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blue2000s · 04-22-2008, 06:41 AM

OK, here's the way it's done. This will probably lead to some useless torque vs power debate that I won't be participating in.

You look at the torque produced at the wheels in every gear for a given vehicle speed. This gives you a set of curves of torque vs vehicle speed. In fact, this will often give you 3-4 gears to choose from at a given speed. You choose the gear that gives you the highest torque at any given speed and you stay there until redline or until the torque curve drops below the torque curve of the next gear. This is part of the process used to define gear ratios and it's also the process you use to decide what shift pattern will give you the best acceleration. In the Boxster, as with just about every other high performance sports car, redline is where you shift in almost every gear.

Here's a spreadsheet showing what I'm talking about. Take off the .txt extension and unzip it.

http://986forum.com/forums/attachment.php?attachmentid=3282

Keeping RPMs between the torque peak and power peak is incorrect and shifting at power peak is incorrect. You ALWAYS have to look at the torque at the wheels if you want to answer this question correctly.

04-22-2008, 06:41 AM	#10
blue2000s Porscheectomy Join Date: Mar 2006 Location: Seattle Area Posts: 3,011	OK, here's the way it's done. This will probably lead to some useless torque vs power debate that I won't be participating in. You look at the torque produced at the wheels in every gear for a given vehicle speed. This gives you a set of curves of torque vs vehicle speed. In fact, this will often give you 3-4 gears to choose from at a given speed. You choose the gear that gives you the highest torque at any given speed and you stay there until redline or until the torque curve drops below the torque curve of the next gear. This is part of the process used to define gear ratios and it's also the process you use to decide what shift pattern will give you the best acceleration. In the Boxster, as with just about every other high performance sports car, redline is where you shift in almost every gear. Here's a spreadsheet showing what I'm talking about. Take off the .txt extension and unzip it. http://986forum.com/forums/attachment.php?attachmentid=3282 Keeping RPMs between the torque peak and power peak is incorrect and shifting at power peak is incorrect. You ALWAYS have to look at the torque at the wheels if you want to answer this question correctly. Last edited by blue2000s; 04-22-2008 at 06:47 AM.