Gas Octane

Good luck with that, keep us posted on what you get. Everytime I tried using 89 I got worse MPG than 87, have no idea why.

 

Hang on a sec.

Energy density in terms of volume and mass, respectively:
Gasoline = 34.2 MJ/L, 46.4 MJ/kg
Ethanol = 24MJ/L, 30 MJ/kg

But E10 (10% ethanol, 90% gasoline) is what is sold at the pump. The energy density of E10 is 33.7 MJ/L in terms of volume (which is how we purchase and use it), or about 1.5% less than that of gasoline.

Sure, pure ethanol, especially in conjunction with water, is highly corrosive to metals. E10 is a blend of gasoline + anhydrous ethanol. Also, I suspect that the grease companies blend in additives to reduce the potential for corrosion, and that car manufacturers and their suppliers have revised materials in fuel-system components to address corrosion potentially related to E10 use.

But I would appreciate pointers to any technical publications you're aware of that document E10-related corrosion in late-model vehicles.

 

hopefully you do not pay more for the gas in your State with the ethanol in it than you did for the out of State better gas mileage gas. As Chris 4x4 stated, Butt Dyno is the questionable approach to absolute fact. The Butt can lie

 

Thank you for the explanation.

Gas in my area is way more expensive than anywhere I've been. For example right now we pay 2.79 for regular, 2.99 for premium.

 

I knew someone was going to ask this question eventually! ("Hey look, that girl's butt is dyno!") Anyway, I love these "best fuel/octane" threads... I have always gone to the ARCO down the street for fuel and never had any problems, but next time I might try the Shell around the corner for 87 octane and see if the 2.7L 4cyl runs noticeably better. Both stations are busy so their fuel is likely to be fresh. P.S. My 4-banger is bangin'! LOL! Oh nevermind, I've had too much coffee. Shut up DGXR.

 

i run 105 Octane race fuel...on my track bike!!! haha naww i only use 91-93 in the truck...i feel that it runs smoother than when i first got it (it had a tank of 87 in it)

but its all personal preference...higher octane is only needed in s/c, turboed, or performance/high compression engines but it wont hurt your truck to use it... try running it with 2 tanks of higher octane and see if you feel a difference...if not you only spent maybe an extra 5-10 bucks all together...

 

Well the Tacoma does have a high compression engine, which is why the manual says for best performance use 91+

Compression ratio 10.0:1

 

I was told the same thing a few times before.

 

Started using 91 recently and it seems to be getting a bit more mpg than the 87.

 

I went on a road trip this weekend 274 miles one way. On the way there I ended up getting 22 mpg at 68-70 MPH the whole way there on cruise control. On the way back I was at 21 mpg maintaining the same speed. This was on 93 octane. I have the 4.0 motor with TRD CAI and custom exhaust.

 

Wind and elevation changes can also play a role.

On the highway with my Scangauge I've noticed that if there is headwind, my MPG drops from ~20mpg to something like 16-17.

 

Wow really? I didn't know that. I dealt with a ton of wind on the first part of the trip and not so much on the second part of the trip.

 

+1, I've run higher octane and basically felt I've just wasted money. 85 up here at altitude works fine.

 

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I try to use the BP/Amoco Super Premium that we used to call White Gas. I think that it is 93 octane

My question is this .... when we see a sign at the pump that says ... "This Gasoline May Contain 10% Ethanol" .... does this include the station's super premium gas too ??

(I had the impression that corn ethanol had less energy in it ... therefore was more difficult to make into the higher octane premium fuels)

I do NOT like "corn syrup gas" in my vehicle and I assume that that the higher octane fuels have a lower chance of having Ethanol in them. Am I correct on this ??

Thanks ..

SOS

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^ I would like to know that as well.

 

I have done a comparison over 3 months. In month 1 I used 87, 2 - 93, 3 - 89. I drove my normal route and each octane had a least 5 fillups. My price per gallon is a calculation on the price of gas yesterday when I filled up. My findings were:

87 - MPG = 23.89342 - $/GAL = 2.299 - $/Mile = $0.096219
89 - MPG = 24.01819 - $/GAL = 2.419 - $/Mile = $0.100715
93 - MPG = 25.25414 - $/GAL = 2.539 - $/Mile = $0.100538

So based on my calculations, 87 is cheaper per mile but 93 is less than 1/2 a cent more per mile. My truck seems to run better on 93 so that is what I will use.

BTW - I noticed a difference once I install my ScanGuage. Once you use it you realize how the truck likes to be driven.

 

I understand that ethanol has higher octane than pump gas (around 95 or something) so it resists detonation better than premium. But ethanol actually has less energy content per volume, which means the fuel mixture has to be richer for the correct fuel/air ratio. If there is 10% ethanol in the pump gas, the computer simply senses how the engine is running (o2 sensors, etc.) and decides that more fuel is needed for the best burn and cleanest exhaust. Theoretically this will result in slightly lower mpg with 10% ethanol in your pump gas.

 

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Thanks for the information. It there a way to stay away from ethanol ??

I had "AvGas" on the brain too.

SOS

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Thanks for the information. It there a way to stay away from ethanol ??

I had "AvGas" on the brain too.

Several months ago, I saw some "mean time between failure testing" on some military small gasoline generator engines ..... and ethanol was basically called a "fuel villain".

Any thoughts on this from the fuel experts here ??

Thanks again to both of you ..

SOS


PS ... Maybe they just wanted to go to diesels on their small generators and do away with gas all together ??? .. Who knows ??

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