Quote:
Originally Posted by thefoos
^^Where is the peak torque on that motor?
I'm not really interested in agruing. These facts about economy have been established a long time ago by IC design engineers. I wish I could find a brake fuel consumption curve out on the internet. The only ones I have are in text books. If you looked at one, you would note that fuel consumption is a parabolic relationship to rpm, with the lowest point of the curve equal to the rpm that peak torque is at.
It is about efficiency. that is what this thread is about anyhow. The more efficient the engine is, the less fuel is used. You guys are over simplifying engine dynamics and boiling it down to rpm's = bad (frictional losses). There are a bunch more variables at work here.
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What you deam as efficiency is not Fuel Economy efficiency. You talking about producing max., power/torque. WIth the appropriate gear ratio, as in todays vehicles it is not necessary to run the engine at this max., efficiency to obtain max., economy.
RPM=bad is true. More RPM means more gas is consume for a given time and and a given distance. If I drove my Subaru at what you call most efficient, I would be consuming gasoline at 3-4 gallons per hour. I know when my engine is running at or below 2000rpm, it is below what you call max., efficiency, and the engine is border line lugging. But I am using very little fuel and that is all that matters.
Are there more variables at work here. Most definitely, gear ratio, weight of vehicle, etc....
But the reality is your average vehicle today is designed for low rpm to achieve max MPG. Not high rpm (3000 rpm) to achieve max., MPG.