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Why Nintendo Closed the

While all engine feature different designs, features, materials, webbing, reinforcement, there's a few things which
all engines share. One of the things that all engines share is a deck and all engines are either an open deck, semi-open deck, or a closed deck. Today we're going to dive in, find out which one is better and why. With all modern engines, the block and the cylinder head are created separately from eachother and then later bolted together to create the engine. The deck is the surface at the very top of your block, which is the surface that the cylinder head mates to. The job of the block is to provide rigidity for the cylinders, obviously give a surface for the cylinder head to mate to, and also allow coolant to surround the cylinders and then pass into the cylinder head, where it can cool the head. and eventually There are three fundamentally different types of decks, which are open, semi-open, and closed. The names refer to basically how the deck looks and how it allows coolant to pass through it. An open deck, as the name suggests, is pretty
much fully open between the cylinders and the engine block walls. Open deck designs have the coolant channel
cast into the top of the deck. This design improves cooling and reduces hot
spots in the cylinder but provides much less strength and rigidity in the top of the cylinder. A closed deck, is basically the opposite of
an open deck and it's nearly fully closed. I say nearly fully closed, because the deck
surface is only drilled for the head fasteners, coolant passages, oil supply and oil drainback
passages. The tops of the cylinders are integrated with the deck. This configuration is found in pretty much
all cast-iron blocks and some high-performance aluminum blocks. Semi open falls somewhere between an open deck and a closed deck design, and every semi-open deck is different. For the most part, it's going to look like
an open deck but with some bridging between the cylinders and the block walls. The area where it bridges is going to be different
for every engine. Looking at it from a top-down perspective, it's pretty easy to see which design is which. For reference, we can look at a Subaru EJ
engine. You can see the open deck design pretty much has a big open area between the cylinders and the block walls. Semi-open looks a lot like the open but it has a little bit of bridging between the cylinders and the block walls and then closed is pretty much fully closed off except for a few passages for coolant and oil and those passages need to line up with the passages on the head and the head gasket. For the most part, you're going to hear most
people say that a closed deck is stronger than an open deck block, and while this is fundamentally true, because more material and more reinforcement around the cylinder is going to make it stronger, that
doesn't mean an open deck block is bad. To demonstrate this, we can look at some modern high-performance engines and a lot of them are open deck. For reference, the Honda K20A and K20C are both open deck, although one of those is naturally aspirated. The BMW N54 and N55 are both open deck. Ford's 2.3L Ecoboost is open deck. But, on the other side of the spectrum, the BMW S55 and the new B58 are both closed deck, Nissan VR38 is closed deck, and so on. As you can see, modern performance engines are kind of a mixed bag of closed deck and open deck designs. and that's just a testament to the point that open deck is not necessarily a bad thing. If you look at some older engines, you'll find that a lot of older engines are closed deck. For example the 2JZ is closed deck, Nissan's RB26 is closed deck. SR20 is a closed deck, Mitsubishi's 4G63T is a closed deck. The general trend here is that modern engines are kind of a mixed bag of closed and open deck designs, where as older performance engines are pretty much just closed deck, but the question is – Why would a manufacturer use an open deck design, especially for a modern turbocharged engine, if closed deck is significantly stronger? and, the reason mostly comes down to. manufacturing costs and thermal efficiency. One of the big downsides to a closed deck design is that it's more expensive to manufacture compared to an open deck design. When you're manufacturing tens of thousands
or potential hundreds of thousands of engines , the cheaper manufacturing method can
result in literally millions of dollars saved for the manufacturer, so it makes sense why they want to use the cheaper method. Not only is an open deck design cheaper to
manufacture, with modern materials, casting, and machining, open deck blocks are a lot stronger
than they used to be. A long time ago, it was common to hear somebody cracking or blowing out the cylinder walls on an open deck block, but that's not really the case anymore, you really don't see these issues occur very often. Another reason a manufacturer will use an open deck design is for thermal efficiency. heat management is key to producing an effecient engine and in today's world, engine efficiency is pretty much the #1 thing that manufacturers are going after, so it makes sense why a lot of them are using the open deck design, because it's just a more efficient design. The area where you're typically going to see strength benefits from a closed or semi-open design is at the very top of the cylinder, since there's really not all that much air pressure when the piston is all the way at the bottom of its stroke, there really still not that much pressure when it's midway through it's stroke, but at the last inch of its stroke there is a massive amount of air pressure, and that's where you're going to see the strength benefits from a closed or open deck, because that extra reinforcing is just right there, at the top of the cylinder, where peak pressure is. In an open deck design, this is where you could possibly see failure, since there is not a whole lot of rigidity holding the cylinder in place inside the block. There is all that space in between the cylinder and the block walls. and when you're having that much pressure in that small of a space, that's where you can see cracking or the cylinder wall blowing out entirely. If not cracking, you could possibly run into cylinder distortion which causes a whole host of over problems and will eventually result in catastrophic failure. So, yes a closed deck block is stronger than an open deck block. There's more material and more structural
integrity, but with modern designs, materials, and manufacturing methods, the strength difference
between the two isn't an drastic as it once was. Many modern engines use a closed deck design
and many of them also use an open deck. Open deck is cheaper manufacture and for most
applications it's more than strong enough. If you're building some sort of crazy high
horsepower application where cylinder pressures are going to be way higher than they were
ever designed for, than a closed deck block will theoretically be the better option. Somewhere inbetween a closed deck and open
deck design is the semiopen deck which provides a little bit of the best of both. It's an important to note that if you're comparing
two different engines, that the design of the deck isn't really a big factor. Yes it's important but there's a lot of other things in an engine that can fail and looking at just the deck is skipping over everything else in the engine block that could potentially fail when you're massively increasing power. So, a closed deck block is not always going to be better than an open deck block. The deck itself might be stronger, but there is still a ton of other things that you need to look at. That brings us to our next point, which is
can you take an open deck block and convert it to a closed deck block. Say you were a building a 1000hp or 1200hp application, could you take an open deck block and make it a closed deck to support that application? and the answer is yes Converting an open deck to a closed deck block typically involves installation of a billet aluminum plate which sits in between the cylinder walls and the block walls. This plate will feature holes to allow coolant
to pass through just as it would with a closed deck. The insert is typically pressed in so it doesn't
jiggle around, since that would effectively eliminate the benefits of reinforcing those
areas. Once it's pressed in, it's typically machined so it's completetly flat and the only way you can really tell that there has been an insert there is that the color of the billet aluminum might be different than the color of the cast aluminum that the block is constructed out of. If you're going for something absolutely insane like a 2000hp or 3000hp application, some manufacturers offer full billet aluminum blocks which feature a closed deck design from the start instead of an open deck design. To answer the
question of which one is better: yes a closed deck design is better. It's stronger, it has more material, it has more structural integrity, It's going to support the cylinders more but that doesnt mean that it's always going to be better than an open deck block, since there's a ton of other things in the block that could potentially fail. So, if you're building some sort of crazy high-horsepower application, yes a closed deck might be marginally better than an open deck design, but if you're not building something absolutely insane, say something less than 700hp, an open deck is probably going to be fine for most situations. for reference, we can look at the Honda K20C, which is an open deck engine, it's the new engine found in the Civic Type R and a lot of tuners have pushed this way past the stock power limits and they're pushing it upwards of 400, 500, even 600hp and the block is just fine. This again, just shows that you really don't need a closed deck design unless you're pushing some crazy power number. So, that's pretty much all I've got for you
guys today. That's everything you need to know about closed
deck and open deck engines. If you guys think there is anything I missed
or anything you want to add, please let me know down in the comments below. Be sure to also let me know what videos you
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