ENGINE AND IMA SYSTEM

The Honda CR-Z is the first car to combine a 1.5-litre i-VTEC engine and the IMA system, giving excellent fuel economy and great emphasis on driver enjoyment. This 114 PS engine is combined with a 14 PS electric motor which also boosts torque, with an impressive 78 Nm at low to medium engine speeds. The combined power figure peaks at 124 PS with a healthy 174 Nm of torque.

Performance and driver enjoyment can be seen as a conflicting need to good fuel economy and exhaust emissions levels. The CR-Z's 1.5-litre, 16-valve, i-VTEC, petrol engine provides driver enjoyment with its enthusiastic engine note, willingness to rev and broad spread of torque. At the same time its modest capacity, boosted by an electric motor can achieve excellent fuel economy and low overall exhaust emissions, including the all important CO2 emissions. The CR-Z is the first Honda hybrid, since the original 1-litre Insight to use a four valve per cylinder head with the IMA system.

The Honda CR-Z emits just 117 g/km of CO2 on the EU test cycle and consumes just 5.0 l/100km of fuel. This CO2 figure is just 1 g/km higher than the original Civic IMA, an incredible achievement considering the over 30 PS power advantage the CR-Z has over its saloon ancestor.

The Honda CR-Z engine used is based on the 1.5-litre Jazz unit with changes to the valve timing allowing for one intake valve to be deactivated at low engine speeds. This creates an additional swirl effect which enables fast combustion and higher exhaust gas recirculation. The effect of this additional turbulence is to reduce emissions and improve fuel consumption. At higher revs, both intake valves are opened to increase power output.

Numerous small changes are made to the engine to suit the characteristics of the Honda CR-Z, integration of the IMA system and installation in the coupe body. The original engine, as it was installed in the Jazz, would not fit under the low bonnet of the car as it stood. The development engineers developed a new intake manifold and a flat air cleaner assembly, to give sufficient clearance and allow space for pedestrian impact protection.

The 1.5-litre i-VTEC engine has not been seen in an EU specification car before and was chosen for its combination of light weight, fuel efficiency and compact size. The block of the 1.5-litre engine is similar to other Jazz engine variants and the Insight meaning that integration of the IMA system is simplified. Because the basic block layout is shared with the 1.3-litre Insight engine, the sump pan that was developed for that car was adopted. This measure assisted the team in the task of reducing the overall engine height and lowering the position in the chassis.

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