MoGas in Aztec with IO-540

NPSH for the fuel pump can be lowered by cooling the liquid being pumped.
 
Sleepingsquirrel said:
Believe it or not before STC for auto fuel there were pilots burning auto fuel. Before AVgas there was auto fuel.
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That's true, but remember that AvGas was created to be a fuel that didn't present any of the problems for aviators that auto fuel had presented. So, it is prudent that one ask the question: "What am I putting in my tank?" and "Will it do the job I need it to?"
 
Alexb2000 said:
Let's say you could run a really long hose from Racetrack and fuel up the 310 under a special waiver, would you do it?

I wouldn't. I want an aviation grade fuel, tested, water drained, filtered, whatever. It's just not worth finding out the hard way I created a problem to save a few bucks.
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Priced "race" fuel recently? Here 100ll is cheaper
 
Ted DuPuis said:
That's true, but remember that AvGas was created to be a fuel that didn't present any of the problems for aviators that auto fuel had presented. So, it is prudent that one ask the question: "What am I putting in my tank?" and "Will it do the job I need it to?"
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I burn 100LL in all my engines , all two of them. One has STC for Mogas, the other can burn Mogas. STC for the engine but not the airframe .

I'm thinking that in Haiti , do as the Haitains do , but could I gain an advantage , suction line fuel cooling with a bag of ice or dry ice? Sticking a forward facing vent to add some dynamic pressure. Blast tubes on the fuel pump (cooling) mentioned before.

If auto fuel is all that is available I'm leaving Haiti. Proverbial Zombie attack is highly likely in haiti.:wink2:
 
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:rofl:
Sleepingsquirrel said:
I burn 100LL in all my engines , all two of them. One has STC for Mogas, the other can burn Mogas. STC for the engine but not the airframe .

I'm thinking that in Haiti , do as the Haitains do , but could I gain an advantage , suction line fuel cooling with a bag of ice or dry ice? Sticking a forward facing vent to add some dynamic pressure. Blast tubes on the fuel pump (cooling) mentioned before.

If auto fuel is all that is available I'm leaving Haiti. Proverbial Zombie attack is highly likely in haiti.:wink2:
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Dont worry!!!!! I saw one of the zombie's car with a sticker that said : " Approved for 87 Octane Fuel":rofl::rofl::rofl:
 
Sleepingsquirrel said:
I have been thinking that a little pressure in the fuel tank would make this vaporlock issue less of a problem. Like drop a cube of dry ice into a tank of mogas. A little dynamic pressure from a vent facing into line of flight. Like on a Cessna or a day tank with pressure source.
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RV tanks are pressurized in flight also. They all (except the -12) have wing tanks that have vent tubes in the airstream to pressurise the tanks. This greatly helps in VP prevention.
 
Geico266 said:
RV tanks are pressurized in flight also. They all (except the -12) have wing tanks that have vent tubes in the airstream to pressurise the tanks. This greatly helps in VP prevention.
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Disagree with your thoughts on RV vent design, but it doesn't really matter since fuel tank pressure is irrelevant. The place where pressure and temperature (and vapor pressure) really matter is downstream of the fuel pump(s).
 
Geico266 said:
I have 550 hours of burning 91 octane mogas in my IO-540. No problems, and I have saved roughly $12,000. Having to burn 100ll to avoid vapor lock is a myth.

The compression is 8.5-1.
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Have you seen any differences in performance and temperatures? I would be interested, I have a Lyc IO-360.

José
 
Piloto said:
Have you seen any differences in performance and temperatures? I would be interested, I have a Lyc IO-360.

José
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None. No difference at all, just lots of money saved. If the compression is under 8.5-1 you should be good to go. Try 50/50 mix and see for yourself. Then try 100%.
 
Geico266 said:
None. No difference at all, just lots of money saved. If the compression is under 8.5-1 you should be good to go. Try 50/50 mix and see for yourself. Then try 100%.
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There's more to it than compression. Your IO-540 is a parallel valve engine, which doesn't flow much air.

An angle valve IO-360/540 (which will make 200 HP or 290/300 HP, respectively) makes more power because it flows much more air. The detonation characteristics on angle valve engines are not nearly as kind as on parallel valve engines.

I would be very careful running 91/93 MoGas on an angle valve engine. I wouldn't worry about it on a parallel valve.

So, the question for Jose is which kind of IO-360 does he have?
 
"Disagree with your thoughts on RV vent design, but it doesn't really matter since fuel tank pressure is irrelevant. The place where pressure and temperature (and vapor pressure) really matter is downstream of the fuel pump(s)."


