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Arty Trost
Joined: 25 May 2006
Posts: 206
Location: Sandy, Oregon
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 Posted: Thu Mar 19, 2009 9:13 pm Post subject: Vapor Pressure and E-10 mogas |
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In this month's issue of Ultraflight magazine, in Rotax Talk by Ronnie Smith, he says (for those of us using two-strokes and E-10 mogas):
"Remember also that there will be an altitude limit on the use of this 10% [ethanol gas]. I think it's around 7500 ft. MSL. Why? Well, car gas will start to vapor lock at higher altitudes so you have to watch this."
He goes on to say that if we're flying about 7500 ft MSL we should use 100LL which has a lower vapor pressure than auto gas.
Anyone heard of this? Had this happen? I know I'll be flying above 7500 MSL on my flight to Florida and am curious if any of you other two-strokers have ever experienced this or heard of it.
Arty Trost
Sandy, Oregon
www.LessonsFromTheEdge.com/uladventure2009.htm
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lucien
Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM
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| Posted: Fri Mar 20, 2009 4:56 am Post subject: Re: Vapor Pressure and E-10 mogas |
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| Arty Trost wrote: | In this month's issue of Ultraflight magazine, in Rotax Talk by Ronnie Smith, he says (for those of us using two-strokes and E-10 mogas):
"Remember also that there will be an altitude limit on the use of this 10% [ethanol gas]. I think it's around 7500 ft. MSL. Why? Well, car gas will start to vapor lock at higher altitudes so you have to watch this."
He goes on to say that if we're flying about 7500 ft MSL we should use 100LL which has a lower vapor pressure than auto gas.
Anyone heard of this? Had this happen? I know I'll be flying above 7500 MSL on my flight to Florida and am curious if any of you other two-strokers have ever experienced this or heard of it.
Arty Trost
Sandy, Oregon
www.LessonsFromTheEdge.com/uladventure2009.htm |
I've heard this too, but havn't tried running E10 in anything yet except my pickup.
I often drive in it up to the local ski area, tho, which ends up at a little over 10,000' MSL once I get to the top and havn't had any problems with vapor lock (tho it's fuel injected which may help?).
In the plane, 7500' MSL is approx. pattern altitude for me and I often bump right up against 10,000'MSL when I do have time to leave the pattern....
I've been lucky and able to find pure unleaded autogas in town and have no problems with it at those altitudes. But I'd be a little worried about E10 way up there.
I flew my FSII here for a while before I sold it and didn't have problems with vapor lock, but again we hadn't been infiltrated with E10 at the time.
I'd say 100LL would be the safest route for flying at high altitudes if you're worried about it....
LS
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LS
Titan II SS |
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John Hauck
Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)
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| Posted: Fri Mar 20, 2009 5:05 am Post subject: Vapor Pressure and E-10 mogas |
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> He goes on to say that if we're flying about 7500 ft MSL we should use
100LL which has a lower vapor pressure than auto gas.
>
Arty:
During my two stroke cross country days, I used 100LL primarily because that
was normally all that was available. It costs more, but two strokes as well
and four strokes operate well on it.
Only drawback during a long cross country my be lead fouling, which can be
remedied in a few minutes by pulling the spark plugs and cleaning the lead
off the plug with a pen knife or piece of safety wire. It is usually soft
and comes right off.
With dual ignition now days, a plug will let you know when it starts to get
loaded up. Then again, today's two strokes may not be affected.
john h
mkIII
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John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama |
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herbgh(at)nctc.com
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| Posted: Fri Mar 20, 2009 5:38 am Post subject: Vapor Pressure and E-10 mogas |
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Wondering if a mix of MO. and AV. would do the trick?
by the way...Av gas is a really good degreaser...beats those spray
cans ...Use carefully...and in the open... Works in a chemical sprayer...Herb
and ...I have two buds who run Hirth engines sucessfully...Twin
opposed model....
At 07:56 AM 3/20/2009, you wrote:
| Quote: |
Arty Trost wrote:
> In this month's issue of Ultraflight magazine, in Rotax Talk by
Ronnie Smith, he says (for those of us using two-strokes and E-10 mogas):
>
> "Remember also that there will be an altitude limit on the use of
this 10% [ethanol gas]. I think it's around 7500 ft. MSL. Why?
