Questions about shift points - Pontiac GTO Forum
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post #1 of 6 (permalink) Old 05-25-2005, 10:33 PM Thread Starter
 
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Questions about shift points

I'm no car guy or racer type but I was thinking about shift points.....

Since max torque usually happens prior to max HP (I think on a stocker it's max [email protected] approx 4400 and max [email protected] 5200 or so) shouldn't the car be set to shift slightly after max tq, wherever the shift allows the revs to fall back into the max tq range 3.5-5k?

Wouldn't shifting at redline actually be causing slower acceleration?

I guess the gearing comes into play deciding how far the revs drop....

Maybe the car does shift appropriately as it is?

But in theory, is my thinking correct?
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post #2 of 6 (permalink) Old 05-26-2005, 08:07 AM
 
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The best way to figure out where to shift is to get your car dynoed and look to see exactly where max TQ and HP are to determine the best place to shift. You also have to determine what type of driving you are doing. For normal driving there is no need to ever exceed your max TQ RPM range. Also as the engine wears your power peaks will move. Ive had my car dynoed 2 times sofar with only 1700 miles on it, at 1700 my max TQ was 250 RPM lower than my first dyno and has much more duration, max HP was 250 RPM higher and also has more duration. The way my dyno graph reads I probably dont need to take my car over 5200 RPM. but the best way to tell is off of a dyno sheet, and each engine will be different.
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post #3 of 6 (permalink) Old 05-26-2005, 09:52 AM
 
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post #4 of 6 (permalink) Old 05-26-2005, 11:23 AM
 
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Quote:
Originally Posted by Braman'sGTO
The best way to figure out where to shift is to get your car dynoed and look to see exactly where max TQ and HP are to determine the best place to shift. You also have to determine what type of driving you are doing. For normal driving there is no need to ever exceed your max TQ RPM range. Also as the engine wears your power peaks will move. Ive had my car dynoed 2 times sofar with only 1700 miles on it, at 1700 my max TQ was 250 RPM lower than my first dyno and has much more duration, max HP was 250 RPM higher and also has more duration. The way my dyno graph reads I probably dont need to take my car over 5200 RPM. but the best way to tell is off of a dyno sheet, and each engine will be different.
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post #5 of 6 (permalink) Old 05-26-2005, 11:43 AM Thread Starter
 
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Cool! Thanks for the info and explanation.

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post #6 of 6 (permalink) Old 05-26-2005, 08:37 PM
 
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Quote:
Originally Posted by RookWV
I guess the gearing comes into play deciding how far the revs drop....
In general, the gearing dominates the equation and you are better off holding the lower gear despite the lower torque and horsepower as long as it is safe to do so. That's probably why many of the racers and quarter mile guys tend to raise their rev limiters.
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