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Definitive Mogas Thread

C

Chris Hill

Well Known Member
If you have experience with Mogas, please post it here.

Include aircraft type, as many engine details as you feel pertinent, duration of use.

If you have used it successfully, please describe your "keys" to success such as mixing fuels etc.

If you have used it with negative results, please describe your results.

I'd like to avoid opinions in this thread and focus on actual experience people have had with operating on Mogas.
Thanks! Looking forward to your information.
 
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92 Octane

92 Octane Mogas (no ethanol)

F51 Winnsboro, Tx
FYV Fayetteville, Ark

use in Rotax 912ULS 10.5 compression

best fuel combination for this engine....difficult to find
 
Chris, we ran mogas..

...in our O-360 -6A for quite a while...50/50 mixed with avgas so we still had some lead in it and it ran really well.

When the last gas station that didn't have ethanol started getting 10%, we quit. We did test the gas for alcohol though, and it showed up....it's a very easy test and if you're not familiar with it, I can explain.

My friend also ran 50/50 in his O-320 powered -4 with good results as well.

We didn't like the hassle of 5 gallon containers in the back of our pickups and pouring it in the hangar and finally just went with avgas.

Best,
 
Not recent experience and not in an RV, but I used to run mogas in my Cessna 180 (Continental O-470-J) routinely. That was before about 1990 or so when I shared a fueling vehicle, no longer available.

More recently when it's been available at airfields, I put it in with the 100LL, which is the routine fuel. Runs fine.

What the engine (now an O-470-K) likes best, though, is the 100/130 green fuel.

Anyway, I lean carefully, even for take-off, and run just a bit richer than peak. I generally fly high enough that even at full throttle I'm running below 75% power.

Carb ice is not a factor - this engine doesn't make much ice, and I have a carb ice detector to tell me when it does.
 
100% 92 Octane mogas for all aircraft for more than 5 years.

IO-540
0-360
0-320
0-235

I do run 100ll through the Lycosourases ocassionally.

Rotax 912

Never had a problem.
 
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Used E-10 mogas for a bit over 300 hours with 2 Subaru engines.

No problem with these engines, they liked it better than 100LL.

Winter fuel was found to have unsuitable vapor pressure late one spring.
 
Using both

I use High Octane unleaded (ethanol free) in my LH tank for cruise and I use 100LL in my RH tank for takeoff and landing.

No chance for a hicup during takeoff and landing and it doesn't know the differance when I switch.

I started this on day one and no problems in four years and 400 hrs.
Engine info in signature below.
 
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About 40% of the 340 hours on my IO-360 have been premium mogas (no alcohol), the other 50% avgas. Usually run mogas locally, avgas when traveling.

No known issues, unless the mogas somehow contributed to my recent rocker boss failure (which I doubt).

greg
 
Auto fuel

I run car gas in an A-75 for four years, summertime only. It does not like to start below about 30 degree. 100LL starts better in the cold an offers a little better performance.
 
E10

E10, premium grade exclusively. Io360, 8.5:1 pistons, p mags, no mechanical fuel pump. Electric fuel pumps in wing roots to overcome potential vapour lock. Worked perfectly for almost 500hours

Frank
 
mogas

Ran Mogas in my Cessna 170 with Continental C145 for about 400 hours with a Peterson STC which required 20% 100LL but does not have to be mixed. You can just run a tank of 100LL once in awhile to get the ratio. I used the Mogas in warmer weather and switched to 100LL for winter and whenever I was away from the home airport. All fuel was tested for ethanol. It burned well with nice clean exhaust, and no lead problems. You could not tell it from avgas except for stains on the airframe which makes it a chore to keep clean. Engine time was 800 SMOH when I sold the plane and was still running strong. I had burned 100LL for the first 200 hours but I had valves hang up so I reamed the guides and cleaned the valves then started using mogas even though it was a hassle hauling gas. My RV6 with an 0320 has never had mogas in it YET but it might!