Well, car gas will start to vapor lock at higher altitudes so you
have to watch this."
>
> He goes on to say that if we're flying about 7500 ft MSL we
should use 100LL which has a lower vapor pressure than auto gas.
>
> Anyone heard of this? Had this happen? I know I'll be flying
above 7500 MSL on my flight to Florida and am curious if any of you
other two-strokers have ever experienced this or heard of it.
>
> Arty Trost
> Sandy, Oregon
>
>
> www.LessonsFromTheEdge.com/uladventure2009.htm
I've heard this too, but havn't tried running E10 in anything yet
except my pickup.
I often drive in it up to the local ski area, tho, which ends up at
a little over 10,000' MSL once I get to the top and havn't had any
problems with vapor lock (tho it's fuel injected which may help?).
In the plane, 7500' MSL is approx. pattern altitude for me and I
often bump right up against 10,000'MSL when I do have time to leave
the pattern....
I've been lucky and able to find pure unleaded autogas in town and
have no problems with it at those altitudes. But I'd be a little
worried about E10 way up there.
I flew my FSII here for a while before I sold it and didn't have
problems with vapor lock, but again we hadn't been infiltrated with
E10 at the time.
I'd say 100LL would be the safest route for flying at high altitudes
if you're worried about it....
LS
--------
LS
Titan II SS
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slyck(at)frontiernet.net
Guest
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| Posted: Fri Mar 20, 2009 5:46 am Post subject: Vapor Pressure and E-10 mogas |
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I don't know the comparative vapor pressures of ethanol and mogas
but auto gas
is blended with higher vapor pressures in the winter for easier cold
weather starting -or at least it was.
Summer blend should be ok at 10K as far as vapor pressure. My
concern is moisture content
which can condense out as carb frost. The quality control of 100LL
would probably be the important factor
to consider when flying over those craggy rocks.
BB
On 20, Mar 2009, at 1:11 AM, TheWanderingWench wrote:
| Quote: |
<thewanderingwench(at)yahoo.com>
In this month's issue of Ultraflight magazine, in Rotax Talk by
Ronnie Smith, he says (for those of us using two-strokes and E-10
mogas):
"Remember also that there will be an altitude limit on the use of
this 10% [ethanol gas]. I think it's around 7500 ft. MSL. Why?
Well, car gas will start to vapor lock at higher altitudes so you
have to watch this."
He goes on to say that if we're flying about 7500 ft MSL we should
use 100LL which has a lower vapor pressure than auto gas.
Anyone heard of this? Had this happen? I know I'll be flying above
7500 MSL on my flight to Florida and am curious if any of you other
two-strokers have ever experienced this or heard of it.
Arty Trost
Sandy, Oregon
www.LessonsFromTheEdge.com/uladventure2009.htm
|
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mdnanwelch7(at)hotmail.co
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| Posted: Fri Mar 20, 2009 6:01 am Post subject: Vapor Pressure and E-10 mogas |
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| Quote: | I often drive in it up to the local ski area C tho C which ends up at a little over 10 C000' MSL once I get to the top and havn't had any problems with vapor lock (tho it's fuel injected which may help?).
--------
|
Lucien C
In your truck C you will likely never have a problem using E10 auto gas C even at 18 C000 MSL.(providing it was built to handle E10) This is because your truck/car is run by a computer ECU C using a miriad of sensors to keep the engine in tune. It uses:
1) a coolant temperature sensor (colder engines get more fuel than warmer engines)
2) MAP (mainfold atmospheric pressure) for incoming combustion air
3) O2 sensor (to determine the Air/Fuel ratio)
4) MAF (mass air flow) to determine the volume of air being consumed
5) FPR (fuel pressure regulator) the computer uses this information to determine the pulse width that the ECU tells the fuel injector to pulse fuel. (i.e. lower pressure gets more pulse width)
There are many other sensors C including those that the engine uses to adjust the ignition timing C fuel enrichment C etc.
Comparing an automobile engine's reaction to E10 has nothing to do with how an airplane engine will react C unless C of course C your airplane's engine is governed by an ECU (electronic computer unit) The ECU monitors all the necessary engine parameters dozens of times a second.
Comparing an airplane engine with a carburetor C and a truck using E10 autogas C is much like comparing an apple with an orange.
