Ignorant question about engine size

[Angilion]

I know jack about cars, so please bear with me.

I see quite a few references to USA cars with massive engines, 5 litres or more, that have x bhp and UK/European/Japanese/etc cars with far smaller engines that have the same power. Why the difference? Are the USA engines just less efficient, or is there an innate advantage to a bigger engine? I'm thinking that maybe the smaller engines are turbocharged/supercharged and the bigger ones aren't, but I don't know much about the subject.

 

[Angilion]

Thanks for the good answers to my question.

 

[Angilion]

OK so has my understand been tested? What is the max power output of petrol? and are we achieving it with todays cars?
Are engine titanium?
Im sure this has been tested by car manufactors, otherwise they are dumbasses.

I suppose it is kinda pointless, it would be like making an unbreakable engine then sticking nitrous in it. You'd just end up dieing, not a great marketing tool

There's no way that the effective power of an engine, let alone of a car (with the added problem of converting that power to movement of the car) is anywhere close to the theoretical maximum.

In any case, a large part of the equation is not the size of the engine per se but the rate at which fuel is burned (I still know next to nothing about cars, but I was curious enough to look up the difference between a turbocharger and a supercharger). So there's a practical limit straight away - you can't just increase the air pressure (and thus the rate at which fuel can be burned) indefinitely. Stuff starts failing pretty quickly. Even if you could, there's the problem of how you power the device to compress the air, since the power for that has to come (directly or indirectly) from the engine. It would get like chasing your own tail - to get more power from the engine, you need to use more power from the engine to power the thing that lets you get more power from the engine.

A titanium engine would be very expensive and not necessary or even useful in most cases. People are not going to pay the extra cost to have a lighter, tougher engine in their family car. There must be other reasons that I don't know about as well, because even the engine in the Bugatti Veyron only has some titanium parts and that was a blank cheque engineering product that was expected to lose stacks of money.