As engine speed increases, spark ignition in petrol engines must be__________________?
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Answer: D. Advanced
Explanation
Higher engine speeds mean pistons travel upward much faster than before. Spark plugs must fire earlier to allow complete combustion before power stroke. This timing adjustment is known as advancing the ignition spark. Combustion takes a finite amount of time to propagate across the cylinder. Ignition delay requires the spark to occur before top dead center position. Centrifugal and vacuum mechanisms automatically adjust timing in older engines.
Automotive engines utilize electronic control units to manage spark advance. Failing to advance ignition at high speeds causes reduced engine power output. Modern vehicles continuously optimize ignition timing for fuel efficiency. Option A leaving ignition unaltered would cause incomplete combustion at high speeds. Option B increased is not a standard timing terminology for spark control. Option C decreased timing would delay the spark, worsening engine performance.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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