Reading car specification for dummies

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.