Serious Eric
Enthusiast
Paolo:
Yes, very close. The boost in engine HP/Tq due to your mods coupled with the 3.73 and that horrible shift to 6th leaves you just slightly shy of where you were with stock motor and 3.07. Interesting isn't it? Makes you realize how well those factory engineers did their homework.
Now leave your motor mods on and go back to the 3.07 and you'll really be helping yourself.
Mad Gray:
I understand your skepticism on hearing that you're making 1400 ft.lb. actual RWT during a dyno pull in 4th ... but it's true. The numbers that the dyno REPORTS to you (470 ft.lb or so) should be better termed "flywheel torque as measured at the rear wheels". That would make more sense.
The Dyno actually has a very simple clever way of factoring out all of the little variables that go into multiplying engine torque into RWT and then producing a tangential force vector to the edge of the drum. Remember, at the dyno shop nobody ever asks you what rear-end ratio you're using or enters any other vehicle-specific correction factor into the dyno program. For that matter wheel diameter and tire profile play a big role in determining the amount of force applied to the dyno drum, but nobody evers measures your axle to tire-edge radius. For a given amount of RWT, a smaller radius wheel/tire will produce a larger force vector at the pavement/dyno, so why doesn't that fake out the dyno?
The dyno measures some torque number (RWT) and we all know that that number is some multiple (M) of the flywheel torque(FT). That multiplier (M) is the result of a combination of factors that act to multiply (and maybe reduce) engine torque. Those factors of course are transmission gear ratio, rear-end ratio, wheel/tire size, etc. So FT = RWT / M. Basically (I don't claim to know too many details of dyno operatio), the dyno calculates the M multiplier as a ratio of drum revolution speed to engine revolution speed. All of the gearing and wheel/tire details act to effect the drum speed at any given engine RPM. A viper with a higher-than-stock gear ratio will turn the drum slower at a given rpm than will a stock viper. So the ratio of drum rpm to engine rpm IS proportional (dyno dependency) to the torque multiplication factor M. The dyno program calculates this engine rpm : drum rpm ratio and applies it to the RWT (1400+) and reports it to you as it's estimate of flywheel torque.
Yes, very close. The boost in engine HP/Tq due to your mods coupled with the 3.73 and that horrible shift to 6th leaves you just slightly shy of where you were with stock motor and 3.07. Interesting isn't it? Makes you realize how well those factory engineers did their homework.
Now leave your motor mods on and go back to the 3.07 and you'll really be helping yourself.
Mad Gray:
I understand your skepticism on hearing that you're making 1400 ft.lb. actual RWT during a dyno pull in 4th ... but it's true. The numbers that the dyno REPORTS to you (470 ft.lb or so) should be better termed "flywheel torque as measured at the rear wheels". That would make more sense.
The Dyno actually has a very simple clever way of factoring out all of the little variables that go into multiplying engine torque into RWT and then producing a tangential force vector to the edge of the drum. Remember, at the dyno shop nobody ever asks you what rear-end ratio you're using or enters any other vehicle-specific correction factor into the dyno program. For that matter wheel diameter and tire profile play a big role in determining the amount of force applied to the dyno drum, but nobody evers measures your axle to tire-edge radius. For a given amount of RWT, a smaller radius wheel/tire will produce a larger force vector at the pavement/dyno, so why doesn't that fake out the dyno?
The dyno measures some torque number (RWT) and we all know that that number is some multiple (M) of the flywheel torque(FT). That multiplier (M) is the result of a combination of factors that act to multiply (and maybe reduce) engine torque. Those factors of course are transmission gear ratio, rear-end ratio, wheel/tire size, etc. So FT = RWT / M. Basically (I don't claim to know too many details of dyno operatio), the dyno calculates the M multiplier as a ratio of drum revolution speed to engine revolution speed. All of the gearing and wheel/tire details act to effect the drum speed at any given engine RPM. A viper with a higher-than-stock gear ratio will turn the drum slower at a given rpm than will a stock viper. So the ratio of drum rpm to engine rpm IS proportional (dyno dependency) to the torque multiplication factor M. The dyno program calculates this engine rpm : drum rpm ratio and applies it to the RWT (1400+) and reports it to you as it's estimate of flywheel torque.
