ENGINE BLOCK DECKS: Open vs Closed vs Semi Open

What is up engine heads, in today's episode we're talking about the differences between open deck engines, closed deck engines and semi-open (semi-closed) deck engines. After watching this video you'll be able to identify the different engine block deck designs but you'll also know how they differ from each other in terms of strength, cooling, their performance potential and more.
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The key difference between open, closed and semi closed engine block decks is the structural reinforcement in the coolant passage area at the top of the cylinders, that is the engine deck area. Open deck engines will have the entire coolant passage are around the top of the cylinders free and open. Semi-closed decks will also be mostly open, but will have structural reinforcements in the form of little "stems" or "pillars" between the cylinders and engine block walls. The name of the closed deck engine is somewhat misleading because the area around the top of the cylinders isn't really fully closed of course, but there are opening left for the coolant to pass through. Subaru is an interesting brand here because they made virtually the same blocks in all three versions of the deck design.
Now if you look up the differences between open deck vs closed deck vs semi closed deck engine blocks online you will likely run into an over-generalization of how closed deck blocks are the strongest because they have the most structural reinforcement and how open deck engines are the weakest because they lack structural reinforcements, but how they have the best cooling because of the largest cooling passages. You'll also likely read how if you're interested in a performance forced induction build you should stick to a closed deck block or reinforce an open or semi open deck block. This information does make sense but it's really outdated and comes from the early days of turboing engines. Closed deck engines are stronger than open and semi open deck ones, but it's not that simple and open decks are not as weak as the internet might try to convince you.
Here's an example. The BMW N54 is BMW's first turbo engine in a pretty long time. Some call the N54 the modern day RB26 or the modern day 2JZ. Just like the 2JZ, the N54 is an inline six cylinder, 3.0 liter twin turbo engine, but unlike the 2jz, which is a cast iron closed deck engine, the N54 has an open deck aluminum block, so it stands at the opposite end of the perceived block strength scale. That means it should be weak right? It should fall apart when boost is increased? But today capable tuners and enthusiasts take the bone stock N54 block to beyond 700 whp. And the N54 is just one example there are plenty more modern open deck designs (k20c, ford ecoboost, volvo t5 and many others) where you can increase the boost without the blocks or the cylinder sleeves complaining at all.
So how come, why are open deck designs so popular today, and why aren't they falling apart under increased boost. They're popular because they're cheaper and easier to manufacture compared to closed deck designs. Open deck engines can be made using high pressure die casting (hpdc) which is cheaper and simpler compared to methods needed for closed deck engine blocks. But the other side of the coin is that casting technology has come a long way, and is far better and more accurate then decades ago, which enables manufacturers to make much stronger and better open deck blocks. On top of that manufactures have access to sophisticated CAD and simulation software that enables a better and more complex block and deck design.
But there's something else that plays an important part as well, and that is tuning technology. ECUs and sensors are much better, much more sensitive and capable than they were decades ago. They are able to sense knock better and react faster to prevent it. The open deck design of the Honda B16 was blamed for the cylinders cracking under boost of these engines in the late 90s. Today we know that the B16 block is good and can sustain well over 400hp on the stock block. What happened in the 90s is that knock happened but the sensors and ECUs did not sense it and react fast enough to preven it. In most cases knock cracks cylinder sleeves, not boost. Just look at the Honda K20 today, capable tuners are taking it well beyond twice it's power level on the stock block. Something that was impossible a few decades ago without significantly shortening the lifespan of the engine. So the key takeaway is that the open deck and semi open deck engines aren't weaker, they actually have a smaller margin of error for knock, but good tuning and modern electrinics are capable of keeping the engine safe, even within a smaller margin for error.
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Daniel
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#d4a #enginebootcamp #engine

[@d4a]

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[@jaimeestrada1502]

This channel is so underrated!

[@OmarOmar-wd5cq]

+1

[@Pchaakh62]

By who?

