Cooling an air-cooled engine

[xwhatsit]

You know, with all the time out from riding, I've been doing a lot of thinking... which is normally a bad thing, but this idea I have seems less stupid than the usual ones so I thought I'd post it up on here.

Now, I'm not planning to do this, but I'd love to give it a shot once I'm out of student life and have a real job, I want to get a bucket racer and try all these silly ideas I have just for kicks.

I'm not a biker originally, I'm from the land of blinkenlights and electronics and nerdy stuff like that. In this scene, kids like to tune their computers to make them faster doing something called `overclocking' -- essentially, over-revving their computers. This generates a lot of heat, so they've come up with all kinds of innovative ways to cool their computers. Big heatsinks, fans, water-cooling, liquid nitrogen, Peltier devices...

So I was looking at some overclocking pics the other day, and I thought... well my bike gets hot in traffic, could I not apply some of the principles here? My particular idea is to water-cool the bike, in classic overclocking style, by taking some thin copper tubing and bending it around in a spiral between the cooling fins on the cylinder head and barrel. Through this you pump water, which goes to a reservoir where you cool it with a condenser or radiator or something. Obviously it's not anywhere near as efficient as a proper water-cooling system like they build into engines, but it seems to be a hell of a lot better in computers than just a plain heatsink and fan setup (which is what an air-cooled bike uses). Also, as the water is contained within the copper pipe, you don't have to worry about hydraulic lock if you blow a head gasket.

Is my idea blindingly stupid, can anybody see anything wrong with it? I'd love to attempt this with a shitty little bucket to see if it would work.

[jrandom]

Cooling the coolant with a condenser is a great idea. Reminds me. Have you ever tried leaving the fridge door open on a hot summer's day to keep the kitchen cool? Works a treat. Try it some time.

[terbang]

I remember the old Ford prefects that used hot water rising and cooled water descending to circulate the coolant. There was a term for it, can't remember it, though it saves having to fit a pump.

[TerminalAddict]

thermo cyclic ??

[Ixion]

Thermo siphon it's called. Was used on many old cars, and the Scott and LE Velocette. Works perfectly well, so long as the radiator can be placed well above the cylinder head (which is why it is not seen now).

Back when bikes had cast iron heads and barrels it was by no means unheard of for people to cut the fins off, and solder a copper jacket on. An old radiator, a bit of hose and Bob's your Mummy's special friend.

Knew a few folk did it for various reasons, with varying success.

Never could quite see why though. Airt cooled bikes don't overheat in this country.

[xwhatsit]

Cooling the coolant with a condenser is a great idea. Reminds me. Have you ever tried leaving the fridge door open on a hot summer's day to keep the kitchen cool? Works a treat. Try it some time.

Lol, so you would need a radiator or summat? CPUs can get pretty hot... hot enough to boil the water... but an engine is a bigger lump I suppose.

[jrandom]

Lol, so you would need a radiator or summat? CPUs can get pretty hot... hot enough to boil the water... but an engine is a bigger lump I suppose.

I was being facetious, inasmuch as a condenser is a way of moving heat from A to B that, being an imperfectly efficient device, inevitably generates more heat in the process.

One way or the other, you'll eventually need a radiator, or you'll just have a bike that overheats its condenser before it overheats its engine...

[terbang]

Thermo siphon it's called.

Thats the words I was racking my brain for. There has obviously been too much brown bubbly stuff consumed since I last heard those words used..!

[xwhatsit]

Thermo siphon it's called. Was used on many old cars, and the Scott and LE Velocette. Works perfectly well, so long as the radiator can be placed well above the cylinder head (which is why it is not seen now).

Back when bikes had cast iron heads and barrels it was by no means unheard of for people to cut the fins off, and solder a copper jacket on. An old radiator, a bit of hose and Bob's your Mummy's special friend.

Knew a few folk did it for various reasons, with varying success.

Never could quite see why though. Airt cooled bikes don't overheat in this country.

Interesting... I thought it might've been attempted in the past, all of my ideas are somebody elses first (bathtub curve? Who woulda thought?!).

As for why... well my bike gets pretty bloody hot in Auckland traffic. Surely it's better on the engine for it to run cooler, and definitely better for my heart so I can stop thinking about seized pistons? Of course, that would be of little use on a bucket, as it's travelling at speed (relative speed, of course ), but I've heard that highly-strung air-cooled strokers do have the occasional problem with heat?

At any rate it would be fun to try.

[imdying]

Never could quite see why though. Airt cooled bikes don't overheat in this country.

There's your answer.

[Ixion]

Interesting... I thought it might've been attempted in the past, all of my ideas are somebody elses first (bathtub curve? Who woulda thought?!).

As for why... well my bike gets pretty bloody hot in Auckland traffic. Surely it's better on the engine for it to run cooler, and definitely better for my heart so I can stop thinking about seized pistons? Of course, that would be of little use on a bucket, as it's travelling at speed (relative speed, of course ), but I've heard that highly-strung air-cooled strokers do have the occasional problem with heat?

At any rate it would be fun to try.

Never heard of an "ordinary" four stroke air cooled engine piston seizing in NZ conditions. Two smokers can be another matter but two strokes always are. And if a two smokers made up its mind to seize, seize it will, water cooling or not.. In general, the hotter and engine runs the better. Air cooled engines are meant to run hot. Use good oil, change often and don't worry about it.

[xwhatsit]

Ah, so when my engine runs better in cold conditions, it does so because of cold intake air, rather than colder barrel/head? That makes sense actually.

So, heat is only a problem when it reaches seizing-levels or causes air leaks? Sweet. So the problem I really want to solve is not cooling my bike, but to stop getting a heart-attack when I can see heat-waves coming off my engine lol.

[TLDV8]

I remember the old Ford prefects that used hot water rising and cooled water descending to circulate the coolant. There was a term for it, can't remember it, though it saves having to fit a pump.

Boxer twin cylinder Bradford's too.

Maybe Jowett's also .......1953 or so sporty version,took it at a Pukekohe race day.

[Ixion]

That's the Jowett Jupiter. Nice car in its day, if you could keep it in crankshafts

[sAsLEX]

Ah, so when my engine runs better in cold conditions, it does so because of cold intake air, rather than colder barrel/head? That makes sense actually.

So, heat is only a problem when it reaches seizing-levels or causes air leaks? Sweet. So the problem I really want to solve is not cooling my bike, but to stop getting a heart-attack when I can see heat-waves coming off my engine lol.

Cold air means denser volume of gas entering the cylinder which means more oxygen which means more boom