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06-24-2016, 02:10 PM | #1 |
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93 Octane or 87 Octane?
Heard someone saying that modern 93 octane gasoline should not be used in our old flatheads. Is there any difference or hazard in using 93 instead of 87 octane?
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06-24-2016, 02:35 PM | #2 |
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Re: 93 Octane or 87 Octane?
Higher octane then you need is a waste of money but not going to hurt anything.
It´s all the non gasoline stuff in the fuel that is no good today. Last edited by flatheadmurre; 06-24-2016 at 03:45 PM. |
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06-24-2016, 02:50 PM | #3 |
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Re: 93 Octane or 87 Octane?
Octane requirements are determined by things like compression ratio, timing advance, etc. A higher octane fuel burns at a slower rate and using a higher rating than your engine needs is of no advantage.
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06-24-2016, 03:16 PM | #4 |
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Re: 93 Octane or 87 Octane?
I've heard in most places premium (93) doesn't have the ethanol/water/corn in it.
That being better for everything over all. |
06-24-2016, 03:46 PM | #5 | |
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Re: 93 Octane or 87 Octane?
Quote:
Anything (octane) more than what is necessary is a waste of $$$.
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06-24-2016, 03:47 PM | #6 | |
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Re: 93 Octane or 87 Octane?
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Quote:
There is a race track (drag strip) near here and at one local station "racing fuel" can be purchased. It does not have ethanol added to it. Of course, it is around $5 / gallon
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06-24-2016, 04:43 PM | #7 |
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Re: 93 Octane or 87 Octane?
Thanks guys. I have been using the 87.
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06-24-2016, 04:55 PM | #8 |
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Re: 93 Octane or 87 Octane?
Your lucky, our race gas is $9.19 a gallon in good old Calif......
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06-24-2016, 07:16 PM | #9 |
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Re: 93 Octane or 87 Octane?
Tony, in each case I think you have to do your local research.
Out here the highest octane gas is the leaded 100 octane aviation fuel. (not legal on the road because we pay road tax when buying fuel) The next highest and road legal is a 98 octane ethanol blend. then there are fuels that run around 95 octane, high in aromatics, but no ethanol (my choice) the lowest octane rating available here is 91 and is the most used fuel here. Interestingly the handbooks for my various two stroke implements (world famous and orange coloured) suggest using the higher octane fuel (95) because it has less impurities in it. These variations come from locally blended and imported fuels (international companies and local companies) Of course your local fuel suppliers will deliver an entirely different set of specs to the market. Essentially the Octane rating is the "anti knock" value of the fuel. My understanding is that a high octane rating means the fuel burns slower. (the flame front travels slower from the point of ignition through the fuel mix in the combustion chamber) This is of little consequence in a flattie that was built to use fuel of about 68 octane and had a compression ratio of about 6:1. Today's fuel has you well covered here. In a High compression engine say 11:1 the conditions are such that the flame front will travel through the fuel air mix so fast that it would cause catastrophic damage. The "anti knock" additive in the fuel stops this. The "anti knock" additive translates into the Octane rating. My disclaimer: You should try to stick with one spec (of fuel) and adjust your timing (vacuum brake) accordingly. (You probably wouldn't notice the difference) Last edited by Bluebell; 06-24-2016 at 07:23 PM. |
06-24-2016, 09:28 PM | #10 |
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Re: 93 Octane or 87 Octane?
I obtained a carb and mechanical pump rebuilt with components that avoid the problems associated with ethanol gas. My engine is a stock 59AB and starts/runs very nicely on 87 octane ethanol gas. Here we currently pay 2.21 per gallon for that. 91 octane non-ethanol is available but costs about 80 to 90 cents more per gallon, AND one has to drive a half hour each way to get it.
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06-24-2016, 10:09 PM | #11 |
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Re: 93 Octane or 87 Octane?
Tony,
I highly suggest you find non-ethanol gas if you can. I don't drive my old cars often, or very far, so a few 5-gallon jugs of the good stuff is all I need. Occasionally I drive to Peru,IL for work and I fill up my gas cans with non-ethanol. the website below lists stations in IL where you can get alcohol-free gas. I see there is a listing in Decatur, maybe not too far from you http://www.pure-gas.org/index.jsp?stateprov=IL |
06-24-2016, 10:31 PM | #12 | |
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Re: 93 Octane or 87 Octane?
Quote:
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06-24-2016, 10:38 PM | #13 |
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Re: 93 Octane or 87 Octane?
Well I'll say this Kube.
Most gas stations in and around where I live state that on there gas pumps 93 oct. 99 out of 100 times is ethanol free. I truely believe it's not needed in our fuel. I've spoke with guys that have worked on old cars longer than I've been living. They've said they've changed out more gas tanks on these old cars since the new use of ethanol in the fuel than ever before. To me that says something. Fuel lines,rubber hoses,rubber diaphragm,fuel pump valves etc. |
06-25-2016, 12:42 AM | #14 |
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Re: 93 Octane or 87 Octane?
Thanks for all the good info. Appreciate all. TM
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06-25-2016, 07:17 AM | #15 |
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Re: 93 Octane or 87 Octane?
In Kansas gas is specifically marked as non-ethanol or the percent it is. Non-ethanol requires a separate hose or there would be mixing with the ethanol fuel. (old photo, not current gas prices!)
Last edited by JSeery; 06-25-2016 at 07:23 AM. |
06-25-2016, 07:45 AM | #16 |
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Re: 93 Octane or 87 Octane?
I wish I could find non ethanol 87 near me.
