All our Vectra models are powered by «super». In exceptional cases, you can also fill the car with gasoline with a lower octane number. Ignition adapts automatically depending on the type of fuel filled (its octane number), see also chapter on ignition, section «Detonation adjustment».
Knock resistance
The octane number is used to indicate knock resistance. This is a comparative value, which is obtained on a special test engine with certain types of measuring fuels. It is often called «research octane», briefly ROZ. Less common more accurate «engine octane», or MOZ. The minimum octane ratings for gasoline required in our country are determined by the German Institute for Standardization in DIN 51607, today the European standard EN 228 is in force:
High detonation resistance was previously achieved by adding extremely poisonous tetraethyl lead. Fuel containing lead must not be used in an Opel Vectra with a catalytic converter, otherwise it will «poisoned», see chapter «Reducing the toxicity of exhaust gases». Unleaded gasoline uses only non-hazardous additives.
Also in European countries with a small share of cars with catalytic converters, unleaded gasoline is sold on all main highways. Difficulties can be within the country and in areas poorly developed by tourists. For long-distance travel, purchase a map of the country from a car club or travel agency, which shows the places where lead-free gasoline is sold, and a spare canister.
Tip: All Vectras with petrol engines have a safety valve in the fuel filler neck that can only fit a thin dispenser gun filled with unleaded gasoline. This should prevent erroneous refueling with leaded fuel. In order to be able to pour unleaded petrol from a spare can in an emergency, you need a suitable funnel. Or when pouring gasoline, the valve cap is pressed down with a clean screwdriver.
Engine Knock: Combustion starts as it should, but at a crucial moment (reverse piston movement) uncontrolled detonation occurs.
Ringing and detonation
With insufficient fuel quality, a ringing in the engine, or detonation, is noticed. Usually, the air-fuel mixture in the cylinder is ignited by a spark of a spark plug in waves, as if a stone is thrown into calm water: the waves diverge in circles. If this propagation is too strong, then the still unburned residue of the combustible mixture can be pressed against the wall. This rise in pressure causes an increase in heat in the remainder of the combustible mixture, which, because of this, can ignite itself. At the same time, he «shoots» towards the flame front rushing towards him from the spark plug. This leads to a powerful increase in pressure in the cylinder. The piston receives a blow to the bottom and transfers it through its connecting rod to the crankshaft bearings. If this effect occurs at high engine speeds, then the harsh combustion noises are overridden by the noise from the movement of the car. This is extremely dangerous for the engine. This knocking at high speeds causes significant engine overheating. Before the coolant indicator goes off, in most cases it is already too late - the base has already melted on one or more pistons.
More familiar is the ringing when accelerating. hear it better. It becomes noticeable if the car goes into full acceleration mode from low engine speeds with gasoline with insufficient knock resistance. But these ringing phenomena almost do not harm the engine.
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