Ignorant question about engine size

Angilion · 17 Sep 2006 at 05:04

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.

Dolph · 17 Sep 2006 at 07:24

In general, the US engines are in a lower state of tune than the european ones. They do, again in general, require much less in the way of maintainance because of it. Service intervals tend to be longer and major work tends to be less frequent.

There are also enviromental considerations, in many ways, the enviroment led restrictions in the US are harsher, and it's easier to get lower emmisions with an engine in a lower state of tune.

To top it all off, there's the actual US market. Until relatively recently, fuel consumption was not an issue because petrol over there was so cheap. They didn't have the economy driver that the europeans have always done, and so the need for small, high output engines with good economy wasn't there in quite the same way. Since Oil prices started their dramatic rise over the last 4-5 years though, that's changing.

Third Opinion · 17 Sep 2006 at 07:46

Yes totally agree.

It is also road conditions. Even their A-road equivalents have 2 or 3 lanes and are dead straight, none of these twisting and turning tight countryside roads we are used to. Plus virtually all of their cars are automatic so like Dolph said they are tuned in accordance to give a smooth ride.

Hate · 17 Sep 2006 at 09:29

plus the north american market covers alaska to florida, from snow to desert and everything inbetween.

Manufacturers thus need to be able to manufacture a car that will work all over, so a larger, lower tuned engine is the way forward as its less stressed.

atpbx · 17 Sep 2006 at 09:32

On a very basic level their cars need to do a shed load more miles than ours do, the engines arent that much bigger either my old mans Nissan is only a 3.5ltr V6 which isnt "huge" by any stretch of the imagination, but its got something stupid like a 150000 mile warrenty on it, the servicing on it is basically like an oil change every 15k which costs something like $20 if you have the top quality oil in it.
They do have plenty of smaller cars over there, but they are the the 2.0 engines.
You just couldnt exist anywhere outside of the major cities in anything less than that, the old fella lives in Clermont near orlando and its 20 minites to drive anywhere.

Angilion · 17 Sep 2006 at 17:59

Thanks for the good answers to my question.

Mickey_D · 17 Sep 2006 at 19:47

It's also dependant on what the cars are used for.

Take my truck as an example. It's a 1981 Chevrolet K-15 4X4 with a 5L (305CID) engine in it, but it only produces 160bhp. But the torque delivery is such that it will haul an unbelieveable amount either in the bed, on a trailer, or both. And since the brake loading is actually improved the more weight you put on the rear tyres, the truck handles better with 1,000lbs of dirt in the bed and 6,000lbs of cut firewood on a trailer. It struggles to do 85mph, but it will do that 85mph pulling a HOUSE behind it. And still stop (relatively) safely.

There's always been a distinct lack of "enthusiasm" in American engines. Even in motorcycles. You can't exactly tell me a Harley Davidson panhead is the epitome of efficient engines. But it does sound oh, so sweet!!

I have also wondered for years how a 1974 Ford Pinto with a 2L engine in it could be so badly smoked by a 1974 Toyota Corolla with a 1.6L. (yes, my brother and I owned those two respective cars. It was my roasting him that pushed him to stuffing a Mustang 5.0L engine into his Pinto!!

)

Oh, and not ALL American engines are so poorly tuned. The 2006 Dodge Neon SRT-4 is pushing 265bhp out of a 2L normally aspirated engine.....

[TW]Fox · 17 Sep 2006 at 19:52

Isn't the SRT-4 a 2.4 Turbo?

ChroniC · 17 Sep 2006 at 19:55

The word tuned is used a lot here, but very little explaination is given into how 5litres can be slower than a 1.8 litre?

What exactly is done to an engine to gain the bhp?
Better pistons? Better carb? Quicker revolutions? Larger cams etc etc?

Hate · 17 Sep 2006 at 20:01

[TW]Fox said:
Isn't the SRT-4 a 2.4 Turbo?

yeah the SRT4 is turbocharged

Pants · 17 Sep 2006 at 20:06

ChroniC said:
The word tuned is used a lot here, but very little explaination is given into how 5litres can be slower than a 1.8 litre?

What exactly is done to an engine to gain the bhp?
Better pistons? Better carb? Quicker revolutions? Larger cams etc etc?

Higher lift & more aggressively profiled cams, biggers valves, wider ports, wider & shorter manifolds, better balanced engines, lighter flywheel & rotating mass in engine... to touch on a few.

I think there are loads more things that affect an engines "state of tune" though.

wassap · 17 Sep 2006 at 20:10

Mickey_D said:
It's also dependant on what the cars are used for.