[@jesskoenmaniac]

ITS BETTER THEN DONUT MEDIA

[@Floodbait_117]

Agreed only found it like 3 weeks ago and watch 1 vid at least every day

[@karigeirsson2720]

Fax

[@codyblea3638]

I love mechanical history, this video is great. Showing how a misconception started. Explaining the reasons for it existing. And describing how the misconception is being countered by new technologies. I love this type of info. Your goal to inform is honest and it staggers me to see how much effort is put into these videos. There are a lot of youtubers out there that can talk about nothing for ten minutes and it shows in their quality. You love this field and want to share it with others. I respect and appreciate your work immensely.

[@d4a]

Thank you for that

[@ethanlau279]

Love the nuanced information on this channel. No bro-science here! Might we be getting an EJ video soon?

[@d4a]

We might. I'll even tell you when. Next Iconic engines video is going to be something something and then right after that next up is the EJ.

[@ethanlau279]

@@d4a Haha, awesome. Subscribed.

[@_viy]

Bro-science))

[@SerbanCMusca-ut8ny]

Agreed. Serious content, I Iike this chan!

[@sushpants]

Awesome video D4A! I assumed sleeving was required on open deck engines but you make a good point about ECU tuning. 20 years ago, most tuning was done using "piggy-back" ECU's or rising rate FPRs which had zero knock control. I remember tuning my JR supercharged Miata and the instructions were to advance timing until there was audible detonation and then pull back 2 degrees. On hot days I could still hear it ping once in a while which was absolutely nerve racking. Again, awesome video and I love the editing :D

[@H33t3Speaks]

Also, it's not just tuning technology that has come a long way, we've made heart stopping discoveries in the world of materials science. There are VERY strong Al alloys.

[@d4a]

True! Should have elaborated on that more.

[@soundseeker63]

@@12OclockLow There is actually a video on this channel where he talks about the different alumunium grades and their properties, though I forget which one it is. One thing I do remember is that the blend of silicon in the alloy makes a big difference to the overall strength. Also as mentioned, considerable improvements have been made in casting techniques which, while not increasing the strength of the raw material its self, does give you stronger components by eliminating air pockets and oxide layers within the parts. This, in combination with advances in CAD design means modern aluminium blocks can be made not only stronger than their ancestors, but lighter too.

[@josediazasmr6014]

Are you talking about titanium?

[@diplonik8174]

open deck crank cases are traditionally a much more demanding job for the cylinder head gasked. The modern MLS gaskets also helped the open block design a lot. Open deck can be casted as dye casting (without water cores) which is very cost effective, this is the main driving force behind it (and better cooling).

[@fazorni]

air cooled vs liquid cooled engines, also: great content

[@d4a]

Thanks for the idea!

[@chippyjohn1]

Other than small engines, air cooled was old and out of date technology in the 1930's. Water cooling is much better.

[@sliwka621]

I laughed at FordEcoBlownGasket being capable of high boost.

[@alexanderbleichner3888]

Focus rs will cracked their block with more boost

[@soundseeker63]

@@alexanderbleichner3888 From what I've seen they were pretty disasterous from the factory! I wouldn't even think about tuning one of those things! lol A shame really as the rest of the car is pretty good.

[@tiagobelo4965]

suby bois can relate

[@ghoulbuster1]

Remember guys, always buy good gaskets.

[@fedjadrndarski5606]

@@alexanderbleichner3888 Focus RS crack it's block with stock boost.

[@loopingcz]

Awesome video! This is becoming one of the best car channels on youtube. Very informative, thank you. Greetings from Czech Republic!

[@michaelfortier7726]

Crazy good info on this engine boot camp. This channel is different from the others that just scratch the surface or give a 'mechanics' point of view (no offence to mechanics, you guys are great at what you do) which doesn't really explore the fundamentals or is more based off of experience. You communicate information in such a clear way and with such in depth explanations that I would give you 3 likes if I could. Amazing content, keep up the good work and I will be sure to follow the channel closely!

