward. This fuel is returned to a single tank and replaced with cool fuel from that tank. API's system was only intended to aid in hot restarts.
What he suggests, is to use a pair of vapor/fuel return lines with a duplex fuel valve. See Andair's model FS20-20 here
http://www.andair.co.uk/system/index.html
This system is very similar to the system used in modern American pick up trucks with dual fuel tanks or the above mentioned Continental system. The system has a feed line running from each tank to the duplex fuel selector. Each tank also has a fuel return line running to the duplex fuel selector. A single feed line and a single return line run from the duplex selector up to the engine's fuel injection system. Each fuel tank also has a vent line, as is now normally installed. This means that a 3rd line must be run to each fuel tank.
This type of system keeps fuel constantly moving from the wing fuel tanks, through the duplex selector, up to the engine. A portion of this fuel is constantly being returned via the fuel selector, to the tank it is being drawn from. In essence, the fuel tank is being used as a fuel cooler, much the oil cooler for your engine. It is this feature which keeps the fuel cool enough to operate with auto fuels with high Reid Vapor Pressure numbers.
You can learn more about this type of system by looking at the way fuel is managed on any fuel injected Mazda or Subaru engined RV. These engines must use this type of fuel system because that is how the system was designed in the original vehicles the engines came out of.
There are a fair number of folks flying fuel injected Lycomings with auto fuel who are using stock or API modified fuel systems with success. This may be due to their geographic location, or because they use a Reid Vapor Pressure tester, available from Peterson Aviation for $65. See
http://www.webworksltd.com/autofuelstc/pa/HodgesTester.html
I asked him to give me an airframe / engine combination utilizing a Continental engine which had passed the STC tests. He suggested looking at Beech Debonairs up to 1970 or 1972 (he was unsure of the cut off year). The engines suggested were the IO-470-J and IO-470-K models. He stated that these airframe/engine combinations are a good example of the vapor return line system he recommends. There were others which passed, but I simply wanted one good example.
Charlie Kuss
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bicyclop(at)pacbell.net
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| Posted: Mon Jul 03, 2006 7:30 pm Post subject: Fwd: MOGAS Use With FI Engines was Fuel Injected |
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For your consideration:
http://www.eci2fly.com/pdf/FIS11x17.pdf
ECI has a new fuel injection system which incorporates constant fuel circulation back to the tanks as described below. It is more similar to the Continental type than to the Bendix.
Pax,
Ed Holyoke
Dan,
I was one of the listers in on that discussion. I called the EAA and spoke to a woman regarding their STCs. They only attempted to obtain STCs for low compression (7.2 to 1) engines. They made no effort to obtain auto fuel STCs for 8.5 to 1 or higher compression engines. I reported this to the list on June 13th. I called Peterson Aviation that same day, but their technical expert was out of town.
I called back and spoke to him on June 29th at length. He was quite helpful. He stated that Peterson had attempted to obtain STCs for 91 octane (minimum) auto fuel for various fuel injected engines. They had success with a number of aircraft with Continental engines/fuel injection. Every Lycoming based aircraft failed. These tests were done over 20 years ago, and they have never revisited this issue since.
He told me that the testing was done to "worst case scenario". At that time, the Reid Vapor Pressure of aircraft fuel was no higher than 6.5 (lower is better). Common auto fuel could range from 7 to 15. The highest Reid Vapor Pressure numbers were "winter blend" fuels designed to aid in vaporization of fuel in the northern US and Canada, where temperatures can drop to -20 F and below. The engine/airframe combination had to pass all the tests using "worst case" fuel (ie 14-15 Reid Vapor pressure)
Due to various "clean air" enactments, auto fuel Reid Vapor Pressures have dropped considerably in the intervening 20 years. This requirement is related to keeping the fuel in the tank of your car from evaporating out into the atmosphere. That is why you have sealed gas tank caps and a charcoal recovery cannister on cars since about 1981.
He stated that in California, any premium auto fuel without ethanol in it, is practically aviation grade, as California specifies a Reid Vapor Pressure of 7. Please note that once ethanol gets introduced into auto fuel, all bets are off. He stated that the biggest problem would be incurred by aircraft owners in States which see cold winter temperatures. During these months, they may be restricted to 100LL, as the local auto fuel's Reid Vapor Pressure may be to high to allow safe operation with a winter fuel blend.
All the hype about problems with fuel system gaskets and seals relates to parts produced over 20 years ago. Most fuel injection servos now in use have been overhauled with materials which are compatible with auto fuel. A simple way to tell is to look at the color of the diaphragms on your Bendix (now Precision Airmotive) servo. If the diaphragms are orange, you've got the late model, compatible materials. If you see black, stick with 100LL or get the servo and fuel distributor overhauled. He stated that in my home state of Florida, I could expect the Reid Vapor Pressure of local fuels to be 8.5 or below.
His opinion was that for "optimum" operation & safety of Lycoming fuel injected engines, a vapor return system should be installed. This should not be confused with the vapor system marketed by Airflow Performance. API's system consists of a manually controlled valve, which the pilot opens prior to a hot restart of his engine. Once this valve is opened, the electric boost pump in engaged. This clears out the overheated fuel sitting in the system, firewall forward. This fuel is returned to a single tank and replaced with cool fuel from that tank. API's system was only intended to aid in hot restarts.
What he suggests, is to use a pair of vapor/fuel return lines with a duplex fuel valve. See Andair's model FS20-20 here
http://www.andair.co.uk/system/index.html
This system is very similar to the system used in modern American pick up trucks with dual fuel tanks or the above mentioned Continental system. The system has a feed line running from each tank to the duplex fuel selector. Each tank also has a fuel return line running to the duplex fuel selector. A single feed line and a single return line run from the duplex selector up to the engine's fuel injection system. Each fuel tank also has a vent line, as is now normally installed. This means that a 3rd line must be run to each fuel tank.
This type of system keeps fuel constantly moving from the wing fuel tanks, through the duplex selector, up to the engine. A portion of this fuel is constantly being returned via the fuel selector, to the tank it is being drawn from. In essence, the fuel tank is being used as a fuel cooler, much the oil cooler for your engine. It is this feature which keeps the fuel cool enough to operate with auto fuels with high Reid Vapor Pressure numbers.
You can learn more about this type of system by looking at the way fuel is managed on any fuel injected Mazda or Subaru engined RV. These engines must use this type of fuel system because that is how the system was designed in the original vehicles the engines came out of.
There are a fair number of folks flying fuel injected Lycomings with auto fuel who are using stock or API modified fuel systems with success. This may be due to their geographic location, or because they use a Reid Vapor Pressure tester, available from Peterson Aviation for $65. See
http://www.webworksltd.com/autofuelstc/pa/HodgesTester.html
I asked him to give me an airframe / engine combination utilizing a Continental engine which had passed the STC tests. He suggested looking at Beech Debonairs up to 1970 or 1972 (he was unsure of the cut off year). The engines suggested were the IO-470-J and IO-470-K models. He stated that these airframe/engine combinations are a good example of the vapor return line system he recommends. There were others which passed, but I simply wanted one good example.
Charlie Kuss
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
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