Innovate Motorsports LogWorks 3 - Manual (Page 126)

LogWorks3_Manual_1.01.doc - 126 -
11.2 LogWorks built-in Trace calculations
These are the calculations built into LogWorks for calculating new channels or traces. Check on
the Innovate Motorsports web site (www.Innovatemotorsports.com) for additional calculations as
they become available.
To understand the calculations a few things must be known by the user:
b. Every calculation is only as good as the data used as basis for the calculation. This is
especially true for horsepower and torque calculations.
c. Many time based calculations are based on an engine cycle. A 4-stroke engine cycle
requires 2 engine revolutions.
11.2.1 Category: Fuel Calculations
Fuel flow (lb/hr) from duty cycle (US) or (cc/min) for International
Requires you to enter the specs of the injectors used (lb/hr) or (cc/min), their rated pressure in
PSI (US) or kPa (int.), the injector duty cycle channel name (easy if you have an LMA-3), the fuel
pressure the regulator is set to, and the total number of injectors. Creates a fuel flow channel in
lb/hr or cc/min total for the engine.
Note: Specifying injectors in lb/hr is actually a misleading metric. Injectors flow a certain volume in
a specified time. Because most fuels have very similar viscosity, but very different specific mass,
an injector rated for example for 10 lb/hr will flow 10lb per hour of the test gasoline, but a very
different number of lbs for example for methanol.
11.2.2 Density and VE
Intake air density
Calculates an air density channel in lb/cuft (US) or kg/m^3 (Internat.) from intake air temperature
and absolute intake air pressure (MAP) channels.
11.2.3 Power calculations
These calculations result in two channels, one for torque and one for power. The US version of
the calculations result in a torque channel in lbft and a horsepower channel in hp. The
International versions result in a torque channel in Nm and a power channel in kW. You can
easily change the formulas to get the results in the units you want. Because these calculations
are based on the acceleration of the vehicle, the speed of the vehicle must be known. It is
assumed the test runs are done in a single gear (3
rd
gear for example). Because vehicle speed is
calculated from gear ratios and tire diameter, the calculations will be unreliable for an automatic
transmission vehicle below the converter lockup rpms. They will be correct at rpm levels above
converter lockup. Because a vehicle does not accelerate any more at top speed, for calculations
based solely on acceleration alone, the torque (and therefore horsepower) would be zero there.
That’s of course not the case. The calculations therefore also require to put in the frontal area and
Cd value of the car to calculate aerodynamic resistance force. As this force is speed dependent