[@flyfaen1]

There is also the issue of long term reliability. Dealing with a lot of open deck engines (Mostly Volvo Modular N and RN series) the main killer long term is cylinder oscillation, even with a MLS head gasket, they vibrate during opperation due to the latteral forces caused by rod-angle. So they fatigue. Typically inserting and welding in small supports to make it semi-closed makes a big difference, and inserting a block guard makes them hold up ALOT. For more extreme cases we use the "D5" block (Diesel variant of the "T5" block) and insert and weld a deck guard, then the block is good for 200Nm per cylinder.

[@soundseeker63]

I've heard people describe the N54/N55 as the new 2JZ too, and while I do like BMW engines and they are definitely tuneable, I doubt whether there is much comparison between them in terms of overall reliability. The N54/55 have so many complexities that the 2JZ just doesn't have (and didn't need). Likewise the new B58, for which they decided to put all the timing gear at the back of the engine... WHY!? It may make good power (and decent MPG) but I sure don't fancy owning one out of warranty! Ditto the Ford Ecoboost /Ecoboom.

[@xIcarus227]

> The N54/55 have so many complexities that the 2JZ just doesn't have (and didn't need) And how exactly do you think these new engines meet emission and fuel consumption targets exactly? You think you can just snap your fingers and get a fuel efficient 2JZ? > Likewise the new B58, for which they decided to put all the timing gear at the back of the engine... WHY!? Weight distribution. With a chain drive that generally doesn't need to be changed for the lifetime of the engine. > Ditto the Ford Ecoboost /Ecoboom. That Ecoboom moniker was attributed by a bunch of uninformed couch warriors over a pretty small amount of cars affected by a coolant pipe issue which could blow up. It has nothing to do with the engine being open or closed deck, and a recall has been made. This is exactly like the Focus RS head gasket fitment issue which was blown out of proportion. People love talking about things they have no idea about.

[@soundseeker63]

@@xIcarus227 Yes thank you in case you chose to ignore it (or can't read) I did quite clearly say the N55 has complexities the 2JZ "DID NOT NEED"... Clearly because there is a difference of 20+ years in terms of the environmental standards the two engines were required to meet. I am quite well aware of why you could not manufacture the 2JZ today, thank you. And no, there is a lot more wrong with the Ford ecoboost than just a coolant pipe. And your patronising tone does you no favors either. Good day.

[@xIcarus227]

@@soundseeker63 > I did quite clearly say the N55 has complexities the 2JZ "DID NOT NEED"... Clearly because there is a difference of 20+ years in terms of the environmental standards the two engines were required to meet. So you claim the N55 didn't need these changes, but also claim it couldn't have ever been put into production without said changes due to emissions. So to conclude, it actually needed these changes else it wouldn't exist 😂 > And no, there is a lot more wrong with the Ford ecoboost than just a coolant pipe. I merely pointed out where the 'Ecoboom' moniker comes from, and why everyone using this term is jumping on the misinformation bandwagon, similar to those who say the EA888 engine is unreliable just because gen1 was poor in that regard. And actually, if you were to compare every budget turbo petrol engine from the late 2000s to early 2010s, you'll notice Ecoboosts were some of the most trouble-free - yet another piece of proof that you don't know what you're talking about. > And your patronising tone does you no favors either. Your ignorant statements don't do you favors either, yet here we are. Good day to you too.

[@soundseeker63]

@@xIcarus227 Can't tell if you're being sarcastic/ deliberately obtuse / trolling or whether you have some genuine issue with understanding written word but, either way, you've used a heck of a lot of words to say absolutely nothing and frankly, you are boring me now.

[@GodKing804]

This is amazing. Could you do the same on modern ZF auto transmissions / modern ones? Edit: i know this is an engine bootcamp series but your dispelling fiction is amazing. People need to to know how strong and fast modern transmissions are becoming.

