Fuel Prices For The July Pilgrimage

[RST Engineering]

I'd like a consensus opinion from the newsgroup denizens who use any of the
popular "fuel pricing" websites as to the one that they find the most
accurate. My personal favorite over the last few years has been Airnav, but
I'm willing to be persuaded that there is better.

Reason being, about two months from today a lot of us will be coming a long
distance to The Money Hole On Lake Winnebago. My best estimate right now is
that it will cost slightly north of 1 AMU to pump the 182 from GOO to OSH
and back. There are a lot of people from both coasts who are going to spend
at least a significant fraction of that and possibly more.

Let's pick ONE site and keep it absolutely up to the minute current from our
local area at least through the week of The Show.

Jim

I know, I know. "consensus opinion" goes in the same sentence as "herding
cats".
jw

[Peter R.]

On 5/22/2007 1:08:32 PM, "RST Engineering" wrote:

> Let's pick ONE site and keep it absolutely up to the minute current from
> our local area at least through the week of The Show.

Airnav has always been on the receiving end of both my fuel/FBO updates and
my fuel research.

--
Peter

[Montblack]

("Peter R." wrote)
>> Let's pick ONE site and keep it absolutely up to the minute current from
>> our local area at least through the week of The Show.

> Airnav has always been on the receiving end of both my fuel/FBO updates
> and my fuel research.


I am always clicking on AirNav.

AirNav, however, sometimes does not click back right away.


.....S-L-O-W


Montblack

[Jose]

> Let's pick ONE site and keep it absolutely up to the minute

I'd go with Airnav.

While it's true I haven't used any of the others, Airnav was first, and
has always been there. That counts for a lot. True, it did drop some
FBO listings when they didn't pony up, but I think that's been fixed.
Competition would have to do way better for me to switch.

That said, I'm not going to Osh, so I'm just an opinion, not a
datapoint. :)

Jose
--
There are two kinds of people in the world. Those that just want to
know what button to push, and those that want to know what happens when
they push the button.
for Email, make the obvious change in the address.

[Montblack]

("RST Engineering" wrote)
> My best estimate right now is that it will cost slightly north of 1 AMU to
> pump the 182 from GOO to OSH and back.


GOO ...funny name.

http://www.airnav.com/airport/KGOO
Nevada County Air Park
Grass Valley, California, USA
(formerly O17)


Montblack
(Formerly 017 in '77)

[Jim Burns[_3_]]

100LL.com has consistently beat Airnav.com on price accuracy and
timely updates for all of the long cross country trips I've taken
during the past 2 years. It's saved me more than $1000 over what
Airnav found for lowest priced fuel near my destinations.


Currently mo-gas at our local pumps is at $3.39. Normally our 100LL
prices will follow mogas but $1 higher. Current 100LL prices have not
followed mogas as high, and current mogas contracts show a down trend
for coming months. I can contract July mogas for $0.05 less than
today's price and August mogas for $0.10 less than today's price. I
would expect that OSH period avgas prices to be pretty close to
current prices.

[RST Engineering]

The problem, Jim, is that I'm trying my best to wend my way across country
taking as little 100LL as possible because of the fouling issue. As a
matter of fact, I plan on landing at Portage between IOW and PCZ just to get
a good load of mogas for the flight home. Thence Blaine and Aberdeen
before I have to start taking on bluegas.

Jim



"Jim Burns" > wrote in message
ups.com...
> 100LL.com has consistently beat Airnav.com on price accuracy and
> timely updates for all of the long cross country trips I've taken
> during the past 2 years. It's saved me more than $1000 over what
> Airnav found for lowest priced fuel near my destinations.
>

[Stealth Pilot[_2_]]

On Tue, 22 May 2007 15:35:26 -0700, "RST Engineering"
> wrote:

>The problem, Jim, is that I'm trying my best to wend my way across country
>taking as little 100LL as possible because of the fouling issue. As a
>matter of fact, I plan on landing at Portage between IOW and PCZ just to get
>a good load of mogas for the flight home. Thence Blaine and Aberdeen
>before I have to start taking on bluegas.
>
>Jim
>
>
have you experimented with your plugs?

on the o-200 the usual REM40-E plugs foul up dreadfully on 100/130
avgas but switching to REM38-E plugs gets rid of almost all of the
problem. I run 100/130 avgas with no problems at all.