Dick DeCramer
RV6 N500DD 400hrs.
RV8 Fuselage...Canoe stage
Northfield, MN
 
Geico266 said:
100% 92 Octane mogas for all aircraft for more than 5 years.

IO-540
0-360
0-320
0-235

I do run 100ll through the Lycosourases ocassionally.

Rotax 912

Never had a problem.
Click to expand...

Thanks for the info. Are those all RV aircraft? Do you check for ethanol? Do you have particular leaning methods that differ from 100LL?
 
For those of you running Mogas in RVs, have you modified your aircraft from a "stock" setup to accept Mogas?

In particular, any special methods for protecting against the ethanol?
 
700 hours on E-10

Chris Hill said:
For those of you running Mogas in RVs, have you modified your aircraft from a "stock" setup to accept Mogas?

In particular, any special methods for protecting against the ethanol?
Click to expand...

I use viton o-rings in the fuel drains. All other components are alcohol tolerant. I asked Lycoming about their fuel pump and they said the material used for the diaphragm is a trade secret, but it seems to tolerate ethanol. Had some problem with low fuel pressure on long, hot climbs so I eliminated some
90 degree fittings to ease fuel turbulence and put a blast tube on the fuel pump. I use one tank of 100LL for takeoff and landing and the other tank of
E-10 for cruise. No issues now.
(IO-360, standard compression, airflow performance injection, dual lightspeed ignition, whirlwind 200RV prop.)
 
Just started flying last spring, about 90 hours worth of 100LL mixed with straight ethanol (E98)

I have been trying different percentages, the last 50 hours or so has been 40% 100LL and 60% E98.

Stock fuel system, had Don at airflow set the bendix FI for E98.

I switch to strait 100LL in the winter, you know how cold it can get in ND:eek:

E98 is what comes out of the ethanol plants, and is what they make E85 with.
 
I ran auto fuel on in O-360 180hp for a number of years before the ETOH was added. And I still tried to burn that. It screwes up the calibration on the capacitance fuel senders.

I bought some 92 octane recreational gas(no etoh) but I haven't used it enough to comment.
 
Chris Hill said:
Thanks for the info. Are those all RV aircraft? Do you check for ethanol? Do you have particular leaning methods that differ from 100LL?
Click to expand...

All RV's, I check for ethanol never found it, leaning is the same.

Here is a picture of my 100 gallon fuel trailer. There is a fuel meter on the nozzle, and I have two filters and both will trap water (supposedly). The first 2-3 gallons of the3 day is pumped back into the tank to make sure there is nothing in the hose or nozzle that can get into the plane. I change filters every year, and hoses every 2 years.

fuel_tank.JPG
 
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Rotax

Rotax prefers mogas so like Larry I always check for ethanol. I never find it in premium, always in regular. Maybe a shortage of ethanol? Now there's a shortage I'm happy about!
 
Ran regular grade mogas in a 1972 172L from 1985 until sold in July of '09. The early years were just about 100% mogas - the later years were always a mix of 100LL and mogas, since it became so hard to find mogas on the road. Never had any issues. At 3000TT on all 4 original cylinders (they had been reworked once for an overhaul) when sold, hard to complain.

Ran a 50/50 mix of premium mogas and 100LL in the RV-6 when purchased in July '09, until ethanol laced gas was all I could find (about 6 months later). Was worried about vapor pressure/vapor lock, but never noticed any difference from 100% avgas.

Now I'm 100% 100LL, lean all the time, and aggressively lean on the ground. And pick the lead balls out around the plugs at annual time. No other issues so far.
 
