Getting technical
The CR-V’s 1997cc 2.0-litre SOHC i-VTEC petrol engine – like the Civic 5-door’s 1.8-litre unit – is part of Honda’s NP4 family of engines.
Both use Honda's VTEC technology and control systems expertise, with a further innovation to boost environmental performance. Delayed intake valve closure is combined with a wide open throttle valve during low-load driving conditions, which means pumping losses are reduced considerably, boosting fuel economy.
In conventional petrol engines, the accelerator pedal is directly connected to a throttle valve that opens and closes, adjusting the volume of intake air. Under low-load conditions (i.e. when the driver is pressing lightly on the accelerator pedal) the throttle valve is opened only slightly. This narrowing of the intake passage causes resistance, pumping losses and has a negative impact on fuel economy.
The 2.0-litre i-VTEC engine features two sets of cams: high output cams and fuel economy cams, which both adjust valve timing and lift. During acceleration and other high-load conditions, the high output cams help deliver a superior driving performance. During cruising and other stable low-load driving conditions, the fuel economy cams retard the closure of the intake valve and the throttle valve is opened wide. In this position, the output would normally be very high but since the intake valve closure is delayed, some of the air/fuel mixture is momentarily expelled back out of the combustion chamber, minimising unnecessary output and thus improving fuel economy.
Thanks to the synchronised operation of the intake and throttle valves, output is optimised and pumping losses are minimised. Meanwhile, the drive-by-wire throttle balances the switch between high output cams and fuel economy cams, making the driving experience smooth, with minimal torque variation.
The VTEC technology only operates if the water temperature is over 60ºC, if 2nd or a higher gear is in use, if the vehicle speed exceeds 6mph and if the engine is revving between 1,000 and 3,500rpm.
In pursuit of even higher fuel economy, the new 2.0-litre
i-VTEC engine also incorporates the latest friction reducing technologies. The piston skirts are shot with a solid lubricant (molybdenum disulphide) while an ion plating process is used on the piston rings to ensure reduced friction. Plateau honing of the cylinders results in a smoother surface and improved oil film retention. As a result, friction is reduced by around ten per cent.
Elsewhere, variable length intake manifolds make the intake system longer at low rpm and shorter at higher rpm – ensuring the optimum intake ram effect is maintained to deliver torquey driving performance throughout the rpm range.
Piston oil jets are another innovation on the petrol engine, a feature usually associated with high performance engines. These supply superior cooling, to improve durability against knocking – allowing the engine to run with a high compression ratio of 10.5:1.
Emissions
Along with improved fuel economy, the new engine offers cleaner emissions performance. The new i-VTEC engine uses an airflow meter and a linear airflow sensor, together with the latest control technology. Together, these achieve extremely precise control over the air/fuel ratio which results in cleaner exhaust emissions.
Also, newly-developed cylinder heads and exhaust manifolds are employed, with two catalytic converters positioned immediately after the manifold. When high temperature combustion gases enter the catalytic converter, its temperature is raised rapidly, helping to optimise performance right after the engine is started.
Overall, the engine is also lighter in weight, thanks to an all-aluminium lower block and plastic material used in the cylinder head cover, chain guard and chain tensioner arm. Aluminium rocker arms and high-strength connecting rods provide a significant reduction in the inertia of moving parts.
2.2-litre i-CTDi diesel engine
Diesel models benefit from improved aerodynamics. Honda’s exceptionally-refined 2.2 i-CTDi diesel features again in the CR-V. It develops 140PS at 4,000rpm while maximum torque is 251lb.ft at 2,000rpm.
The more stylish, sleeker exterior of the CR-V is not only pleasing on the eye – it also helps the diesel-engined car improve its fuel consumption figures. The more slippery shape of the car boosts economy in the Combined cycle from 42.2mpg to 43.5mpg. Slightly revised gearing, a remapped ECU and reduced tyre rolling resistance also contribute to this performance. It means the cruising range is also increased by 12.5 per cent.
Acceleration and top speed figures also benefit: maximum velocity is now 116mph, while the 0-62mph dash falls to 10.3 seconds.