Stealth Pilot

[Montblack]

("RST Engineering" wrote)
> The problem, Jim, is that I'm trying my best to wend my way across country
> taking as little 100LL as possible because of the fouling issue. As a
> matter of fact, I plan on landing at Portage between IOW and PCZ just to
> get a good load of mogas for the flight home. Thence Blaine and Aberdeen
> before I have to start taking on bluegas.


Blaine?

When you know your tentative (Depart: OSH) schedule, let me know. You can
hunker down at Blaine (if need be) or soldier on. A place to bunk (with
shower and flushing toilet <g>) ...and a car will be available - should you
want it, or need it.

We (@ ANE) will take care of Gail ....and you.

That said, I'll be returning from OSH early Saturday evening (8pm-ish), so I
won't be around when you stop by our 'little' airport.

Your OSH event chairs:
Taking them back with you?
Leaving them behind when your week is up?

Your call. I'm open either way. If they're heading West, don't forget to
leave room.


Montblack
http://www.airnav.com/airport/KANE

[RST Engineering]

"Montblack" > wrote in message
...

>
> When you know your tentative (Depart: OSH) schedule, let me know. You can
> hunker down at Blaine (if need be) or soldier on.

Like the diapers say, Depends. If we get an early morning VFR departure,
I'd like to be in western Nebraska for the evening. If we get the usual
crappy Wisconsin IFR mornings, I'll take you up on that.

A place to bunk (with
> shower and flushing toilet <g>) ...and a car will be available - should
> you
> want it, or need it.

Flushing toilets? FLUSHING TOILETS??? We don't even have those up here in
the wilds of Grass Valley {;-)

>
> We (@ ANE) will take care of Gail ....and you.

Bless you.

>
> That said, I'll be returning from OSH early Saturday evening (8pm-ish), so
> I
> won't be around when you stop by our 'little' airport.
>
> Your OSH event chairs:
> Taking them back with you?
> Leaving them behind when your week is up?


Keep 'em. They are the "Oshkosh Chairs" from now on.

Jim

[B A R R Y[_2_]]

Montblack wrote:
> ("RST Engineering" wrote)
>> My best estimate right now is that it will cost slightly north of 1 AMU to
>> pump the 182 from GOO to OSH and back.
>
>
> GOO ...funny name.

How about FOK?

[Jay Honeck]

> Reason being, about two months from today a lot of us will be coming a long
> distance to The Money Hole On Lake Winnebago. My best estimate right now is
> that it will cost slightly north of 1 AMU to pump the 182 from GOO to OSH
> and back.

Well, although I can't officially sell mogas at the airport out of our
Mighty Grape, I *can* be persuaded to sell it to friends. For those
who are coming to the Pre-OSH Pool Party, let me know in advance,
please, and I'll make sure we're topped off.

Thus far I know Jim & Gail, and Darrel are in the mogas market.
Anyone else? Jack, you got the mogas STC on your Arrow? Edwin, how
'bout for your Maule?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Jonathan Goodish]

In article om>,
Jim Burns > wrote:

> 100LL.com has consistently beat Airnav.com on price accuracy and
> timely updates for all of the long cross country trips I've taken
> during the past 2 years. It's saved me more than $1000 over what
> Airnav found for lowest priced fuel near my destinations.

Interesting. While Airnav is often incorrect (old data), 100ll.com is
more often incorrect in my experience. Certainly, 100ll.com appears to
be consistently less accurate just in my local/regional area.

In any case, I've concluded that the best method is to find the airports
with low price trends, and then call them to get an update on prices and
availability. During the post-Katrina run-up, the cheaper fields
quickly sold out and, because they didn't raise prices with the market,
couldn't afford to refill the tanks until prices came back down again.
It would be a shame to land somewhere with legal reserves, only to find
out that their tanks are dry.