[@jhuntosgarage]

Nice work my man! Green screen is an excellent addition. Maybe consider adding yourself in on clips of dyno runs, etc where you actually were not there; just for fun. Excellent work. Thanks for sharing!

[@d4a]

I should! And then like cover my ears or do woot woot sounds lol

[@micahgunnell]

Love your videos! Just technical enough without being boring. Funny but not surprising that no EJ engines were featured 🤣 It seems to be the consensus that you need to go closed deck for anything over +100-150hp for us STi owners. Looking forward to seeing that video! 👍😊

[@andoletube]

I love the way you say engine "Blaahck"! Really enjoying your content and style of explanation. Hope you get more subs. Excellent channel.

[@dreamride8512]

This channel has everything! I can understand everything easy af, his voice is somehow relaxing, and this channel has videos for every single bolt of a car! After watching all the videos uploaded here you can build a car your self from the beginning!! Love you so much!!!!

[@802Garage]

Wow this was a great video! I predict this channel growing A LOT very soon. 100K by June? Probably. Keep up the great work and don't forget about me when you're a big dog!

[@d4a]

I'll never forget about ya!

[@802Garage]

Hooray! I'll be up there soon too. Just gotta make some magic like you. Hahaha.

[@d4a]

@@802Garage There's no magic, just slave labor 😂😂 you have plenty of talent and a non-Russian accent, I see a bright future!

[@802Garage]

Hahaha shhh, you'll tell people the get rich quick KZbinr secrets! 😂 It's your slave labor that creates the magic. 😬

[@roguefab]

Absolutely phenomenal explanation. Never stop making these videos!

[@quirinonavarro1857]

So agree with your point... that is a matter that always worried to engine fabricators. In the early 60s, Smokey Yunic always used to say: You need to avoid (damn) combustion detonation at all cost... that is a good advice now as was then. Good channel, keep the hard work... greetings!!

[@jorman915]

I’m glad someone explained this

[@d4a]

I'm glad you watched it!

[@dior2397]

As beginner i've been trying to learn more about the engine rather than bolt on mods or other mods and your channel has taught me a lot about what I wanna know. Hope you hit a million+ followers one day you deserve it bro.

[@TurboHappyCar]

Really good stuff man! These videos are killin' it.

[@cowx73pw]

Such good information I love the green screen very helpful with the background information Great video keep it coming

[@Skillzpatchi]

Ford focus rs have that same problem with there open deck block because of the headgasket

[@owenjaeckle8542]

ive been hooked on this channel for the past few days. so glad I found it!

[@crxtodd16]

Subscribed! I keep learning new things from your channel. Thanks for always putting out such great info!

[@jay_321]

Thanks for the explanation. The 3.6L Pentastar V6 has an open deck block and I have wondered what the advantages and disadvantages are. Now I have a better understanding.

[@pedroebarbosac]

Man... I am your fan!!! You remember me my dad, he could easily spend days talking about engine configurations, specs, tuning... keep it up!

[@valentinuiliqnow6198]

my favorite day of the week becouse your show

[@jesskoenmaniac]

Thanks for all your videos, its very helpfull

[@kenlipper874]

Really interesting, keep up the good work!

[@8gti9]

Great video! Very informative 👏

[@Loplyful]

Your explanations are concise and easy to understand, thanks for teaching us petrol head newbies some new things!

[@jpbredenkamp5091]

Subscribed, this was an excellent breakdown!!

[@sirhaney]

This channel has helped me so much with doing my build right

[@mhmdsam6203]

Very useful bro , preciate it , keep going the good stuff

[@swflracing]

Subscribed. Keep up the good work

[@Uli_Krosse]

That was a very extensive explanation. Thanks a lot! Also thanks to the YT algorithm which sometimes does indeed seem to get things right ...

