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You demonstrated that you are no mechanic with your first post in this thread (water cooled without radiator is nothing even close to air cooled). Maybe that was enough?

There are many good reasons for prefering water cooled engines... engine life (the subject of this thread) isn't really one of them. Said another way. there are many good reasons for perferring air cooled engines... engine life (the subject of this thread) isn't really one of them.

Air cooled engines are better where lowest possible weight matters. Air cooled is better where simplicity is important. Water cooled is better where reduced noise is important. Water cooled is better where small size is important (air cooled engines require a fair amount of room for air to flow around, water cooled can be smaller all told)... on and on... there are good reasons for each type.

Water cooled is clearly best for cars because weight doesn't much matter and there is usually plenty of room for radiators and other overhead. Air cooled is clearly best for certain types of industrial engines where simplicity and reliability are more important than size or noise. Most small aircraft engines are air cooled becuase they are simple and reliable with no water pumps and other junk to fail. For a long time most off road cars were the same way for the same reason. When it comes to motorcycles it depends on the design. Air cooled I4s are bulky things (I have a 1100cc air cooled motorcycle, the engine is about the same size as a 2L car engine) because there must be space between the cylinders which makes for a long floppy crank shaft so for inline engines water cooling makes a huge amount of sense. Certain angles of V engines are awkward to air cool (at least when the crank shaft spins along the same axis as the wheels) and water cooling makes sense there too. For V and Boxer engines where the shaft is perpendicular to the wheel rotation (BMW, Ducatti) air cooled is just fine. For singles air cooled is usually just fine. In no case is it necessarily a longevity issue... my air cooled 1100cc has almost 80,000 miles on it and the engine runs fine.

Randy wrote:I don't know. It just seems to me that no new sports car is coming out with an air cooled engine. I mean when was the last time an F40 or Corvette came out with an air cooled engine.

Once again, I am no mechanic but air cooling seems stupid when you can get something that is liquid cooled for about the same price.

I didnt read the last page but for sports cars its all about losing the weight. If I could drop 200lbs of cooling system out of my car thats that much more faster I can make that car go with the same engine.

Randy wrote:I don't know. It just seems to me that no new sports car is coming out with an air cooled engine.

http://www.porsche.com/

(Actually, Porsche's last air-cooled car was made in 1999 IIRC, but that's new enough for our purposes)

That out of the way. MOST cars are water cooled for Emissions purposes. Constant temp = consistant burn, etc.

This argument is also pretty rediculous anyway if you consider that the average motorcycle owner will NEVER own a bike long enough to get anywhere close to normal (as in, no abuse) engine failure.

If you ride like normal, and maintain your motorcycle, there is really no end-user benefit to either water or air-cooling. In fact, from a purely non-technical standpoint, the advantage goes to the air-cooled bike asa it's less complicated and doesn't require coling-system maintenance. (Not like most water-cooled vehicle owners maintain their cooling system anyway!! Most people don't bother until a hose ruptures or the engine overheats, etc.)

TechTMW wrote: doesn't require coling-system maintenance. (Not like most water-cooled vehicle owners maintain their cooling system anyway!! Most people don't bother until a hose ruptures or the engine overheats, etc.)

thats me . I see there is a problem but dont feel like fixing it so it gets worse until I have to fix it lol. My problem is I work on crap all day at work and really dont feel like working on crap when I get home lol.

Yeah, that would be my dad, too. He says he's never had a problem not changing coolant or brake fluid but he's always owned throw-away Fords that he got rid of before anything went horribly wrong. I just recently flushed my bike's coolant and switched over to "lifetime" Engine Ice, which I plan to flush in two years anyway.

I would imagine the engine location and chassis design and, well, entire everything design is much more open to change and different concepts with water cooling. which is likely why cars use it. you can do just about anything with the engine location and it doesnt matter. Plus imagine trying to air cool a big V8..... when not moving.... I mean sure you could hook up fans and such like with a radiator, but you can make the whole package lighter if you have an aluminum radiator that is much smaller than all the fins on the engine would add. Plus the size and area space of the engine are much reduced.
bikes get away with this, even in stop and go traffic, though on hot days some will have problems. Airplanes embrase this because of the forementioned reasons and the engines are designed for constant operating, which is way easier on them than stop and go, plus, there is a LOT of air up there, and usually much faster than street legal speeds. But aircooled for street vehicles doesnt seem like an ideal design. But that doesnt mean that motorcycle dont get away with it and make fine vehicles with prove records anyways.

Dear Mr Gummiente,,, OK you own a Harley, its too bad you don't understand how the engine works on ur Harley, you should be embaressed, but I can explain it to you. A Harley engine is designed by retarding the timing to almost making the engine almost miss fire to make that famous Harley exhaust sound, on ur Harley the plug fires when the piston is almost at the bottom of the cyl. You see? When that plug fires and ignites the hot gases it also heats up the whole exposed cyl cause the piston is almost at its lowest postion, that inturn causes the engine to run very hot cause the heat spends more time in the cyl before the piston reaches tdc and opens the exhaust valve and releases the hot gases, thats why Harleys overheat, run hot and have engine problems.

Fascinating...

moto, I'm gonna have to disagree, the harley sound is generated from a single pin 45 degree vtwin design with an offset firing pattern, it has nothing at all to do with ignition timing.

MotoF150 wrote:Dear Mr Gummiente,,, OK you own a Harley, its too bad you don't understand how the engine works on ur Harley, you should be embaressed, but I can explain it to you. A Harley engine is designed by retarding the timing to almost making the engine almost miss fire to make that famous Harley exhaust sound, on ur Harley the plug fires when the piston is almost at the bottom of the cyl. You see? When that plug fires and ignites the hot gases it also heats up the whole exposed cyl cause the piston is almost at its lowest postion, that inturn causes the engine to run very hot cause the heat spends more time in the cyl before the piston reaches tdc and opens the exhaust valve and releases the hot gases, thats why Harleys overheat, run hot and have engine problems.

That's...... *amazingly* incorrect. I'd love to see you get any ICE to run by having the spark plug fire at the bottom of the cylinder.

The sound, as Dichotomous obviously knows, comes from the firing pattern. The first piston fires when the crankshaft is at the 0° position. The second piston fires when the crankshaft hits 315°. The crankshaft completes that rotation, then goes through a whole rotation with no pistons firing, and the first piston fires again at 0°.

It's the offset firing - 315° between first and second piston firings, but then 405° between second and first piston firings - which generates the sound.

The spark plugs fire when the piston is nearing the top of the stroke, just like any other 4-stroke engine.