cyberstudio

This is a complex question with no simple answer. But in my humble opinion, the biggest difference is in "smoothness". The more cylinders you have, generally the smoother will be your torque curve, meaning that you get more or less the same torque regardless of rpm.

For a typical 4 cylinder engine, torque is weak at low rpm. A 5 cylinder engine is significantly smoother than 4. A 6 cylinder shows additional improvement, but not as much an increase as you go from 4 to 5.

There are several configurations for 6 cyclinder, for example, inline or "straight". A straight 6 is a very long engine, and it can no longer be placed in the traverse orientation in the engine compartment. You will find such cars with a relatively long engine compartment, with the front wheels very close to the front bumper, and with some room between the front wheels and the firewall (e.g. Lexus IS250, BMW, Mercedes). This configuration is not good for front wheel drive - you will find almost all straight 6 to be rear wheel drive cars (or all wheel drive).

Volvo is one of the mainstream manufacturers with 5 cyclinder engines. The engine is now just short enough to be placed in the traverse orientation and therefore you find Volvos to be front-wheel drive cars (or all wheel drive). Having an odd number of cylinders, the engine is not naturally balanced and requires certain designs in the crankshaft, flywheel, engine mounts, etc. to compensate.

There are a lot of other configurations, such as H4, V6, H6, etc. Technology has been improving and if you drive for example a 4 cyclinder late model Camry you may notice that while it still drives like a 4-cylinder its smoothness has improved significantly.

V6, being shorter than straight 6, can be placed in the traverse orientation and suitable for front wheel drive. V6 is a lot more popular than straight 6 because front wheel drive is more popular than rear wheel drive.

Horsepower = torque x rpm. It is very common to find high horsepower 4-cylinder cars which revs up to 8,000rpm. Such cars are usually not smooth to drive. Depending on your style you may prefer a car with more cylinders than 4.

[ 本帖最後由 cyberstudio 於 2008-6-4 01:15 編輯 ]