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Old 09-28-2007, 08:17 PM   #16
grndslm
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Re: Performance upgrades that don't lower fuel efficiency

Quote:
Originally Posted by ec437
The best way to drive for fuel effeciency is to accelerate at 80% throttle, staying in the highest gear possible...
I know this isn't completely true all the time. I can always ride with my car in 5th gear... but it's not a good idea. I think it's typical to keep things inbetween 2000-4500rpm.

How much the throttle's open also really doesn't seem to matter much of anything with my car either, but I have 17" low pro rims on a Corolla. It's pretty crazy that no matter how much I drive in city vs hwy and how fast on the interstate I drive 70 to 95mph... I consistently get 26mpg with these rims.

The only way I can get better than 26mpg ever is if I know where I'm going, haul ass and cut the car off way before I see a stop sign or a light that I'm familiar with it's timing or a long 2-lane road with a 90deg turn. Once I've gotten to the line or rounded the turn, I pop it in third and drop the clutch in to place so no damage is done to my starter. By doing this I've gotten ~31mpg, my only variation from the number 26.

Quote:
Originally Posted by ec437
and when you get up to speed, mantain it. When do you have to slow down, engine brake with the lower gears.
This was the meat of my digging up this ancient thread: How is engine braking good for fuel economy, I don't get it? I just use my brakes, and (as previously mentioned) I turn my engine off when I'm slowing down because it's fuel injected and doesn't benefit from even idling in my experience, much less more strain. Is there really more strain on engine by engine braking, tho? I dunno... I guess more gas being sucked out, no, but more strain on the engine, yes.
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Old 09-28-2007, 09:15 PM   #17
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Re: Performance upgrades that don't lower fuel efficiency

No... when an EFI engine is braking (when your foot is off the gas but still above idle) it injects zero fuel. When your foot is off the gas, the computer will inject enough fuel to maintain idle... which, if the engine is being spun faster, means it needs to inject no fuel.

If you push in the clutch or put it in neutral, it returns to idle where it begins injecting fuel again.
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