JKG

[Margy Natalie]

Jay Honeck wrote:
>>Reason being, about two months from today a lot of us will be coming a long
>>distance to The Money Hole On Lake Winnebago. My best estimate right now is
>>that it will cost slightly north of 1 AMU to pump the 182 from GOO to OSH
>>and back.
>
>
> Well, although I can't officially sell mogas at the airport out of our
> Mighty Grape, I *can* be persuaded to sell it to friends. For those
> who are coming to the Pre-OSH Pool Party, let me know in advance,
> please, and I'll make sure we're topped off.
>
> Thus far I know Jim & Gail, and Darrel are in the mogas market.
> Anyone else? Jack, you got the mogas STC on your Arrow? Edwin, how
> 'bout for your Maule?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
Jay,

I don't believe you are selling anything. You are offering to fill up
your friends and they are accepting your kind offer to keep their plugs
clean, but they would never let you actually pay for their gas. :-)

Margy

[Darrel Toepfer]

"RST Engineering" > wrote:

> I'd like a consensus opinion from the newsgroup denizens who use any
> of the popular "fuel pricing" websites as to the one that they find
> the most accurate. My personal favorite over the last few years has
> been Airnav, but I'm willing to be persuaded that there is better.
>
> Reason being, about two months from today a lot of us will be coming a
> long distance to The Money Hole On Lake Winnebago. My best estimate
> right now is that it will cost slightly north of 1 AMU to pump the 182
> from GOO to OSH and back. There are a lot of people from both coasts
> who are going to spend at least a significant fraction of that and
> possibly more.
>
> Let's pick ONE site and keep it absolutely up to the minute current
> from our local area at least through the week of The Show.
>
> Jim
>
> I know, I know. "consensus opinion" goes in the same sentence as
> "herding cats".

AOPA has fuel pricing through Anywhere Map which has access costs of $30
per year... Gots to be an AOPA member too for the discount... Course
they get their data from: http://www.100ll.com

Golden Eagle Flight Prep has a link to fuel pricing (its a free download
from http://www.duats.com/cirrus.shtml or http://www.flightprep.com )
They link to AirNav for fuel pricing...

EAA is linked for fuel prices through here and made requests of the
membership to keep it current and list your favorites for flying to
Aventure 2007: http://map.aeroplanner.com/tools/fbomap.cfm Requires at
least a Premium subscription of $12.95 per month or $119.95 per year...
Also "rideshare" through here:
http://www.airventure.org/rideshare/default.asp

So I really didn't find anything new... Maybe we need to list airports
within walking distance of mowgas and bring our fuel cans? ;-)

[Darrel Toepfer]

Darrel Toepfer > wrote:

EAA is linked for fuel prices through here and made requests of the
membership to keep it current and list your favorites for flying to
Aventure 2007: http://map.aeroplanner.com/tools/fbomap.cfm

Mybad, even their free version includes access to FBO's and Fuel Prices...

[Rich S.[_1_]]

> "RST Engineering" > wrote:
>
>> I'd like a consensus opinion from the newsgroup denizens who use any
>> of the popular "fuel pricing" websites as to the one that they find
>> the most accurate. My personal favorite over the last few years has
>> been Airnav, but I'm willing to be persuaded that there is better.

Got to put my two cents worth in here. A few years ago (2002) I used Airnav
to plan our trip to Oshkosh from the northwest, with stops in Washington DC,
New York, and Macinac Island. My thought was to use mogas where possible.

We left home and flew to Pullman in eastern Washington for the first fillup.
When we were passing 25 mi. north of Helena, MT, the engine quit - vapor
locked. Contributing factors were the high temperature (85 F @ 9500'), the
(I suspect) old mogas I bought in Pullman, and my fuel system design, having
the electric pump forward of the firewall and no forward-facing air scoops
on the tank vents.

Fortunately things cooled off on the glide down and I was able to effect a
restart as I was about to enter downwind for a soybean field; which would
likely have totaled the plane and possibly us as well. We flew in to Helena
and replaced the mogas with 100 LL.

