Discover the true meaning of horsepower

Discover the true meaning of horsepower image

Text: / Photos: Brent Co | posted February 08, 2007 08:00

In the auto arena, discussions of one-upmanship are common, such as how much horsepower (hp) and torque certain vehicles make. It is easy to claim that one's vehicle makes x amount of hp and y NMs (Newton-meters) of torque because the manufacturer's brochure/owner's manual said so, or that a particular power-generating aftermarket piece (such as air intakes or bolt-on turbo kits) adds b amount of hp because it was written inside the said piece's product literature. But has one really determined if the manufacturer's claim is true?

One way of finding out if these claims are true is to go to Speedlab. Located along the Welcome Rotunda-bound area of Quezon Avenue (specifically one or two buildings before the Petron station on Quezon Avenue near Honda Quezon City), this 1,700 square meter one stop shop is a haven for all one's auto mechanical needs, aside from offering customers the opportunity to tune their vehicles using a chassis dynamometer made by Dastek (a reputable South African-based auto performance company).

The crown jewel of Speedlab, the Dastek chassis dynamometer (or dyno for short) measures power whilst a vehicle is in motion. This means that a chassis dyno measures a vehicle's power capabilities via the wheels that drive the vehicle (whether front or rear wheel drive), unlike engine dynos where only the engine is tested (with great effort to the dynamometer directly at the flywheel). "An engine generates power at the flywheel which is transferred to the gearbox via a clutch and pressure plate. The gearbox in turn transfers the power to the differential which again powers the drive-shafts which are coupled to the wheels. All these devices absorb some of the power and as a result the power that is delivered at the wheels is substantially less than the power delivered at the flywheel. The losses may vary between 18 and 28 percent. The power at the wheels is what will determine the performance of the vehicle. The main problem is that all manufacturers specify power on the flywheel and not on the wheels," said Speedlab marketing manager Sidney Ang.

Another unique aspect of the Dastek dyno is that it is both an inertia dyno and a load dyno. With regard to the former, this means that the Dastek dyno has a brake attached to the one roller which will keep the vehicle at any given speed. With this style of dynamometer the vehicle can be driven and tuned at constant engine speeds under various load conditions. With regard to the latter, the Dastek dyno also works on the basis that the vehicle is driven at full throttle in fourth gear from a low speed (usually 120 to 140 kph). It is then measured how fast the vehicle accelerates the rollers and from there the power is determined. The vehicle is then taken out of gear (or the clutch disengaged) and the deceleration measured by allowing the rollers and wheels to slow down by themselves. "This is the only way to properly tune a vehicle and determine power output at all parts of a vehicle's rpm (revolutions per minute) range, not just at full throttle," said Speedlab operations manager Ferman Lao.

There are three forms of Speedlab dyno sessions. The first is what is known as baseline runs, where three loaded runs are performed on the vehicle, which determines the vehicle's horsepower and torque. The second is a group session developed exclusively for car clubs, in which they can have exclusive use of the dyno for one whole day, with group discounts. The third is known as tuning sessions, where a vehicle owner gets the opportunity to discern whether particular power-generating aftermarket pieces add horsepower to the vehicle and is determined by the amount of power (or the amount of power-generating aftermarket pieces) the client wishes to bolt on to his or her vehicle. "If you have camshaft gears, air/fuel controllers, ignition spark amplifiers/ignition boxes, boost controllers or stand-alone engine management systems, you will definitely need tuning sessions," said Lao.

Should one have the need to modify his or her vehicle's engine into something straight out of The Fast and The Furious, Speedlab also offers the following auto performance upgrades: 1) Custom fabrication, in which the certain parts are made by Speedlab in order to facilitate better airflow or oil flow in and out of your vehicle; 2) Performance parts installation, including turbo kits and nitrous oxide (a well-known power adder) kits; 3) Corner weighing, the best form of suspension tuning and is particularly helpful if one's vehicle has coilovers or adjustable shocks; and 4) Electronic control unit (ECU) tuning, in which the engine map (overall engine behavior) is calibrated.

If one has the urge to one-up his or her rivals at the dragstrip, at the auto show, at the drift course, at the racetrack or during discussions about horsepower bragging rights, then one should call 376-4648 or 376-4651 for more details.