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87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: rrp0403 ()
Date: January 05, 2018 03:36AM

I've read that corvairs typically run better and are designed for premium gas, but all the registered premium brands around me are ethanol gasoline. Would I be better off using 87 ethanol free gas, the premium 93 or the unregistered 91 octane ethanol free gas that is sold at a reputable marine gas station?

Asking for a friend.

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Re: 87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: JimBrandberg ()
Date: January 05, 2018 04:05AM

Around here we only have 87 ethanol, 89 ethanol and 91 non-oxy. A Scion guy said Amoco has 92 non-ethanol.
I try to put in 91 non-oxy for winter storage and then whatever octane the engine will bear without pinging during regular use. Maybe 87 for a 80 or 95 HP; 89 for a 102 or 110 HP; 91 for a 180; maybe 89 for a 140 but probably 91.
Around here 89 used to be only a few cents more than 87 but the last year or two it's about a 10 cent hike. The 91 is another 20 cents or so. It's a different decision for a daily driver than for occasional use.
I don't know about marine gas. When I wondered about low lead aviation gas 15 years ago, my racing buddy said the av-gas has different properties, I didn't dwell on it but just accepted his advice.
87 ethanol free is not available here that I know of, it would be nice for the lawn mower, snow blower and chain saw.
I think the Minnesota gas situation is driven by the corn squeezing lobbyists.
It will be nice to read other opinions.
Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: 87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: vairmech ()
Date: January 05, 2018 04:40AM

Yes, aviation fuel has different properties and the 100LL works quite well in a Corvair! The 87 aviation fuel WILL spark knock in a Corvair!
If that gets a little expensive you can get very good results by mixing 50/50 with 87 octane and if you use premium gas you can go to a 25% of 100LL.
This is for the stock HP engines and most 110/102 engines.
The aviation fuel is also good for storage.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: 87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: Wagon Master ()
Date: January 05, 2018 05:42AM

Ironically the only ethanol free fuel around here is 90 octane, available at the local grain elevator co-op.

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Re: 87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: Melb-Mike ()
Date: January 05, 2018 05:42AM

I buy AV-gas from our local airport for $3.99/gal. It is the 100 LL gas. However I've been told it isn't really 100 octane but more like 94 octane. Also, the gas has been oxygenated since aircraft fly at higher altitudes. If you have a high compression engine, it could cause a lean condition. At least that's what my race gas supplier told me. I ran it in my Lotus race car & did notice my AFE gauge showing a leaner reading at times but never caused me a problem. And all my Corvairs love the AV-gas. No knocking at all, even on a hot day with the A/C on at low rpm.

In North Carolina, a lot of gas stations sell ethanol free gas but I never checked to see if any offer different octane. In Florida, very few stations sell ethanol free.

64 Greenbrier
64 Spyder (needs restoration)
65 Corsa 140, restored
66 Corsa turbo, restoring now
66 Corsa 140 "RR" code coupe fully restored
67 Pontiac GTO restored
69 Corvette 427 convertible restored
2004 Caterham R400 (Lotus super7)my race car
2015 Porsche Panamera S
2015 Corvette Z06
1965 AC Cobra (Factory Five)

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Re: 87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: triumphcorvair ()
Date: January 05, 2018 05:42AM

I've been using AVGAS in my 71 Triumph Bonneville now for the past 3 years. Yes, it is a bit pricey but I'm willing to forgo the expense of the gas versus the expense of gummed up parts since I'm only using it while the bike is in storage.

It kicks over on the first try after sitting for a while so I have no complaints. Not sure I would be able to put it in my Vair as I would be broke.

Darrell McCracken
Huntsville, Texas

65 140 Monza
71 Triumph Bonneville

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Re: 87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: red monza ()
Date: January 05, 2018 06:09AM

We can get ethanol free regular gas and premium gas...but just at a few stations, the regular competes with premium with ethanol in it price wise. I have to run Premium in 4 of my vehicles. My corvette has 11.15 to 1 compression ratio.Two of the 4 are corvairs and I prefer premium in them...tried 91 octane once and it kept running after cutting it off and I could tell it had less power.

My question is this....why do we have 3 grades of gas...we only need two, regular and premium...my guess is that its a way to increase the price of premium. Sams Club gas stations only have the two and it stays full of cars buying gas.

Sams Club....reg is 2.32 premium is 2.65...difference 33 cents
Citgo........reg is 2.29 premium is 2.89...difference 60 cents...Citgo has the 3 tier gas rip off...I am not sure but will pay more attention next time, the jobbers only have 3 hoses coming off their trucks...one is diesel and the other two?????

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Re: 87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: curt ()
Date: January 05, 2018 06:48AM

My understanding is the higher octane has a lower vapor pressure than the lower octane gas. I never had vapor lock till I got 93 octane non ethanol when on a road trip.

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Re: 87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: corvairsince70 ()
Date: January 05, 2018 06:52AM

I search around for stations selling no-ethanol premium (93 octane). They are around. Use this web site to find them in your area.

pure-gas.org

Dennis
Nashville area
'68 Conv 140 PG
'66 Corsa Conv 180
'66 Corsa 140

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Re: 87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: Frank DuVal ()
Date: January 05, 2018 07:33AM

There used to be three tanks in the ground for the three octanes available at the pump. Even back in the late 60s at some name brand stations.