I have since corrected the design deficiencies but I can't do anything about
the weather (no matter what ALgore says). One thing I can do is be very
careful as to when and where I burn mogas. I will not buy it from a source
which is unknown to me. This lets out every strange airport. I will not use
mogas on hot days nor at high altitudes.

Mogas burns clean and costs a buck or so less. 100 LL tends to foul my plugs
and costs more. My engine will run with two or three fouled plugs. It won't
run at all if it vapor locks. I've told this tale before and have gotten
used to the inevitable flaming. I'm *not* recommending that anyone use any
particular fuel. Fill it up with Dilithium crystals if you like. I'll spend
the extra buck for avgas when I head out over the Rockies for OSH.

YMMV

Rich S.

[Gig 601XL Builder]

Rich S. wrote:
>> "RST Engineering" > wrote:
>>
>>> I'd like a consensus opinion from the newsgroup denizens who use any
>>> of the popular "fuel pricing" websites as to the one that they find
>>> the most accurate. My personal favorite over the last few years has
>>> been Airnav, but I'm willing to be persuaded that there is better.
>
> Got to put my two cents worth in here. A few years ago (2002) I used
> Airnav to plan our trip to Oshkosh from the northwest, with stops in
> Washington DC, New York, and Macinac Island. My thought was to use
> mogas where possible.

I think I found your problem. You went from the NW to OSH with stops in DC &
NY.

[Rich S.[_1_]]

"Gig 601XL Builder" <wrDOTgiaconaATsuddenlink.net> wrote in message
...
>
> I think I found your problem. You went from the NW to OSH with stops in DC
> & NY.

I used cheap no-lead charts, too! :)

[Matt Whiting]

Rich S. wrote:

> I have since corrected the design deficiencies but I can't do anything about
> the weather (no matter what ALgore says). One thing I can do is be very
> careful as to when and where I burn mogas. I will not buy it from a source
> which is unknown to me. This lets out every strange airport. I will not use
> mogas on hot days nor at high altitudes.

Why is mogas from an unknown source worse than avgas from an unknown source?

Matt

[M[_1_]]

On May 24, 11:44 am, "Rich S." >
wrote:

>
> We left home and flew to Pullman in eastern Washington for the first fillup.
> When we were passing 25 mi. north of Helena, MT, the engine quit - vapor
> locked. Contributing factors were the high temperature (85 F @ 9500'), the
> (I suspect) old mogas I bought in Pullman, and my fuel system design, having
> the electric pump forward of the firewall and no forward-facing air scoops
> on the tank vents.

What model of the plane is this?

[Rich S.[_1_]]

"Matt Whiting" > wrote in message
...
>
> Why is mogas from an unknown source worse than avgas from an unknown
> source?

Although I cannot cite a reference, it has always been my belief that Avgas
is subject to tighter inspection procedures from the refinery to the
customer. Also, I think that Mogas is blended more specifically for seasonal
use. If the FBO is not selling a large quantity (compared to the size of his
tank) you may get Mogas that is several months old. This means it could be
blended inappropriately for the season - or simply be just old gas with less
volatiles and/or water from condensation.

Rich S.

[Rich S.[_1_]]

"M" > wrote in message
oups.com...
>
> What model of the plane is this?

CP-323a Emeraude, although the fuel system was of my own design and
construction. I have added a blast tube to cool the electric fuel pump and
an air scoop on the vents to pressurize the fuel tanks.

http://temp.corvetteforum.net/c4/elwood89//harvey5.jpg

Rich S.

[Montblack]

("Rich S." wrote)
> CP-323a Emeraude, although the fuel system was of my own design and
> construction. I have added a blast tube to cool the electric fuel pump and
> an air scoop on the vents to pressurize the fuel tanks.
>
> http://temp.corvetteforum.net/c4/elwood89//harvey5.jpg


Nice pic


Montblack

[Rich S.[_1_]]

"Montblack" > wrote in message
...
>
> Nice pic

Thanks. We were flying in formation with an RV-4, headed up to Snohomish for
a Sunday morning breakfast. His wife snapped the picture.

Rich S.

