The accelerator pedal and fuel consumption

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Re: The accelerator pedal and fuel consumption

Post by theholycow » Fri Oct 14, 2016 10:54 am

tankinbeans wrote:Up to now I've used non-oxy 91, but am trying regular 87 to see if there will be much difference aside from the lower energy content.
Energy content is the same between different octane ratings. The rating measures resistance to preignition/detonation. A higher octane rating can be run with different spark timing that can produce more power without causing spark knock. Sometimes labels on gas pumps even describe it as "AKI (Anti Knock Index)" in fine print.
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Re: The accelerator pedal and fuel consumption

Post by IMBoring25 » Fri Oct 14, 2016 11:08 am

A signature update is in order.

I don't remember what you said it is. If it's a premium-recommended or premium-required engine, it will have to pull timing to run regular and the off-design operating parameters may cost you a little mileage. If they don't require or recommend premium in that engine, there is likely no benefit to running 91.

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Re: The accelerator pedal and fuel consumption

Post by Rope-Pusher » Fri Oct 14, 2016 11:20 am

IMBoring25 wrote:A signature update is in order.

I don't remember what you said it is. If it's a premium-recommended or premium-required engine, it will have to pull timing to run regular and the off-design operating parameters may cost you a little mileage. If they don't require or recommend premium in that engine, there is likely no benefit to running 91.
in addition:
"When the frost is on the pumpkin,
that's when it's time for .....
purchasing lower octane fuel because the cold air makes detonation less likely.
The ecu won't have to pull back on the spark advance and all DOG's chittlin will produce rated horsepressure."
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Re: The accelerator pedal and fuel consumption

Post by tankinbeans » Fri Oct 14, 2016 12:28 pm

theholycow wrote:
tankinbeans wrote:Up to now I've used non-oxy 91, but am trying regular 87 to see if there will be much difference aside from the lower energy content.
Energy content is the same between different octane ratings. The rating measures resistance to preignition/detonation. A higher octane rating can be run with different spark timing that can produce more power without causing spark knock. Sometimes labels on gas pumps even describe it as "AKI (Anti Knock Index)" in fine print.
Correction to your correction. There are certain stations that offer non-oxygenated E0 premium 91 octane fuel, while all 87 octane has 10% ethanol or more. I know there's a slight deficit in the energy contained therein when ethanol is added.

I was using the 91 non-oxy up until now.
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Re: The accelerator pedal and fuel consumption

Post by IMBoring25 » Fri Oct 14, 2016 1:43 pm

If you can't get E0 87 that throws a wrench in the calculus.

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Re: The accelerator pedal and fuel consumption

Post by tankinbeans » Fri Oct 14, 2016 1:56 pm

IMBoring25 wrote:If you can't get E0 87 that throws a wrench in the calculus.
Ours is one of them states with a renewable mandate and most fuel has some amount of ethanol.

I'm honestly curious what the difference will be. Compression in my new rig is pretty high, 13:0, and it's fairly broken in.
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Re: The accelerator pedal and fuel consumption

Post by Rope-Pusher » Fri Oct 14, 2016 4:33 pm

tankinbeans wrote: Image
Ours is one of them states with a renewable mandate.
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Re: The accelerator pedal and fuel consumption

Post by AHTOXA » Fri Oct 14, 2016 10:47 pm

tankinbeans wrote:
AHTOXA wrote:I drive my Forester like this as well - low revs and wide throttle. With a slow car you can do that without being a menace to society. If I tried that on the bike, I'd be in jail very quickly. Or dead.
Do you mean keeping it in 6th most of the time, if above 1500 revs, and matting it to slowly accelerate? I ask because I recently traded Ms. Frizzle for Bubonic Freddie (the extra power wore of as a novelty and tickets are no fun) and am seeking to maximize the mileage. Freddie is tarred rated 29/41/33.

Up to now I've used non-oxy 91, but am trying regular 87 to see if there will be much difference aside from the lower energy content.
Not 6th, but all lower gears as I accelerate. I'll usually nearly mat it while shifting somewhat early around 3k revs. Because I shift early I don't accelerate that fast, but the throttle is very open.

To be honest though, it's just how I drive. I don't do it for fuel economy or what not. Frankly, I care little what my fuel economy is.
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Re: The accelerator pedal and fuel consumption

Post by theholycow » Sat Oct 15, 2016 7:19 am

AHTOXA wrote:Not 6th, but all lower gears as I accelerate. I'll usually nearly mat it while shifting somewhat early around 3k revs. Because I shift early I don't accelerate that fast, but the throttle is very open.
That is how I drive fuel-injected cars too, though some cars at much lower RPM. In the VW, with its short gears, good power-to-weight ratio, and low RPM torque, 3000 RPM would have been ricing around like a teenager begging for a ticket. I shifted that car when it hit somewhere between 1200 and 2000 (depending). In my wife's Sunfire, with better gears, a little less torque, and less patience than I used to have (yeah, been a bit more zoomy lately but still obeying limits) I'll hit 2000-3000.

Although fuel economy is a critical factor for me and I have found that it always responds more favorably to that driving technique than to any competing technique, I too would do it the same even without the fuel economy benefit. I prefer to use whatever torque there is (a little or a lot) instead of any unnecessary "vroom", and the ability to do this is one of my favorite advantages of manual transmissions.
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Re: The accelerator pedal and fuel consumption

Post by AHTOXA » Sat Oct 15, 2016 10:39 am

Sometimes when I'm cruising on the bike I fall into the same habit and end up shifting low around 3k revs (redline is 10k). Then, on a long on-ramp or something I'll peg it in 2nd, wind to to 10k wide open and :shock: :lol: :lol: giggle like a little school girl inside my helmet.
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Re: The accelerator pedal and fuel consumption

Post by Rope-Pusher » Sat Oct 15, 2016 2:51 pm

AHTOXA wrote:Sometimes when I'm cruising on the bike I fall into the same habit and end up shifting low around 3k revs (redline is 10k). Then, on a long on-ramp or something I'll peg it in 2nd, wind to to 10k wide open and :shock: :lol: :lol: giggle like a little school girl inside my helmet.
If you let the little girl out of your helmet it would be sorta kinda like an Italian tune-up.
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Re: The accelerator pedal and fuel consumption

Post by tankinbeans » Sun Oct 16, 2016 11:23 am

You know, Tony, it's irresponsible to have your helmet near little school girls.
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