See why air-cooled engines are legendary
8:27

See why air-cooled engines are legendary

Roadshow
[MUSIC] Hey folks cooling again got one of your emails about high tech cars and modern driving. This one comes in from JD. He's in Garden Grove, California. He wants to know about an engine you almost never see anymore. He says why don't car manufacturers make air cooled engines? They seem to have a cult following especially in Porsche 911 and Volkswagen circles. Is there any added benefit to having an air cooled engine as opposed to a water cooled? Yeah, well cult is the right word JD. There's an undying cult around the two great air cooled cars Of mass production history. The Porsche 911 and the Volkswagen beetle. Now the 911 went out of air cooled production after the 98 model year. The beetle ceased production, I think, in 2003. You're never really quite sure with Volkswagen. You always hear theres some country where they're still making beetles. So maybe there's one out there. But as far as I know, it's gone as well Air cooled engine is such a different animal, we're gonna bounce over to a really cool portion shop here in a minute to walk through and understand how it works. But before we do that, let's get something to contrast it to and do a quick refresher on how water cooled engines work. That's what most of us are driving, let's go. Ok, so here's. the big Ford V-8. This guy is a classic water cooled layout that shows us the five major components in just about every water cooled engine, starting with these down here. These are actually some cavities you see around the cylinders. These are cast in when the block is made, and there are some in the head as well. These are called water jackets. This is where the coolant flows, that kind of green stuff that leaks when you've got a coolant problem. It flows through here to absorb heat from the cylinders, which of course are nothing more than extremely hot explosion chambers. That heat has to be gotten rid of or this engine self destructs. So stage one is transfer heat through the metal into this coolant water. All that hot coolant once it comes out of the engine has to get cooled in the radiator. This is what you've seen many times in the front of almost any car through the grill. That's why cars have grills is to allow air to flow over this thing. And inside here the hot cooler is traveling very slowly through all these veins. Hands to exchange out it's heat into the surrounding air, so hot, cool comes in here from the engine, washes down through this little channels and then exits cooled at to that lower pipe over there and goes back to the engine to get more heat and do it all over again. Now obviously engines running in different conditions, hot days, cold days, the engine is cold, it's just got started and the engines [UNKNOWN] hard going up the hill towing who knows what You have to have some control over this story just runs really nilly that's what this little guy does this is literally a $6 part and critical this is the thermostat this is a little valve that opens and closes based on its mechanical reaction to heat the heat of the court that it sits in the middle of the stream of. It's not unlike the way you keep your bath the right temperature by turning hot and cold on and off. It kind of does that kind of switching as well. Now what that thermostat is really turning on and off is the flow of coolant what makes it flow. The water pump typically bolted right on the front of the engine right here. It also has access to those water jackets. And it can move the coolant around between the engine and the radiator. It's typically driven by a belt, like you see on this Ford. But newer engines are now adding electric water pumps, so they don't put so much drag on the engine to run it, and get a little better mileage that way. But either way, this is what keeps the coolant moving from the engine to the radiator, where it can get lowered in temperature, and then come on back. The last part of the system is the other radiator, there is one inside your car as well. Not just this one in the engine bay. It's called a heater core. It's a little tiny radiator, but it works just like this big guy. Hot coolant goes in one side, bleeds heat off into the air and then cooler coolant goes out the other pipe. This is when you turn the heat on in your car. That's where heat comes from in a water cooled car. Electric cars can be a little different, because they don't have a water cooling system. We'll cover that some other time. Now, lets go see how air cooled differs from this. [MUSIC] S Car Go is a well known Porsche performance shop in Marin County, California. They love air cooled engines around here. [MUSIC] Okay, let's compare and contrast. First of all that big radiator that we saw back at our shop, you won't find that in an air cooled Porsche or a beetle. Instead, it kinda starts here with the fan like a water cooled car has, but it's drawing in air based on a belt connection to the engine RPM, not unlike a lot of cars And then immediately forces that air into a duct that flows the cool air down over the engine and exhausts the hot air out down to the street. In a water cooled car, this fan would be pushing air through that radiator. But here it doesn't exist. So it's a direct flow over the engine. It's actually kind of a more elegant system in that respect. Here's a more exposed version of that same kind of engine that really shows you where the cooling actually takes place. This is the top of the engine remember a Porsche 91 is a flat arrangement, here's the top that blows here, pushing air down here and it goes across the cylinder and the head. Notice that these two guys have deep fins up and down their height This is analogous to the fins on the radiator. They both kind of do the same thing. They take something hot and give it lots of surface area to interface with cool air and evacuate that heat. There's just no water used here. [MUSIC] .Okay, let's finish our journey of hot air. Here's the bottom of the car. The air comes down over you can just see them up there, the cylinder and the head. The finned components we just saw on the bench, blows down towards the street, down at the bottom here. Note one other key part though, we talked about that little radiator in a water-cooled car, the heater core that heats the cabin. These are somewhat part of a similar system. These are heater boxes, they pull heat off the exhaust system without getting the toxic fumes involved. That heat of clean air, is attached to these big pipes that go down the body of a car and then a fan blows over a heated Pipe in the cabin and that's how you get cabin air inside of a car that doesn't have hot coolant like other cars do. By the way, a dirty little secret about air cooled Porsches, they aren't just air cooled, they are also oil cooled in a sense. Now the oil is mainly there for lubrication, but here, this is the competition 911, you can see a great big front Oil radiator. This has the hot engine oil come to it be cooled by air flowing over it and send cooler oil back. It's another way to evacuate heat off the engine. The oil is already flowing and absorbing heat. Why not use it as a cooling medium. But again, it's still an air cooled car because the oil is not primarily there to be a liquid cooling system. And you can see the pipelines flexible and rigid they go down the body of the car, take the oil to the engine and bring it back up here. Now of course, on a standard consumer market Porsche you wouldn't have seen this, you would have seen a little cooler tucked up under the right corner of the chin, perhaps With a little fan blowing over a much more discreet radiator. But it's the same concept. It'll all pretty elegant technology. So why's is it now obsolete? Rob King, owner of Escargo, and an air cooled engine lover, says there are two main reasons. One of which was emissions. Air cooled engines warm up slowly and run across a wider range of temperatures when operating. That makes clean and exact burn and mixture harder to nail down. that'll kill you in an EPA test cycle. And then there are power limits. As we demand more power from an engine each model year, he tends to increase, especially in this era of turbo charging So that's why air cooled doesn't work out some turbo motors because that's where they start burning up. That's why they went to the water cooler. Keep the temperature is lower so they can do more with it. Run a higher compression, run more boost, get more power out a lot easier. So what we will continue to see hundreds of thousands of very happy 911 912 and beetles ply the road successfully for decades to come. We shall not see their kind again. At least not a new car showroom. Victims to the twin terrors of our appetite for bigger, heavier and faster cars. That means power output that air-cooled literally can melt down under. And ever-tightening emissions standards that even give water-cooled engines fits. [MUSIC]

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