[Tim Hickey]

I have a Zenith CH-300 with an O-320. I had a similar problem in the
beginning. I did as you have done, plus insulated the fuel lines,
installed a small heat reflective shield over the gascolater, and ran
a blast tube down to the mechanical fuel pump. Since then (about 1990)
I have run over 9000 gallons of mogas through the machine with out
problem. Although I will always let the engine (and the fuel pump that
is bolted to the case) cool between flights. If I know that I will be
doing flights without allowing a cool down period, I will put 100LL in
one tank, and take off on it.







On Fri, 25 May 2007 09:02:46 -0700, "Rich S."
> wrote:

>"M" > wrote in message
oups.com...
>>
>> What model of the plane is this?
>
>CP-323a Emeraude, although the fuel system was of my own design and
>construction. I have added a blast tube to cool the electric fuel pump and
>an air scoop on the vents to pressurize the fuel tanks.
>
>http://temp.corvetteforum.net/c4/elwood89//harvey5.jpg
>
>Rich S.
>
>

Zenith CH-300 Driver.

[Morgans[_2_]]

"Tim Hickey"> wrote

> If I know that I will be
> doing flights without allowing a cool down period, I will put 100LL in
> one tank, and take off on it.

Do you notice a need to make much (or any) mixture change when changing from
100LL to mogas, or visey-versey?
--
Jim in NC

[Rich S.[_1_]]

"Tim Hickey" > wrote in message
...
>I have a Zenith CH-300 with an O-320. I had a similar problem in the
> beginning. I did as you have done, plus insulated the fuel lines,
> installed a small heat reflective shield over the gascolater, and ran
> a blast tube down to the mechanical fuel pump. Since then (about 1990)
> I have run over 9000 gallons of mogas through the machine with out
> problem. Although I will always let the engine (and the fuel pump that
> is bolted to the case) cool between flights. If I know that I will be
> doing flights without allowing a cool down period, I will put 100LL in
> one tank, and take off on it.

Sounds like you have addressed all the issues that might arise from burning
"good" mogas. Obviously, nothing can insure failure from bad or contaminated
fuel, whatever the grade. I had insulated all my firewall-forward tubing
during the original construction, but insulation only delays heat, it
doesn't stop it. Sometimes I wish I had a thermometer which would monitor
under cowl temps. When it gets hot out, I can't believe the blast furnace
air that emits from the oil filler door. I remember one featured airplane in
Sport Aviation which had cowl vents which fell open whenever there was no
air pressure inside the cowl. Seems like a good idea to vent the hot air
when you shut down.

My Emeraude has both a mechanical pump and an electric pump. If I had to do
it over again, I would mount the electric pump near the rear tank, to insure
fuel flow. There is something to be said for the original design which had
nothing but gravity flow from the cowl tank along with a forward-facing tube
on the fuel cap. Sometimes simple is best.

Tailwinds,
Rich S.

[Jay Honeck]

> Sounds like you have addressed all the issues that might arise from burning
> "good" mogas. Obviously, nothing can insure failure from bad or contaminated
> fuel, whatever the grade. I had insulated all my firewall-forward tubing
> during the original construction, but insulation only delays heat, it
> doesn't stop it. Sometimes I wish I had a thermometer which would monitor
> under cowl temps. When it gets hot out, I can't believe the blast furnace
> air that emits from the oil filler door. I remember one featured airplane in
> Sport Aviation which had cowl vents which fell open whenever there was no
> air pressure inside the cowl. Seems like a good idea to vent the hot air
> when you shut down.

All good ideas. I, too, have often wondered why I have all the data
in the world on my JPI engine analyzer, but no "under-the-cowl"
temperature readings.

I suppose CHT and EGT are the pertinent temps, but that doesn't show
what all those hoses, wires, and connections are enduring. I'd bet
it's well over 200 degrees at the firewall, in the summer during a
long taxi -- but I don't honestly know.

Regardless, as you know we've run over 8500 gallons of mogas through
Atlas (and an unknown amount through our old O-320-powered Warrior)
without so much as a burp. Different fuel systems, I guess.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Tim Hickey]

I can tell no difference between running 100LL and Mogas.




