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Hot weather and autogas?



 
 
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  #1  
Old July 23rd 03, 09:27 PM
Rich S.
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Default Hot weather and autogas?

Hi Troop..........

The weather forecast for Idaho today is staggering! 107° F in Boise, 108° in
Twin Falls and 110° in Mountain Home. Montana is similar with 108° forecast
in Helena.

Last year, on my way to OSH, I planned my fuel stops to take advantage of
autogas availability. I stopped at Pullman, WA and filled up. As we were
flying past Helena, Montana, the OAT showed 85° at 9500'. Fuel pressure went
to zero and the electric pump (ahead of the firewall) made no difference.
Within one minute the engine quit. Not rough. QUIT.

I'll spare you the details, but fortunately, as I was about to turn downwind
for a soybean field, it had cooled off enough to restart. Cautiously, we
climbed and made our way to Helena, 25 miles distant. Draining the autofuel
and filling up with 100 LL solved the problem.

Unless you are *absolutely* sure that your engine will not vapor lock in
extreme temperatures, do not run autogas. It is not worth the few bucks
difference. Don't worry about the 100 LL fouling a plug or two - your plane
will still fly.

I am not looking for an discussion or argument about autogas. I use it
regularly in moderate temps. I will not use it when the mercury rises to
these levels.

Keep 'em flying,
Rich S.


  #2  
Old July 23rd 03, 11:51 PM
Larry Smith
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Default


"Rich S." wrote in message
...
Hi Troop..........

The weather forecast for Idaho today is staggering! 107° F in Boise, 108°

in
Twin Falls and 110° in Mountain Home. Montana is similar with 108°

forecast
in Helena.

Last year, on my way to OSH, I planned my fuel stops to take advantage of
autogas availability. I stopped at Pullman, WA and filled up. As we were
flying past Helena, Montana, the OAT showed 85° at 9500'. Fuel pressure

went
to zero and the electric pump (ahead of the firewall) made no difference.
Within one minute the engine quit. Not rough. QUIT.


What were you flying?

Fuel pumps work better against vapor-lock when closer to the source.

I'll spare you the details, but fortunately, as I was about to turn

downwind
for a soybean field, it had cooled off enough to restart. Cautiously, we
climbed and made our way to Helena, 25 miles distant. Draining the

autofuel
and filling up with 100 LL solved the problem.

Unless you are *absolutely* sure that your engine will not vapor lock in
extreme temperatures, do not run autogas. It is not worth the few bucks
difference. Don't worry about the 100 LL fouling a plug or two - your

plane
will still fly.

I am not looking for an discussion or argument about autogas. I use it
regularly in moderate temps. I will not use it when the mercury rises to
these levels.

Keep 'em flying,
Rich S.


Yes, mogas is more volatile, but couldn't you have mixed it with 100LL? Do
you have your firewall-forward fuel lines well-insulated with firesleeves?
A friend complained about vapor-lock until he band-it clamped that orange
silicone Aeroquip stuff on his lines. And don't forget to seal it on the
ends so that oil and fuel don't soak into the insulation. See Tony
Bingelis on Firewall Forward. Some people seal it with RTV silicone, some
with that expensive stuff Tony says to buy as a group.

Better to discuss it than not to discuss it. And then have to cuss it
later.


  #3  
Old July 24th 03, 12:38 AM
BRUCE FRANK
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Default

What kind of plane? I used to have high desert vapor lock on my old
International Travelall...5000 feet and 110 degrees F in the shade. Nothing
I did, and I mean NOTHING stopped the vapor lock problems until!!! I
installed an electric fuel pump at the fuel tank With insulated fuel lines
in the engine compartment and a 1/16" diameter bleed line that vented back
to the tank (so that after sitting for a while any vapor that formed in the
line would vent back to the tank unblocking the line when I flipped on the
fuel pump....the bleed line was insurance as I ran it almost a year with the
tank mounted fuel pump with no problems...The fuel pump seemed to create
enough pressure to collapse or force through any bubbles in the line...but
the heat soaked engine would start more quickly once the bleed line was
installed) I also by-passed the block mounted fuel pump to reduce engine
block heat transfer into the fuel. I put another 100,000 miles on that
vehicle, most of it rock crawling in Utah's Canyonlands in the summer time,
with never even a hic-up caused by fuel vapor blocking the line.