[@richiet6381]

This gentleman is awesome! Subscribed

[@jacobski5726]

Lovely story tell voice and such good content!!!

[@tolrem]

Very interesting.Never knew anything about all this.

[@gregeconomeier1476]

Your knowledge and speaking skills are superb. Additionally, the editing that you (or someone) puts into these vids is also superb. All around good stuff!

[@d4a]

Thank you. I'm a one man show. Script, research, recording, editing, all me :)

[@jamesgeorge6551]

Dude. What you say is true, 100%. Richard Holdener proves what you say. In reality, if you plan on adding boost, you need to have sufficient fuel, and sufficient octane. E85 and 100+ octane really make a massive difference. #2 is timing. Start conservative, and work your way up, if adding timing doesn't add power, stop adding timing. #3 if you're going past 10 psi, you should add ring gap to the top ring. If you add ring gap, cam and springs, then boost, SBE 6.0 LS engines will go over a thousand horsepower. A cam(s) swapped K24 will push 600+ horsepower, no problem. Great content, keep up the goodness, my freind.

[@exoticcreature3059]

So it's settled then. Closed deck iron bwuaack all the way!

[@JoeIsCrazyWillman]

For me it's open deck aluminum all the way.... Much more NA compression can be accomplished on pump gas, making for a far more volumetrically efficient engine

[@marcelocuadrado6955]

finally a channel where aw speaks with knowledge and logic of the issues. very good!

[@zmankiller11]

Nice video, thanks as always. Like the green screen too

[@michaellorenson2997]

Excellent, thanks! Liked and subscribed.

[@kenny1394]

This channel is so great

[@benjaminavdic5631]

28k away from 100K keep it up

[@alsharifhusain]

Very informative !!

[@dokvist]

Love the green screen and the graphics. Nice addition to the great content.

[@andrewmarquez815]

Very informative thank you from the 🇵🇭

[@siyandazikhali5677]

Thanks teacher keep them coming

[@sammydubourg8421]

I'm glad you acknowledged you don't pronounce L's great job!!!

[@bobjoejoe204]

Great video once agin man.

[@danronck3636]

Great Video, thanks a lot man🙏🙏🙏

[@kensmechanicalaffair]

Doing gods work my man.

[@mc1996]

Nice to see the new green board to be used :D Really, keep this type of content and you soon will be one of the best, greattest channel.

[@marchutchings8834]

good work buddy

[@sharpemang]

Another awesome video! I don't know how I found your channel, but I'm glad I did! For ideas for future videos, would you be able to do the turbocharged Mazda BP-4W engine that was found in the Mazdaspeed Miata and Protege?

[@d4a]

Those are cool engines no doubt, but very niche, so I'll likely do them only once I have built up iconic engines and run out of mainstream choices :)

[@bennyz1971]

great video, more of that 👍👍

[@morreracingteam6004]

I got EJ20G closed deck what subaru havent done after 90s anymore even back then it was pretty rare.

[@madsciencebuilds]

This video was extremely informative,thanks. Waiting for my duratec/ecoboost/Mazda MZR video😉

[@walangchahangyelingden8252]

Thank you very much man.

[@motomarmot6544]

Great content

[@MrTurbo_]

The 1.6 EcoBoost engine is open deck but there are multiple people running 450bhp on a completely unopened block, though over time the cooling channel between the cilinders often fails, so I'd still rather get some sleeves installed when pushing for 450bhp

[@driftisland]

I like such style. Keep doing )

[@AlexandruSava92]

The best video’s on KZbin 👍

[@mrnicktoyou]

I guess you don’t need a block that can handle 2000hp when you’re only ever going to make 500hp.

[@H33t3Speaks]

oooof that's a burn

[@calebnation7797]

My car has a closed deck iron block and forged internals... too bad the rest of the drivetrain can only handle 250lb/ft before dropping its guts.

