[68WarDog]

While watching a recent episode of Engine Masters, it was interesting to see that straight Ethanol (85%) ran cooler and made more power than straight gas. All that being said, would the 10/15% Ethanol blends also be capable of making more power than straight gas and run the engine a bit cooler?

[johnta1]

I'd have to check my notes, but I doubt that percentage of ethanol will make much difference in cooling. The increase in 'octane' of the 10/15% would help it make more power if it is utilized properly.
(but not nearly the amount of a 85/100% ethanol)

[JLMounce]

All things being equal, a 91 octane E10 mix and a 91 octane pure gas mix should support roughly the same amount of power.

The big difference is in the volatility of the mixed fuel. With 10-15% ethanol included, the boiling point of the fuel lowers fairly dramatically and it's stoich rating drops from around 14.7:1 to around 14.1:1. These two things are typically where classic cars get in trouble. First, you start boiling fuel in the carburetor bowls sooner. In high altitude locations, that boiling point may be as low as around 170 degrees. The second being that the car may be running lean for the type of fuel in use.

This is where we get people that state todays fuels are crappy. Today's fuels aren't really crappy, they're just designed to work in a different environment, namely under pressure and with modern adaptive engine management.

Once your fuel mix starts getting above 50% ethanol, the positive benefits of the more abundant alcohol fuel begins to be realized. The volatility in the fuel reduces and the intercooling effect of evaporating alcohol starts to become more pronounced. The effective octane of a true E85 fuel is around 105, but it's cooling effect in the combustion chamber will tend to add some knock resistance. Most e85 out of the pump is going to be somewhere between e70 to e75 however. All of this benefit occurs at the cost of additional fuel. Stoich for e85 is around 9:1 and thus typically takes about 30% more fuel to make the same power.

In regards to the core question, e10/e15 fuel won't likely make any more power than pure gasoline at the same octane levels. At least nothing you'd actually notice. It can cause issues with tuning and carburetor operation depending on your location, how hot your engine runs etc. These fuels are designed to be operated at pressures from 40-150psi, which helps to increase your boiling point of the fuel and avoid any type of vapor lock. The 5-7psi of fuel pressure you run with a carburetor simply isn't enough to counteract the volatility in the mixed fuel.

If you still use a carburetor, finding pure gasoline is your best bet IMHO. If you're running any type of electronic fuel injection, your car won't usually bat an eye to standard oxygenated e10 in your tank. Just don't expect it to make more power or run any cooler.

[The Champ]

FWIW - the suppliers don't recommend running E15 in anything older than 2001.

If they aren't comfortable in FI cars using it, I'm sure not putting in my cars with carbs (unless I get the carb rejetted to work with it).

[mgarblik]

Now that non-ethanol gasoline is readily available in my area, I use it exclusively in my cars with carburetors and small equipment. Have been for 2 years now. The fuel is 90-91 octane rating. Hot start issues, poor idle quality, hot, dieseling, gone. No ping or detonation. My cars love it. The biggest difference has been small air cooled engines. My old 2-stroke Lawnboys would diesel for 10-15 seconds after shutting them off with E10 fuel. With pure gas, carbs stay clean, do not collect moisture, and run much better.

In an engine without O2 sensors and a way to compensate for different fuels, I don't see how an E10-E15 fuel can make more power than gasoline if the engine is tuned for gasoline. Any Ethanol in fuel has less BTU in a gallon than gasoline, so it can't make more power without burning more of it.

[64speed]

I can get 93 octane at a regular gas station here or I can go get ethanol free 93 at the marina I have seen no difference other than substantially increased cost.

[Formulajones]

Nothing but 10 percent ethanol fuel available here. That's all Ive used for 17 years. No issues to date, no dieseling, no vapor lock. Use it in the classics on a daily basis.
I've always had my carbs run a pinch on the rich side of things anyway so the change over was easy and basically not even noticable.

[Formulabruce]

Originally Posted by Formulajones

Nothing but 10 percent ethanol fuel available here. That's all Ive used for 17 years. No issues to date, no dieseling, no vapor lock. Use it in the classics on a daily basis.
I've always had my carbs run a pinch on the rich side of things anyway so the change over was easy and basically not even noticable.

The "Rich" side of things" That is key. Fuel economy, due to less dense fuel suffers at around 30% ( any new car window sticker tells the story)
You need MORE fuel when alcohol is involved, to do the Same Work.
This " can" lead to a hotter engine if not rich enough mixtures.

[72projectbird]

Non ethanol is virtually impossible to find around here, same thing with E85. So I get screwed at both ends lol

I'd run E85 in my GN if I could, but since that's not gonna happen without it being a giant pita, I run 93 and progressively spray VP M1 as the boost increases.

[Formulajones]

Originally Posted by Formulabruce

The "Rich" side of things" That is key. Fuel economy, due to less dense fuel suffers at around 30% ( any new car window sticker tells the story)
You need MORE fuel when alcohol is involved, to do the Same Work.
This " can" lead to a hotter engine if not rich enough mixtures.

Yes. I think what has happened is as more people use AFR gauges and are so fixated on 14.7:1 stoich, they miss the bigger picture. For starters 10% ethanol is no longer 14.7:1, it's 14.

Most hot rods I tune don't really run all that well at those AFR numbers anyway, whether it be due to camshaft overlap, other internal engine variables, or just the simple advent of alcohol enriched fuels.

