91 Ethanol Free vs 93 / 10% Ethanol
 

Up until this spring, I always filled up my TAs at the local BP station which was the only station in town with 93 octane fuel. Every other station had 91 octane as its premium. Well, this year BP changed its fuel and still offers 93 octane, but now all their fuels are 10% Ethanol Blend - it used to be that only their lower octane fuels had ethanol.

So, I can go down the street and get 91 octane with no ethanol or I can get 93 with 10% blend. Not sure which way to go here. Maybe stick with the BP fuel and run Gibbs Carb Defender?

If I run the no ethanol 91 and find my car misses the extra 2 points, does anyone make an octane boost product that does NOT leave red deposits in the combustion chambers and on spark plugs?

Thank you.

The bad things that ethanol does to fuel systems not completely designed for it I would take the plain any day. Pulls water in and can accelerate rust in tank carb corrosion rot rubber lines etc etc.

Gotta’ say, that was my initial knee-jerk on this issue. Now, if only you could grab any octane boost that did not leave those darn red deposits on everything...

How often do you pound on it? If your answer is "I never get it above 40 mph", don't worry about the difference in the octane. It is not going to matter. And if it bothers you that much, take a degree or two out of the timing.

Does your car need 93 octane?

Yesterday was the first truly ‘hot’ day of the season at 91*. Car ran just fine, but I noticed that when I shut her off, she did chug and diesel a couple of revolutions which I have never had happen before. This was also the first full tank of 91 octane that I have run through the car after discovering the my ol’ reliable BP station was blending ethanol in everything. So I’ve got a couple missing points of octane and 10-15 extra degrees of ambient air temps working against me all at once. She’s a manual car, so it looks like I will need to shut her off in gear and let the clutch out as I turn the key to the ‘off’ position.

I would say you have carbon build up, running too rich or both as running too rich causes carbon build up. Higher octane will only mask this. Also, what is your idle set at? An idle 100 rpm too high can also be a cause.

I’ve run the 10% ethanol 93 octane for years without any of the corrosion or rubber deterioration I’ve heard about. I tried the pure gas 91 for a few tanks and the only thing I noticed was the higher price of the 91. I’m sticking with 93 from a high volume top tier station.

Are you suffering from any detonation? If you have none I would run the lower octane. Unless your trying to shave ETs or prevent detonation. JMO

This may help:

http://www.thecarburetorshop.com/Octane.htm

Jon

[That's an interesting read, Jon..

QUOTE=carbking;6028733]This may help:

http://www.thecarburetorshop.com/Octane.htm

Jon[/QUOTE]

While a highly debated topic, the ONLY time I had issues with 10% ethanol since I started driving in 1982 was last year when I let my generator go 2 full years without starting it. Orfices in carb plugged up.

With that said, I am also not running 50 year old fuel lines or carb parts....

My 11:1' ish kre head motor also likes the 93 octane BP gas. Even with timing tuned down, it tends to diesel a little when turning off when running 91 octane. I can assure you there is no carbon buildup in this motor :)

I tried tuning on both qjet and Holley carb to no avail. Finally decided to just run BP 93 and not worry about it

Assuming your fuel parts are within 20 years old, I would not worry about 10% Ethanol and use what ever the car likes best!.


Sent from my SM-G965U using Tapatalk

10% Ethanol cuts fuel milage 3 to 5 percent so that's a 3 to 5 percent power loss at any given rpm!

If it where me for under 500 bucks I would buy one of the add on Alky injection kits and run the 91 octane non Ethanol fuel and then only have the Alky injection set up to come at at 3/4 throttle .

Once you put 2000 miles on the car the milage increase will pay for the injection system!

fuel
 

Try what works for me. add a gallon of leaded race fuel to about 20 bucks of 91 fuel. stopped the run over. that will drive you crazy. Thanks Bob.

I would definitely use the non-ethanol.

A little tidbit of information.

If you want to know if your fuel has Ethanol in it, take a 500ml water bottle, put about 1" to 1-1/2" water in it and mark that water level on bottle. Fill the bottle up with fuel to within 2" from the top. Shake it up Gently, and the ethanol will mix with the water and the initial water level mark will rise on the bottle if the fuel contains ethanol. Be careful when opening bottle as it will pressure up some.

They make ethanol test kits that are cheap. I used them years back and I'd bet they are still available all over the internet if someone is interested in knowing just how much ethanol is in there.

The scary part is when I was testing it at the 2 stations I frequented at the time, I found ethanol as high as 17% even though the pumps advertise 10%. And that varied quite a bit so in reality you never really know how much you're pumping in. I'm guessing that stuff isn't regulated as tightly as we would like to think. Haven't done that in years but I don't see any reason it would be different now. It's one of the biggest reasons I tend to tune the cars a little bit on the fat side to keep things safe, as ethanol rises, so does the engines fuel requirement. Better safe than sorry.

I've been running "10%" ethanol blend for years in every car here with no ill affects. 91 is the best we have here in AZ. No issues with any of the cars dieseling at shutoff in winter or during the hot summer. One car is 11:1 compression with iron heads and is a 4 speed. I have it idling up around 1,000 rpm and it shuts right off no problem and runs perfect on the 91 octane.

If ethanol free makes you feel better then by all means use it. We have one station within a 100 mile radius of my house that even carries ethanol free and it was just built last year. Unfortunately it's only offered in 87 octane which I can't run anyway so it's just not an option for me.

And that is why guys running E85 are constantly monitoring every gallon they put into their race car.

What most people seem to forget is that ethanol is alcohol and washes cylinders clean as they run resulting in short engine lifespans. Why do you think guys running alcohol need to re-ring their engines every few seasons.

You pick up more power but IMO its not worth the added wear.

Those of you on the west side of Houston Texas, can obtain ethanol-free, 89 octane from Buc-ee's. The Katy and Waller stores. Price is around 3.75/gl. The pumps are over at the RV islands. I use it in my dirt bikes and t/a.

A little off subject perhaps. Why does a motor "run on" with "too much timing" when shutting it off? There is no spark when the motor is shut off, so why does the ignition timing matter?