E85 vs E30. Just a curious Joe asking away

[BEZO760]

Hey all, pretty new to the whole car world and I'm learning shit literally everyday. So far I've replaced the full exhaust and header myself. (I forget if a "full exhaust" replacement includes the header... Still a little funky on correct terminology but oh well) installed some coilovers and aftermarket Perrin air filter. Seibon Carbon fiber hood (drilling holes for the quicklatch hood pins was nerve racking), Verus Engineering Street splitter, lightweight rims, summer tires (the set would be called wheels?) wrapped the roof of my car and did my first oil change all in the span of 4 months. Before I do anything I try to do as much research as possible since I'm a big believer in doing it right once.
I recently switched over to e85 using the OFT tune that is provided. Car runs great. My buddy and I got to talking about e85, e10, e30, etc.. And he mentioned that Focus ST's like to run e30 instead of e85 which confused me a little because I always associated the a higher number (85) to be a higher rating thus more hp? 85>30 so wouldn't people prefer e85 over e30?
I guess my question would be whats the difference and why do people choose lower ethanol levels when e85 is available? I may be asking the wrong question entirely which shows my newness.
Thanks in advance for any responses!

[BEZO760]

Here is a picture of a couple days ago before I got to drilling the holes for my hood pins. Oh and that wheel gap will be gone by tomorrow, I promise.

[EAGLE5]

I assume the reason is that the stock fuel pumps and/or injectors of the ST cannot handle pumping the extra fuel needed to run straight e85, so people cheap out on replacing parts and just run e30.

The twins can handle e85 easily when not running a turbo. If you put on a big enough turbo or supercharger, you're going to either need to run some lower ethanol mix, like e30, or upgrade the fuel pump and injectors. In that case, the smart thing would be to run a bigger fuel pump, bigger injectors, and a flexfuel system.

[why?]

rims are the things on a basketball hoop.

Wheels are the things you mount tires onto.

boost complicates everything, and makes it more expensive.
http://www.marshpowerhousefab.com/products is the best place for carbon products for our cars.

Besides that, you are doing good. Research first. Welcome to the absurdly expensive hobby.

[NoHaveMSG]

E85 means 85% Ethanol
E30 is 30%

Ethanol is more knock resistant. It has less BTU's then gas by volume but burns at a much richer stoichiometric ratio. It is also excellent at pulling heat out of the system due to the richer fuel/air ratio.

[ermax]

I have a friend with an F80 M3 who has a tune and if I recall he said he has to mix it down to 30% too. Who knows why those guys want to run E30. They may not have injectors capable of keeping up with the demands of E85. We are lucky with our cars to be able to run E85 with nothing more than a tune. They may also be running E30 for extra fuel economy.

[BEZO760]

Originally Posted by jsimon7777

I assume the reason is that the stock fuel pumps and/or injectors of the ST cannot handle pumping the extra fuel needed to run straight e85...
The twins can handle e85 easily when not running a turbo.

So in simple terms their vehicle just wouldn't function properly if they were to run e85? So instead they run the highest they can safely run and that would be e30?

Also... I keep seeing people refer to the 86 platform as "the twins". Is it because the fa20 motor if split in half would have a left and right side twin? I hope I'm not completely wrong ��

[BEZO760]

Originally Posted by ermax

I have a friend with an F80 M3 who has a tune and if I recall he said he has to mix it down to 30% too. Who knows why those guys want to run E30. They may not have injectors capable of keeping up with the demands of E85. We are lucky with our cars to be able to run E85 with nothing more than a tune. They may also be running E30 for extra fuel economy.

This was basically the same little conversation I had with a buddy. My guess is they just can't run it.

[bcj]

The twins are the Subaru BRZ and the Toyota GT86.
Fraternal though. One has a mustache. The other has a blobfish nose.

Scion FR-S is the older brother who was killed on deployment.
We don't talk about him. It's too paintball.

[NoHaveMSG]

Originally Posted by BEZO760

So in simple terms their vehicle just wouldn't function properly if they were to run e85? So instead they run the highest they can safely run and that would be e30?

Also... I keep seeing people refer to the 86 platform as "the twins". Is it because the fa20 motor if split in half would have a left and right side twin? I hope I'm not completely wrong ��

Straight ethanol takes more then twice the fuel/air as gasoline. So if you don’t have big enough injectors you can not safely run it.




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[EAGLE5]

Originally Posted by bcj

The twins are the Subaru BRZ and the Toyota GT86.
Fraternal though. One has a mustache. The other has a blobfish nose.

Scion FR-S is the older brother who was killed on deployment.
We don't talk about him. It's too paintball.

Too paintball? LOL. Get yourself a real phone.

[EAGLE5]

Originally Posted by BEZO760

So in simple terms their vehicle just wouldn't function properly if they were to run e85? So instead they run the highest they can safely run and that would be e30?

Won't function properly? Sure. I wouldn't call that simple terms, but you're in the ballpark. Twins = Toyota/Scion + Subaru. Triplets, I guess.

[bcj]

Originally Posted by jsimon7777

Too paintball? LOL. Get yourself a real phone.

(sic)

[serialk11r]

I didn't know E30 was a common blend at the pump :O

E25 or E30 is sort of the "optimal" mix for fuel economy, I think since more ethanol has some trouble vaporizing quickly. MPG drops a bit faster as you add more since the efficiency gains are smaller than the BTU/gallon you're removing.

E85 is crazy knock resistant, without a built engine it's hard to fully utilize it, so you might as well just run more gasoline to make the tank last longer. On E85performance.net I think I recall reading about people running pretty decent boost on 15:1 pistons lol. Assuming the govt. corn subsidies don't run out, I would love to be a car enthusiast in the Midwest for the cheap 100 octane fuel at the pump