Worse m.p.g. Using higher octane

[VAMike]

Not to get too far OT, but...
The official reason for the ethanol is to create less emissions.
Yet burning ethanol itself creates CO2.
And blending it in lowers gasoline's miles per gallon, thus creating more emissions.
At some point it starts to feel a bit like a corn growers' lobby shell game.

High concentration ethanol has been a corn lobby game for a long time. The basic premise of using a little bit to reduce emissions makes sense--there are a lot more bad things coming out of the engine than just CO2, and I'm always fascinated that people seem to forget just how bad engine exhaust used to be. Using oxygenates in fuel has certainly reduced smog, and that's a net win, but there doesn't seem to be a way to significantly reduce CO2 other than by reducing fuel consumption.

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[Racket]

The biggest flaw in the accusations that CO2 is bad is that it's not so much.

 

[D Fresh]

The dealer I bought it from never mentioned using 87 octane,so with people that don’t have mechanical experience,and this younger generation,women,etc….. are not going to even think about opening the owners manual,or get online and listen to so many different opinions,there going to buy the cheapest gas they can find,and in my area it’s going to be 86 octane.

My 15 year old daughter began learning how to drive this year. She understands that different vehicles require different fuels. Younger generation, women, what?

 

[Dunedain Ranger]

I've run Shell 93 Octane after draining the dealer tank of gas, and I average between 24-26 mpg if I don't beat on it. I won't and haven't used any other brand of gas.

 

[VAMike]

The biggest flaw in the accusations that CO2 is bad is that it's not so much.

 

[Chris M]

my truck sat for three weeks.
its running like a three legged dog right now.
its a slug.

anyone think my octane evaporated away??

Nah.
It's probably justs not happy you let it sit for three weeks.
How dare you!

 

[dtech]

But they still detect ping/detonation based on either sound or more recently & experimentally, on changes in ion current flow. But even with that rather advanced method an entire cycle of ping must occur for it to be detected & reacted to. If the engine were constantly running on that edge, that's a lot of pinging that is allowed to happen and it can still be detrimental. But also, any time the ECU has to de-tune to avoid knocking, power & mpg will drop. My guess is they program in safe ranges for expected octane levels rather than always pushing to the limit at any given moment & fuel.

H

Here's a link an article on ion sensing - a swedish company Mecel I think had some patents on it, eventually Delphi bought it, but GM was using it in Saturns, some Isuzus and apparently HArley Davidson as well. Saab though may have been the 1st as they intro'd it in the later 1990s. but it hasn't seen widespread adoption in autos.

https://www.vehicleservicepros.com/...21174614/making-sense-of-ion-sense-technology

 

[ScrappyLaptop]

just as an FYI on ion detection to control knock - I'm familiar with that as it was introduced on Saabs in the 1990s, a joint development with a Swedish University. The main advantage over acoustic knock detection is that it passes an ion measuring current pre combustion over the spark plug gap and can make timing adjustments on each cylinder to prevent knock from occurring, last I heard only BMW and Bugatti were employing it, I think the license cost is high plus what I referred to with the advances in microprocessors acoustic detection has become effective in controlling knock.
And from what I recall reading timing isn't continually advanced and retarded, but the ecu makes periodic reads to determine baseline octane and adjusts accordingly.

Wow, the method used by Saab back then really isn't too different - just that the precision and noise-to-signal processing now is orders of magnitudes better, as you'd expect. Thanks!

 

[ScrappyLaptop]

Here's a link an article on ion sensing - a swedish company Mecel I think had some patents on it, eventually Delphi bought it, but GM was using it in Saturns, some Isuzus and apparently HArley Davidson as well. Saab though may have been the 1st as they intro'd it in the later 1990s. but it hasn't seen widespread adoption in autos.

https://www.vehicleservicepros.com/...21174614/making-sense-of-ion-sense-technology

Thanks! It turns out the "experimental" version I came across was trying to overcome the shortcomings.

 

[ScrappyLaptop]

High concentration ethanol has been a corn lobby game for a long time. The basic premise of using a little bit to reduce emissions makes sense--there are a lot more bad things coming out of the engine than just CO2, and I'm always fascinated that people seem to forget just how bad engine exhaust used to be. Using oxygenates in fuel has certainly reduced smog, and that's a net win, but there doesn't seem to be a way to significantly reduce CO2 other than by reducing fuel consumption.

One of my first jobs was driving a delivery van for a local company - I think I'd just gotten my license, so this was many decades ago. I'd come over the last hill into the Bay Area and could *taste* the air. Engine exhaust was indeed very bad back then.

 

[GSD4EVR]

Stick with the manufacturer's recommendation. I like that most common grades aren't going to have any bad effects, but I've found that my engine is a great barometer of how an octane/ethanol grade can influence mileage. I recently tried a 93 octane, zero ethanol gas and my mileage was superb, better than any other fuel. Of course it cost an arm and a testicle as well!

ETA: Removed double word

 

[BCRanger]

I've never believed in putting anything higher than lowest possible octane level on domestic vehicle. Just went on a a loooong road trip (~ 6k total) with a Canopy Camper that destroyed our aerodynamics. Like 18mpg @ 70, 15mpg @ 80mph. And I can pretty confidently say that higher octane did make things 1-2 mpg better as well as improved throttle response and general drivability under load.

Here' my theory FWIW -- any other small inline turbo if it were made by someone other than big three would require higher octane; Ford probably worked pretty hard to make it possible for the engine to run on 87, because they would never have been able to sell a truck that required premium to traditional truck buyers. But itis probably somewhat compromised. Someone prob. mentioned this already, but the manual states directly that under load you want higher octane.

 

[ishman1995]

I have the tremor ranger and that is suppose to get worse has mileage at 19mpg combined. Idk how does is rating that but I get a combine of 22mpg driving alot of city miles. I also use 93 octane only from reputable gas stations.

 

[BCRanger]

My 15 year old daughter began learning how to drive this year. She understands that different vehicles require different fuels. Younger generation, women, what?

Thank you!!

 

[NickTheEnforcer]

I started running sam's club premium the first fall/winter because northern IL winter-blend was making it ping and hesitate a bit. Premium cleared it up so I've been running it ever since. It did take about 2-3 weeks to see the mpg increases.

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