I hate having to end this merciless piss take HAHAHA. Fair play Shrek for staying cool!
Open deck is done because it is cheaper to produce, the mould can be withdrawn intact and used again but it produces inherantly weaker blocks. The cylinder has less support at the most critical point, a small increase in cooling ability near the hottest part of the engine gets it an honourable mention with regard to advantages other than cheapness.
Closed deck is better for performance as it helps resist deflection caused by combustion pressure at T.D.C. It also creates a more stable and consistent face for the head gasket to seat on. Downside is the mould has to be sand or equivalent and is lost in the manufactuing process, longer set up time and the casting has to be carefully cleaned.
Some mass market high performance engines use open deck blocks, there are ways to get around the disadvantages and you should definatly not take this as an indictment of open deck designs, but if performance is the objective and money is no object bracing the cylinder walls against the structure of the block is the best solution.
the reason i brought this up is that Dodge's new cup engine is open deck and hotrod.com and the magazine says that this also helps the block to not distort when tightening the bolts and another thing is the gasket shaped like the block or the head?
Well now, Nascar rules escape me the moment but I would imagine that they use road car based blocks. And by this I mean a block which would pass as a road car block under scrutiny but may be sort of 'blueprinted' at the casting stage, i.e. maximum metal condition.
If Dodge are updating their engine block chances are it will have had a full re-design, the bore spacing may have changed and the wall thickness of the cylinders may have increased. Switching to an open deck block alone would not improve the deformation you get from head bolt crush.
come on Shrek, you are clever lad, you understand how the engine bolts together eh? The Head gasket has to be shaped like the block AND the head dosen't it? After all one is just a mirror image of the other!
I suppose you could say that because a typical head gasket only has holes where the cylinder head water galleries are that it looks more like the head, but (if the block it sits on is open deck) BUT...
There are many ways to seal a head, a gasket is just a nice neat way to do it, some tuned engines will use individual solid rings on each cylinder and a seperate gasket which mainly does the water jacket sealing. In the case of an open deck block it is possible that the water jacket need only be sealed around the outside edge, so in this case I guess you could say that the gasket was more like the block, but you won't find very many done that way.
Well, a closed deck gives you a more rigid block. It's harder to manufacture for reasons evident. It's also evident you'll have a better gasket support and a larger area to "resist" the push of the air inside the cylinders. I have no idea that it made the block easier to distort. Why? Intuitively it seems the contrary would happen.
Anyway, many people could not know what a closed deck is, so there you go.
Closed deck: the water holes are half closed.
Semi-open deck: they're not as closed, (duh) but there are some ribs in place.
Fully open deck: there is a clean space between the cylinder and the block external surface.
I was not able to find pictures of an F1 block, recent or old. I have plans for a Cosworth but I was not able to distinguish the kind of deck. Perhaps some member would be so kind? Thanks, you guys.
You know, I can see where the open deck could be better for cooling, and have a re-usable cast, but I cannot see what else it would be better at... Except for maybe some weight savings?
About the head gasket...
After changing a few in my youth on various cars that I had owned, I always wondered why there even WAS a gasket there to blow in the first place... I always thought that machining a 1mm trapezoidal rib onto the head, and a matching trapezoidal groove on the block at 1.25mm would give great sealing that COULDN't blow out... An with the added .25mm (or so), you could even add some Loctite to it.
I'm sure that it would need to be added at the design stage, and not able to be added to an existing casting, but when you are changing your 4th head gasket on as many cars within a 2 year stretch, you will come up with ANY reason that it is the designers fault for your troubles...
After changing a few in my youth on various cars that I had owned, I always wondered why there even WAS a gasket there to blow in the first place... I always thought that machining a 1mm trapezoidal rib onto the head, and a matching trapezoidal groove on the block at 1.25mm would give great sealing that COULDN't blow out... An with the added .25mm (or so), you could even add some Loctite to it.
I'm sure that it would need to be added at the design stage, and not able to be added to an existing casting, but when you are changing your 4th head gasket on as many cars within a 2 year stretch, you will come up with ANY reason that it is the designers fault for your troubles...
Nope. You cant. Even with block and head from the same material, they expand differently due to temp. Also an engine block is not that rigid, it torsions and the gasket is the one in charge to absorb diferences. Without that differences, combustion gases, water an oil could mix up.
And I guess changing 4 gaskets in 4 different cars in 2 years time is not a design problem, but bad luck
"You need great passion, because everything you do with great pleasure, you do well." -Juan Manuel Fangio
"I have no idols. I admire work, dedication and competence." -Ayrton Senna
About the "grooved" head & Loctite concept by Conceptual, some Ford racing engines I know, like Zetec, Cosworth and Duratec can use bimetallic or solid copper gaskets. In that last case you have to fit a ring on a groove on the head (you have to machine it, altough some models have "weird" rings that serve the purpose). This ring "bites" into the copper guaranteeing the seal.
Gaskets are also there to separate oil recycling into the cylinder head from water running around the block, so I'm not sure how good your machining would have to be (oil-proof, so to speak) to have a gasket-less head, specially when it heats, expands, cools and contracts. Besides, you know, the things inside are moving at 10.000 g's or so, so, hard to do, I'd say. And, "extra-besides", why? It's not like you're saving money, let me tell you.
EDIT: Thanks, Belatti, our posts crossed. Is that a closed deck and are those copper gaskets in your pictures or am I already blind? I'd say "blind", but... what's the story?
I only can see copper coloured (but not copper definitively) valve seats.
I can see no gasket, and but a groove in the outer part of the block, where the deck its open. That engine is cutted for an expo so maybe the gasket was removed.
About the metalic gasket you mention, of course there are different materials for gaskets, the thing is you need something that compresses and moulds between block and head. Or I think so.
Here, another Asiatech (ex Peugeot) pic, probably from 2001/2002:
"You need great passion, because everything you do with great pleasure, you do well." -Juan Manuel Fangio
"I have no idols. I admire work, dedication and competence." -Ayrton Senna
