Cool/Heat: running cooler at the gas pump. (news to me)

[TXmark]

I have a '37 Buick straight 8, I've had the car less than a year. from the start she ran hot, after a lot of advice on the Buick forum and a lot of work. I found an easy way to run 15 to 20 degrees cooler on that pre-war straight 8.
I made a 60 mile trip to a car show this last Saturday, she ran 180 to 200 degrees on 87 octane 10% ethanol fuel. on the return trip Sunday morning I topped off with 93 octane non-ethanol the car ran 15 to 20 degrees cooler.!!!!! the temp outside was the same both ways.
A Google search proved my suspicion, Ethanol fuel burns a lot hotter!!

I now live in eastern North Carolina where non-ethanol fuel is available, when i lived in Houston TX it was no where to be found because of population density it what I was told.

[Skip Lackie]

Not to hijack your thread, but the ethanol is not (directly) related to population density. Rather, it is related to an area's non-compliance with the EPA's air quality regulations. And urban areas tend not to be able to achieve compliance, so must sell only oxygenated fuels. And ethanol is only commonly available fuel oxygenate right now.

[Mike Van Veghten]

No alcohol runs hotter thAn gasoline. It actually runs cooler..! All alcohols do. Look up the BTU's under the combustion process, Ethanol, Methanol run cooler that any pure gasoline.
The fact that your ignition timing may have had a small effect with the alcohol could have caused this change.

One example -

http://www.afdc.energy.gov/fuels/fuel_comparison_chart.pdf

Mike

[deco_droid]

so the google search was wrong then?

[sweetolbob]

Gasoline 114,000 BTU's/gal, Ethanol 76,100 BTU's/gal.

I won't speak to the other factors but gasoline has about a third greater heat generation capacity than ETOH.

[TXmark]

The alcohol when burned produces water vapor thus resulting in lean condition alcohol does burn cooler and produce less btu .Air cooled engines run 40 to 50 degrees hotter on ethanol

[Lamar]

The difference was in the change from 87 to 93 octane not the alcohol. Sounds like the ignition timing is adjusted to run the 93, the 87 lights off easier and burns quicker so it needs less advance than 93. I would also point out that back in the olden days before the reformulation of gasoline that regular gas was 91 to 93 octane with "lead" 87 octane did not exist. Lamar

[TXmark]

my Buick owners manual recommends an octane rating of 70 to 78

[Skip Lackie]

my Buick owners manual recommends an octane rating of 70 to 78

Yes, because your compression ratio was/is somewhere around 6.5 to one. Compression ratios increased rapidly after the introduction of the Cadillac and Oldsmobile OHV V8s in 1949, which required much higher octane fuels. Also, of course, the octane numbering system changed in 1971/72. The US used to use "research" octane, while many other countries used "motor" octane. The post-1972 system we have now is the average of the two numbers -- making all pre-1972 octane numbers incorrect.

[WCP]

Just completed a 2400 mile drive to Nashville and back a week ago. I burned non-ethanol fuel where available and otherwise mid-grade ethanol laced fuel. Today I calculated my tank by tank fuel mileage for my 259 CI 2 BBL. The non-ethanol fuel yielded a very consistent 10% or better mileage advantage.

[JoeHall]

Just completed a 2400 mile drive to Nashville and back a week ago. I burned non-ethanol fuel where available and otherwise mid-grade ethanol laced fuel. Today I calculated my tank by tank fuel mileage for my 259 CI 2 BBL. The non-ethanol fuel yielded a very consistent 10% or better mileage advantage.

I believe you. But where did you find non-ethanol? Last June on a trip to So-Cal in the GT Hawk, I had to use whatever was available, which was ethanol about 90 percent of the time. I avoided Pilot gas though, since after a tank of it in Arkansas, the Hawk was clattering like never before, at the next gas exit about 300 miles down the road.

[WCP]

Mostly in New York State and also a tankful at a Sunoco in Gallipolis, Ohio.

[AC0J]

I have always been told that higher octane is to prevent detonation. The higher the compression, the more octane needed to prevent detonation.
Most cars with 10 to 1 or less compression will do fine on 87 octane. I have never experienced a noticeable gain in performance with higher octane gas.
I also have ran small block chevy's with 11 to 1 compression and have never experienced detonation problems with regular pump gas.
However, I do get considerably more miles per gallon with NO alcohol, which leads me to believe that fuel is more efficient. I can see that making an engine run cooler.
When you figure your mileage by miles per dollar instead of miles per gallon, then alcohol free fuel is a better value every time. Even in e-85 ready vehicles.

[Lamar]

In our situation(old engines) it has nothing to do with compression ratios, take that off the table. It all comes back too volatility, the rate at which gas ignites and burns across the cylinder(it really doesn't explode when burning correctly) in the combustion process. An older long stroke small bore engine requires a much different octane than a modern big bore short stroke engine, carbed vs fuel injection also plays a part along with fuel distribution (manifolds). Modern fuel just isn't blended to work with what we are discussing here, so we have to use what we can get that will do the best job of "getting by". In many cases that is 93 pump gas even in straight eights etc. Hope this helps explain a little, both my fingers are tired. LOL Lamar

[AC0J]

Octane has nothing to do with it. It is the ethanol.

http://www.nicoclub.com/archives/gasoline-octane-myths.html