Guys: I ran mogas in my C-182P for thirteen years in CA (bladder tanks) using 100LL when on the road, I have done the same (91 RON) with my -9A for 986.5 hours, almost six years now. I use 100LL only when on the road and can't get mogas. I have not tested for ethanol but assume everything here in Reno is 10% or better ethanol. I have a stock O-360 with P-Mags and -9A airframe with no mods for mogas. I do change the o-rings in the four fuel drains every condition inspection. No problems noted. Dan (updated 9 Mar 13)
 
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I Use E10 93 Octane Autogas

... in my RV-7A. IO-360, Bendix Silver Hawk fuel Body, stock Van's Aux fuel pump.
I started out with a 50/50 mix of 87 octane E10 with 100LL in one tank, and a 5 parts 87 Octane E10 to 1 part 100LL in the other tank last summer (8 months ago). No issues starting that aren't any different than 100% 100LL. I have seen one instance of low fuel pressure on final (E10 winter blend on a warm winter day) but the Aux pump was OFF. Turning it ON rectified the issue.
I am now running 100% 93 octane E10, and haven't seen any issues. I expect that when warmer weather arrives, the Winter Blended fuel will have some issues, so will be running a 50/50 mix in one tank for insurance. Except for the smell, I can't see any performance differences.....
Total time with some portion of E10 is about 150 hours......
 
~1000 hours running 87 octane in my RV-6. The only time I run 100LL is on trips. Am now running 10% Ethanol since that's all I can get now. Only time I have ever had problems is on quick turn-arounds where there is not ample time for the float bowl to cool and clear the vapor. With the 10% I am running now the boost pump is kept on at all times. In my rocket it is set up with pumps at the wing roots, no fuel selector, and no engine-driven fuel pump.
 
160 hp carb'd RV-4. For several years, premium non-ethanol mogas unless I'm traveling & can't get it. Works a LOT better than avgas; plugs don't foul & oil stays clean longer.
I've read unverified accounts that say Lyc mech fuel pump diaphragms don't like ethanol, so I'm a little leery, but I'd love to hear from someone that can refute the I-rumor.

Charlie
 
Yes another covert...:)

rocketbob said:
~1000 hours running 87 octane in my RV-6. The only time I run 100LL is on trips. Am now running 10% Ethanol since that's all I can get now. Only time I have ever had problems is on quick turn-arounds where there is not ample time for the float bowl to cool and clear the vapor. With the 10% I am running now the boost pump is kept on at all times. In my rocket it is set up with pumps at the wing roots, no fuel selector, and no engine-driven fuel pump.
Click to expand...

I have been happy with this setup since day 1 on the injected 360.

One question I meant to ask you a long time back Bob... The 87 octane... what compression ratio are you running and do you have EI..i,e an advance greater than the 35 degrees that Mags give you?

I have always run premium but would like to run regular, but I'm a bit nervous with the greater advance the Pmags provide.

Thanks

Frank
 
frankh said:
I have been happy with this setup since day 1 on the injected 360.

One question I meant to ask you a long time back Bob... The 87 octane... what compression ratio are you running and do you have EI..i,e an advance greater than the 35 degrees that Mags give you?

I have always run premium but would like to run regular, but I'm a bit nervous with the greater advance the Pmags provide.

Thanks

Frank
Click to expand...

O-360-A1A/MA4-5, Bendix mag and Electroair, stock compression. Absolutely no problems with 87 octane. Very rarely anymore do I use 100LL.

As soon as I get my Rotec TBI's back from Australia for the latest mods, I will be switching over.
 
EI?

Thanks Bob,

How much advance does the Electroair give you?

I.e is it the stock 25 degrees or more than that??

Frank
 
The ignition is the stock 25 degrees, but advances at partial throttle settings. Rarely do I ever see it go past 28-29 degrees at altitude.
 
Hi Frank,

My experience running regular in a previous -4 with 160 hp was that cyl head temps went up 'noticeably'. Sorry, it's been too long & I didn't keep records so I can't quantify it. I only had a 1 cyl temp gauge, so I was a little uncomfortable to continue with regular. Would probably work fine & if you have a full fledged engine monitor, you should know pretty quick, anyway.

Charlie
 
frankh said:
E10, premium grade exclusively. Io360, 8.5:1 pistons, p mags, no mechanical fuel pump. Electric fuel pumps in wing roots to overcome potential vapour lock. Worked perfectly for almost 500hours

Frank
Click to expand...

I like that idea, how did you mount them?
 
