Why Does Ethanol Make So Much Power? (Versus Gasoline)

Ethanol has less energy than gasoline, but it can make so much more horsepower!

Ethanol contains less energy than gasoline, and yet it can make so much more power! How is that possible? This video will cover the differences in air/fuel ratios for ethanol vs gasoline, the energy density differences (by mass and volume), fuel economy differences, and octane number differences. Critically, the reason for octane number differences will be explained, with both the chemical composition and the cooling effect of ethanol providing a large advantage. Finally, we'll look at real world testing to see how much more power ethanol can make, as well as the efficiency differences of E85 ethanol vs E10 gasoline. And if ethanol really is more efficient, then why do you get worse fuel economy using E10 vs E0 (gasoline)?

Whenever a fuel is listed as E10, E15, E85, E100 or E##, the number simply represents the percentage of ethanol in the fuel by volume. So for example, most pump gas today is E10, meaning up to 10% ethanol by volume, and the rest is gasoline.

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[EngineeringExplained]

If you'd like to learn more about ethanol, I have two other detailed videos on the subject:

[IndaloMan]

I am in my 60s and spent decades doing corporate whiteboard presentations like this (but not with complicated maths!). Love this channel for the simple presentations explaining complex processes.

[BimmerWon]

This is why I always drink ethanol instead of gasoline since it makes me more powerful.

[maggotpudding]

I've had e85 kit on my car for bit over a year and couldn't be happier about the purchase. I've only suffered about 15% mileage increase but the fuel is less expensive enough to compensate for it. Not to mention e85 is readily available in Finland and not even made from plants but biowaste. Good stuff.

[youssefosama]

One of the reasons I entered engineering school 5 years ago is because of you.
I want to thank you for every video you made explaining things this simply and easily has actually helped me a-lot during college.

[JordieG]

Another benefit you didn’t mention was, on Turbocharged engines the added mass of the ethanol in the Air/fuel charge compared to gasoline significantly improved turbocharge response. That extra mass is able to impart more energy on the turbine therefore improves response. While E30-40 is the sweet spot chemically, going above that can improve low end torque by improving turbo response. That was a fantastic video BTW!

[julianomse]

This is known here in Brazil since the 80’s. If you want to tweak your engine, specially turbocharging, you should adapt it to ethanol. And we’re using 11:1 CR in gasoline engines for a long time, because we were the first country in the world to abolish completely tetraethyl lead in 1989, substituting it by E25

[mechproject]

Great Video. I did a study on this when I was in college, but we we only focusing on power not efficiency. Everything you said applies, but also the cooling effect of the ethanol means that the air is denser. We had a port injected engine with boost (I forget how much boost), and we saw a temperature drop of 40°C just from before and after the fuel had been injected. This means that by the time it got the intake valves we could get more mass of air+fuel mix into the cylinder and make even more power. Yeah ethanol is pretty cool (pun intended).

[igorschannel]

Here in Brazil our Gasoline is sold with 27% Ethanol directly from the pump and our cars are able to use any mix between Ethanol and Gasoline, we have hydrated ethanol on our pumps too. They call it "Flex Power" since you can decide on either running on Gasoline or Ethanol.

[u.e.u.e.]

You could also have mentioned:
- burning velocity/point of highest pressure in the downward movement of the piston
- effect of E0/E10/E30 on power and economy of non-flex vehicles
- CO/NOx emissions at E0/E10/E30/E85/E100
- the ethanol content of the highest efficiency corellated with your other video about loosing energy in growing/harvesting botanicals and making ethanol from an engineer's perspective.
There's still a lot to talk about ethanol use in ICEs. 😉

[ethanwestbrook]

I recently finally tried first couple tanks of e85 in my 5.0 f150 and I'm surprisingly impressed. Much more throttle response and obvious overall power increase. Also seems to coast longer and faster for some reason. Seems to be happier and run even better on the e85 than on premium.

[jedpratte]

Have been using e85 for 10 years now in 4cyl race applications. Have ran 90% tested pump e85 in 122CI motors at 10:1 compression at over 40 psi of boost on 62mm+ turbos. The fuel is amazing considering it costs $2.35 at the pump but performs like c16

[scottaseigel]

All very interesting, but there’s another number that I care far more about, mi/$. This determines my operating cost. It turns out my Ram 1500 runs most cheaply (i.e. gets the highest mi/$ ) using ethanol free premium which ironically costs the most per gallon! It travels 490 miles on a $120 tank of EFP versus just 315 on $98 tank of E85.

[bobo]

I gained 36hp and 55 lb/ft on my subaru wrx just from switching to e85. It went from 25 to 23mpg, but turbo spool was faster due to larger exhaust volume. If it's available, I would recommend it! It was usually about a dollar a gallon cheaper than premium and had more power. Why not? The problem as you said, is that we try to use e85 without making the engines designed for it. You can increase compression and boost with e85. Mpg isn't as bad if you build for it.

[ericlotze]

Can we get a Dimethyl Ether video? I am LOVING these fuel focused videos, and giving our Compression Ignition Engines a bit of this format would be amazing!

[upshifter]

I flippin love this channel and every second of this video!

Been running an E20 blend in my 3.5 ecoboost for a little while now and this vid just scientifically backs up my rudimentary impression from doing so. So the Ford study here is eerily relevant for me.

Thanks for another banger Jason!

[PFIBrent]

great video ! I so love tuning on ethanol, you can always just feel how much smoother they run . Some of those knock tests you talked about would be fun, may have to just try it and see how much further we can push our stuff.

[soyunpinchehuevon]

In Brazil we have around 27% Ethanol in the gasoline. For a long time we had a famous rule that said that it was worthy(in $/mile) using ethanol whenever the price was 70% of the gasoline(since most cars nowadays are flex). More efficiente engines make this ratio go up to 75%. This creates an interesting market effect that whenever gas prices go up, people tend to switch to using ethanol, making its price go up too, when gas prices go down, ethanol prices also go down. Prices tend to reach an equilibrium near that 70% ratio.

[bigdaddymak]

They've done this on engine Masters several times! It runs way lower intake temps and you can force way more ethanol in the combustion chamber because the molecules are smaller!! But the downside is it takes A LOT more fuel when you use it because of the lower BTU

[machdaddy]

I remember years ago going to an IHRA event. Examining the dragsters up close I noticed their fuel plumbing was huge, compared to NHRA.