Take my truck as an example. It's a 1981 Chevrolet K-15 4X4 with a 5L (305CID) engine in it, but it only produces 160bhp. But the torque delivery is such that it will haul an unbelieveable amount either in the bed, on a trailer, or both. And since the brake loading is actually improved the more weight you put on the rear tyres, the truck handles better with 1,000lbs of dirt in the bed and 6,000lbs of cut firewood on a trailer. It struggles to do 85mph, but it will do that 85mph pulling a HOUSE behind it. And still stop (relatively) safely.

There's always been a distinct lack of "enthusiasm" in American engines. Even in motorcycles. You can't exactly tell me a Harley Davidson panhead is the epitome of efficient engines. But it does sound oh, so sweet!!

I have also wondered for years how a 1974 Ford Pinto with a 2L engine in it could be so badly smoked by a 1974 Toyota Corolla with a 1.6L. (yes, my brother and I owned those two respective cars. It was my roasting him that pushed him to stuffing a Mustang 5.0L engine into his Pinto!! )

Oh, and not ALL American engines are so poorly tuned. The 2006 Dodge Neon SRT-4 is pushing 265bhp out of a 2L normally aspirated engine.....

Thats what i understood, the yanks love/need masses of torque, according a friend over in seattle the amount of old cars with spaceship miles is amazing, if we see a car with more than 150-200k here its an oddity, with taxis being the exception.

Mickey_D · 17 Sep 2006 at 20:11

[TW]Fox said:
Isn't the SRT-4 a 2.4 Turbo?

You are indeed correct. I was half thinking of the SRT and half thinking of the SRT-4. Sorry for the mistake.

ChroniC · 17 Sep 2006 at 20:11

Always wanted to know this, if what you say is true, then let say you took material used on nasa shuttle or something as ridiculous, created an engine out of them at only 1litre! as an example.

Made the cams from similar material or titanium or such, able to with stand the heat.
Then would the only thing holding a 1 litre back from being an insane rock be the fuel?
Surely its irrelevant of size and more of revolutions? thus the max power output is based on explosive power of the fuel?

Mickey_D · 17 Sep 2006 at 20:12

wohoo said:
Thats what i understood, the yanks love/need masses of torque, according a friend over in seattle the amount of old cars with spaceship miles is amazing, if we see a car with more than 150-200k here its an oddity, with taxis being the exception.

Yup, over here the only two limiting factors to most cars doing 250,000+ miles is being totalled in an accident or rusting out.

Mickey_D · 17 Sep 2006 at 20:13

ChroniC said:
Always wanted to know this, if what you say is true, then let say you took material used on nasa shuttle or something as ridiculous, created an engine out of them at only 1litre! as an example.
Made the cams from similar, or titanium or such, able to with stand the heat. Then would the only thing hold a 1 litre back from being an insane rock be the fuel?
Surely its irrelevant of size and more of revolutions? thus the max power output is based on explosive power of the fuel?

Take a look at the Mazda rotary engine. The original 1.0L used in the RX-2 can quite easily be pushed to 300bhp. Granted, it's not going to last long doing that, but it is possible.

ChroniC · 17 Sep 2006 at 20:20

Mickey_D said:
Take a look at the Mazda rotary engine. The original 1.0L used in the RX-2 can quite easily be pushed to 300bhp. Granted, it's not going to last long doing that, but it is possible.

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

Flibster · 17 Sep 2006 at 20:28

ChroniC said:
Always wanted to know this, if what you say is true, then let say you took material used on nasa shuttle or something as ridiculous, created an engine out of them at only 1litre! as an example.

Made the cams from similar material or titanium or such, able to with stand the heat.
Then would the only thing holding a 1 litre back from being an insane rock be the fuel?
Surely its irrelevant of size and more of revolutions? thus the max power output is based on explosive power of the fuel?

1.5l 4cylinder Turbo from a F1 car:
14000rpm - 1500bhp
Also - lifespan on 200 miles.

Previous 3l V10 F1 engines:
20000rpm - 1000bhp
Life of around 700 miles

Current 2.4l V8 F1 engines:
20000rpm - 800bhp
Life of around 700 miles

The turbo lump weas running on exotic fuel - the current V8's are essentially running on unleaded.

Also the current V8 engines are not allowed to use beryllium and other exotic material.

Make of that what you will

Simon/~Flibster

Angilion · 17 Sep 2006 at 21:30

ChroniC said:
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.

rpstewart · 17 Sep 2006 at 21:56

The main reasons for not using titanium are:

A) cost
B) It's actually 60% heavier than aluminium (but far stronger)
C) It's very difficult to work with. Virtually impossible to weld so everything needs to be cast / machined.
D) Machining needs to be done in an inert atmosphere because Ti shavings tend to spontaneously combust.