Quality of car fuel (petrol) is measured by RON number (say RON 89 OR RON 91 etc.). This number is a measure of compression a fuel can bear before bursting under pressure. Different car engines have different compression ratios in their cylinders. For example civic x 1.8 has 9.?? and 1.5T has a compression ratio of 10.?? . This means that low quality fuel (ron 89) may explode before spark is ignited in civic 1.5T and result in knocking which is very harmful for the engine
The knocking issue is well known to the car Engine design engineers so in all modern car engines including civic 1.5T they install knock sensors on the cylinders. These are nothing but small microphones connected to the engine controlled computer. They can listen the knocking sound and inform the computer.
The car computer can adjust the spark timing ( advances or retard) so that there is no knocking and the engine runs smoothly even with low quality fuel. This may result in reduced performance of the engine but no damage to the engine.
CONCLUSION: if we use RON 89 FUEL IN CIVIC 1.5T THE ENGINE WILL PRODUCE LESS POWER WITH OUT ANY DAMAGE TO THE ENGINE.
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