Holy MPG - more MPG research

[90Haccord]

And the saga continues in search of more MPG for my cb7.

my car is a 1990 honda accord EX AUTO.

Previous installments have dealt with tuning the engine and using acetone as fuel MPG gainer.

This time, I'd like to share some more in my quest.

My car has been running shitty for the last year or so, hesistation, no "power". So my mechanic suggested I run a different type of gas to see if it helped. HOLY HELL DID IT EVER. I'm a cheap guy, I run what the car calls for 87 octane as cheap as I can find it. But with this new "ethanol" bullshit, my car was running like crap. Low and behold, last week I found a non ethanol shell station in a little country town. I drove the same routes I did before only I drove it HARD, I mean I ragged it out. Normal MPG is 23-24 COMBINED, this tank with the 87 octane "regular" shell non ethanol I got 26.78 driving like a nutcase. I was shocked, MPG went up with shell gas big time. Car was running better also, so just for the hell of it I ran a tank of shell v-power 93 octane through it. WOW is all I can say, car is so smooth, no hesistation, nothing. Now for the real kicker, MPG is sitting at 31.25 COMBINED. I shit you not, I'm sticking with shell gas non ethanol if I can find it.

Now I should mention my car has 230K of MOSTLY city driving, so the old gal has been around the block a few thousands times litterally. Someone said she might not be able to run on 87 octane anymore as thats what she was rated for when "new". I'll continue to use 89 octane shell "PLUS" and see what happens.

Hope this helps someone in their quest for more MPG. Yes I know octane doesn't have shit to do with MPG, but my car is PUUUURRRING on 93 octane like she is a brand new gal. I'm a believer.

[skyrckt337]

Ethanol is Crap Anyway

The dirty little secret of ethanol is that a measured amount of ethanol provides 13% less energy than the same amount of gasoline. The fact of the matter is that gasoline is an incredibly efficient fuel and that unit per unit it puts out a great deal of energy. 10% ethacrap doesn't sound like much until you multiply the 12.8 oz. per gallon by the 15 gallons in your tank. That means that 1.5 gallons of your entire tank are only producing 87% of the energy that the other 13.5 gallons produce. In fact, ethanol is so inefficient that there is only a 23% yield on ethanol versus an 80% yield for gasoline. (www.theoildrum.com) So to sum all of this blah blah up it is as simple as this: you would have to have a tank containing 17.25 gallons of ethanol to attain the same distance travelled as 15 gallons of gasoline. In other words if your driving habits dictate that you get 400 miles off of a 15 gallon tank you would be getting 26.67 mpg. In order to get the same 400 miles off of a tank of ethacrap you would have to burn 17.25 gallons and would get 23.1 mpg. This is a decrease in mileage of 13.3%. WOW!!! That number sounds vaguely familiar to the original number that we used describing the potential energy of ethacrap. While I haven't worked the numbers, I would assume the loss in horsepower for that garbage would be about the same.

[Jon]

I've been running 87 ethanol for YEARS and no matter what I do or how well I tune the car I get 22-23 MAX (90 LX Auto) and kept telling myself I should be getting a little bit better. I bumped up to premium and got a solid 23, 24 sometimes. Looks like I'll be switching over to a non-ethanol blend and see what I get.

Awesome info!

[VentoGT]

If your computer is not calibrated to advance timing on a higher octane fuel than 87, you are NOT getting any benefit other than added cleaners/detergents in the gasoline.

You are right that higher ethanol content will provide worse mileage, but it has nothing to do with octane rating. Especially with hi-test being 50 cents cheaper in some places per gallon than regular, that will add up. Please keep this in mind. Maybe try staying at Shell or Chevron with their lower octane blends and see what you get. Most of the discount gas chains don't use the same amount of detergents in their fuel than the Chevrons and Shells.

My $.02

[skyrckt337]

Addendum to my response

If you convert all of those numbers back to an entire tank of gasoline, we find that at about 3mpg less you will get about 45 fewer miles on a standard 15 gallon tank. I am dying to know one thing though. Where in Atlanta are you buying high test for .50 a gallon cheaper than regular? Also, assuming $4 a gallon gas, you could actually spend up to $4.40 per gallon of non ethacrap gas and get the same cost of fuel per mile.

[TypeG]

your igntion timing is probably way off if the car doesn't run right off of 87. later.

[js593]

I agree with Ethanol, Its crap. I cant get more then 19 MPG.

[wed3k]

your igntion timing is probably way off if the car doesn't run right off of 87. later.

lean that bitch out...

[zigg_1311]

lean that bitch out .... lol

[Karl]

I have no problem getting 29mpg city in my accord, all atock on 87octane.

[VentoGT]

Where in Atlanta are you buying high test for .50 a gallon cheaper than regular?

Durrr...sorry--I meant 50c more EXPENSIVE sorry about that...I remember when all fuel was basically 10c more than regular for mid grade, 10c more than mid for 93...now the prices seem to be a helluva lot more for premium. Just wanted to make sure that you werent using a higher octane than your manual calls for as it wont make a difference [again, if your ECU can't take advantage of higher octane fuels].

I've been driving cars that require premium [including my M5 now that has no knock sensor so loooookout for bad gas] for a while, so I'm very cognizant of certain fuels running well and certain ones not. Chevron is my go-to, followed by Shell, BP, and Mobil.

[Otto]

Massachusetts has had 10% MBTE for the longest time, and now 10% ethanol for the last 4 or 5 years. No issues over here, CB has been getting ~31-32mpg this summer. I'll get gas wherever, though I've been getting Sunoco mostly this year.
I run all my engines hard sometimes.
And you have two variables, changed gas and drove extra hard. Gotta change one thing at a time to know what is making a difference.

[90Haccord]

What the heck are you talking about?

I said I DROVE IT HARD on 87 octane non ethanol and mileage went up 3mpg.


Thats pretty easy to see what is going on from previous bests of 24ish using cruise control all day long.

[Otto]

Argh, sorry, read and responded too quick when I first got up this morning. Really just wondering the results of each gas under similar driving conditions.
How hard is it to find gas without Ethanol in your area? There's none around me, so I guess I'll never know what I could get out of a gallon of straight gas.

[skyrckt337]

Hey Vento,

I was wondering if you had tried QT gas and if you had any probs. I am an Atlantan that now lives in Florida, and would give my left arm for a QT. Gas down here on the gulf coast all comes from basically one supplier. Regardless of the name on the sign, almost all stations are owned by a company called Phillips oil. (No not the big national chain) So, no matter where you go is all the same. The only other real option is Murphy at Wal Mart stores.