Suction Head and the VP of the liquid determine if the fuel pump cavitates or not .
So yes pressurizing the tank does add to the NPSH helping keep fuel in a liquid state at the suction of the pump where mechanical means (centrifugal or positive displacement) increases the pressure at the discharge. :yesnod:
 
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Geico266 said:
None. No difference at all, just lots of money saved. If the compression is under 8.5-1 you should be good to go. Try 50/50 mix and see for yourself. Then try 100%.
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I have seen 30 avgas / 70 mogas on an Aztec D with IO 540 with no changes in EGT / CHT. No issues with vapor lock either.... But they are test pilots in the eyes of the FAA....:dunno:
 
Geico266 said:
None. No difference at all, just lots of money saved. If the compression is under 8.5-1 you should be good to go. Try 50/50 mix and see for yourself. Then try 100%.
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Thanks for the info. How do you get MOGAS to your plane. None of the FBOs that I regularly fly to has it (KRDU, TJBQ, KFXE, KORL, TJIG). No savings if I can not get it.:(

José
 
You gotta spend money to save money...

fuel_tank.JPG
 
The biggest issue with mogas is not detonation or vapor lock (JMHO). It is fuel contamination, ethanol, and "old fuel" sitting in the tanks. If you are going to use mogas you need to become a "fuel quality freak"! Learn how to test for ethanol, and filter the fuel going into your plane.

I always check for ethanol, never use fuel more than 30 days old, sump the tank often, and I change filter and hoses my fuel trailer once a year.

The savings is substantial if you are careful and cautious.
 
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If you are mostly flying locally with no need for refueling out of your home airport then storing MOGAS at your hangar makes sense. But if your flights are over 500nm there is no savings because most FBOs don't have it. To me that would be the biggest issue.

As far as the MOGAS quality I never heard on the news any issue about it. And there is billions of daily users of it. You hear more about contaminated food products than on MOGAS.

José
 
Piloto said:
Thanks for the info. How do you get MOGAS to your plane. None of the FBOs that I regularly fly to has it (KRDU, TJBQ, KFXE, KORL, TJIG). No savings if I can not get it.:(

José
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Jose,
What airplane are you flying? TJBQ avgas price is $ 6.90 and TJIG is $ 7.80. Probably makes sense to have somebody deliver a few galons of mogas to the airport. Mogas in PR is ethanol free...:yes:
 
Cmercado said:
I have seen 30 avgas / 70 mogas on an Aztec D with IO 540 with no changes in EGT / CHT. No issues with vapor lock either.... But they are test pilots in the eyes of the FAA....:dunno:
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As I said, I wouldn't expect issues with Aztec engines. But if you were talking about something with a 200 HP 360 or 300 HP 540 then I would be cautious and at the very least would want a good engine monitor.
 
guardrail said:
Ever worry about that handle wearing a spot through on the battery cover and arcing?
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:rofl:

I staged the handle for the photo so you could seen the fuel meter on the handle. This is how I know I have pumped 7,000 gallons through it. ;)
 
Piloto said:
As far as the MOGAS quality I never heard on the news any issue about it. And there is billions of daily users of it. You hear more about contaminated food products than on MOGAS.

José
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And so goes "link #1" in the chain of events that leads to contaminated fuel bringing down an airplane. " It can't happen to me because it has never happened before." :mad2:

I am speaking from experience, not trying to argue with you. ;)
 
Piloto said:
As far as the MOGAS quality I never heard on the news any issue about it. And there is billions of daily users of it. You hear more about contaminated food products than on MOGAS.
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There was a recent incident where gas stations pumped (IIRC) Jet fuel into a bunch of cars.

I schlep fuel from the corner gas station in 5 gallon cans.
 
Ted DuPuis said:
As I said, I wouldn't expect issues with Aztec engines. But if you were talking about something with a 200 HP 360 or 300 HP 540 then I would be cautious and at the very least would want a good engine monitor.
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A good engine monitor and numbers on each cylinder. Balance the injectors so the cylinders peak at the same time and you are good to go. There are many RV's running 200+ HP IO-360's with no issues. One guy has gone 5,000 hours on his engine, 3,400 hours before overhaul 100% 87 octane with ethanol. Several builders have been using ethanol fuels with no I'll effects at all. I'm not in that camp yet, but there are many areas of the country where ethanol is in all mogas grades of fuel.

So far I cannot find any information on the difference in the valve placement for running mogas safely, but I'm looking! :D
 
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Geico266 said:
7000 gallons @ $2 / gallon savings = $14,000

That is worth the $1,000 I spent on the fuel trailer huh? :dunno:
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I completely agree and for those concerned about contaminents/water, could you not just prefilter/separate the fuel just as you have with a spin on filter/seperator?
 
