Engine Mazda SkyActiv-G 2.5

Engine Mazda SkyActiv-G 2.5

The Mazda SkyActive 2.5 engine is installed on Mazda 6 and Mazda CX-5 cars. The engine appeared along with the two-liter version of SkyActive 2.0. The engine replaced the old Ford MZR L-series motors of 2.3 and 2.5 liters. Like all engines in this series, the motor is very modern. High Compression ratio 14:1, Dual S-VT phase change system, 4-2-1 outlet manifold (spider), direct fuel injection, specially shaped pistons that ensure optimal fuel combustion throughout the entire stroke, hydraulic lifters.

Engine 4-stroke, 4-cylinder, 16-valve petrol with electronic fuel injection and ignition control, with a longitudinal arrangement of cylinders and pistons rotating one common crankshaft, with an overhead arrangement of two camshafts with variable valve timing on the intake and exhaust camshafts shafts. The engine has a closed-type liquid cooling system with forced circulation. Lubrication system – under pressure and splashing.


Manufacturer Hiroshima Plant
Also called SkyActiv-G
Production years 2011
Cylinder block alloy aluminum
Fuel system injector
Configuration inline
Number of cylinders 4
Valves per cylinder 4
Piston stroke, mm 100
Cylinder bore, mm 89
Compression ratio 14
Displacement, cc 2488
Power output, hp 192/5700
Torque output, Nm / rpm 256/3250
Fuel type 95
Euro standards Euro 4
Weight, kg
Fuel consumption, L/100 km
— city
— highway
— combined
Oil consumption, gr/1000 km up to 800
Recommended engine oil 0W-20 / 5W-30
Engine oil capacity, liter 4.5
Amount of engine oil for replacement, liter ~4.3
Oil change interval, km 15000 (7500)
Normal engine operating temperature, °C
Engine lifespan, km
— official information
— real

When building the petrol aspirated Skyactiv-G, the predecessor MZR 2.0 with a compression ratio of 10.0 was taken as the basis. Increasing the compression ratio increases the temperature and pressure in the cylinder at the end of the compression stroke. This promises higher efficiency and power, but at the same time a strong tendency to detonation – the explosive combustion of the air-fuel mixture, which leads to overheating and destruction of rings and pistons. A compression ratio close to 14 is more typical for highly accelerated sports engines running on fuel with a high octane number that is resistant to detonation. A lot of innovations have been made to the Skyactiv-G design so that it can painlessly digest regular 95 gasoline and work to reduce mechanical losses in order to improve efficiency.

Ion sensors built into the ignition coils are designed to protect the engine from detonation. The whole point is that the operation of the motor is on the verge of detonation and ensures the most efficient combustion of the mixture. Ionic sensors are more sensitive and allow better control of the moment of detonation in each cylinder – and before that it was monitored by only one traditional guard installed in the block. The new sensor monitors detonation by fluctuations in the ion current in the gap between the spark plug electrodes after the mixture has ignited. When it burns, ions are formed that make the medium conductive. The sensor applies voltage to the center electrode of the spark plug and measures the current flowing between it and the grounded side electrode.

The updated fuel system with direct injection provides pressure up to 200 bar! With an increase in pressure in the cylinder, this became necessary for proper mixture formation (previously, Mazda used direct injection mainly for supercharged engines, but the pressure did not exceed 115 bar). At the output, this solution provides efficient combustion, that is, high power, efficiency and environmental friendliness of the engine.

As before, the high pressure fuel pump is driven by the camshaft, but this time from the exhaust. It is complemented by six-hole nozzles (for better fuel atomization). With good evaporation, gasoline also brings down the temperature in the combustion chamber, and this also reduces the likelihood of detonation.

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