Fear of displaying some of my mechanical ignorance has withheld me from asking this question for a long time, but it's got the better of me!
Why aren't these motors used? So simple, and air cooled which would eliminate marinising etc? Couldn't cool air be funnelled from above the deck to the engine?
Just curious!
Dave
Who put that damned eggbeater down there???
Are they torquey enough for the job? You're right though, they go forever. And ever. And ever...
Carbon Really Ain't Pollution.
I guess the answer is yes, but they do require a fan (as on the car as well) and because of their RPM V torque band, they are not ideal for Marine Aplications, but I am sure they could be "hotted up" to suit, way back there used to be heaps of Air cooled Diesels in Boats, for some reason they just faded away, maybe to get a heap of HP they would require a gigantic fan system to keep them running.
One reason I can think of straight away is that annoying Dak Dak Dak Dak sound would piss me off after a few hours.
Then if you wan't the answer to that question, why isn't there just a water cooled engine like the one on your car just running a fan?
Why marinise with salt water jackets at all, seems the cause of all the long term problems.
Timi I don't know if they'd be strong enough, but surely they'd have to compete with a single cylinder yanmar or the like? My old man has a 2 ltr combie and you just can't kill it, even after 30 years.
Dicko...............can't stop laughing!!!!!!!!!!
Rag - that's another point, why isn't there??
the main reason is Air circulation, in a car you are moving through fresh Air, but stuffed away in an enclosed, insulated room/box, you would never get enough circulation and it would slowly cook itself, they have enough trouble getting Air just to run a Water cooled pair of Diesels in a Gameboat, you need all sorts of forced air circulation or they will "suffocate"!
also remember there is a few ways that Boat Motors are cooled, most do not get salt water anywhere near the Engine, some have a keel cooling system, where the fresh water is pumped along the under side of the Boat in pipes and cooled by the Sea Water, others have a heat exchange system where there is a small "radiator" and the sea water cools that, some just pump raw salt water through the Block, and indeed some are Air cooled.
So what is it Noel? Yes it can be done with a fan or no it can't because it would cook itself to death?
If cooled air was blown/funnelled or whatever from abovedecks to the engine room, wouldn't that suffice? Yes there are many ways of cooling an engine, but why is not air cooled the most popular and preferred? It just seems to me that it would be the simplest and least expensive, but obviously there's more to it?
Cheers
Dave
Donny Hewitts boats at Vikki Point had a mix of yanmar raw water cooling and honda air cooled. The honda was nosier but certainly had the revs and torque. Not exactly a v8 roar though.
T o air cool an engine it needs to have some form to disapait the heat. With an air cool engine they have fins on the engine heads, cycinders and the block. The heat travels out these fins and is disapaited, so the hotter its going to get in an application the bigger the fins = big engine for low hp. A lot of high end air cooled motors also have large oil coolers to help so it all starts to add up.
I could see a vw engine being used in a light weight speed boat (them little low looking 10 footers) with air tunneled around the engine, they would be nice and flat for an application like that.
cheers
blaze
The industrial dak daks are very expensive as they were stronger built and a lot had goveners etc. They made only a very low constant Hp if you wanted them to last the rated hours they were designed for. The Dak daks in a car have a gearbox and can only cope with high revs in short bursts and will die if pushed very hard without modification to ports and so on. A combi and weight of a beetle were perfect goveners as they literally stopped them being run really fast. They were used widely on everything but became very expensive compared to a 40hp kubuta or any of the others in diesel and so on. Army and airforce used them on heaps of welding units and generators , pumps and they could run them on crap fuel , drop them from planes adn all parts were user serviceable.
Industrial dak daks ran water pumping and hydraulic units a that I know of for years but even back then they were old hat and not much else to compete. Hondas then came - quarter size and more reliable and with more effecient gensets and pumps could do a similar job if you were happy to keep changing oil- bigger sump would have been nice- some came on pallets wher you could strap a 44 of fuel and a 20litre of oil and after the 44 of fuel ran out you opened the tap to empty the oil, opened the other tap to put fresh in and connected up the next 44gal. Ran for years that way.
Most ultralights moved to air cooled subaru's - (robin) and some even run radiator cooled subarus as they were more modern , overbuilt , reliable and had an industrial section that allowed them to be rated at a good HP and longevity.
Anyone who has ever been on a aircooled diesel boat _ I'll speak louder so you can hear me!!!!!!!!!!! Crap they were noisy and all a GM supercharger and deafness was only minutes away even with the best soundproofing of the day. Some were used widely in ww2. Many of the old aircooled diesel were so heavy and carried so much oil you may as well have been steam powered.
So------
If you wanted a old, inneffecient low HP motor that will shake nuts off a tree I'd put one in a boat.
PS I have seen them on riverboats in Vietnam years ago.
You're a very knowlegeable bloke cormorant and I enjoy reading your replies in lost of threads. If I may ask, what is your trade and your work history? ( not joking, geniunely interested).
So the outcome is....... air cooled inboards are noisy, heavy, and not overly powerful? I've often wondered. I've looked at the lawn mower and at gen sets and thought "why aren't you in a 40 footer cruising along at 8 kts.
I guess now I know.
Cheers and thanks to everyone.
Dave
I suspect that the main reason would be getting fresh cool air to cool your motor would be the biggest drama against the wobbly motor. That being said tho you could also add a heat exchanger unit and run the engine oil through the heat exchanger. this would probably reduce the need for fresh air by probably 30% or so.
What bought around this theory of wobbly boat motors?
Jack.
Hi Jack
They just seem to be so efficient and reliable. I've often looked at Dad's combi and wondered why something so simple is not used as an inboard.
Dave
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