[@exvils]

there is opel/gm 2.0 4cyl closed block that hold 2000+hp, dunno engine code (c20let?) but it was featured in 1320video while they were in brazil

[@soundseeker63]

​@@calebnation7797 Exactly. People seem to forget that when discussing which engines are best for tuning. The weakest link in most modern cars isn't the engine block at all! lol

[@calebnation7797]

soundseeker63 there’s a guy in a group I’m in running ~1200whp on a stock block (60psi of boost) which is just stoopid power for a 1.8 motor, but he had to drop so much money elsewhere in the drivetrain that’s it’s insane.

[@stevesolo16]

Piston design and materials have allowed for a larger margin of error, too. Thicker ringlands, better forgings, and higher quality materials make surviving an ignition, boost or less than "as advertised" octane fuel problem, better in recent years. However, it is usually the human factor that destroys an engine. The desire for better track times or beating a competitor leads to higher boost levels until you find the limitations of your engine. It is called, "The Human Condition." As competitors, we like to "ride the edge." That is what makes life interesting!

[@Alvon_PR]

Some extreme modified bike, piston 58mm to 72mm, we use method bypass, because it's impossible to use factory water jacket deck Sorry for bad english

[@kamilzmich5961]

There is a variation of the honda b series, the B20. with larger bores than the b16/18, the sleeve design was changed to a siamese style (all 4 cylinder sleeves joined together). Now, the larger bore made the cylinders slightly smaller, and weaker, and have been known to crack. The interesting thing with these however is that they can take a little bit of knock in the higher RPM, but knock in lower RPMs will almost always result in a cracked block, even NA! Yet if you can tune it right, they can hold 3 times the stock power. Theres more to a block than just the sheer size and shape of the metal, there must be some kind of resonance going on that isn't initially obvious.

[@ERUtube]

I enjoy your videos!. I would like an OM606 video.

[@gaspererjavec7108]

Im in the proces of building a b20 vtec that i want to rev to 9k, so because of the long stroke and heavy piston block reinforcing is a must, im posting it, you drill holes from the outside and thread aluminum rod in to it to secure the cilinders in place.

[@carlweeks9256]

I have never seen an open deck cast iron, however the Chrysler 2.2/2.5 are "Semi" open on one side (front of car when transverse mounted), and closed all 3 other sides. And the Chrysler Neon 2.0 are Semi open, but in a different way. For Aluminum blocks, I have noticed the GM North Star V8s are actually open deck (were introduced in the 1990s!). Chrysler 2.7, and 3.2/3.5/4.0, are closed deck aluminum blocks, which is what I prefer!

[@mpetersen6]

Ah, 2.7 Sludge-o-Matic. The sludge problem is actually caused by the small draon holes the head gasket

[@rolandomanzaneda538]

Love your channel men...

[@H33t3Speaks]

Volkswagons AE113 is a pretty remarkable motor too, my friend.

[@DeYmOKits2871]

I have a closed deck and after see this video I motived to boost mi car, thank you very much!! C:

[@squirtjosie7]

I believe that some Gardner diesel engines had no cooling passages between the head and block. There was separate external plumbing to carry coolant to and from the block and the head. There were passages to allow oil to drain from the rocker area back to the sump. I believe that this design originated from these engines being originally designed for marine use. They had a reputation for extreme reliability but this probably results from over-engineering and relatively low specific power output. But they had REALLY closed engine block decks.

[@salmanalmahal5373]

Thank you very much bro

[@Gchang54]

Please do a series on the ls/lt

[@densamme1752]

There is actually a significant problem with closed engine decks (especially old ones) when applying boost. That is the cooling capability of the block, a partially or fully closed cooling channel can ruin a block FAST since it don't have much excess cooling capacity in any given area of the engine (the early SAAB turbo engines was notorious for this problem) an oil-cooler and modern oils help but if your engine is hot when you turn it of you risk hotspots on the cylinder walls.

[@gracielkelly9645]

Could you do a video on ECUs and standalone engine management units.

