Mr. Gasket 8703 Hot Rod Calculator User Manual
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— do noT Clear CalCUlaTor —
rPM — Based on gear Ratio, Speed and Tire Diameter
From the above calculation, it is estimated that the mighty 5.0
LX will be going about 70 MPH at 5,500 RPM in 2nd gear.
In this example, calculate your RPM at 65 MPH in 5th gear. you
will need to find the correct multiplier for 5th gear. Recall that the
final-drive ratio is 3.08 and 5th gear is 0.68.
KeysTroKe
disPlay
5. Multiply the final-drive ratio and 5th gear ratio, and enter that
as your Gear Ratio:
Gear
raTio
2.0944
6. Enter your cruising speed of 65 MPH:
sPeed 65.
MPH
7. Calculate the RPM:
*
rPM 1760.004**
* Repeated presses of
will toggle through the inputs and outputs,
starting with the entered speed.
— do noT Clear CalCUlaTor —
** It is estimated that the 5.0 LX will be cruising at about 1,760 RPM
while going down the highway at 65 MPH in overdrive, resulting in
decent fuel mileage due to a low load on the 5.0 liter engine.
Gear ratio — Based on RPM, Speed and Tire Diameter
In this example, you want to solve for performance out on the
highway. The 5.0 LX peaks in Torque at about 3,000 RPM.
When you want to downshift from 5th to 4th and safely overtake
another car at the LX’s peak Torque RPM, what final-drive ratio
will enable the LX to reach 3,000 RPM at 65 MPH in 4th gear?
Recall that 4th gear is direct drive and therefore would be the
same as the final-drive ratio you are solving for.
(cont'd)
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