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I should add that yes, as Bob Spidell stated, there=E2=80=99s no actual =
thing as =E2=80=9Caviation unleaded=E2=80=9D but at least theoretically =
the fuel suppliers control RVP, etc to the ASTM specs required by the =
FAA-issued STC=E2=80=99s for aircraft use. In fact, the refineries and =
distributors are supposed to maintain specific trucks only to deliver =
car gas for aircraft use to avoid any cross-contamination. It carries =
no road tax (a huge part of car gas prices) but the cost of the separate =
refinery streams and distribution costs still price it well over a buck =
a gallon more than car gas at a nearby gas station. Our airport sells =
mogas for $4.30 per gallon. Costco had 93 octane for $3.30 the other =
day.
=20
In my limited experience our airport=E2=80=99s car gas has been very =
consistent. But I don=E2=80=99t have an auto gas STC for my present =
plane because 100 LL works fine for me and there=E2=80=99s little price =
difference. And I=E2=80=99m sure that 100 LL is pretty consistent =
across the country. Not too sure what I=E2=80=99d get out of a mogas =
pump at some unfamiliar airport.
=20
As they say, YMMV
=20
=20
From: Karl Vacek [mailto:Stearman809@GMail.com]=20
Sent: Monday, August 26, 2019 12:22 PM
To: shop-talk@autox.team.net
Subject: RE: [Shop-talk] Electric String Trimmers
=20
The gas I buy at the airport for my lawn equipment is indeed aviation =
unleaded. In the early 1980=E2=80=99s the EAA ran a project to prove =
that low-compression aircraft engines could safely run on unleaded car =
gas. Peterson Aviation in Nebraska did a similar project. Both sell =
STC=E2=80=99s to allow use of that specific fuel in applicable aircraft. =
Basically a permit to allow the use of unleaded auto fuel a specific in =
aircraft under specified conditions.
=20
The wide marketing of gasohol soon after the STC=E2=80=99s became =
available caused issues =E2=80=93 the FAA permission is ONLY for =
straight unleaded =E2=80=93 no alcohol. Here in the Peoples Republic of =
Illinois the corn lobby has us inundated with gasohol, and there are =
only a handful of places in the state where you can fill up a car or =
truck with ethanol-free car gas.
=20
For use in those planes so certificated, many airports now carry =
=E2=80=9Caviation mogas=E2=80=9D =E2=80=93 regular unleaded without =
alcohol. It=E2=80=99s not to be sold for on-road vehicles, just planes. =
And airports can legally pump it into cans for small-engine use.
=20
I have plenty of the blue stuff (100 LL) in the Stearman, but =
haven=E2=80=99t ever put it in any lawn equipment. Almost the same =
price, so that=E2=80=99s not the issue, but my lawn equipment just =
doesn=E2=80=99t need lead. Even my 3-wheel Harley (well, it=E2=80=99s a =
2-cycle Harley Davidson golf cart) uses unleaded just fine.
=20
Used to be better to use 80 octane (red) but that=E2=80=99s pretty much =
gone today. That was good for mowers, etc. too. As noted, 100 LL has =
4x the lead of old 80 octane, so lead fouling can be an issue in =
aircraft engines. Some guys who have the auto fuel STC even run 75% =
auto gas and 25% 100 LL to simulate old 80 octane. When 80 octane went =
away and 80 octane engines that to switch to 100 LL, many pilots =
experienced lead-fouling issues, and many top overhauls were done. =
Sometimes guys lapped the guides with the cylinder in place too. But =
that=E2=80=99s largely over now, as most engines have appropriate valves =
and guides to allow regular use of 100 LL. Personally I=E2=80=99ve not =
had an issue with 100 LL in my engine, which has stock WWII era valves =
and guides, and I have indeed had occasion to pull three cylinders over =
the years and disassemble the valves, with no lead fouling issues =
present.
=20
As far as purple gas being available at Warbird events, I=E2=80=99ve not =
ever seen it, but my Stearman is at the lower end of the Warbird =
spectrum. We do have a Grumman TBM Avenger on the field, and Tom uses =
100 LL in that =E2=80=93 it=E2=80=99s got a Wright 2600-20 (1900 HP). =
And P-51=E2=80=99s regularly fill up with 100 LL. Maybe the purple =
stuff is available sometimes, but not commonly, and as far as I know =
most Warbird engines run fine on 100 LL.
