Q: What is the difference between the 180hp and 225hp engines?
A: From the article linked below:
"The higher-output 165-kW (225-hp) engine uses a high compression ratio (8.9:1) for a turbocharged unit. The 1.8-L engine was extensively modified to attain the higher output reliably. The pistons, connecting rods, and big-end bearings were uprated to accommodate the higher combustion pressures. The double-mass flywheel and clutch were modified to match the greater performance. The intake manifold, turbocharger, and exhaust manifold are new.
A Type K04 turbocharger forces air into the combustion chamber via two charge-air intercoolers. Compared to the less powerful 132-kW unit, a modified airflow path, together with a larger air cleaner, ensures that the air reaching the engine has a temperature only about 30¡C higher than ambient. This 80% charge-air intercooler efficiency keeps the engine supplied with an optimum flow of oxygen-rich air. Maximum boost pressure at the intake manifold can reach 200 kPa (29 lb/in2).