Open Deck 5

[enginesrus]

I can understand using them on a low budget project, but I can not understand them being used in production automotive engines, especially over 60 HP.

 

[Lou Scannon]

I can understand using them on a low budget project, but I can not understand them being used in production automotive engines, especially over 60 HP.

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"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[CWB1]

Not sure what is supposed to be special about 60 hp, but if a design functions well and is cheap then it meets two critical criteria for most product designs.

 

[BrianPetersen]

An open-deck block is sure a whole lot easier to cast.

For most production automotive engines, "low budget" is really high up on the design priority list.

 

[Tmoose]

Subaru may not have had the best success keeping headgaskets in several of their open deck engines, but some other manufacturers have given it a pretty successful go .


Mercedes 5.5 L V12

http://i.ebayimg.com/images/g/mAQAAOSwEjFXfnmO/s-l1600.jpg

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Does this qualify ?

http://speedhunters-wp-production.s3.amazonaws.com/wp-content/uploads/2011/01/DSC3024_copy.jpg

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The closed deck N55 is reportedly "better" but the N54 BMW does OK for itself.

http://f80.bimmerpost.com/forums/at...1c36a&attachmentid=1245562&stc=1&d=1437060892

http://www.carbuzz.com/news/2016/5/2/Engines-Exposed-The-N54-Was-BMW-s-Iconic-Tuner-Engine-7733074/

 

[enginesrus]

60HP I was thinking of a 55 HP Geo metro 3 cylinder engine. And how less HP is going to exert much less major thrust pressure on a cylinder wall, and cause less cylinder movement or in my terms cylinder flapping. That movement will tend to cause highs and lows in fire ring contact area. I see the design as for lack of better terms, BAD. And more like having a canary in the design and budget office, screaming "cheap, cheap, cheap". Its just not the case when engineering for cheap comes back and bites you. Cheap and saving money now doesn't always work in the manufacturing world, just think recalls.

 

[Mr168]

There's also an argument to be made for increased cooling capacity of an open deck engine.

Seems to be reliable enough thus far. Heck, even Ford is using an open deck block in the V6 EcoBoost engines that's becoming the heart of a significant portion of their product line.

 

[SwinnyGG]

The benefits of an open deck block are not only related to manufacturing cost.

1) Open deck blocks typically result in better control of the temperature of the cylinder wall in the combustion chamber. This is important.

2) Open deck blocks are easier to manufacture- sure this means lower cost, but it also means more consistent parts. More consistent parts make more reliable engines.

3)Open deck blocks (because of the cooling factor) result in less variation in bore shape over the stroke length. This leads to better ring sealing, which leads to better durability in the long term and (marginally) cleaner-running engines.

 

[enginesrus]

It is also to blame for head gasket failures. As long as the design is used for normal easy driving then maybe there are those listed advantages.

 

[SwinnyGG]

There are literally millions of open deck engines operating as we type, and not all of them are being babied around parking lots.

A lot of high specific power engines- motorcycles, small displacement engines from companies like Honda, etc use open deck blocks.

 

[TugboatEng]

What about an open deck block causes head gasket failures?

 

[SwinnyGG]

What about an open deck block causes head gasket failures?

Nothing that can't also happen on a closed deck block if they aren't correctly engineered/manufactured/assembled.

 

[TugboatEng]

I hear about the top of the cylinder oscillating but I find that hard to believe considering many engines have replaceable cylinder liners that are a clearance fit in the block meaning they can actually move around and they still don't cause head gasket failures.

 

[SwinnyGG]

Open deck liners are typically replaceable, but have to be pressed out. They are held in place by slight interference fits, thin-film adhesives (like retaining compound), mechanical trapping between the block vault and cylinder head, or some combination of all three.

Depending on design details, with some open-deck blocks it is possible to achieve higher bore/gasket sealing pressures at the inner edge of the bore, which results in better head gasket robustness.

I don't know where the OP is getting his information, but it's not very good.

 

[TugboatEng]

I was referring to diesel engines with wet liners and one specific engine with clearance fit dry liners. All of them can move a bit yet head gasket problems are rare.

 

[BigClive]

The Jaguar V12 is a notable open deck engine.

 

[Tmoose]

A couple of Toyota engines have been notorious for head gasket issues. Sometimes coolant to outside world. Sometimes combustion to the coolant jacket.
A bud had an SR5 whose inline 4, like many others, developed an external leak at around 100k miles. Not awful longevity, compared to cars of the 60s and 70s, but some makes then and now can be counted on to keep their inline 5 cylinder (!!) heads sealed up for FAR longer.
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Th Toyota 3vZ-E iengine is iron, with a closed deck. V6, so it is kind of like a pair of threes.

https://www.yotatech.com/forums/att...92-3vze-motor-mount-frustrations-100_0478.jpg

Here is one of the factory modification for improved gasket durability.

https://www.yotatech.com/forums/att...01885158-3vz-e-headgasket-recall-eg94-003.jpg

apparently Even that relatively short cylinder head suffers ( enjoys?) enough thermal expansion that lubing the gasket reduces chafing and wear over time.

 

[enginesrus]

jkKRY, I get my info from my little logical brain. And others that are in the know seem to agree. Engineering is a logical endeavor to me.

https://www.youtube.com/watch?v=3xd48wGEdg0

https://www.youtube.com/watch?v=ZbhOfXQWcuk

 

[SwinnyGG]

Engineering is a logical endeavor- but logic and intuition are not the same thing. Many core principles of engineering are logical, but counter-intuitive.

People who modify engines (such as the people whose youtube channels you have linked) may be great at modifying engines- but that doesn't make them great engine designers. Again, not the same thing.

 

[SwinnyGG]

I was referring to diesel engines with wet liners and one specific engine with clearance fit dry liners. All of them can move a bit yet head gasket problems are rare.

I am familiar with at least one wet-liner diesel with clearance fit liners, but the liners are mechanically trapped in place when the heads are installed. Head bolt clamping forces pins the liner in place, between the vault and the block. When the engine is at operating temperature, the liners are no longer clearance fit; differential expansion wedges them in place.

If the liners are clearance fit and not trapped in any way, they absolutely will move- side force in any conventional internal combustion engine is significant- unless you're talking about a large marine diesel that is a crosshead design, with which I have no experience.

What specific engine are you talking about- not arguing with you, just curious if we have experience with the same series.