Bruce A. Frank

"Rich S." wrote in message
...
Hi Troop..........

The weather forecast for Idaho today is staggering! 107° F in Boise, 108°

in
Twin Falls and 110° in Mountain Home. Montana is similar with 108°

forecast
in Helena.

Last year, on my way to OSH, I planned my fuel stops to take advantage of
autogas availability. I stopped at Pullman, WA and filled up. As we were
flying past Helena, Montana, the OAT showed 85° at 9500'. Fuel pressure

went
to zero and the electric pump (ahead of the firewall) made no difference.
Within one minute the engine quit. Not rough. QUIT.

I'll spare you the details, but fortunately, as I was about to turn

downwind
for a soybean field, it had cooled off enough to restart. Cautiously, we
climbed and made our way to Helena, 25 miles distant. Draining the

autofuel
and filling up with 100 LL solved the problem.

Unless you are *absolutely* sure that your engine will not vapor lock in
extreme temperatures, do not run autogas. It is not worth the few bucks
difference. Don't worry about the 100 LL fouling a plug or two - your

plane
will still fly.

I am not looking for an discussion or argument about autogas. I use it
regularly in moderate temps. I will not use it when the mercury rises to
these levels.

Keep 'em flying,
Rich S.




  #4  
Old July 24th 03, 02:24 AM
Cy Galley
external usenet poster
 
Posts: n/a
Default

Well Rich, It was only 77 ° today. Supposed to get down to high 40s or low
50 tonight and we are 160 miles south of Oshkosh. Is supposed to get to 90
some this week end but I am heading North this Friday to look for green
planes that break off axles.
GRIN

Have a safe flight!

--
Cy Galley, TC - Chair, Emergency Aircraft Repair, Oshkosh

Editor, EAA Safety Programs
or

Always looking for articles for the Experimenter

"Rich S." wrote in message
...
Hi Troop..........

The weather forecast for Idaho today is staggering! 107° F in Boise, 108°

in
Twin Falls and 110° in Mountain Home. Montana is similar with 108°

forecast
in Helena.

Last year, on my way to OSH, I planned my fuel stops to take advantage of
autogas availability. I stopped at Pullman, WA and filled up. As we were
flying past Helena, Montana, the OAT showed 85° at 9500'. Fuel pressure

went
to zero and the electric pump (ahead of the firewall) made no difference.
Within one minute the engine quit. Not rough. QUIT.

I'll spare you the details, but fortunately, as I was about to turn

downwind
for a soybean field, it had cooled off enough to restart. Cautiously, we
climbed and made our way to Helena, 25 miles distant. Draining the

autofuel
and filling up with 100 LL solved the problem.

Unless you are *absolutely* sure that your engine will not vapor lock in
extreme temperatures, do not run autogas. It is not worth the few bucks
difference. Don't worry about the 100 LL fouling a plug or two - your

plane
will still fly.

I am not looking for an discussion or argument about autogas. I use it
regularly in moderate temps. I will not use it when the mercury rises to
these levels.

Keep 'em flying,
Rich S.




  #5  
Old July 24th 03, 03:07 AM
Jim Weir
external usenet poster
 
Posts: n/a
Default

Cy...

I know you've got your share of volunteers, but if you need an IA to sign of a
certificated major repair, I'm happy to do it. I'll be on the field from Monday
to Saturday...leave a note for me in the press tent if you need help.

Obviously...no charge. (Knew you knew this, but had to say it.)

Jim



"Cy Galley"
shared these priceless pearls of wisdom:

I am heading North this Friday to look for green
-planes that break off axles.



Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com
  #6  
Old July 24th 03, 04:02 AM
Rich S.
external usenet poster
 
Posts: n/a
Default

"Cy Galley" wrote in message
news:HzGTa.130839$ye4.92382@sccrnsc01...
Well Rich, It was only 77 ° today. Supposed to get down to high 40s or

low
50 tonight and we are 160 miles south of Oshkosh. Is supposed to get to

90
some this week end but I am heading North this Friday to look for green
planes that break off axles.
GRIN

Have a safe flight!


