WHY YOUR ENGINE DOESN’T MELT

by Nicol Louw

ROUGHLY a third of the energy contained in fuel is converted to “power” in an internal-combustion engine. The other two-thirds are lost to the cooling system and along the exhaust pipe (ignoring frictional and other losses). To put engine cooling into perspective, a normal household kettle is rated at about 1 kW (electric power). This means that a Bugatti Veyron Super Sport at full power (883 kW) loses about the same amount of energy to the cooling system as is generated by 883 kettles. Let’s investigate what happens to the heat energy.

THE HEAT SOURCE

The heat energy is realised from the fuel during the engine’s combustion cycle where the chemical energy is converted to heat. One litre of fuel contains 34 MJ of energy (or 46 MJ per kg). Therefore, if for example a vehicle consumes 6,0 litres/100 km at a steady speed of 100 km/h, 0,00671 litres are consumed per second. This equates to roughly 57 kW of potential chemical energy being fed through the engine. Using the thirds approximation, around 19 kW is dispersed through the cooling system.

HOW IS THE HEAT DISSIPATED?

In a four-stroke engine, the power stroke (where combustion takes place) lasts for 180 degrees of the crankshaft’s rotation. The peak gas temperatures can reach up to 2 500° Celsius in the combustion chamber, but the average temperature, however, is much lower owing to the increase in volume as the piston moves away from top-dead centre (TDC). The combustion heat is mostly transferred to the metal areas (such as the pistons, cylinder walls and valves) by means of turbulent convection. The rate of heat transfer depends on the gas temperature, surface area and temperature of the metal surfaces, as well as the time for the process to take place. From there, the heat energy is conducted by means of the metal areas to the cooling system (water jackets in a water-cooled engine and metal fins in an air-cooled engine). The remaining heat energy escapes past the exhaust valves and through the exhaust system during the exhaust stroke of the engine (piston moving towards TDC after combustion).

AIR-COOLED

Direct air-cooling involves removing heat from the engine’s cylinders and heads by means of convection. The metal fins fitted to air-cooled engines essentially increase the surface area in contact with the ambient air to increase the heat-transfer rate. Many air-cooled engines will also employ an oil cooler in which the heat from the oil is also transferred to the atmosphere. Approximately 10% of an engine’s cooling can take place through oil-cooling alone.

In many cases, a fan is needed to increase the airflow over the engine fins when natural convection is not enough. An air-cooled Porsche was an example of such an application. This is less of an issue in motorcycle or aviation applications because such engines are subjected to direct airflow at speed. The main reason why air-cooling has lost favour in modern applications is that the heat capacity (specific heat) of air is approximately four times less than water per kilogram. With increasing engine outputs, air-cooling alone is incapable of removing enough heat to prevent the engine from overheating. Another reason is that, with air-cooling, precise control of engine temperature is difficult to achieve and this negatively influences the emissions and performance of engines equipped with the technology.

WATER-COOLED

A water-cooled engine is also air-cooled because the final means of dispersing heat is mostly via a water-to-air radiator. Water-cooling refers to water as the working fluid in a closed cooling circuit. This circuit consists of a thermostat to regulate the water flow, water pump to circulate the water in the circuit, and a radiator (with cooling fan). The cooling circuit consists of rubber piping between the radiator and engine and then continues as water galleries to the cylinders and heads of an engine. These water jackets are placed in optimal regions to remove the combustion heat efficiently from the metal components. This closed circuit is pressurised at the operating temperature to increase the boiling point of water. Anti-freeze is added to the water to further increase the thermal properties of the working fluid, to prevent corrosion to engine components and provide lubrication to the water pump (see Antifreeze dangers below).

Cooling simulation engineers spend countless hours modelling the entire cooling circuits of powerplants and that includes the airflows over radiators and through the engine bays. The cooling performance is influenced by the ambient temperature, driving speed, resistance to airflow through the radiator and in the engine compartment, as well as the area and efficiency of the radiator and the specification of the fan. The size and placement of water jackets can be experimented with as well as the flow rate of the working fluid. Once the optimal hardware solution is found, the engineers will spend their time calibrating warm-up strategies to lessen emissions during cold starting. These strategies are made possible by electronically controlled water pumps and thermostats and valves that can close coolant galleries when required.

THE FUTURE

A lot of potential energy in the fuel is wasted as heat energy, either to the cooling system or through the exhaust. Turbocharging has managed to recover some of the lost energy leaving the exhaust system and combined with downsizing, led to more efficient engines. The next step will be to recoup the wasted heat energy and use it for either propulsion or running other power-consuming functions. Although many such systems have been experimented with, a solution has not yet made it into production owing to cost, complexity or added mass.