On Fri, 25 May 2007 22:52:36 -0400, "Morgans"
> wrote:

>
>"Tim Hickey"> wrote
>
>> If I know that I will be
>> doing flights without allowing a cool down period, I will put 100LL in
>> one tank, and take off on it.
>
>Do you notice a need to make much (or any) mixture change when changing from
>100LL to mogas, or visey-versey?
>--
>Jim in NC
>
>

Zenith CH-300 Driver.

[Matt Whiting]

Tim Hickey wrote:
> I can tell no difference between running 100LL and Mogas.

I could tell a big difference with my 182. Back then my cost to fill up
was about 50% of the prevailing avgas price and that was a very
noticeable difference! :-)

Matt

[Morgans[_2_]]

"Matt Whiting" > wrote in message
...
> Tim Hickey wrote:
>> I can tell no difference between running 100LL and Mogas.
>
> I could tell a big difference with my 182. Back then my cost to fill up
> was about 50% of the prevailing avgas price and that was a very noticeable
> difference! :-)

Besides the plane being heavier (more money in the wallet <g>) could you
tell if the mixture was different, if you ever ran one tank mogas and one
with 100LL?
--
Jim in NC

[Matt Whiting]

Morgans wrote:
> "Matt Whiting" > wrote in message
> ...
>> Tim Hickey wrote:
>>> I can tell no difference between running 100LL and Mogas.
>> I could tell a big difference with my 182. Back then my cost to fill up
>> was about 50% of the prevailing avgas price and that was a very noticeable
>> difference! :-)
>
> Besides the plane being heavier (more money in the wallet <g>) could you
> tell if the mixture was different, if you ever ran one tank mogas and one
> with 100LL?

Never tried that. We typically ran something close to a 50/50
mogas/100LL mix most of the time. We always filled with mogas at the
home drome, but we filled with 100LL at other airports. Since both my
partner and me flew mostly cross country flights, nearly every other
top-off was with 100LL.

The airplane flew great on this mixture up to as high as 13,000 feet.
Never had a hiccup of any sort related to fuel.


Matt

[john smith[_2_]]

In article >,
(Tim Hickey) wrote:

> I can tell no difference between running 100LL and Mogas.

I sure could in my Continental A-65 Champ.
The engine seemed sluggish with mogas. It didn't seem to have as much
power.

[Jay Honeck]

> > I can tell no difference between running 100LL and Mogas.
>
> I sure could in my Continental A-65 Champ.
> The engine seemed sluggish with mogas. It didn't seem to have as much
> power.

I know you probably realize this, but your observation makes no
sense. There is no difference in "power" between avgas and mogas.

If there were, the FAA would never have approved mogas as an aviation
fuel in *any* aircraft.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Morgans[_2_]]

"Jay Honeck" > wrote

> I know you probably realize this, but your observation makes no
> sense. There is no difference in "power" between avgas and mogas.


Actually, there are slightly more BTU's in a gallon of mogas than in a
gallon of avgas.

If an engine was to have its fixed advanced spark too far forward, the lower
octane mogas could produce less power. That is the only way I could think
of, other than a high compression engine that needed the higher octane to
keep from knocking.
--
Jim in NC

[Jack Allison]

No have mogas STC for said Arrow. Ergo, I must burn blue stuff :-)


--
Jack Allison
PP-ASEL-Instrument Airplane

"To become a Jedi knight, you must master a single force. To become
a private pilot you must strive to master four of them"
- Rod Machado

(Remove the obvious from address to reply via e-mail)

[Matt Whiting]

Jay Honeck wrote:
>>> I can tell no difference between running 100LL and Mogas.
>> I sure could in my Continental A-65 Champ.
>> The engine seemed sluggish with mogas. It didn't seem to have as much
>> power.
>
> I know you probably realize this, but your observation makes no
> sense. There is no difference in "power" between avgas and mogas.
>
> If there were, the FAA would never have approved mogas as an aviation
> fuel in *any* aircraft.