I'd use it for sure. |
06-25-2016, 11:28 AM | #17 | |
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Re: 93 Octane or 87 Octane?
Quote:
Thanks Scott. Peru is right down the road a bit. A straight shot down I-80. |
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06-25-2016, 12:44 PM | #18 |
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Re: 93 Octane or 87 Octane?
In Iowa you can get it most stations without alcohol. Costs 30 cents extra most places.
I use it the old cars and my outboard motor. |
06-25-2016, 12:51 PM | #19 | |
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Re: 93 Octane or 87 Octane?
Quote:
If your area allows ethanol free fuel, great, I'd use it myself. I know in some highly rural farm areas such fuel is available. In the metropolitan areas, it is restricted regardless of octane. The only exception that I am aware of is racing fuel.
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06-25-2016, 01:18 PM | #20 |
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Re: 93 Octane or 87 Octane?
Kube it is becoming more common in larger cities. Used in lawn equipment etc.
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06-25-2016, 01:56 PM | #21 |
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Re: 93 Octane or 87 Octane?
We have several stations here in Oshkosh that sell ethanol free fuel. Only about 5 cents more per gallon.
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06-25-2016, 04:16 PM | #22 |
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Re: 93 Octane or 87 Octane?
As flatjack sees it differently, I thought I'd paste this link:
https://www.fuelfreedom.org/what-is-octane/ To achieve the octane rating Tetra ethyl lead was added to the fuel. It is nasty stuff. This is the lead that was removed from the fuel. It had the benefit of lubricating the valves and seats. I don't know what additive is used these days to achieve the required "octane rating", but nowadays (generally speaking) hardened valve seats are required where they may have never had them. (off topic) |
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06-25-2016, 04:42 PM | #23 |
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Re: 93 Octane or 87 Octane?
"Actually octane is a hydrocarbon that is blended into fuel to prevent it from auto igniting. It's use maintains an orderly flame front across the combustion chamber. The octane rating is used to rate the performance of the particular fuel being used."
An iso-octane mixture is made in many refineries in a unit called an Alkylation unit. BTW an octane rating is a measure of the resistance of gasoline to ignition. The higher the octane rating the more resistant to ignition. The unknown sample is compared to a mixture of iso-octane with a rating of 100 and n-heptane with a rating of 0. |
06-25-2016, 06:37 PM | #24 | |
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Re: 93 Octane or 87 Octane?
Quote:
When I drove thru Iowa a while ago (heart of cornbelt and many ethanol plants), I was confused by there being two 89 octane choices, one that cost 25 -30 cents more. It was not identified as non-alcohol, so I asked the clerks. None of them could tell me the difference. On my way out, a local told me that the higher-priced stuff was indeed alcohol-free.
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06-25-2016, 08:58 PM | #25 |
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Re: 93 Octane or 87 Octane?
Now I'd like to hear or read a good explanation why ethanol free would be more expensive.
The process involved in making ethanol has got to be none cost effective. |
06-25-2016, 09:02 PM | #26 |
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Re: 93 Octane or 87 Octane?
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06-25-2016, 10:33 PM | #27 |
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Re: 93 Octane or 87 Octane?
Supply and demand, supply and demand.
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06-26-2016, 09:50 AM | #28 |
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Re: 93 Octane or 87 Octane?
In my area the Kwik Trip gas stations have a separate pump for Recreational Gas that has no ethanol.
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06-26-2016, 06:08 PM | #29 |
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Re: 93 Octane or 87 Octane?
Yoy might want to remember the lower the octane, the more BYU's of heat per pound of fuel. Therefore, you get better mileage with the lowest fuel your engine can run on.However, engines with higher compression ratios need a better fuel. These engines are more efficient and therefore may get better fule mileage. Combustion chambers also have Octane numbers. Thats why I like to have a tight chamber, this improve turbulence and allows a hier compression with a lower Octane fuel. Kinda like chasing your tail
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08-15-2016, 12:00 AM | #30 | |
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Re: 93 Octane or 87 Octane?
Quote:
Also 87 octane goes bad after two weeks. I don't even use it in my Benz, or my 86 Laser Turbo. |
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08-15-2016, 02:58 AM | #31 |
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Re: 93 Octane or 87 Octane?
And then, I also grew up with gas and oil. We signed up with Atlantic Richfield that
went to Atlantic the ARCO. I think there were 3) 5,000 gal tanks. Being a curious kid, don't you think I would see the truck driver flipping valves or something on the tanker?? No he just stuck the hose in the next tank. Then comming into the 1960's 1970's the big thing was the so called sealer of weights and measures. He would fill a glass jug to make sure the pump pumped an exact gal. Next stick test tubes in the gas to check the grade if good he puts a sticker on the pump. This full service gas station / shop is right across the street. I'm always over there I see no stickers on pumps and yet to see delivery guy flipping any valves. Am I missing something? It wouldn't surprise me one bit if you know what I'm thinking. Guess there are no more gas cops but pull in a weight station and they will stick test tubes in ya diesel... |
08-15-2016, 09:41 AM | #32 |
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Re: 93 Octane or 87 Octane?
Busting the myth: High octane gasoline is not necessarily more expensive than low octane gasoline, because the octane rating of a fuel can be manipulated in inexpensive ways, for example, the addition of water to fuel will raise the octane rating. Gasoline with ethanol added will have a higher octane rating because ethanol contains water, and attracts water, while gasoline does not. Therefore, buying fuel on the basis of its octane rating is merely an in dictation of how fast a fuel will burn, not how the octane rating was achieved.
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