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Old 10-04-2011, 05:17 PM   #19 (permalink)
Patrick
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Hot Tamale - '10 Toyota Prius III
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Quote:
Originally Posted by tjts1 View Post
You're thinking about peak torque at any given RPM. At part throttle cruise on flat ground you don't need that. You're just playing around inside the torque curve area. If you install taller gearing your airflow and torque remain the same even though you reduced the RPM for a given cruising speed. If you have a good OBD2 tool (scan gauge, ultra gauge, Torque app etc), get on the highway and cruise at a fixed speed in 4th gear on flat ground, note the throttle angle and MAF reading, then shift to 5th. You'll see the same angle and MAF reading despite the reduced RPM. Your injector pulse width will be different because fuel pressure is vacuum referenced. Thats why all OBD2 systems use MAF not injector PW to calculate fuel consumption.
The equation holds at any RPM, torque, or power. Just like E = I X R, it's a mathematical and physical fact. If you decrease rpm for a given power, you must increase torque. If you lower RPM at the same torque, you have decreased power.
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