Benefits of ethanol on naturally aspirated engines (Science inside)
 

Hey guys,

Just wanted to make a quick thread about ethanol and it's benefits in naturally aspirated cars. It appears the S2000 community is really way behind when it comes to ethanol use with NA cars. I want to talk about the science behind ethanol and why you will make more power without changing timing at all.

*Little background* Mechanical engineer with ~5 years of powertrain development/calibration experience.

Myths:

1. Our cars already reach MBT on 93 octane. You won't make more power on E85 because you won't be able to up the timing.
2. Ethanol is only useful on FI cars
3. Ethanol is corrosive and will eat fuel lines
4. Ethanol will burn your churches and rape your women

The reality:

1. This is incorrect. The chemical makeup of E85 is the reason for power gains without any timing changes at all. (See science below)
2. There are many benefits to be had when running ethanol in a motorsport setting
3. While there is some merit to this, it's important to note that all cars past the year 2004 are all legally mandated to be capable of handling at least "small" amounts of ethanol. This is because normal pump gas contains up to E10 (more soon to come since a recent legislator change)
4. This is true, hide yo kids, hide yo wife.

Here's the science:

-Chemical make-up of ethanol: C2H6O
-Chemical make-up of gasoline: C8H18

This brings us to our first reason why ethanol can result in a net power output gain. Ethanol includes an oxygen atom in it's chemical composition. This means that per unit volume, ethanol has a greater amount of oxygen than gasoline. It is a small scale application of "chemical supercharging". This is why you will see vehicles, with absolutely no changes to timing or the tune (minus adding fuel volume to compensate for the higher volume requirement of E85) will produce more power and torque.

Additionally, because this composition, ethanol has much greater in-cylinder cooling capabilities. A fantastic SAE study/article can be found here: https://www.sae.org/publications/tec.../2013-01-2610/ The crux is that ethanol has a low evaporation rate. This leads to greater in-cylinder cooling potential and greater thermal efficiency. There has been many "grassroots" case studies that have been able to observe lower oil temps on track because of this phenomenon.

Conclusion:

E85 has huge benefits in even a NA application in race settings. I'd like to make this thread as a good place for people to ask questions about E85 that they might otherwise be unsure of. Together, we might be able to shed some light on a fuel that has taken the motorsport world by storm and for good reason, but seems to be VERY seldom used in the NA S2000 world. Hopefully, this will act as a good catalyst to get the S2000 world back up to speed with some other communities (people are still using piggyback ecu's here?).

Cheers,

Will

I've been running ethanol in my NA car for three years now, it's a great fuel.
No real downsides at all except you need to fill it up more often :)

Should we start a how to convert to E85 in this thread? I'm really interested in going E85 since I'm from Iowa and a majority of our pumps here have E85.

Exactly. And even then, by me it's almost a full dollar cheaper than 93 octane.

Sure I can add it.

One huge benefit is all things being equal, your engine will run cooler. Think of it as a coolant system upgrade. The cooling of intake charge and exhaust temperature are a big benefit to engine and engine bay parts longetivity and makes the S2k an even more reliable track powerplant as well as better AC in the summer.

Another benefit with e85 is your ignition timing error cushion. Think of it like this: Your tuning oem s2000, your a newb and your wide open on the throttle from 7k-9k rpms. You have 3 types of fuel:

87 octane: unbeknowst to you ideal ignition timing is 18 degrees btdc. At 19 it starts knocking.(you better realize and pick 18)
93 octane: unbeknowst to you your ideal timing is 18 degrees btdc. At 20 it starts knocking(you are good aslong as you pick 18 or 19 degrees)
E85(102 octane): unbeknowst to you your ideal timing is18 degrees btdc: at 22 it starts knocking.(aslong as you pick 18-21 degrees of timing your good)

As you can see if you or a tuner used e85, youd be at peak power and well in the safe zone even if there was a miscalculation.
If you were on 87octane your margin of error is much tighter. E85 will let you get away with a tune thats a few degrees off from an absolutely perfect tune while still giving you peak power. Major benefit especially in FI applications but still helpful NA.

Or just watch this lol:

I have never had an engine gain power from a pump fuel without timing changes. Using E85 or any other higher octane pump fuel without ignition timing changes will not result in any notable power gains.