- One of the highest
revving production cars on the road today is the beloved S2000, peaking at 9,000 RPM. But 9,000 RPM, those are
frigging rookie numbers compared to what a Ducati can do. I'm talking 12, 15, even 17,000 RPM's. And my Italian engineering buds, they can pull that off with
technology from the 1950s. So I want to know how is Ducati making such high revving engines with tech older than a consumer microwave? The answer lies with the
desmodromic valve system, and it is an ingenious way to pump those rookie rev numbers up. So today, we're going
to take a closer look at the secret Ducati sauce that is desmo. Figure out how it works
and more importantly, see why we don't see car manufacturers using this tech in their engine. I bet after this video, a lot of you're going to start Googling Ducati v4 engine swaps
into your Honda Civic. It could happen, I've seen weirder things. (upbeat music) Thanks to Morning Brew for
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to subscribe to Morning Brew. Now let's get back to the show. The desmodromic valve system
or desmo if you're cool is a valve system where the cams both open and close the valves. And before we get into
why you'd want this, let's talk about the more
traditional valve train setup most commonly used in engines today. Now in a conventional
engine, as the cams rotate, they push open the valves via a system of push rods or rockers or bucket lifters. This is how air gets in and
exhaust gets out of the engine. The cam lobes push the valves open for a precise amount of and distance and then as the cam lobe rotates away, the spring closes the valve again. This spring is putting constant pressure on the valve to hold it close and that's known as seat pressure. And the valve train has
to overcome that pressure in order to open the valve. So as the cam spins faster,
the valve opens faster, but it will always
close at the same speed. The spring rate of a standard
valve spring is constant. If the cams spin too fast, the cam could start pushing
the valve open again before the spring has had time to close. This is called valve float and there are a number of problems that could come from valve float. First off, if your valve is not sealing your cylinder properly, you could be losing
compression during combustion, and that could stop your
engine from making power. Second off, it could
mean that unburnt fuel is getting into exhaust and igniting causing backfiring or damage
to your catalytic converter. While that last one does
sound pretty, pretty cool, if you have an interference engine, you're not going to
like what happens next. An interference engine is
an engine that is designed to have the valves extend past the point where the piston would
be at top dead center. That normally is not a
problem because the valve is always closed when the piston is up. But if the valve is closing too slowly, the piston will reach top dead center before the valve has moved. And your valve and piston are going to get into a little fist fight. And when a valve and a
piston get in a fist fight, you know who wins? Your mechanic. He loves when those two fight. He loves unhealthy relationships. He can fix moving metal, but
he can't fix his broken heart. Now, a lot of people fix this
problem with stiffer springs, springs that can close the valve faster. But the problem with
that is now the engine has to work harder to overcome the stiffness of those springs. The valve seat pressure is higher. When the force being put into
the engine from combustion can't overcome the force of the spring, the revs will stop increasing. So springs need to be
stiff enough to close, but soft enough to open. With modern springs, most car engines can't rev higher than 7,500 RPM. And there are some fancy solutions like progressive springs
or even beehive springs, but even the highest revving supercars are only really making about 11,000 RPM. So now we understand the problem. So let's look at the solution. That Italian solution. Solution-ay. (upbeat music) Ducati's desmo engine doesn't use springs so there's no tension in the valve train. Instead it uses a cam shaft that has two lobes for every valve. One to push the valve open like normal, and the other pushes on
an inverted rocker arm that pulls the valve back up. For this to work, a valve
with a special collar and grooves need to be
used called a poppet valve. So as the engine revs up, the valves opening and closing speed will increase at the same time. So now there's no spring force
for the engine to overcome. There's no valve float
and the valves all seal exactly when they're supposed to. And while Ducati didn't come
up with this technology, they did start using it as early as 1956 and have had desmodromic valves on almost all of their
flagship bikes ever since. If you want to know more about that bike, click that link right there. That was the first B2B a guy
very similar looking to me did it wasn't me though, it was weird. He wasn't as good as I am. Let me know how he is now. It's easy to love desmo engines for the mechanical marvel that they are, but if that doesn't get you
going, fricking sound will. Since a desmodromic valve system mechanically forces the valves closed, the sound made by the
engine has a roughness to it that is like no other engine. Unlike in an engine with valve springs, the valves in a desmo engine
are being slammed closed with no elasticy. The sound you're hearing
is the metal of the valve hitting the metal of the valve seat, hundreds and hundreds of times a second. Ducati still uses the desmodromic system in their engines today and
it was an ingenious way around the internal forces
created by valve springs. But just because you're on top, doesn't mean you're going to stay there. And in the 90's, valve spring engines from Yamaha, Honda and Suzuki
all reached higher RPMs with the introduction
of lighter materials. See the valve spring
engines have to overcome the force of the spring, but the valve itself is
lighter than a poppet valve, therefore it has less inertia. And since the desmo engine needs an extra rocker and more cam lobes, the whole valve train
has more mass to move. So eventually, materials got light enough that the desmodromic valve train wasn't any more efficient
than a standard one. The playing field leveled out. But Ducati decided to stick
with their desmo engine because it's what they know best, desmo is Ducati. (chair wheels rolling) The first Ducati desmo system
was in the 1956 125GP bike. And at the time Ducati, they were using traditional coil springs in their valve train. But the metallurgy of the
1950s plus the rev limit that the bike could achieve
was enough to weaken and fracture those springs. So to the desmo system they went. And as a result, the single cylinder 125GP could rep to 13,000 RPM. But don't think just because
Ducati nailed it in the 50's that the desmo system
didn't evolve, oh no. An early version of the desmo system known as the Trailbero used three cams, an intake cam, an exhaust
cam and a central cam to close the two. It was kind of like
having a dual overhead cam and a single overhead
cam at the same time. As time went on, Ducati
refined the design. By 1987, the Ducati 851 was
using four valves per cylinder on an L twin, meaning that it
would have needed six cams. And instead of using six cams, Ducati had started to
use L-shape rocker arms that made contact with cam loads on either side of the same cam. They also moved to chain-driven timing as the cams were now separated to either side of the V configuration. From the gears to chains to belts. Those are both three items that my parents used
to discipline me with. In modern times, Ducati is even experimenting
with springs again. The Desmosedici Stradale
uses keeper springs attached to the rockers to
help them return to position. These springs help reduce
wear in the valve train and lengthen the amount of time between valve service intervals. Buy hey, Ducati didn't
rest on their laurels and just twiddle their thumbs. Oh no, they kept improving
the desmo system. And just this past year in Moto GP, they set a top speed
record of 225.5 miles per on a Desmosedici GP21. Think I can go 225 on this thing? Let's see.
