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Old 03-02-2018, 05:58 PM   #231
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Drive it easier so that you do not notice the torque increase.

More torque = more fuel.
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Old 03-02-2018, 08:24 PM   #232
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Torque /= more fuel. There is much more than that to it. Many built and tuned motors that make more power than stock get better economy. Buddies integra with no displacement change went from 120ftlbs to 220ftlbs and went from 27mpg hwy to 41mpg hwy and a red line of 5000rpm to 12000 rpm. Yes, crank bearings lasted about as long as a tank of fuel. The 444ci diesel makes 3.5x the torque at better MPGs than I was getting.

If you want the math answer I'll have to break out my books. It all boils down to the motor being merely an air pump.
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Old 03-02-2018, 08:53 PM   #233
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I think engines are more efficient when they are making their peak torque, but not most economical.

Diesel engines are vastly different from gasoline engines. It could be due to the much higher compression ratios they run (22:1 in diesels compared to 9:1 in gasoline), but a diesel engine can get better economy when more fuel is dumped in.
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Old 03-02-2018, 09:56 PM   #234
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Rollin’ coal FTW.
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Old 03-03-2018, 12:11 AM   #235
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I've been accused to rolling some coal a few times. 21MPG over that tank and to top it all off I got to cover 3 lanes of Portland traffic in what was essentially a black out all because some turd decided my blind spot was better than not running into me or my dad on his new motorcycle. If you are rolling coal all the time with it and over fuelling MPGs tank fast. Add a load and it goes down even faster.

Gas and diesel engines are very similar other than direct injection being inherently more efficient and no throttle body on a diesel.

In general peak torque is the point of peak efficiency and many motors have that as peak economy too. But RPM must be taken into account for torque too. There are too many variables to know to be able to break down one of our engines mathematically. Best case would be a complete guess. Even flame propagation within the combustion chamber can effect power. I only have experience with calculating therohetical motors with no friction taken into account. I've done all types of induction, including the differences in turbo charging and supercharging, as well as carborated, TBI, MPFI and direct injection. Its all very interesting. Its just fun to read the theory even if you dont understand the math. Lots of calculus was used.
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Old 03-03-2018, 12:42 AM   #236
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> the point of peak efficiency and many motors have that as peak economy too.

That part is probably something you overheard that isn't correct. An engine peaks when it is roaring like a somebitch and burning the highest percentage of the fuel that is being delivered. That is rarely the point of peak economy. It could happen, but that's not really the way engines are usually designed.
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