engines of cars are much quiter and calmer even they are of higher capacity compared to motorcycle engine.why?

Answer 1

Most motorcycles are air cooled. Thus they have engine block has thinner walls with fins.

Almost all car engines are watercooled. The engine block is thicker since it needs to have channels where water needs to circulate.

The bigger and thicker engine block and the water surrounding the cylinders serve as sound insulation that keep engine noise down on watercooled systems.

Answer 2

They have alot of extra equipment that motorcycles don't have. They have a large heavy flywheel that helps to balance out the engine as it spins. Some engines also have harmonic balancers that smooth it out even more. The exhaust on a car is also much larger and longer than it is on a bike. It goes from the headers down into the catalytic converter, through a resonator and finally through the muffler. Most motorcycles have a straight through flow style of exhaust with only a small muffler.
With that being said, there are a few large bikes that have smooth quiet engines such as the Honda Goldwing. That bike is practically a car however. It has air conditioning, radio, heat.. and they are smooth and quiet. Most bikes are not like this though.

Answer 3

Here I go again (I need to save these answers so I can just cut and paste them every time they are repeatedly asked!).
First, the sheet metal around the engine of a car helps muffle the sound.
Second, have you noticed that the air cooled engines are louder/noisier than the water cooled engines (like an old VW Beetle or van had THAT quite of an engine!)?
That is because an air cooled engine runs hotter, hence the clearances need to be looser, causing more noise.

Answer 4

One major reason is that a cars exhaust system is 10' long, with a catalytic converter and a muffler twice the size of a bikes gas tank.
While a bike has an exhaust system 2-3 ' long with a muffler the size of a large soda bottle.

Answer 5

Many motorcycles are just as quiet (or even quieter) than cars. But for those that aren't, there are many reasons why...

Motorcycles typically rev much higher than autos.
Many motorcyclists install custom exhausts which are louder.
Motorcycles don't have the extensive exhaust system cars do.
2-stroke engines are generally noisier than 4-stroke (usually dirt bikes are 2-stroke).

Answer 6

Ever been to a NASCAR race? Sit on the front row of one and then ask this question. Basically most motorcycles don't have exhaust systems that are as restrictive as car exhausts. If you put straight pipes on a V8 car it will be much louder than any Harley.

Answer 7

Purchase a Honda GoldWing Motorcycle, as quiet as a car same vibration as a car better gas mileage and generally quicker

Answer 8

That's really not true. Generally people want cars to be smoother and quieter. Most Harley riders don't want smooth or quiet. You wouldn't believe how many Japanese Cruiser owners put on after market exhaust systems to make their bikes much louder.

Answer 9

not true... ever hear a Honda gold wing? can't even tell it's running! exhaust systems are the "engine quiet mechanism"