Dyno run, or sometimes called a power run is a method of measuring an output of a car.In other words, we are measuring the horsepower and the torque of the car.But there is two types of dyno run generally used in automotive, the first one is called a chassis dyno run where the tyre is mounted on the dyno roller and the other one is called as engine dyno, where the power is measured from the engine crankshaft or the flywheel.
THE CAR IS PLACED ON THE ROLLER
Chassis Dyno Run vs Engine Dyno run
A lot of people got confuse between those two, especially the reading or result.A engine dyno will always get a higher result than a chassis dyno result. Why? because an engine dyno doesnt count for the mechanical loss in the gearbox. When you do a chassis run, some horsepower will be loss in the drivetrain.An engine dyno result will be called as Brake Horsepower (BHP) while a chassis dyno will gives out the Wheel Horsepower (WHP).
The dyno result the manufacturer gave is mostly the Engine’s horsepower, thats why if you do a dyno run on your car, you will never get the same result as stated in your specifcation. Generally the wheel horsepower (WHP) result will be around 15-20% lower than the engine horsepower (BHP).
POWER IS MEASURED BY THE ROLLER UNDER THE TYRE
On last saturday, KDI decided to send my car for a Dyno run. So we went to Sunway to get the car dynoed. We choosed a workshop called as JC Racing or JC Asia Motorsport to do our Dyno run.The cost for the dyno run is Rm80 for 3 run and if you want to check your air fuel ratio as well, you have to add up another Rm20. The price of a dyno run varies from different places but mostly will fall somewhere between rm60-rm120. But if you want other services on the dyno such as tuning your piggyback controller(apexi safc, greddy e-manage) or even your standalone management/ecu (haltech, motech) the price will be somewhere from RM200-Rm1000 per tuning session of unlimited run.
THE CAR IS STRAPPED UP TIGHTLY TO PREVENT THE CAR FROM MOVING
The process of the dyno run started by placing the car on the dyno roller, as you can see in the second picture, the front tyre is placed directly on the roller. For a rear wheel drive car, the rear tyre will be placed on top of the rear roller, and for a 4wd car, all of the four tyre need to be placed directly on top of the four roller. The car is than strapped tightly using multiple strap as can be seen on the picture above to prevent it from moving forward or side to side during the dyno run.
THE PARAMATERS ON THE DYNO COMPUTER INCLUDES BOOST, RPM, AIR FUEL RATIO AND SPEED
After the car is securely strapped, the mechanic will start to generally check the car condition such as engine oil level and radiator coolant level. To get the RPM reading on the dyno graph, an electrical clamp will be clamped at the ignition coil input which will give an rpm reading to the dyno machine. For a turbo car, the boost pressure will be tapped from the blow off valve vacuum line. And if you opt for air fuel ratio reading, a wideband oxygen sensor will be placed inside your car muffler as can be seen in one of the picture below.
THE WIDEBAND OXYGEN SENSOR PLACED INSIDE THE MUFFLER
With everything set up, the technician will get in the car and start warming up the car. After the car is warmed up, he will shift to third gear and start to accelerate the car to its redline or maximum rev, once the run is finished there will be a graph of horsepower, air fuel ratio and boost pressure displayed on the computer.Once the run is finished, the technician will print the result and you can keep it for your own reference.
THE RESULT GRAPH
The result which will be printed show your car horsepower graph, maximum power, maximum torque, air fuel ratio and boost pressure. The red coloured line on the graph is the horsepower of the car. The max horse power we manage to get is 141 whp (165-170bhp) at 4850 rpm and the max tourque we achieved is 20.80 kg/m or 203Nm at 1 bar or 14.7psi off boost pressure. But sadly one of the car air flow sensor had a problem so the full potential of the car cannot be measured. As you can see the air fuel ratio, the second graph at the bottom, the reading should be at somewhere at 12 to get the best power and the safest engine condition, but on this car the air fuel ratio rise up to 16-17 on boost which is very lean and which lead to a high combustion temperature and may cause the engine to blow. Thats why we can only measure up to 4850 rpm while the car redline is at 7000rpm.
[youtube:http://www.youtube.com/watch?v=eMEynjV6dsE 425 344]