Now, blender pumps are all the rage, as in-ground tank rules are severe. Two tanks easier to upkeep and report than three tanks. You push a button on the pump and it blends regular (whatever regular is in your altitude, 87 here) with premium.

There is a 7-11 in Richmond (Short Pump area) that has buttons for : 87, 88, 89, 90, 91, 92, 93. I should post a picture when I find it.

Blender pump must have also been the Sunoco 260 pump back in the 60s with all those choices on a lever.

Frank DuVal

Fredericksburg, VA

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Re: 87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: EM-racer ()
Date: January 05, 2018 08:21AM

To those of you that use AVGAS for street use remember it is not legal as AVGAS does not have road taxes. I use it in my autocross car that is trailered to all events
Gene Barr
Eustis, Fl.

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Re: 87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: Phil Dally ()
Date: January 05, 2018 08:40AM

Running CA street legal unleaded VP 101 available at the pump from the VP retail store.

SuperVair REALLY likes it and it should at $9.99 per gallon!!


[vpracingfuels.com]

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Re: 87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: 66vairman ()
Date: January 05, 2018 08:42AM

rrp0403 Wrote:
-------------------------------------------------------
> I've read that corvairs typically run better and
> are designed for premium gas, but all the
> registered premium brands around me are ethanol
> gasoline. Would I be better off using 87 ethanol
> free gas, the premium 93 or the unregistered 91
> octane ethanol free gas that is sold at a
> reputable marine gas station?
>
> Asking for a friend.

First --- you don't say what Corvair engine you have. There were Corvair's sold with engines that used regular gasoline. If you have a higher output engine then you should use higher octane fuel.

As for the ethanol hysteria -- Amazingly I've been burning ethanol blended fuels (as most Corvair owners do) with ZERO problems. Of course you need to install fuel hoses that tolerate ethanol (Gates Barricade hose).

When lead was removed from gasoline the refineries increased the octane through refining that did make gasoline more volatile. This was decades ago and now REID vapor pressure actually changes with the season to promote better Winter starting and resist vapor lock conditions in the summer. That said the common use of fuel injection allowed gasoline to be more volatile, or more prone to evaporate out of carburetor bowls after an engine shut down. Solution - install an electric fuel pump.

As for buying AVGAS - AVGAS is exempt from road or automotive/truck transport taxes and therefore is ILLEGAL to purchase for use in an automobile or truck. The loophole is that it can be sold in containers as long as the seller believes it will NOT be put into an automobile.

If you have an O2 sensor (some folks upgrade to fuel injection, or use a wide band sensor for tuning, etc.) the 100LL AVGAS will contaminate the sensor. It also shortens spark plug life.

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Re: 87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: Melb-Mike ()
Date: January 05, 2018 11:57AM

You can burn 87 octane in a CORVAIR but those who have the Corsa 140 HP engine will get knocking especially during hot weather. Two of my cars have the 140 HP engine the Corsa with A/C knocks terribly when running the A/C in summer. I usually blend about 4 to 5 gal of AVGAS to premium gas. To those who are concerned about my neglecting to pay road taxes on this, worry about something else.

With regards to Oxygen sensors getting fouled with 100LL, it isn't a major issue since the amount of lead is very very low. Blended fuels reduce it further. With regards to spark plugs needing more frequent replacing, it's likely true but is that a major hurdle in cars like ours who typically consume plugs every 12,000 to 15,000 miles ? Most of us don't use our Corvairs as daily drivers. Anyway, air cooled engines in airplanes (Lycomming and Continental) don't have issue with plug fouling and these engines, aside from being dual plugs, are very similar to ours. I really don't see a problem but to each his own.

64 Greenbrier
64 Spyder (needs restoration)
65 Corsa 140, restored
66 Corsa turbo, restoring now
66 Corsa 140 "RR" code coupe fully restored
67 Pontiac GTO restored
69 Corvette 427 convertible restored
2004 Caterham R400 (Lotus super7)my race car
2015 Porsche Panamera S
2015 Corvette Z06
1965 AC Cobra (Factory Five)

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Re: 87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: Frank DuVal ()
Date: January 05, 2018 03:16PM

Mike, I do not worry about that tax. I do worry why you do not run premium fuel in your 140s. They need it. The design of the engine is to use premium of the day. If you retard the timing to run regular, you are losing HP and running hotter! Knocking is bad. Now, if I misread what you wrote, and you are running premium and still knocking, so adding some "octane booster" from the airport, ignore my comments.....

Frank DuVal

Fredericksburg, VA

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Re: 87 octane ethanol free vs 93 octane premium vs 91 octane ethanol free boat gas
Posted by: Melb-Mike ()
Date: January 06, 2018 05:27AM

Frank, I do run 93 octane fuel in all the Corvairs but the one (66 Corsa) with A/C still knocks at low rpm so I blend some 100LL with it.

64 Greenbrier
64 Spyder (needs restoration)
65 Corsa 140, restored
66 Corsa turbo, restoring now
66 Corsa 140 "RR" code coupe fully restored
67 Pontiac GTO restored
69 Corvette 427 convertible restored
2004 Caterham R400 (Lotus super7)my race car
2015 Porsche Panamera S
2015 Corvette Z06
1965 AC Cobra (Factory Five)

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