[@Whateva67]

Look at boostedboiz, they’re running 1000 hp in an H22 which is an open block design,their problems were in using a stock accord 5 speed with no lsd which would only take around 720 wheel hp before stripping 3rd gear,the engine holds up fine without being built up much,only adding a big ass turbo and a tune will reap big power.

[@tomaszicha9191]

green screen is cool addition to your chanel. wish you luck and many sponsors.

[@bluegizmo1983]

The major issue with open deck blocks isn't cracking or breaking the cylinder walls, it's that they eat head gaskets like crazy because the top deck surface of the cylinder walls move around and wear/tear through the head gaskets!

[@Lightsheder]

0:31 WTH :))))) was not expecting that!

[@tebohomofokeng6767]

Thank you.

[@bradywebb1311]

Closed deck has more surface area for head gasket sealing. That's the real main advantage. Greater distance between the cylinder and any passages=better sealing. And, anybody that builds boosted engines knows, keeping the head sealed is one of the hardest parts.

[@ronabbott2053]

have learned a lot from your videos, thanks for making me bit more knowledgeable

[@codymoncrief8478]

I like to consider myself as a semi-open optimist as well ...

[@JohnPulliam82]

The knowledge is great but the voice is what does it for me 😆😆😆 At night I put the videos on and fall asleep to the Boost School Series 😆😆😆 #DRIVING4ANSWERSASMRSLEEP

[@quietknight8250]

Very informative, thanks for the clip. There is a 'but' however and it's about open deck advantage, you've very clearly and concisely explained the advantage of closed vs. open and what mitigates the disadvantage of the open design but a design that's 'not as bad as you might have thought' is hardly a recommendation and hardly a justification for a manufacturer to adopt that design, so, that raises the question 'what is the advantage of the open deck?'. Clearly it's about additional cooling but an aluminium block dissipates heat better than iron anyway which lends weight to the argument for a closed or semi closed design, manufacturers (most of the time) know what they're doing, so, again, what exactly, or perhaps, how great is the benefit of the open deck?

[@d4a]

As I mentioned in the video, the cost of production is a massive incentive for manufacturers to use the open deck design, and today they can more than ever because of all the reasons I mentioned in the video. Yes, ultimately a closed deck design is superior in terms of durability, but open decks are here, and will keep being ever more common probably, it's what we have and they're definitely not as bad as many think.

[@rogerking7258]

Another advantage of open deck design is that you can use the head gasket cheaply to "tune" coolant flow around the engine. For example, you might put larger coolant holes in the gasket towards the back of the block to encourage more coolant flow in this area which is normally hotter than the front of the block; or you might do the same to encourage greater coolant flow around the exhaust side of the cylinder head. Same advantage pretty much applies to a semi-open deck. Obviously if you're a manufacturer producing stock engines you'll get this right on a closed deck engine by machining correctly positioned coolant holes from the beginning, but if you then modify the engine for bigger power your requirements will change and it's a lot easier to modify a head gasket than a block.

[@Travis_Montgomery]

My S60r engine is currently transitioning from an Open deck design to a Semi-Open design thanks to some LA Sleeves. Because I cracked it.

[@MarcelloTheBandit]

I have one caveat to this. The Volvo Modular 5 cylinder R blocks were prone to cylinder cracking or warping if you turned the boost up higher than 19psi UNLESS you had reinforcement right at the tops of the cylinders. After that, you could do over 25-28psi and see around 550bhp.

[@AaronAnonymous]

Can you do a vid on the 1UR-FSE? not many, if any, videos explaining that engine.

[@JohnHobitakis]

Do a video on the b58 engine!!

[@jamesmerkel9442]

11:05 am cat back after being gone day & 1/2, but we were rained in for few days straight & real rained almost every day or gray whole yr on NOW 2/17/21'. He was whining few mins b4 we got to him say 10min window.