It is amazing what the mind can do once it decides that something is
true. Look at all of the drug test results on the large sheet you now
get with prescription drugs. Many show the results of both the placebo
and the drug during the studies. I'm always amazed at how much the
placebo "helps" as compared to the real drug. People who think they are
taking the drug get better also!

If you think mogas will reduce your power, then your mind will make it
happen. :-)

Matt

[Matt Whiting]

Morgans wrote:
> "Jay Honeck" > wrote
>
>> I know you probably realize this, but your observation makes no
>> sense. There is no difference in "power" between avgas and mogas.
>
>
> Actually, there are slightly more BTU's in a gallon of mogas than in a
> gallon of avgas.
>
> If an engine was to have its fixed advanced spark too far forward, the lower
> octane mogas could produce less power.

How so?

Matt

[Morgans[_2_]]

"Matt Whiting"> wrote >

> How so?

Whem I was much younger, an all cars had points and condensers, I would do
my own tune-ups.

Sometimes the timing would need to be adjusted. How to do it, if you did
not have a timing light handy?

I would loosen the distributor bolt, until it was tight enough to move by
hand, but not so loose that it would not vibrate around. After that, I
would get the engine warmed up, and take it out on the road, and punch it.
It was not so obvious if the timing was retarded a bit, until it was really
retarded. It was _quite_ obvious when it was too far advanced, as would not
have much power, and would knock like crazy.

That a good enough answer?
--
Jim in NC

[Matt Whiting]

Morgans wrote:
> "Matt Whiting"> wrote >
>
>> How so?
>
> Whem I was much younger, an all cars had points and condensers, I would do
> my own tune-ups.
>
> Sometimes the timing would need to be adjusted. How to do it, if you did
> not have a timing light handy?
>
> I would loosen the distributor bolt, until it was tight enough to move by
> hand, but not so loose that it would not vibrate around. After that, I
> would get the engine warmed up, and take it out on the road, and punch it.
> It was not so obvious if the timing was retarded a bit, until it was really
> retarded. It was _quite_ obvious when it was too far advanced, as would not
> have much power, and would knock like crazy.
>
> That a good enough answer?

Maybe to another question. You didn't address why having the timing
advanced too far would cause a greater power loss with mogas than with
avgas. And noise from igniting the mixture too soon and detonation are
two different phenomenon.

Matt

[Morgans[_2_]]

"Matt Whiting" <> wrote

> Maybe to another question. You didn't address why having the timing
> advanced too far would cause a greater power loss with mogas than with
> avgas. And noise from igniting the mixture too soon and detonation are
> two different phenomenon.

Sorry, I'll try again.

The higher octane of 100LL will allow more advanced spark settings without
knock and detonation, than will the lower octane mogas.

End result would be that the mogas could show a loss of power, when avgas is
still allowing the engine to function normally.

I don't disagree with the fact that in normal conditions, and a normal
engine, the power of an engine running 100LL or mogas should be virtually
the same.
--
Jim in NC

[Matt Whiting]

Morgans wrote:
> "Matt Whiting" <> wrote
>
>> Maybe to another question. You didn't address why having the timing
>> advanced too far would cause a greater power loss with mogas than with
>> avgas. And noise from igniting the mixture too soon and detonation are
>> two different phenomenon.
>
> Sorry, I'll try again.
>
> The higher octane of 100LL will allow more advanced spark settings without
> knock and detonation, than will the lower octane mogas.
>
> End result would be that the mogas could show a loss of power, when avgas is
> still allowing the engine to function normally.


This is only true for engines that have very advanced ignition timing,
which isn't true for most GA piston engines, or engines with very high
compression ratios, again, not true for most GA piston engines. Keep in
mind that most were designed to run on 80 octane avgas...


> I don't disagree with the fact that in normal conditions, and a normal
> engine, the power of an engine running 100LL or mogas should be virtually
> the same.

Yes, I can't imagine many GA piston engines where this wouldn't be the
case. Maybe a turbocharged engine running very hot.