Not coming this year, Cy. I have imposed enough on the good offices of the
Emergency Repair Crew. I hope you guys will have a relatively quiet time of
it. Please tell the crew that I am thinking of them and still remember their
good-natured and able assistance. 2002 was a year to remember, for sure.

Rich S.

P.S. Current temperature in Helena, MT @ 8 PM is 96°.


  #7  
Old July 24th 03, 04:19 AM
Jay Honeck
external usenet poster
 
Posts: n/a
Default

P.S. Current temperature in Helena, MT @ 8 PM is 96°.

And tonight in Iowa City, IA we're expecting record-breaking LOW
temperatures. It is absolutely perfect sleeping temperature.

But I suppose your blazing heat will arrive in the Midwest just in time for
(you guessed it!) Oshkosh 2003...
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"


  #8  
Old July 24th 03, 04:34 AM
Rich S.
external usenet poster
 
Posts: n/a
Default

"Bob Olds" wrote in message
om...

I use a mixture of 100LL and mogas. My RV-4 sat in the sun all day
with temp. 95 F. As I taxied I noticed a miss now & then,so I turned
on the electric boost pump and had no further problem in the flight.
My boost pump is located beside the fuel selector valve,at the lowest
point possible.
The engine driven pump makes suction in the fuel line from the valve
to the pump. With a suction/vacuum the boiling point is lowered =
vapor lock.
With a boost pump in the engine compartment, you add another hot place
for the fuel to boil.
I have had the same problems with 80 oct.,100LL and mogas. They are
all problems when the tank gets so hot.

Bob Olds RV-4 , N1191X


Bob.............

Your recommendations to prevent vapor lock are sound. However, unless you
have tested the system under actual extreme conditions, it is best to not
trust it. 100 LL (much as I hate its cost and tendency to foul plugs) is
more resistant to vapor lock than mogas. Especially mogas out of a tank at
an airport which may be last Winter's blend.

Rich S.


  #9  
Old July 24th 03, 08:04 AM
BRUCE FRANK
external usenet poster
 
Posts: n/a
Default

Rich,

All I was doing was offering a relatively straight forward mod of the fuel
system that will prevent fuel blocking vapor lock. I know of several home
builders who have made similar mods to their fuel system to assure trouble
free operation. Heck, I have read stories of low wing aircraft vapor locking
on 100LL, so avgas is not the panacea for a system running hot and high.

Bruce A. Frank

"Rich S." wrote in message
...
"BRUCE FRANK" wrote in message
...
What kind of plane? snip.....


Bruce..............

Read the post again. If you are *absolutely* sure that "YOUR ENGINE" will
not vapor lock - have a ball. Burn kerosene if'n you want. If you have the
slightest doubt, put in 100 LL fer chissake. I'm trying to prevent anyone
else in this group from having a problem.

Repeat - I am not trying to start an argument about autofuel. I am trying

to
warn those folks who have been happily burning car gas (as I was) at low
altitudes and moderate temperatures. It ain't gonna freakin' work at

10,000'
when you can fry eggs on the cowling.

Rich S.




  #10  
Old July 24th 03, 03:15 PM
Bill Daniels
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Default

I've posted this story before but this thread seems a good time to repeat
it.

One hot afternoon in Albuquerque I was pre-flighting my Archer and noticed
that the 100LL in the fuel tester was fizzing like champagne. I showed the
fuel tester to another pilot who was also pre-flighting his homebuilt. He
in turn showed me his tester full of amber auto gas which showed no bubbling
at all. In this case, the mogas clearly had a much higher vapor pressure
than the 100LL. I chose to delay my departure until the next morning - he
fired up and flew away.

On the other hand, during a recent road trip to New Mexico, my Jeep Grand
Cherokee suffered two fuel pump failures within a week - both pumps were
brand new. The failure mode was possibly due to winter gasoline blend that
was mistakenly shipped to service stations during the hot season as a result
of the ongoing shortfall in US gasoline stocks. Winter gas has a big load
of volatile components to aid cold starting but will boil and vapor lock in
the summer. In my case, the volatile fuel likely caused the in-tank fuel
pump to cavitate, overheat and fail.

The service writers in both dealerships who replaced the bad pumps told me
that they had been inundated with fuel pump failures and otherwise
unexplained hot stalling.

Diesels are sounding better all the time.

Bill Daniels

 




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