Any years Fuel requirements for tired engines

[Jeff Rosansky CLC #28373]

Hello,

This is for our 55, but I'd think it would apply to just about everything.
Our 55 needs a minimum of 82 octane, which isn't a big deal.
But it got me wondering about tired engines. I haven't done a compression check, but the engine hasn't been opened so I'm sure the engine is tired.
Would a tired engine need more or less octane than new? I'm sure the compression is down so the original 8.5:1 isn't there anymore, so it won't need higher for that. But would a higher octane help get back what power she's lost by not having full compression?
This is entirely an academic question because anything I put in it will be fine. But it just got me wondering.

Thanks

[Big Fins]

I would just go with an 89 or 90 octane Deathanol free gasoline. That pretty much covers anything fro 7.5:1 up to 10:1 compression engines.

[Michael Petti]

I use ethanol free 90 octene. Engine runs better on it.

[dn010]

Ethanol free, tired or not!

[TJ Hopland]

I believe lower compression the lower octane requirement.   Look at a lot of the pre war stuff like tractors that were more in the 5:1 range, those especially once they were warmed up would run on just about anything including kerosene which the internet says is in the 20-50 range for octane rating.

Higher octane fuel in itself isn't going to help performance but it could allow things like more advanced timing or non ethanol that could help a bit. 

[Jeff Rosansky CLC #28373]

Thanks guys.
Ethanol free isn't realistic, so I've just been using mid-grade for the last 7 years.
Runs just fine.

I was just curious more than anything else.

Thanks again

[Big Fins]

Thanks guys.
Ethanol free isn't realistic, so I've just been using mid-grade for the last 7 years.
Runs just fine.

I was just curious more than anything else.

Thanks again

Why not? Or is just that The Show Me state is backward in it's thinking? Deathanol free is the only way to go.

[James Landi]

The higher octane prevents pre-ignition...so with an old engine with compromised compression, logically, lower octane would be ok based on the ASSUMPTION that less compression will create less heat--- however, many old cars have moderately compromised cooling systems (aka: rust in water jackets, clogged head gaskets that create hot spots in the head, scale in the radiator).   Therefore, using the highest octane might help to keep the engine from knocking under load during long drives in summer heat.  (I use a pint of Marvel Oil with each fill up--- helps hot old engines to start much faster-- when carb is  hot, the gasoline can often boil in the carburetor from sitting a top a heat soaked engine.... Marvel oil helps )

[Jeff Rosansky CLC #28373]

Why not? Or is just that The Show Me state is backward in it's thinking? Deathanol free is the only way to go.

Well, there are stations around. They aren't overly far, but just not in an area that I normally drive.
I realize ethanol isn't great, but what does ethanol free get me? Fortunately, both cars run just fine. I usually run mid-grade with a little Marvel's.
I drive the 70 somewhat spiritedly (if you can't hear the back barrels open up, what's the point of having them??), and I drive the 55 more respectfully.
What does ethanol free get me that I don't already have?

[Big Fins]

What does ethanol free get me that I don't already have?

It gets you a fuel pump diaphragm that doesn't rot away, fuel lines that don't collapse under suction, unless they are ethanol resistant lines, carburetor parts that don't swell and shrink when being left to soak in the mixture and mostly, there are no products to separate after sitting a while.

You do as you are comfortable doing sir. I learned the expensive way. It doesn't really have any effect on a modern fuel system. The materials used are designed to work with a certain blend mixture. Some can tolerate up to 85% deathanol.

[TJ Hopland]

Sitting is where ethanol really can get messy.  If you are able to drive regularly and cycle through it in many cases its fine.  That is one advantage to having a car that barely gets to the teens for MPG, it doesn't take that much driving to burn a tank of gas.   If you think or know its gonna sit is when its worth the extra cost and time to get the non ethanol stuff.     

[cadillacmike68]

Deathanol - Really???

[PHIL WHYTE CLC 14192]

Here in the UK you have the choice of any fuel as long as it has ethanol in it. It goes bad in no time at all.

[TJ Hopland]

USA was moving in the direction of ethanol in everything everywhere all the time but I think even before every state got it at all a few of the states that got it early had groups that successfully lobbied to have an option.  Here in MN it was the Minnesota Street Rod Association which is a fairly large group with I'm sure plenty of lawyers and politicians as members that knew how to navigate the process.  I'm pretty sure we were among the first states to have ethanol mandated in the early 90's and among the first if not the first to get the exception. 

The reason its premium grade is that satisfied the pro ethanol people that the higher cost would for the most part keep the average user using the ethanol stuff.  The hot rod people were likely mostly using premium anyway and small engine users the volume is small enough that the cost or 'pollution' was minimal.  As the later states got it they either knew there would be issues or after there were issues were able to look at the states that had it longer and had the exception and just more or less adopted the same premium option.      

[Big Fins]

Go back in time. Ethanol was used in the mid 1800's even.

https://clf.jhsph.edu/viewpoints/ethanol-timeline-how-we-got-here

And then, there is Portland OR.

https://en.wikipedia.org/wiki/Ethanol_fuel_in_the_United_States

[James Landi]

"Sitting is where ethanol really can get messy.  If you are able to drive regularly and cycle through it in many cases its fine.  That is one advantage to having a car that barely gets to the teens for MPG, it doesn't take that much driving to burn a tank of gas.   If you think or know its gonna sit is when its worth the extra cost and time to get the non ethanol stuff."  TJ   

I'm a shade tree mechanic, and I've rebuilt carburetors that were filled with a chemical that won't burn that accumulates on the bottom of a fuel tank--- it's called "phase separation" and it occurs when moisture (water) in partially full tanks mixes with ethanol gas.  Up here in Maine where fair summer weather is truly a short season, non-ethanol is much preferred; however, T.J. makes an important point.  Running your car around, burning through gas,  and getting it up to temperature on the open road (i.e. not stop and go around town) can keep the old v8 engine running well. 

[TJ Hopland]

I can't find it at the moment but I used to have a late 30's photo from Iowa of a gas station selling ethanol.  They went all out in the marketing.  I don't remember if it was the pumps themselves or if they just had giant corn cobs everywhere.  Fun picture anyway I don't think back then it was mandated it was likely something someone thought could make them some money.   

[Jeff Rosansky CLC #28373]

It gets you a fuel pump diaphragm that doesn't rot away, fuel lines that don't collapse under suction, unless they are ethanol resistant lines, carburetor parts that don't swell and shrink when being left to soak in the mixture and mostly, there are no products to separate after sitting a while.

You do as you are comfortable doing sir. I learned the expensive way. It doesn't really have any effect on a modern fuel system. The materials used are designed to work with a certain blend mixture. Some can tolerate up to 85% deathanol.

True. I should have mentioned that I have new rubber lines, fuel pump and carbon guts are good for ethanol too.

[TJ Hopland]

If you have bought any lines or kits made in the last 20 or so years they should at least be resistant to the usual 10% ethanol.  If you are running older than 20 year old parts you are on borrowed time anyway.