Internal combustion engines — which statements are correct? Consider the following statements about reciprocating engines: (1) Compression ratio for petrol engines typically ranges from 6 to 10. (2) A higher compression ratio in diesel engines results in higher peak pressures. (3) Petrol engines operate on the Otto cycle idealization. Choose the correct option.

Introduction / Context:
Basic engine design parameters like compression ratio and thermodynamic ideal cycles strongly influence performance, efficiency, and fuel requirements. This question checks recall of typical values and standard modeling assumptions used in engine theory.

Given Data / Assumptions:

• Conventional spark-ignition petrol engines with modern but naturally aspirated configurations.
• Conventional compression-ignition diesel engines.
• Use of ideal cycle models for conceptual understanding.

Concept / Approach:
Petrol engines avoid excessively high compression ratios to prevent knock with typical fuels, hence the usual range of about 6 to 10 in textbook contexts, though modern engines with knock control can be higher. Diesel engines rely on high compression ratios to achieve auto-ignition, which increases peak pressures. The Otto cycle is the constant-volume heat addition idealization for spark-ignition engines, while the Diesel cycle is the constant-pressure heat addition idealization for compression-ignition engines.

Step-by-Step Solution:
Evaluate (1): Textbook range 6–10 is historically accurate for SI engines; many practical engines fall near this band.Evaluate (2): Increasing compression ratio increases end-of-compression temperature and pressure; diesels therefore see higher peak pressures.Evaluate (3): SI engines are modeled by the Otto cycle for analysis and comparison.Therefore, all three statements are correct.

Verification / Alternative check:
Engine design manuals and thermodynamics texts consistently pair petrol engines with the Otto cycle and diesels with the Diesel cycle, and they discuss the respective compression ratio implications.

Why Other Options Are Wrong:
Any option omitting one of the three correct statements fails to reflect standard engine theory and practice.

Common Pitfalls:
Confusing ideal cycles with real indicator diagrams, or assuming modern knock sensors invalidate the general compression ratio guidance; the idealized associations remain valid for fundamentals.

Final Answer:
All of the above