A more realistic option is to recover some of a turbocharger’s energy when it has more energy than it needs (normally bypassed via the wastegate) to produce a boost set point. Formula One will introduce such a system known as Energy Recovery System – Heat (ERS-H). This electric motor/generator unit connected to the shaft running between the turbine and compressor of a turbocharger will not only recover extra heat energy, but will also be able to eliminate turbo lag by spinning up the turbo when the unit is in its motoring mode. Expect to see this technology filter down to production vehicles in the near future.

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RENAULT MÉGANE COUPÉ 1,6 EXPRESSION

Outgoing Renault SA boss Xavier Gobille is one of those rare modern car bosses – a true petrolhead, ex racer and straight talker. Chatting with him during the recent launch of the facelifted Mégane, he recalled the dire situation the company was in a few years ago. “You always deserve the result you get,” he explained. “And we deserved what we were getting.” His wording was a bit stronger than that, but I got his point. He leaves Renault in a far healthier state than he had found it, but understands that remnants of the bad reputation will undoubtedly linger for a good few years still, especially in terms of service. In terms of product, however, Renault has had a good run, and is looking to get even stronger.

New models in key segments

According to Gobille, a number of key new models are on the way to South Africa, including the all-new Clio 4 and the affordable Duster crossover. Both will be here within the next six months. But already available is its all-important revised Mégane line-up, now offering better value for money than ever before.

I spent much of my time during the launch driving the impressive new “affordable” Coupé model, the 1,6 Expression. Priced at R209 900, it offers a lot for the money. Similarly sized coupé models from Volkswagen and Opel are a good R60 000 or so more expensive.

Subtle design changes, clever features

Visually, you’d be hard-pressed to notice the changes. There are small modifications to the lights and bumpers, and this model rides on smart 16-inch Kaleido alloy wheels. Inside, there are dark charcoal upholstery, satin chrome finishing for the smart digital instrumentation and some very good, upmarket finishes – almost the entire facia features soft-touch plastic.

The standard features list is comprehensive and includes cruise control, a height-adjustable driver’s seat, dual front, side, curtain and anti-submarining airbags, Isofix mountings at the rear, manual air-conditioning and a radio/CD player with MP3, Bluetooth, iPod and USB connectivity.

Other safety features include ABS with EBA and EBD, but there is unfortunately no electronic stability system.

As is the case with all Mégane Coupé models, the slinky looks hide quite a spacious cabin, and even the boot is of a decent size.

Performance and Dynamics

The launch drive took place in Johannesburg and therefore at altitude. The 1,6-litre engine offers 81 kW at 6 000 r/min and 151 N.m of torque at 4 250, and did feel a bit lacking in oomph. It’s fine for cruising and relaxed city driving, but more enthusiastic drivers may find it a tad too lethargic. Renault claims a 0-100 km/h time of 10,5 seconds and a 195 km/h top speed. Overall, you’ll have to use that six-speed manual gearbox quite often if you’re in a hurry, and then the engine sound can become quite tiresome.

But to think of this particular model as a driver’s car would be to miss the point. It is aimed at those looking for a stylish, comfortable and practical car that is also different. Performance is unlikely to be a high priority.

The 1,6 Expression certainly plays the comfort card well. It has superb seats and the ride comfort is undoubtedly aided by those plump high-profile tyres. That said, it lacks the overall suspension refinement of a Scirocco or Astra GTC.

Summary

There isn’t too much available at this price level that offers a similar combination of style and size (practicality), never mind one that is covered by a five-year/150 000 km warranty and five-year/100 000 km service plan. The particular Mégane may play the glamour, “look at me” game, but backs it up by being a surprisingly solid, no-nonsense vehicle that, for its intended audience, is likely to tick all the boxes.

Specifications:

Model: Renault Mégane Coupé 1,6 Expression

Engine: 1,6-litre, four-cylinder, petrol

Power: 81 kW/6 000 r/min

Torque: 151 N.m/4 250 r/min

Fuel consumption: 6,9 L/100 km

CO2: 159 g/km

Top speed: 195 km/h

Acceleration (0-100km/h): 10,5 sec

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RANGE ROVER SPORT SC V8 HSE DYNAMIC

by CAR magazine 

THE first iteration of the Range Rover Sport did not sit comfortably with all fans of Land Rover’s marquee brand. Although suitably flashy and capable off- and on-road, it wasn’t a sportier version of the iconic Range Rover model but a purposefully styled and luxuriously appointed development of the Land Rover Discovery 3,

replete with a steel semi-monocoque and chassis-frame platform. However, the recent launch of the Evoque boutique compact SUV has done much to establish Range Rover as a nameplate as opposed to a model and, as a result of the new Sport version’s underpinnings, the pretender is now perilously close to the throne.