MoGas

O-200 and IO-360 w/9:1 compression about 300hrs with each.
approx 50/50 mix of avgas and 91 octane w/ no ETOH
Never had a problem except for brown stains....on the belly...of the plane
 
Chris Hill said:
Pierre, would you please post that here in order to get all of the info in one place. Thanks!
Click to expand...


Test For Ethanol In Mogas​

While I am not Pierre, the test for ethanol is very simple. The theory behind the test is water is absorbed into ethanol.

Take a test tube / fuel tester and put 1/4 by volume of water in it and mark the tube with a sharpe. Add 2/3rds by volume of the fuel to be tested and shake for a few seconds. Allow the mixture to sit and separate for a couple of minutes. If all of the water separates (back to the sharpe line) then you have no ethanol. If the amount of water seems to increase then you have ethanol. Give it a try. :D

EAA makes a test kit with instructions if you are insterested. http://www.eaa.org/autofuel/autogas/test_kit.asp
 
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Let me clarify what Larry said. If you have ethanol, you will end up with MORE "water" in your tester, which is really now a water-ethanol mixture. Ethanol migrates into water from the fuel because it is more soluble in water than in gasoline.

greg
 
Fuel pressure

Fred.Stucklen said:
... I have seen one instance of low fuel pressure on final (E10 winter blend on a warm winter day) but the Aux pump was OFF. Turning it ON rectified the issue.
Click to expand...
RV-4 with 160hp O320 running premium mogas (no ethanol) at home and 100LL on the road. I have seen low fuel pressure on occasion (1.5-2psi).

Question: How is low fuel pressure related to mogas?
 
Greg Arehart said:
Let me clarify what Larry said. If you have ethanol, you will end up with MORE "water" in your tester, which is really now a water-ethanol mixture. Ethanol migrates into water from the fuel because it is more soluble in water than in gasoline.

greg
Click to expand...

Thanks Greg & Charlie. You are correct, I corrected my post. If the amount of "water" increases then you have ethanol in the fuel. Ethanol absorbs the water and increases it's volume.
 
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Vapour lock

JohnInReno said:
Question: How is low fuel pressure related to mogas?
Click to expand...

The standard fuel pump set up is a "hydraulically incorrect" way to pump a high vapour pressure liquid..i.e fuel.

If you suck on fuel you reduce its pressure. If you suck on the fuel hard enough it will boil.

Pumps can't pump boiling fuel (well they will to a degreee until the boiling liquid has completey flashed to vapour)

If you heat the fuel the vacuum level at which it will boil reduces.

This is a very dangerous condition because if the fuel flashes completly to vapour your engine will quit.

Now think about where you mechanical fuel pump is located..It has to suck it uphill and the pump is in a nice hot place..Worse of all world.

There are other disadvantages of using an all electric system of course but you can at least make it hydraulically correct.I.e the pumps always push..Never suck.

frank
 
No lead 87 octane in an O-360 - RV9A

We're able to get 87 octane, no lead, without ethanol. When I built my Superior O-360 engine we ordered 7.2 compression pistons and we've seen no indication of detonation. I expect we could have used 8.5 compression pistons and not seen any detonation.

In the rite wing of my 9A, I mix 30% av with no lead and use the rite wing for takeoff and landings. The left wing is filled with no lead.

Problems? When the airplane is parked in the warm Tucson sun, no lead (left wing) will cause the fuel pressure to drop to 1lb so the electric fuel pump is turned on. After 15 minutes of flight however, that problem disappears. My guess is vapor lock which is solved by the cooler temps provided by flight.

The one time I mistakenly filled up with no lead with ethanol the engine stalled right after landing and ran poorly. Never again!
 
