Honda P engine

The smaller version was discontinued in December 2013, when it was replaced by the new S07 series engine, but the P10A continues to be built in Thailand.

The engine uses a single overhead camshaft to drive two valves per cylinder (one intake, one exhaust, for a total of six).

Instead the exhaust gasses collect in the passages of the cylinder head itself and are fed directly into the catalytic converter.

Honda claims this design helps to warm the catalyst quicker in order to more effectively filter out harmful emissions.

[1] The larger P10A shares an 80 mm (3.15 in) bore spacing and most other basic dimensions with the 1.5-liter four-cylinder NA engine, increasing parts commonality and simplifying manufacture.