The 4 Wheel Load Dyno
The 4×4 dynamometer basically consists of two separate dyno’s of which one dynamometer can be adjusted to accommodate different wheelbases.
The speed of the front and rear dyno’s is controlled individually and is by no other means connected. Either one of the two dyno’s can therefore be used individually as a normal front or rear wheel drive. When performing a constant speed (eddy current brake) 4×4 dyno test, the speed controller of the dynamometer controls the front and rear roller speeds to be exactly the same. The power readings are shown individually to show the powersplit on the front and rear dyno’s. The constant speed facility enables the user to either put a fixed load on the brake or to hold the vehicle at a certain rpm.
This is especially handy when a problem is encountered at a specific rpm or load condition. Where applicable, the loading facility can also be used to do engine mapping, using the system mentioned below, or any other system available.
Road simulation testing is done on a loading dyno, since it can simulate uphill, towing and head wind conditions.
Up to 64 sensors (temperature, pressure, etc) can be added to this system which may help the serious tuner in assessing problems. Normal inertia dyno testing can also be done on the 4×4 dyno, provided the vehicle is equipped with a lockup facility on the transfer case. Otherwise normal 4×2 inertia dyno testing can be done on either of the two dyne’s.
2 Wheel Inertia Dyno
This inertia type dynamometer is very popular, due to its affordability and repeatability. The weight of the rollers is calculated to accurately simulate road conditions and therefore lends itself to an ideal tuning tool for performance related dyno tuning.
Full load remapping can be done on the inertia dynamometer which has the advantage that it does a complete power and torque curve in less than 30 seconds. This reduces the dynamometer time dramatically and subsequently engine wear. Furthermore the engine does not overheat as easily as with the constant speed or loading dynamometers. The knurled rollers ensure good traction and limits unnecessary heat buildup in the tires.