[E4ODnut]

[QUOTE=capnbass91;274492]With an Ultra-Gauge the manual says this:. Where engine load is calculated as:
% Load = Current Air Flow/Peak Air Flow. OR % Engine Load = Current Engine Torque/Peak Engine Torque. Method used if vehicle dependent.

I don't mean to hijack this thread, but I've been curious as to how to calculate engine load. The above quote makes sense to me.

If you use torque, then you have to have a means of determining torque. A dyno is the only thing I can think of. Not practical for most people.

Air flow is probably the most practical, but it depends on how you can determine air flow.

If you have a Mass Air Sensor equipped vehicle, and the means to interperet it's signal, the MAF sensor has done the work for you and the math is simple, no other inputs needed.

However. What if you don't have a MAF sensor and use a speed density system to calculate air flow (Manifold Absolute Pressure) sensor, RPM and engine displacement? The same could be said for Alpha - N, in which you don't use MAP, but rather throttle position, RPM and engine displacement. Of these two methods, it is generally considered that MAP/RPM gives a more accurate picture of actual engine load.

Now the calculations as to what your air flow actually is get somewhat complicated. With both methods you also have to take into consideration the volumetric efficiency of the engine at different speeds and loads. If you know the volumetric efficiencies, then you can do the calculations but these numbers are not normally available. Other than general statements to the effect that volumetric efficiency normally tracks the torque curve, I haven't come across any published figures for any engine.

So, my question is, how can you determine percent of engine load, with any reasonable degree of accuracy using a speed density or Alpha - N system?