Reading car specification for dummies

Arief Hidayat, The Jakarta Post, Jakarta

When a new car is launched, the car's specifications are always to be found in its advertisements. Usually, the specifications provide details such as capacity, power, ignition, performance, fuel consumption, etc.

From these specifications, prospective buyers will be able to tell a little something about the car's performance. However, these detailed specifications often use overly technical automotive terms that are probably alien to your average car buyer.

So, how can you read a car's specifications?

1. Four Parallel Cylinder, DOHC, VVT-I. This means the car's engine has four pistons in a parallel configuration. DOHC stands for Double Overhead Cam. A cam is a component that regulates the opening and closing timing of the valve in the ignition chamber. The valve itself is divided into two types: one to bring the fuel in and the other to dispose of ignition residue at the end of the exhaust pipe (muffler). If DOHC is included in the specifications, then there are two types of valve for each valve.

2. VVT-I stands for Variable Valve Timing. This means the opening and closing of a valve can be actively carried out by a computer, with oil pressure regulating how long and how high the valve must be opened.

The benefit of the VVT system is that power is available at any time and is very efficient in terms of fuel consumption. Based on the engine and wheel rotations, gear position, car load (the number of passengers) and the opening of the gas throttle, which are monitored by a censor, the computer will instruct the valve to open and close according to the car's needs. The letter "I" indicates that the car uses a fuel injection system.

3. Capacity of 1,497 cc indicates the total capacity for all four pistons. Divided by four, this leaves each piston with a volume more or less of 370 cc.

4. Power: 103hp@6,000 rpm. This means the engine can produce power equal to 103 horsepower with the engine cycling at 6,000 per minute.

5. Torsi 158 Nm@4,200 rpm indicates that at 4,200 rpm, the car will achieve its peak power. Normally, this is called having power on mid rpm. The good thing is that one will not have to shift gears too often because the power is always available at mid rpm.

6. Specific power 68.9hp/liter. This means that every 1,000 cc of fuel can produce as much as 68.6 hp of power. The more hp produced, which is equal to the volume of the engine, the better the engine design. As a comparison, a Formula One racing car ranges between 350 hp to 450 hp for 1,000 cc.

7. Ignition system: For example, if the specs say TOYOTA Direct Ignition, this means the car no longer uses a distributor to separate ignition in each cylinder. Instead, each cylinder is provided with a coil for ignition. So the distribution of ignition timing is computerized.

8. Performance: 0 - 100 km/hour nine seconds. A passenger car normally need 13 seconds to 15 seconds from a stopped position to reach 100 km/hour. The car in this example can manage to get to 100 km/hour in less than 10 seconds, so it cannot be taken lightly. This means that the car can be used for high-speed racing. This ability is the result of applying Variable Valve Timing (VVT), making power available at any time. The benefit of VVT is also apparent in more efficient fuel consumption.

9. In regard of dimensions, the most important thing is the vehicle's weight because this relates to the power provided by the engine. Divide the vehicle's weight by the horsepower available in the car. The lighter the load carried by the engine, the smoother the engine will work. For example, the power available in a TOYOTA YARIS is 103 hp while the load is 960 kilograms, so the load is 10 kilograms for each hp.

10. Transmission can be judged by the ratio of each gear, for example first gear to second gear is 3.17 to 1.90, which is pretty loose. The number 3.17 means first gear rotates 360 degrees after it rotates 3.17 times.

Final drive is the last gear that is directly connected to tire axle. For this specification, final drive is 4.31, which means in order to have a 360 degree tire rotation, it requires a 4.17 rotation from the final drive. The gear will determine how strong the car is. For racing, the final drive usually needs to be "tuned". The smaller the final drive ratio, the stronger the car, which generally means higher fuel consumption.