Reduced drag coefficient
One of the key elements behind the new CR-V’s excellent fuel economy is a 12 per cent lower drag coefficient. A significant part of that reduction is down to careful analysis of the air flow beneath the car. The use of strakes ahead of the front and rear wheels, cover panels beneath the cabin and a rear undercover decrease levels of turbulence.
The CR-V’s slippery body also keeps down wind noise, further helped by the curved shapes of the A-pillar cross section and door mirrors, and by using double seals around all the doors.
Getting technical
As well as developing one of the highest peak torque figures among its contemporaries, Honda’s 2.2 diesel is incredibly flexible, offering near maximum output over a broad spread of engine speeds. Meanwhile, the 6-speed gearbox fully exploits the engine’s characteristics, the tall sixth gear making for relaxed and refined cruising.
Innovative use of materials and production technology has resulted in an engine that is light in weight, compact, yet immensely strong.
Key technologies include a continuously-variable swirl control valve (more detail below), an advanced common rail system and a variable nozzle turbocharger.
There are also many developments that help improve noise levels and general refinement. These include offset cylinders, a second order balancer shaft and an acoustic engine cover – while friction is minimised through features such as roller follower rocker arms. Close-coupled, under-floor catalytic converters contribute to the low emissions performance.
Intelligent combustion control
A continuously-variable swirl control valve is located in the intake manifold chamber, and provides smooth control of the swirl ratio, varying from a high setting during idling and mid-range operating conditions, to a low setting at higher rpm.
The common rail injection system – providing pressures up to 1600 bar – regulates injection pressure and timing to give the best possible performance in all driving conditions. A small amount of fuel introduced prior to the main injection – called the pilot injection – helps lower combustion noise.
This common rail system works with the variable nozzle turbocharger to control intake pressure, producing higher intake pressures at a lower speed, as well as better fuel economy and fewer harmful emissions through lean burn combustion.
Exhaust gas recirculation, under the control of an electrically operated EGR valve, increases intake air volume and reduces oxides of nitrogen and particulates. Plus, water cooling of the exhaust gases prior to their recirculation helps to further reduce the formation of oxides of nitrogen.
Other features include:
• Engine glowplug quick cold start system
• Compact oil filter and oil cooler to reduce weight
• Low servicing costs: 12,500mile or annual oil change, and 25,000mile air filter change
• Pendulum type engine mountings, acoustic engine cover and under engine tray minimise engine noise
Transmissions
The new 2.0-litre petrol is available with either a 6-speed manual or 5-speed automatic gearbox, while the diesel model continues to use the 6-speed manual from the Accord 2.2-litre model – specifically adapted for the four-wheel drive application.
Positioning the gear shift lever at the base of the centre console on all the latest
CR-V models means there’s greater front seat foot room and a flat and uncluttered floor.
Both manual transmissions benefit from light and fluid gear changes, thanks to the use of multi-cone synchronisers. An automatic, self-adjusting clutch gives consistent pedal performance and weight throughout its life.
The new 6-speed transmission on the petrol-engined CR-V gives a wider spread of ratios, while the final drive ratio has been lowered to compensate for the increased wheel size. Larger synchronisers provide a crisper shift feel, while a higher capacity clutch provides better take up of power.
Automatic gearbox
Lower noise and relaxation were the key aims when developing the new 5-speed automatic ‘box for the CR-V 2.0-litre. Better fuel economy was an unexpected bonus.
The high-capacity auto transmission is an electronically controlled, constant mesh unit with lock-up torque converter and Grade Logic control. Lock-up operates from second to fifth gears.
Grade Logic is able to determine actual driving situations by measuring a variety of parameters including throttle position, road speed, rates of deceleration and acceleration and brake pedal application. Then, based on a series of shift maps, it selects appropriate shift points to provide smooth driving feel, reduced gear ‘hunting’ on steep inclines and enhanced engine braking on downhill stretches. A switch is now provided to select D3 when the lever is in the ‘D’ position. This enables the driver instantly to make use of added engine braking, for example, when descending a hill.
The DBW throttle helps to smooth gear shift shock and delay through the balancing of engine power at every point during the shifting process.
A super-thin torque converter, double-row idle gear and tightly packaged second gear clutch help to keep the transmission unit compact.
2007 Honda CR-V #13