Can I drive a small car in a mountainous area?

Do you think it is risky to drive a 1.3cc engine car (e.g. Mazda Demio- 2004) to mountainous areas?
Justine

Driving up a mountainous road not only requires special skills and adequate preparation but also a reliable and tough vehicle.

The mountainous roads and tracks are usually steep, winding and slippery.

These mountainous terrain features pose grave challenges to motorists and can be life threatening.

It can be risky to drive up and down a mountain in a small 1.3 litre car. This is because driving up a mountainous landscape can take a major toll on a small engine.

Driving up the mountain puts a load on any engine especially as the height above sea level causes gravitational and engine air intake volume issues.

As you drive up the mountain, the load of a car becomes heavier and it also becomes more difficult for the engine to get adequate intake air.

Bigger car engines will be able to carry the load easier and employ an altitude compensator to increase air intake and avoid loss of critical engine power.
On the other hand, smaller engines tend to be overloaded by gravity, consume a lot more fuel, lose vital power or tend to overheat.

When driving down the mountain a motorist requires engine power (engine brake) to safely slow down the car without burning the brakes.

Bigger size engines will work better in this regard. The flip side is the fact that bigger vehicles and engines tend to strain brakes and make handling more challenging when driving down the mountain.
Driving a small 1.3 litre Mazda up the mountain can be risky and requires adequate preparation, skills and a sturdy vehicle.

What is VVTi in a lay man’s language?
Justine Rukundo.

‘VVTI’ means ‘Variable Valve Timing with Intelligence’. Variable valve engine timing systems allow air intake and exhaust valves to open earlier or later in the 4-stroke cycle.

This technology was developed by automakers in the 1960s in order to improve volumetric efficiency, decrease harmful emissions and reduce fuel pumping looses or improve fuel economy.

From the 1990s to date the use of this technology by different car manufacturers has increased albeit in varying ways. Honda call it VTEC, Mitsubishi – MIVEC, BMW – VANOS and Toyota call it VVTi. There are two main types of variable valve timing: cam changing and cam phasing. Camshaft changing is where the Engine Control Unit selects different cam profiles depending on the engine load and speed. On the other hand camshaft phasing is where an actuator rotates the camshaft changing the phase angle.

Camshaft phasing advances or retards valve lift events by rotating the camshaft over a range of about 60 degrees relative to the crankshaft angle. Retarding the camshaft’s timing, helps the engine to achieve better high RPM torque, while advancing the intake camshaft’s timing produces better power at low RPM. To achieve this feat the VVTi system employs the engine computer (ECU) which uses sensors like the crankshaft position sensor and the camshaft position sensor to know how fast the engine is rotating by monitoring the position and location of the pistons and valves.

The VVTi system employs the use of a special oil control valve to act as a hydraulic actuator which adjusts the camshaft via a rotating rotor. This process is aided by other sensors such as the oil temperature sensor, coolant temperature sensor, mass air flow sensor which join the other sensors to give the ECU an all round status of the engine performance.

This informs the decision to vary timing in order to achieve better engine efficiency. It should be noted that timely and periodic engine maintenance with the manufacture recommended engine oil grade is crucial for the proper functioning of the oil driven actuator valve and indeed the whole valve train.

Do you think retreaded tyres are a low cost option? What are the pros and cons
Rukundo.

Retreading used tyres is similar to putting new soles on old shoes. It is a cost effective way to reuse old tyres and is widely done by commercial fleet operators of buses and trucks.

Some private car owners use retreaded tyres too. Retreads save money and work almost as well as the new tyres. However, there are challenges with using retreaded tyres. Used tyres must be retreaded by reputable retreaders using approved materials and equipment.

Poor quality retreads can lead to accidents when the retreads fail and you lose traction while driving on the highway. Before you decide to retread a used tyre the tyre side walls and structure should be inspected to confirm that they are not damaged. In case they are weak or damaged the retread will not be successfully.

Can too much heat cause a car to explode?

Hi Paul, there has been a warning circulating on social media that due to the hot weather, motorists should not fill their tanks with petrol to avoid an explosion. The same message recommends keeping the tank half full. Is this true?
Kakaire.

Vehicle fuel tanks are designed with a venting system for relief when vacuum and pressure build up. This prevents excess pressure build-up and allows us to fuel the tanks or draw fuel from them. The older vehicles in the 1960s to 70s used fuel filler caps to vent the tanks. Environmental protection from fuel fumes has encouraged car manufacturers to design ‘in tank’ fuel tank venting systems which work with the emission system. It is therefore not true that vehicle fuel tanks will start exploding during this hot season.

Cars driven in the gulf fill their tanks and drive in temperatures between 45-50 degrees Celsius without exploding or catching fire.
Here our average weather highs have been 35 degrees Celsius.

In reference to the car of the year article that run in Daily Monitor on January 12, 2017, you talked about the reliability of the Toyota Harrier or Lexus. Please throw more light on how many litres per kilometre does it cover.
Emmanuel Okiror

The Toyota Harrier 3.0 litre petrol V6 engine delivers a fuel economy result of 8.06 kilometres per litre when driven in urban start, stop traffic. On the highway, the fuel economy improves to 10.2 kilometres per litre (km/L) if you drive an average speed of 100 -120 kph. The 2.2 litre Harrier delivers a fuel economy result of 10.5 km per litre during urban driving and about 12 km per litre on the highway with moderate speeds of about 100 km/ hour.

These fuel economy statistics can be varied (improved or worsened) depending on one’s driving style,(overloading, aggressive or gentle acceleration), careful use of the overdrive facility or cruise control, car engine maintenance condition, tyre condition and choice of fuel.