It's a better idea to tune for best drivability, and then see what those AFR's yield. Most will likely be surprised at just how rich things are running. Typically my stuff idles around mid 13's for AFR and cruises at those AFR's too. Sometimes they'll dip into the 12's for AFR when things like PV circuits open under a light throttle loads. Perfectly normal and my plugs stay clean, no issues. In fact they still return very good fuel mileage and drivability will very closely mimic an EFI car. They are just all around happier at slightly richer air fuel ratios.

Truth be told, trying to lean these things out to the 9th degree won't yield a big gain in fuel mileage anyway. In fact it's a very minimal difference.

Trying to run E85 is a different story, with AFR's typically in the 9's for stoich, yeah that's going to be a significant difference in fuel mileage.

[The Champ]

Originally Posted by Formulabruce

The "Rich" side of things" That is key. Fuel economy, due to less dense fuel suffers at around 30% ( any new car window sticker tells the story)
You need MORE fuel when alcohol is involved, to do the Same Work.
This " can" lead to a hotter engine if not rich enough mixtures.

The 30% reduction in fuel mileage is for E85, not E10 or E15.

FJ said he was running E10 - which reduces fuel mileage by 3 - 4%. E15 reduces fuel mileage by about another 2%

[Formulabruce]

Originally Posted by The Champ

The 30% reduction in fuel mileage is for E85, not E10 or E15.

FJ said he was running E10 - which reduces fuel mileage by 3 - 4%. E15 reduces fuel mileage by about another 2%

Yes, I should have made sure to point out that the reduction in economy is E-85, and that's what you see compared ( cruising range) on window stickers.

[geeteeohguy]

Alcohol is higher octane than gasoline. Runs cooler. That said, it has 50% of the energy gasoline has, so your 15 mpg gas engine will get 7 mpg running E85 to do the same work.
Alcohol absorbs water ,which destroys fuel systems not designed for it.

In my personal experiences, living in hot and dry CA for the past 62 years and driving the same exact cars for the past 40+ years, E-10 fuel is inferior in every way to pure gasoline in cars with carburetors. I get less fuel mileage, and now have percolation and stalling issues in some of my cars that never had issues before. When I drove my '67 GTO to Colorado this past summer, I picked up 2 mpg running pure gasoline over the ethanol stuff. Ethanol has less energy than fuel, so it takes more to make power. It is a government ploy just like the 'climate change' crisis. Hogwash. Alcohol is great for specialized drag cars, etc. In a street driven, carbureted car, it's a diaster.

[grandam1979]

I use pure gas in my 2004 Ram work truck luckily I drive past a coop station that has E0-90 they call it 90 octane. When I started using it mileage went up 1.5-2mpg I’m always checking it.

[locomotivebreath]

I drive an 09 civic to work . Once in awhile I have the opportunity to fill up with pure gas 90 octane in Indiana . MPG goes up 2 and the midrange torque is very noticeable in the little 1.8 .

[Formulajones]

I get pretty respectable mileage with the classics using E10 91 octane.

The bird gets 17 highway, just a completely stock RAIII setup with 3.31's.

The Z gets 21 mpg with a TKO 5 speed, stock DZ engine.

Both of those are driven everywhere.

My 600hp chevelle gets a little over 15 mpg with 4.10's and a 4L80E

Dad's goat with the 571 ci Pontiac making over 700hp gets mid 15's regularly on it's road trips, with 3.42's and 4L80E.

These cars pretty much all do better than most of your SUV's on the roads today. So they are actually fairly economical to drive in comparison.

[Formulabruce]

Originally Posted by Formulajones

I get pretty respectable mileage with the classics using E10 91 octane.

The bird gets 17 highway, just a completely stock RAIII setup with 3.31's.
.

10.5:1 and 91octane .. e-10 pump gas? Did you retard the timing?
Stock cam? Stays cool enough?

[Formulajones]

Originally Posted by Formulabruce

10.5:1 and 91octane .. e-10 pump gas? Did you retard the timing?
Stock cam? Stays cool enough?

I'm running 11:1 with iron heads on the Z engine. It's a stock engine. It likes 36 degrees of timing. It hasn't run above 175 degrees on the hottest summer days in AZ, most of the time it runs in the 160's.

The other engines, like my Formula, is 10.13:1 with the factory 12 heads, stock cam etc.... I have a slightly dished piston in it to keep compression manageable. It likes 34 degrees and also runs about the same temps as the Z.

The other 2 cars I mentioned are aluminum headed engines so the compression may seem more conservative, dad's at 10.84:1 and my Chevelle at 10.2:1. The goat also likes 34 degrees while my Chevelle likes 38 degrees. These 2 cars are a struggle to get them to run much above 165 degrees. Most of the time they hover around 158-162.

[Skip Fix]

Here Buccee's stores have non ethanol gas.

[Formulajones]

Buccee's is a midwest thing right? We don't have any of those in Arizona.

They built one new station up here in Prescott about 3 years ago, a Circle K, that has ethanol free gas but it's only 87 octane so it's not even worth using for me. That's the only station I've ever seen any ethanol free gas. They've built other new stations since, some of them Circle K's, and they don't carry any ethanol free fuel. Makes me think the first one 3 years ago was a test run. I guess they aren't selling enough of it so they haven't bothered with it at the newest stations anymore. Funny to me since I've considered Arizona a classic car mecca, yet there just doesn't seem to be a big push for any ethanol free gas around here, no one cares.