Matt

[Ray Andraka]

Jay Honeck wrote:

>
> All good ideas. I, too, have often wondered why I have all the data
> in the world on my JPI engine analyzer, but no "under-the-cowl"
> temperature readings.
>

Jay, there's no reason you couldn't take one of the unused channels and
put a thermocouple on it. Hmm, maybe not. If you put it on the IAT, I
think that will change the carb temp to TIT. That's assuming you have
the oil temp, OAT, and carb temp probes like I do.

[Ray Andraka]

Matt Whiting wrote:


>
> This is only true for engines that have very advanced ignition timing,
> which isn't true for most GA piston engines, or engines with very high
> compression ratios, again, not true for most GA piston engines. Keep in
> mind that most were designed to run on 80 octane avgas...
>
>
>> I don't disagree with the fact that in normal conditions, and a normal
>> engine, the power of an engine running 100LL or mogas should be
>> virtually the same.
>
>
> Yes, I can't imagine many GA piston engines where this wouldn't be the
> case. Maybe a turbocharged engine running very hot.
>
> Matt

There are plenty of high compression GA piston engines that can't use
mogas because the octane requirement is too high. The majority of GA
engines are lower octane (something like 78% of the engines IIRC). The
majority of the hours flown in piston aircraft however is done by the
21% of aircraft that have higher octane requirements than mogas can
offer, my 260 HP O-540-E4B5 included. It is a normally aspirated 6
cylinder engine, but with high enough compression that there is not
sufficient detonation margin with less than 96 octane fuel.

[Matt Whiting]

Ray Andraka wrote:
> Matt Whiting wrote:
>
>
>>
>> This is only true for engines that have very advanced ignition timing,
>> which isn't true for most GA piston engines, or engines with very high
>> compression ratios, again, not true for most GA piston engines. Keep
>> in mind that most were designed to run on 80 octane avgas...
>>
>>
>>> I don't disagree with the fact that in normal conditions, and a
>>> normal engine, the power of an engine running 100LL or mogas should
>>> be virtually the same.
>>
>>
>> Yes, I can't imagine many GA piston engines where this wouldn't be the
>> case. Maybe a turbocharged engine running very hot.
>>
>> Matt
>
> There are plenty of high compression GA piston engines that can't use
> mogas because the octane requirement is too high. The majority of GA
> engines are lower octane (something like 78% of the engines IIRC). The
> majority of the hours flown in piston aircraft however is done by the
> 21% of aircraft that have higher octane requirements than mogas can
> offer, my 260 HP O-540-E4B5 included. It is a normally aspirated 6
> cylinder engine, but with high enough compression that there is not
> sufficient detonation margin with less than 96 octane fuel.

I'd like to see your source of these statistics.

Matt

[Ray Andraka]

Matt Whiting wrote:
> Ray Andraka wrote:
>
>> Matt Whiting wrote:
>>
>>
>>>
>>> This is only true for engines that have very advanced ignition
>>> timing, which isn't true for most GA piston engines, or engines with
>>> very high compression ratios, again, not true for most GA piston
>>> engines. Keep in mind that most were designed to run on 80 octane
>>> avgas...
>>>
>>>
>>>> I don't disagree with the fact that in normal conditions, and a
>>>> normal engine, the power of an engine running 100LL or mogas should
>>>> be virtually the same.
>>>
>>>
>>>
>>> Yes, I can't imagine many GA piston engines where this wouldn't be
>>> the case. Maybe a turbocharged engine running very hot.
>>>
>>> Matt
>>
>>
>> There are plenty of high compression GA piston engines that can't use
>> mogas because the octane requirement is too high. The majority of GA
>> engines are lower octane (something like 78% of the engines IIRC).
>> The majority of the hours flown in piston aircraft however is done by
>> the 21% of aircraft that have higher octane requirements than mogas
>> can offer, my 260 HP O-540-E4B5 included. It is a normally aspirated
>> 6 cylinder engine, but with high enough compression that there is not
>> sufficient detonation margin with less than 96 octane fuel.
>
>
> I'd like to see your source of these statistics.
>
> Matt

I believe the numbers were from AOPA. I'd have to do some digging to
find them now. Those are the approximate numbers they were throwing
around about a year ago.