Mike Welch
MkIII
Get quick access to your favorite MSN content with Internet Explorer 8. Download FREE now! [quote][b]
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jbhart(at)onlyinternet.ne
Guest
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| Posted: Fri Mar 20, 2009 6:46 am Post subject: Vapor Pressure and E-10 mogas |
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At 09:46 AM 3/20/09 -0400, you wrote:
| Quote: |
Summer blend should be ok at 10K as far as vapor pressure. My
concern is moisture content
which can condense out as carb frost. The quality control of 100LL
would probably be the important factor
to consider when flying over those craggy rocks.
BB
|
Bob,
Given equal handling and storage of E-10 and non E-10 fuel, I would think
that the E-10 would reduce the ice tendency. With the alcohol in the fuel,
it would take up the water and pass it on through to the engine. Any
additional water that can not be held in the alcohol will fall out and
remain in the bottom of the tank or carb bowl and have no effect on carb
icing.
I believe the greatest threat of carb icing come from high humidity air and
not the fuel.
Jack B. Hart FF004
Winchester, IN
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lucien
Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM
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| Posted: Fri Mar 20, 2009 7:16 am Post subject: Re: Vapor Pressure and E-10 mogas |
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| herbgh(at)nctc.com wrote: | Wondering if a mix of MO. and AV. would do the trick?
|
Blends like this seem to be acceptable by Rotax as they recommend it to get the octane rating correct if part of the gas is 87 regular.
By that time tho you may as well just run 100LL period as a convenience measure.
I ran my 447 on my trike on pure 100LL for about 100 hours. Turned out the plugs lasted almost 50 hours before I began to notice any problems. So I think the fouling issue might not actually be that bad. It wasn't for me.
I ran 100LL a fair bit in my 503's as well (more than 30% of the time for sure on the one I put on my trike to replace the 447) and didn't start getting a mag drop for at least 40 hours.
So I'd just run 100LL and install a fresh set of plugs at the start of the trip to zero them out.
When I go places underneath my 912 I usually put at least some 100LL in the tank if not a full tank. Gives an extra bit of insurance against vapor lock as I climb up towards the stratosphere.....
LS
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_________________
LS
Titan II SS |
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aslsa.rng(at)gmail.com
Guest
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| Posted: Fri Mar 20, 2009 3:06 pm Post subject: Vapor Pressure and E-10 mogas |
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Part of the vapor lock problem in airplanes versus automobiles is how the fuel is sent from the tank to the engine. I don't know of a modern car that pulls fuel from the tank. The fuel pump is in the tank and pushes it to the injectors. If you think you're going to have a problem with vapor lock you might want to think about putting a Facet pump close to the tank so any draw is short and from there on it's pushed to the carb(s). My two cents.
Rick
do not archive
On Fri, Mar 20, 2009 at 9:01 AM, Mike Welch <mdnanwelch7(at)hotmail.com (mdnanwelch7(at)hotmail.com)> wrote:
| Quote: |
| Quote: | I often drive in it up to the local ski area, tho, which ends up at a little over 10,000' MSL once I get to the top and havn't had any problems with vapor lock (tho it's fuel injected which may help?).
|
--------
Lucien,
In your truck, you will likely never have a problem using E10 auto gas, even at 18,000 MSL.(providing it was built to handle E10) This is because your truck/car is run by a computer ECU, using a miriad of sensors to keep the engine in tune. It uses:
1) a coolant temperature sensor (colder engines get more fuel than warmer engines)
2) MAP (mainfold atmospheric pressure) for incoming combustion air
3) O2 sensor (to determine the Air/Fuel ratio)
4) MAF (mass air flow) to determine the volume of air being consumed
5) FPR (fuel pressure regulator) the computer uses this information to determine the pulse width that the ECU tells the fuel injector to pulse fuel. (i.e. lower pressure gets more pulse width)
There are many other sensors, including those that the engine uses to adjust the ignition timing, fuel enrichment, etc.
Comparing an automobile engine's reaction to E10 has nothing to do with how an airplane engine will react, unless, of course, your airplane's engine is governed by an ECU (electronic computer unit) The ECU monitors all the necessary engine parameters dozens of times a second.
Comparing an airplane engine with a carburetor, and a truck using E10 autogas, is much like comparing an apple with an orange.
Mike Welch
MkIII
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