=20
One of the things that allowed higher boost pressures during WWII was =
water injection. That=E2=80=99s still an option.
=20
Thanks !!
Karl
=20
=20
=20
Subject: Re: [Shop-talk] Electric String Trimmers
=20
Keep in mind that Low Lead Avgas, like 100LL, still has 4x the amount of =
lead that standard automotive gas contained. The guys who run this =
stuff in race cars and the like often report issues with lead deposits =
on valve stems and seats. I have personally see a valve stem so leaded =
up that it stuck open. Use at your own risk.
=20
It was probably blue, and it was probably 100LL. Half the lead of most=20
of the earlier grades, most everyone's pretty much still standardized on =
this.
Some places and applications (warbird events?) you may find more heavily =
leaded super-sauce for your high-boost blown motors. The reason the=20
Merlin went from 800HP to 1700+HP in production was all that sweet,=20
sweet American leaded 130-octane gasoline.
John
=20
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</o:shapelayout></xml><![endif]--></head><body lang=3DEN-US link=3Dblue =
vlink=3Dpurple><div class=3DWordSection1><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'>I should add that yes, as Bob Spidell stated, there=E2=80=99s no =
actual thing as =E2=80=9Caviation unleaded=E2=80=9D but at least =
theoretically the fuel suppliers control RVP, etc to the ASTM specs =
required by the FAA-issued STC=E2=80=99s for aircraft use.=C2=A0 In =
fact, the refineries and distributors are supposed to maintain specific =
trucks only to deliver car gas for aircraft use to avoid any =
cross-contamination.=C2=A0 It carries no road tax (a huge part of car =
gas prices) but the cost of the separate refinery streams and =
distribution costs still price it well over a buck a gallon more than =
car gas at a nearby gas station.=C2=A0 Our airport sells mogas for $4.30 =
per gallon.=C2=A0 Costco had 93 octane for $3.30=C2=A0 the other =
day.<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'><o:p> </o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'>In my limited experience our airport=E2=80=99s car gas has been very =
consistent.=C2=A0 But I don=E2=80=99t have an auto gas STC for my =
present plane because 100 LL works fine for me and there=E2=80=99s =
little price difference.=C2=A0 And I=E2=80=99m sure that 100 LL is =
pretty consistent across the country.=C2=A0 Not too sure what =
I=E2=80=99d get out of a mogas pump at some unfamiliar =
airport.<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'><o:p> </o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'>As they say, YMMV<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'><o:p> </o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'><o:p> </o:p></span></p><div><div =
style=3D'border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in =
0in 0in'><p class=3DMsoNormal><b><span =
style=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span>=
</b><span style=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif"'> =
Karl Vacek [mailto:Stearman809@GMail.com] <br><b>Sent:</b> Monday, =
August 26, 2019 12:22 PM<br><b>To:</b> =
shop-talk@autox.team.net<br><b>Subject:</b> RE: [Shop-talk] Electric =
String Trimmers<o:p></o:p></span></p></div></div><p =
class=3DMsoNormal><o:p> </o:p></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'>The gas I buy at the airport for my lawn equipment is indeed aviation =
unleaded. In the early 1980=E2=80=99s the EAA ran a project to =
prove that low-compression aircraft engines could safely run on unleaded =
car gas. Peterson Aviation in Nebraska did a similar =
project. Both sell STC=E2=80=99s to allow use of that specific =
fuel in applicable aircraft. Basically a permit to allow the use =
of unleaded auto fuel a specific in aircraft under specified =
conditions.<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'><o:p> </o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'>The wide marketing of gasohol soon after the STC=E2=80=99s became =
available caused issues =E2=80=93 the FAA permission is ONLY for =
straight unleaded =E2=80=93 no alcohol. Here in the Peoples =
Republic of Illinois the corn lobby has us inundated with gasohol, and =
there are only a handful of places in the state where you can fill up a =
car or truck with ethanol-free car gas.<o:p></o:p></span></p><p =
class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'><o:p> </o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'>For use in those planes so certificated, many airports now carry =