This newcomer’s aluminium full-monocoque platform – engineered in parallel with the Range Rover’s – is said to be 39% lighter than that of its predecessor and, even though this Sport SC V8 still tipped our scales at a brawny 2 452 kg, the testers agreed that the newcomer felt appreciably more wieldy and surefooted than its predecessor, but more about that later.

The Sport is 149 mm shorter and 55 mm lower than the Range Rover, but it’s the test unit’s exterior packaging, replete with a trim option that replaces the silver finish of the grille, foglamp trims and bumper valances on the standard vehicle with a black finish, that makes the loudest statement. Although not all testers were won over by the finer detailing – the slim headlamp and miniature taillamp clusters that were inspired by those of the Evoque aren’t arguably as effective on the blockier Sport – the overall look is imposing and exudes sportiness, power, status and, moreover, expensive taste.

The appointments and finishes of the Sport’s cabin certainly mirror the exterior’s sense of occasion, but whereas its predecessor felt comparatively snug inside, especially in terms of headroom and rear legroom, the newcomer feels airier (helped by the effect of the panoramic sunroof) and the longer wheelbase affords more space in the rear, although it’s still not commodious. Still, there is something pleasingly tactile about the (impractically light) leather trim, brushed aluminium accents, chunky switchgear and LED reading lights operated by the slightest of touches.

Although the (dual-screen) touchscreen interface is not smartphone-fast in its responses and looks a tad too derivative of those on other Jaguar/Land Rover products, it combines smartly with the crisp display of the LCD instrument cluster and offers a variety of options, from a host of interior lighting colours, the Terrain Response settings, axle articulation and wade-depth data (if specified) and no fewer than three sound-encoding options for the potent 19-speaker Meridian surround-sound system. Whereas the front seats are 14-way electrically adjustable and can offer heating as well as cooling functions, the rear passengers sit somewhat upright but have a separate climate controller, a heated bench as well as an entertainment system with a single remote control, auxiliary inputs, two screens integrated in the headrests and a pair of cordless headphones. An electric tailgate (an omission on the previous-generation vehicle), soft-closing doors, a surround-camera system with front and rear PDC and adaptive cruise control are some of the other highlights.

Given the lofty sound fidelity of the audio system and the raft of creature comforts at passengers’ disposal, it would be understandable that gentle cruises to the tunes of your favourite music would be the order of the day. However, there is something utterly compelling about the bare-chested baritone of the 375 kW supercharged 5,0-litre V8 motor, which is smartly synced with a slick eight-speed transmission.

By virtue of its Dynamic Response active lean control, Active Rear Locking Differential and Torque Vectoring by Braking systems, the flagship Range Rover offers prodigious grip when cornering at speed. The electronic power steering gives the tiller a satisfying weight and more than one tester remarked that the surfeit of grip was contrasted by the body’s compulsion to lean, albeit never drastically. The dynamic behaviour of the active air suspension also drew praise; given its 21-inch footwear and the performance-bent of the model, the Sport rides compliantly, with only deep pockmarks upsetting the ride momentarily.

With such performance on tap (the test unit dispatched the zero-to-100 km/h sprint in under five seconds – three tenths faster than Range Rover estimates), it was a relief that the red-callipered Brembos stopped the V8 SC so smartly.

And while we believe lead-footed owners might struggle to attain CAR’s fuel index of 16,56 litres/100 km, our fuel route return of 14,10 litres suggests a measured driving style can contain the Sport’s thirst.

Test Summary

Without wishing to damn the Range Rover Sport with feint praise, some of CAR’s testers remarked that the product’s reinvention has raised questions about the justification for its more expensive Range Rover sibling, which used to be in a different class (in a metaphorical sense) to the former.

Although a Jeep Grand Cherokee SRT8 may represent the “bargain” thunder SUV at its list price, the Range Rover Sport, at least in V8 HSE Dynamic guise, now has the packaging and refinement to make potential buyers question why they’d need to spend in excess of R1,3 million to acquire an exclusive four-wheel-drive performance machine such as a Mercedes-Benz ML63 AMG, M-fettled BMW X5, a top-flight Porsche Cayenne and, given the lavish appointments of the SCV8 HSE Dynamic, a normal Range Rover. Its showy, new-money image might not be to everyone’s taste, but it’s a pretender no more.