(engine revving) Close, I was close. My mom said don't do it. That's the only reason why I stopped. But using desmo in a
motorcycle engine is one thing. What about taking this type of valve tech and putting it into a car engine? Do we need to enter into
the Donut multi-verse? Theorize a vehicle and engine combo? Talk about what might've been? Answer the big what-ifs? No, no, we don't. That's because the desmodromic engines in the auto world are already a thing. In 1954, Mercedes won their first F1 race with a desmodromic engine. The W-196 had a 2.5 liter straight 8 making 340 horsepower at 10,000 RPM. And to say this thing sounded
brutal is an understatement. It makes John Wick look like John Mulaney. So he did all of this
because his dog got killed? What a joker.
(audience laughing) If you want to see more John Mulaney bits, leave a comment down below. And this sound, as awesome as it is, is probably the biggest
reason why you don't see four cylinder desmos in
your everyday hatchback. One of the hardest working
departments at any automaker is a department of noise,
vibration and harshness, NVH. It's their job to refine
and meter all the sounds that a car makes from both inside and out. They study the harmonics of a car and can either refine a
car sound in a sports car, or it could totally go
away in an economy car. If you ever want to see
how much the NVH department can change a car's sound, just know that the engine in a Lotus Exige is also in a 2012 RAV4. And one of the places that
engines create the most noise is in the valve train. With a modern engine
valve noise is lessened with soft, progressive
springs and hydraulic tappets. These reduce the force in the
valve as it comes to a close. But in a desmo system,
as we mentioned earlier, the metal is slapping away at each other. While the sound of a thousand
mortars hitting a pestle might be fun in a super bike, that doesn't really fly
in the automotive world, at least on the streets. Ducati's largest desmo engine
only have four cylinders and they make less than 250 horsepower. So for a car to be that loud, it's a pretty tough sell
for most auto manufacturers. A more powerful engine with more cylinders would obviously make even more noise since it had more slappy valves. Dude, slappy valve's a character due. Instead of steam boy,
we have slappy valve. And slappy valve loves getting spanked. I'm slappy valve. Oh have I been naughty? Don't punish me for it. (screaming) If you're a parent watching
this it's okay, it's just fun. Dude, slappy valve could
be the thing that we, Slappy valve is great. - [Cameraman] I want 10%. - I'll give you 10% of the
credit and 0% of the revenue. And those slappy valves
actually cause another problem that stops this tech
from coming to road cars, and that is wear. The forced closing of the valve creates stress on the valve seat and that can weaken the metal of the valve or the cylinder head. Since a desmo engine also has no spring to give seat pressure to the valve, the valve seal can be thrown
out of whack pretty easily once that metal is weakened. Also, because of the way the rocker arms have to be configured
to pull up the valve, the desmo system relies on a
little bit of sliding friction between the cam and the rocker arm. Any amount of friction
in an engine is bad news. And especially if it has
something that is moving, as often as the valve train. Because of this maintenance on a desmo is more frequent than most valve trains. Superbike engines are already designed to be driven a lot less than car engines. The average car, it's driven
for about 12,000 miles a year. While the average superbike
is around 3000 miles a year. That's like (computer beeping) like a couple thousand miles difference. You do the math. And the final problem with desmo engines and so many other pieces of tech that we've talked about on this show, frigging costs, man. Since the desmo system
uses an extra rocker and a special valve and cam shaft, there's added material costs. And the added components
make it more complex to build and maintain so it means that a desmodronic hatchback
would be really expensive. It's all about money
at the end of the day. Freaking dollar, dollar bills, y'all. And I know what you thinking, yeah, let me take this 4V R
engine, 250 horsepower, 15,000 RPM, throw it in my Civic, have a little Jap-Italiano,
frickin sick ride. You can even call it
the Jerry Jap-Italiano. - [Announcer] Ladies and
gentlemen, James Pumphrey. (audience applauding) - Today we honor a lost innovation. Let us remember its legacy. Let us remember it's rising light. Though no longer with us
due to safety regulations, their up and down contributions will live on in our hearts forever. Here with a special performance
from epidemic sound, please welcome Nolan J. Sykes. (audience applauding) (light piano music) Show your respect for pop-up headlights by going to donutmedia.com. It's got a beautiful airbrush design, and honestly, it's hard to
put a price on such a legacy. But, if I were to guess I'd say, they're available for 29.98. Which is in fact way less than $30. So go pay your respects at donutmedia.com. (light piano music) Bless up and down. - Thank you guys so much for
watching this episode of B2B. Hey, we did another bike video. Maybe may we'll do a whole bike show. Maybe next year? Maybe that's what's on the horizon? So if you could, click
that subscribe button. Click that like button
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Silence of the Lambda. Follow me on Instagram @Jeremiahburton. Until next week, bye for now.