=E2=80=9Caviation mogas=E2=80=9D =E2=80=93 regular unleaded without =
alcohol. It=E2=80=99s not to be sold for on-road vehicles, just =
planes. And airports can legally pump it into cans for =
small-engine use.<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'><o:p> </o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'>I have plenty of the blue stuff (100 LL) in the Stearman, but =
haven=E2=80=99t ever put it in any lawn equipment. Almost the same =
price, so that=E2=80=99s not the issue, but my lawn equipment just =
doesn=E2=80=99t need lead. Even my 3-wheel Harley (well, =
it=E2=80=99s a 2-cycle Harley Davidson golf cart) uses unleaded just =
fine.<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'><o:p> </o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'>Used to be better to use 80 octane (red) but that=E2=80=99s pretty =
much gone today. That was good for mowers, etc. too. As =
noted, 100 LL has 4x the lead of old 80 octane, so lead fouling can be =
an issue in aircraft engines. Some guys who have the auto fuel STC =
even run 75% auto gas and 25% 100 LL to simulate old 80 octane. =
When 80 octane went away and 80 octane engines that to switch to 100 LL, =
many pilots experienced lead-fouling issues, and many top overhauls were =
done. Sometimes guys lapped the guides with the cylinder in place =
too. But that=E2=80=99s largely over now, as most engines have =
appropriate valves and guides to allow regular use of 100 LL. =
Personally I=E2=80=99ve not had an issue with 100 LL in my engine, which =
has stock WWII era valves and guides, and I have indeed had occasion to =
pull three cylinders over the years and disassemble the valves, with no =
lead fouling issues present.<o:p></o:p></span></p><p =
class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'><o:p> </o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'>As far as purple gas being available at Warbird events, I=E2=80=99ve =
not ever seen it, but my Stearman is at the lower end of the Warbird =
spectrum. We do have a Grumman TBM Avenger on the field, and Tom =
uses 100 LL in that =E2=80=93 it=E2=80=99s got a Wright 2600-20 (1900 =
HP). And P-51=E2=80=99s regularly fill up with 100 LL. Maybe =
the purple stuff is available sometimes, but not commonly, and as far as =
I know most Warbird engines run fine on 100 LL.<o:p></o:p></span></p><p =
class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'><o:p> </o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'>One of the things that allowed higher boost pressures during WWII was =
water injection. That=E2=80=99s still an =
option.<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'><o:p> </o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'>Thanks !!<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'>Karl<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'><o:p> </o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'><o:p> </o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#44546=
A'><o:p> </o:p></span></p><p class=3DMsoNormal><b><span =
style=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif"'>Subject:</sp=
an></b><span =
style=3D'font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Re: =
[Shop-talk] Electric String Trimmers<o:p></o:p></span></p><p =
class=3DMsoNormal><o:p> </o:p></p><div><p class=3DMsoNormal>Keep in =
mind that Low Lead Avgas, like 100LL, still has 4x the amount of lead =
that standard automotive gas contained. The guys who run this =
stuff in race cars and the like often report issues with lead deposits =
on valve stems and seats. I have personally see a valve stem so =
leaded up that it stuck open. Use at your own =
risk.<o:p></o:p></p></div><p =
class=3DMsoNormal><o:p> </o:p></p><div><blockquote =
style=3D'border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in =
6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5=
.0pt'><p class=3DMsoNormal =
style=3D'mso-margin-top-alt:0in;margin-right:0in;margin-bottom:12.0pt;mar=
gin-left:11.4pt'><br>It was probably blue, and it was probably =
100LL. Half the lead of most <br>of the earlier grades, most =
everyone's pretty much still standardized on <br>this.<br><br>Some =
places and applications (warbird events?) you may find more heavily =
<br>leaded super-sauce for your high-boost blown motors. The =
reason the <br>Merlin went from 800HP to 1700+HP in production was all =
that sweet, <br>sweet American leaded 130-octane =
gasoline.<br><br>John<o:p></o:p></p></blockquote></div><div><p =
class=3DMsoNormal><o:p> </o:p></p></div></div></body></html>
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