Magic numbers

Ever wondered how to get from A to B?

The following is collection of calculations and conversions that we find useful on a day to day basis.

If you know of any other “Magic Numbers” that are not listed and you think are useful please drop us a line and let us know:

Calculating Power:

BHP = Torque (Nm) x RPM / 7120.916
BHP = Torque (lbft) x RPM / 5252.117
KW = Torque (Nm) x RPM / 9549.305

Converting KW to BHP – 1KW = 1.341022 BHP

Converting Nm to lbft – 1Nm = 0.737562 lbft

As a rule of “thumb” Engines and Dynamometers require 6 Gallons of water per HP per Hour for cooling.

Dynamometer calibration arm lengths:

Metric ( Kg and Nm) 1019.72mm = 10:1 ratio.

Imperial (lb and lbft) – Easy, 1lb at 1ft = 1lbft.

Note these distances are from the centre of the dynamometer and not the dimensions for the calibration arm itself.

The calibration arm should refelect the difference in dimensions from the dynamometer centre line to the machines designated calibration arm mounting point.

Pressure Conversions:

1 bar = 14.5 PSI
10M = 1 bar
1ft (head) = 0.43 PSI