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2015 Kia K900 First Drive

Can Kia build a rear-wheel-drive luxury sedan that people will actually cross-shop with the established players? That's what an epic Super Bowl commercial tried to sell people on a few weeks ago, and we had a chance to take the red pill and spend a day piloting Kia's new 2015 K900 premium luxury full-size sedan to see just how deep the rabbit hole really goes.

Related: 2015 Kia K900 Video

Kia hosted this drive event in a location befitting a premium status: Newport Beach, Calif. From there, we wound down the Pacific coast and inland through parts of Southern California's wine country, which gave us a solid mix of highways and city streets as well as canyons to get a good feel for the K900's merits.

Kia plans to offer a V-6 and V-8 version of the K900, but only the V-8 will be available at launch this March. Its starting price is $60,400, including a destination charge. Our V-8 tester was also equipped with the VIP Package, which pushed the sticker price up to $66,400.

The K900 certainly looks the part of a luxury sedan — minus the kitschy portholes on either side. V-8 models feature adaptive LED headlights that are designed to mimic natural light. The element housings each fit four LEDs inside them and have a 12-degree range of motion for better illumination around dark corners.

Under the hood of our tester was a 5.0-liter V-8 that makes 420 horsepower along with 376 pounds-feet of torque. It is mated to Kia's first eight-speed automatic transmission, which curiously comes without paddle shifters in the K900. Instead of adopting the air suspension from the Hyundai Equus, Kia elected to go with a fully independent front and rear multilink setup. The company indicated that it was able to hit its ride and comfort goals without the air suspension; it also offers a simpler setup for easier maintenance and keeps the car's price down. I had no qualms with this decision; ride quality was excellent even over broken pavement, and the big sedan glides down the highway with nonchalance.

Kia representatives were careful to stay away from describing the K900 as "sporty" and with good reason — the K900 goes for comfort all the way.

On curvier roads, body roll was noticeable, especially when making quick steering changes. The V-8 prioritizes even power delivery over quickness, which means you have to work a little harder to find the engine's sweet spot, but I was never left wanting for more oomph. The K900 is no lightweight at 4,555 pounds, but the V-8 never really felt taxed. Four different selectable drive modes — Normal, Sport, Eco and Snow — are offered.

Kia engineers said cabin isolation was a focus for the K900. Wind and road noise is reduced by adding a full belly pan on the underbody, extra insulation and laminated front and side windows. While the K900 wasn't the quietest car we've been in, noises were muffled enough inside that conversations could easily be had between front and rear passengers, even at highway speeds.

When the K900 debuted at the 2013 Los Angeles Auto Show, one of our editors noted that it "still doesn't quite 'feel' like a luxury car," and after a day with the production version, that perception hasn't changed.

All of the traditional touch points in the car are covered in leather or soft materials, but the devil is in the details and that's where the K900 falls short with silver-colored plastic trim pieces where you'd expect to find something more upscale. The plastic multimedia controller also feels flimsy; a more substantial controller would have fit in better for this class.

The added tech from the VIP Package was impressive, particularly the head-up display. It is easily visible in bright sunlight, with customizable display options including navigation directions, blind spot warning, smart cruise control settings and your speed. If you wear polarized sunglasses, the display isn't visible.

The backseat is comfortable and spacious with more than 38.2 inches of legroom and an almost equal amount of headroom. In fact, the second-row accommodations were so nice that for a few legs of the drive, I elected to sit in the backseat instead of the front passenger seat. The Rear Seat VIP Package, which is part of the VIP Package, adds rear climate controls, power reclining and ventilated rear seats with power lumbar support, and a convenient USB charging port in the center armrest, a helpful addition in our gadget-happy culture.

Kia knows the checkered history of non-luxury carmakers trying to break into this segment — the Volkswagen Phaeton comes to mind. But the K900's purpose isn't solely to bring a luxury car to market at a non-luxury price. No, Kia is interested in changing its brand perception. Its success won't be in sales; it will be in people walking by the K900 in showrooms, taking pause and slowly changing their impression of the brand.

While Kia has built a fine, comfortable luxury sedan with incredible technology and a lot of bang for the buck, the big issue still remains: Would someone pay more than $60,000 for a Kia? The answer for most will be "probably not." But the fact that I drove the K900 and think that it's still worth the price tag might be the real win for Kia.

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