Geico266 said:
7000 gallons @ $2 / gallon savings = $14,000

That is worth the $1,000 I spent on the fuel trailer huh? :dunno:
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And if you take an Aztec in PR as an example, you are saving almost $ 4 per gallon..... At 30 gal/h is $ 120 in savings per flight hour.... Do the math....:yes:
 
Geico266 said:
A good engine monitor and numbers on each cylinder. Balance the injectors so the cylinders peak at the same time and you are good to go. There are many RV's running 200+ HP IO-360's with no issues. One guy has gone 5,000 hours on his engine, 3,400 hours before overhaul 100% 87 octane with ethanol. Several builders have been using ethanol fuels with no I'll effects at all. I'm not in that camp yet, but there are many areas of the country where ethanol is in all mogas grades of fuel.
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I won't jump on the ethanol fuels either. I was suprised to find I had issues on my boat after running car grade after just 3 seasons. Switched back to ethhanol free and haven't had issues yet. Thankfully quite a few filling stations around are starting to carry E-free, saves the marina mark-up.
 
guardrail said:
I completely agree and for those concerned about contaminents/water, could you not just prefilter/separate the fuel just as you have with a spin on filter/seperator?
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Yes, notice the dual filters on my trailer? :lol:

You just need to be very careful about fuel. You need to become a "fuel quality freak".
 
Geico266 said:
A good engine monitor and numbers on each cylinder. Balance the injectors so the cylinders peak at the same time and you are good to go. There are many RV's running 200+ HP IO-360's with no issues. One guy has gone 5,000 hours on his engine, 3,400 hours before overhaul 100% 87 octane with ethanol. Several builders have been using ethanol fuels with no I'll effects at all. I'm not in that camp yet, but there are many areas of the country where ethanol is in all mogas grades of fuel.
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That's good to hear, and not surprising provided careful operation and CHTs/induction air at reasonable temps. Balanced injectors don't have much to do with it, though.

My guess is that detonation characteristics on an angle valve engine on 87 would be about like a Navajo on 100LL. In other words, manageable, but does require proper operation. Simply telling others to go ahead and try it without an explanation and understanding of the potential side effects is at best irresponsible.

So far I cannot find any information on the difference in the valve placement for running mogas safely, but I'm looking! :D
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It's not the placement of the valves, it's the flow and associated cylinder pressures that go with it, as I already explained. Simple formula: same displacement, same RPM, more power, equals more airflow which means higher ICPs. But what do I know, I just did detonation tests on these engines for a living for years. :rolleyes:
 
Piloto said:
Thanks for the info. How do you get MOGAS to your plane. None of the FBOs that I regularly fly to has it (KRDU, TJBQ, KFXE, KORL, TJIG). No savings if I can not get it.:(

José
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http://pure-gas.org/

(and 5gal cans)

or http://flyunleaded.com/ for a list of on-airport mogas

There are a couple of airports in my area that offer ethanol free mogas. You won't find it at any big (towered) airports
 
Cmercado said:
Jose,
What airplane are you flying? TJBQ avgas price is $ 6.90 and TJIG is $ 7.80. Probably makes sense to have somebody deliver a few galons of mogas to the airport. Mogas in PR is ethanol free...:yes:
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I fly a Mooney 201 to PR and normally fill in 60 gallons. The ramps rules in PR are very strict. They would not even allow a car near an airplane to unload baggage. They are very concern about liabilities, so I doubt they would allow a MOGAS fuel truck on the ramp. Even at TJMZ the gate guard would not allow my sister in law car to come next to the plane. We have to hand carry all the luggage to the parking area.

BTW last summer I went non-stop from KFXE to TJMZ and was greeted by a US Border Patrol helicopter. They did a ramp check but were very polite. They question why someone coming from Florida would even think about landing at TJMZ were there are no facilities at all, but plenty of trees to relief yourself. Oh well

José
 
Piloto said:
I fly a Mooney 201 to PR and normally fill in 60 gallons. The ramps rules in PR are very strict. They would not even allow a car near an airplane to unload baggage. They are very concern about liabilities, so I doubt they would allow a MOGAS fuel truck on the ramp. Even at TJMZ the gate guard would not allow my sister in law car to come next to the plane. We have to hand carry all the luggage to the parking area.

BTW last summer I went non-stop from KFXE to TJMZ and was greeted by a US Border Patrol helicopter. They did a ramp check but were very polite. They question why someone coming from Florida would even think about landing at TJMZ were there are no facilities at all, but plenty of trees to relief yourself. Oh well

José
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A month ago I was rampchecked too by the CBP guys in TJMZ ....But I was flying from TJIG... Very polite too. Then I realized I was the first plane to arrive that morning so probably they have to justify their presence there...

In TJIG there are some ramps that allow you to bring gas... Just PM me and I will give you some info...
 
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