MoGas use

Was a big fan of MoGas when I owned a Cesna 150. Never under stood why 2 STC's were required. Afterall the airframe does not burn the fuel. Right? After buying my RV-4 in Oct. 97 I found out. Everything was fine with Mogas until the first warm day of May. The initial start and climbout was fine, but the hot start and subsequent takeoff had to be aborted. The engne was running rough and I cleared the plugs thinking this was the problem but before I broke ground the engine quit. This problem continued until a mechanic I met told me it was vapor lock caused by auto-gas. Yes the fuel lines were insulated. I changed my procedure to include Mogas left tank and Avgas in the right. All take offs and landings on Avgas, cruise on autofuel. This worked fine until I was unable to fly for several months and the entire fuel system gummed up. Had to replace the fuel pump and lines and rebuild the carb. Auto-fuel has very pore long term storage properties. Moral to Story. Gas and oil are cheapest part of flying. Don't risk your life on less.!!
 
Exactly

Mogas is fine but relying on the "hydraulically incorrect" mechanical fuel pump is pretty risky from a vapour lock perspective.

Frank
 
More than 300hours with car gas!

Hi Chris!

Since now, we have flown on car gas 91 Octane more than 300 hours. It is an IO-360 8.5 : 1 Superior with "Airflow Performance Fuel Injection" and "Dual Lightspeed Plasma III Ignition". The FI is approved for 100% Ethanol. The Diaphragm material of the mechanical Fuel Pump is a secret. I will replace the Pump with 500Hours. I added a blast tube to the pump and had never had any problems with vapor or low fuel pressure, even as we crossed the Andes in Peru at 14000ft.
I change the o-ring in the fuel drains every year.
The first 40 hours I used Avgas. Then for a couple of hours Avgas only for LDG/TO and for last 300 hours mostly (95%) car gas 91 Octane or higher if possible.
We used in Brazil car gas with 30-40% Ethanol, with less performance but no problems.
But it is very important to filter the fuel with a very fine filter. I use the "F3C SMALL FUEL/WATER FUNNEL" from AS. The bottom line is, that you can have some very fine, like gum, particles. This gum has no color and is little bit sticky and will block your filter. It is only present if you use ethanol blended car gas.
I will keep posting here every 300hours my further experiences.
In Asia is no Avgas, that means, I can only use car gas.

Detlef
www.flight-around-the-world.org
 
Great info everyone! Thanks

Detlef, do you have any information on long term storage as mentioned in post #43? Thanks for the great info!
 
Chris Hill said:
Great info everyone! Thanks

.......do you have any information on long term storage as mentioned in post #43? ....
Click to expand...


Hi Chris!
Last year, we shipped a couple of barrels of car gas into the Antarctic and added a fuel stabilizer (Sta-Bile??) Since Liliana got ill, we left our plane in Argentina for 5 month. As we came back, I filtered the fuel again, but no gum in it. I started the engine normal and flew with no problems.
But we had to change our plans for the Antarctic. We will do this flight in about two years and I`m sure, that we cannot use it anymore.
Don Rivera from "Airflow Performance" suggested to flush the injection system with Avgas if we don't fly for a couple of months.
I would recommend to drain the car gas before winter time and use Avgas in the low flying time season.

Detlef
 
Is anyone running 87 Octane mogas with a 160hp O320-E2D? I know 87 octane is fine with the 150hp O320-E2D with the 7.0:1 compression ratio. However, if upgrading an O320-E2D to 160hp 8.5:1 compression pistons, can you still safely use 87 octane, or are you now in the 91 octane realm?

Thanks,

-Dj
 
'Sport Fuel'

I didn't see a reference here to the new marketing emphasis - across many different owners of recreational engines that need E0 gasoline - to develop suppliers of 'sport fuel' in all 50 states. The basic concept is to marry together a mix of recreational groups (vintage boat, car and motorcycle owners are all examples) with mogas-compatible aviation interests in order to benefit from the larger, collective demand for non-ethanol mogas. Consequently, the collective term 'Sport Fuel' was developed to help this initiative suceed.

A short introduction to the Aviation Fuel Club and 'sport fuel' can be found at:
http://www.aviationfuelclub.org/news.phtml?xARTICLE=FFC13870

Jack
 
1979 C-152 Lyc O235;
1959 C-172 Con O300;
1960 Debonair Con O470J

All three are club planes that get flown regularly, Almost exclusively on 87 Mogas. Haven't experienced any problems whatsoever.
 
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