open deck vs closed deck

[safeaschuck]

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?

Wall thickness of the cylinder is easier to control and with coolant passages it is easier to kept a consistent, free flowing system, in some cases you miht end up with thicker cylinder wall for the same size engine block, which is good, but all it does is help to minimize the loss in structural strength. It's a 100% cost based decision for mass market use. If you were producing a bona fide race engine it would be closed deck as sho0wn in some of the pictures here


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...

Of course their have been engines with NO head gasket, sealing ring, or anything. You plunge a blind hole almost all the way through a block of metal (the engine block/cylinder) Put holes in the blind end for spark plug and valves, and everything is fitted from the open end. An absolubte nightmare to manufacture and build, but you will never need to change a head gasket. Just pray you never need to re-lap the valve seats

On Belatti's pics of the Cosworth you can see the closed deck, Between the two cylinders, at valve height you can see the material that makes up the cylinder wall joins at the top, just under the cylinder head. If this was an pen deck engine that gap would continue all the way up to the top of the casting meaning you could see into the cooling galleries when looking at the engine from the top with the head removed.

What I have not ever seen are the decks of a Top Fuel engine

I thought someone might mention this, hope you don't mind me telling everyone belatti? On top level drag engines they fill all the cooling galleries with liquid metal to give maximum strength. Water cooling can be completly eliminated for such a short run, absolubte strength is the only priority. Looking at the top of one of these engines, the only holes are for the pistons and the head bolts.

And I'll throw in the only thing more that I know (haha). On some open deck engines aftermarket tuning companies offer 'spectacle plates'. named as such because on a 2 cylinder engine (for example) they would resemble the frame of a pair of round spectacles (obviously without the arms - duh). These can be inserted in the cooling gallery from above to strengthen the cylinders near the top.
Because the casting will not necasarily have any location surfaces, some machining of the block may be neccasary. This can be quite an expensive process although very little material is removed.

[Belatti]

What I have not ever seen are the decks of a Top Fuel engine

I thought someone might mention this, hope you don't mind me telling everyone belatti? On top level drag engines they fill all the cooling galleries with liquid metal to give maximum strength. Water cooling can be completly eliminated for such a short run, absolubte strength is the only priority. Looking at the top of one of these engines, the only holes are for the pistons and the head bolts.

NP, I was joking about that... I meant "What I have not ever seen are the OPEN decks of a Top Fuel engine"

[Crazy Bored]

Here is a picture I took of a Top Fuel engine block, if anyone is interested.

[ISLAMATRON]

most of them use an upgraded version of a dodge 440 "hemi" block dont they? cant remember.

EDIT:The engine used to power a Top Fuel drag racing car has its roots in the second generation Chrysler Hemi 426 "Elephant Engine" made 1964-71. Although the Top Fuel engine is built exclusively of specialist parts, it retains the basic configuration with two valves per cylinder activated by pushrods from a centrally-placed camshaft. The engine has hemispherical combustion chambers, a 90 degree V angle; 4.8" bore pitch and a .54" cam lift. The configuration is identical to the overhead valve, single camshaft-in-block "Hemi" V-8 engine which became available for sale to the public in selected Chrysler Corporation (Dodge, DeSoto, and Chrysler) automotive products in 1952.

[Ciro Pabón]

Welcome, Crazy Bored. I can't see the picture, but thanks (if you need any help for re-posting it, just tell me). So, here is another picture.



The block is made of aluminium, Islam, so, no, it's not a common engine, as you already said. Here you have an interesting (I hope) video about how they dissasemble and assemble it in 10 minutes (that's what I call a full pitstop... ). You can see the bare block, at the 2:00 minutes mark.

Drag Racing: Inside the Heart of the U.S. Army Top Fuel Dragster

Man, I love those engines.

[riff_raff]

"What are the pro's and cons to each and which one does Formula 1 teams build?"

That's a hard question to answer. Technically it's really a combination of the two.

With regards to production engines, the open deck design is used when the block is cast using "permanent mold" type tooling. The open deck design allows the part of the mold tool that forms the cooling jacket to be removed cleanly after casting. Permanent mold casting tools are used for high production rates, allow use of high-strength hypereutectic aluminum alloys that cannot be sand cast, and allow block castings with thinner sections that can be lighter. The drawback is that the open deck block design is structurally weaker.

The closed deck design is used when the block is sand cast. The sand casting process allows the use of integral cooling jackets around the cylinder liner that cannot be produced with other casting techniques. Lower strength hypoeutectic aluminum alloys are the only aluminum suitable for sand casting. And the section thicknesses of a sand cast part must be thicker than a part produced from a permanent mold tool. However, the closed deck design with an integral liner is a stronger structure than the open deck design.

Many F1 engines use what is mostly a closed deck design, but they have separate liners. The open liner coolant jackets allow the block to be 100% machined from billet, maximizing strength and minimizing weight. Very similar to that Top Fuel block picture that Ciro posted. So I guess that technically does not make them truly a closed deck block design.

[Ciro Pabón]

Thanks for your concise and precise answer, riff_raff. Man, we've been missing you a lot these last days.

[Lux123]

It's possible to cast closed deck with a permanent mold (high and low pressure casting). A disposable sand core is used to form the water jacket. It's the method Honda was using for the diesel engine block.

[Ciro Pabón]

Welcome and thanks, Luxor. Can you use a sand core with high pressure casting?

[tok-tokkie]

I believe Harley Davidson used Rapid Prototyping to make the cooling core for the cylinder heads of a recent engine of theirs. Polystyrene or some similar material which vaporises when the liquid metal hits it. No sand cleaning problem (but what about vapour voids in the casting?).

An expensive and slow system but it would offer advantages of precision and repeatability for a competition engine block I would think.

[Lux123]

Yes its possible to use a sand core with high pressure casting. Honda gave it a bit of help with a baked ceramic surface coating for the core. The casting was also semi-solid method. Lower mold filling speeds, but still high pressures.

I believe some other high pressure casting equipment suppliers were experimenting with sand cores too, but I don't know if anything was ever commercialized.

The polystyrene method mentioned by tok-tokkie is fairly well established, although not widely used, and called "lost foam". I understand from an old colleague who did his Phd on the process, the problem is not so much the polystyrene vapour, but the glues used to stick the PS together (for commercial systems not from RP route)which can lead to casting defects. BMW makes or made cylinder heads for the straight 6 engined road cars this way.

High quality sand casting (like cosworth type process) is still the main production route for race blocks though I think.

[Edis]

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:

That engine uses separate steel rings approximatly 0.8 mm thick to seal the cylinders. Water and oil passages are sealed by separate rubber o-rings.

Since the seal is separate from other cylinders and the coolant circuit, and is of an 'open' type, a small leak from one of the cylinders would not cause too big issues.

"What are the pro's and cons to each and which one does Formula 1 teams build?"

That's a hard question to answer. Technically it's really a combination of the two.

With regards to production engines, the open deck design is used when the block is cast using "permanent mold" type tooling. The open deck design allows the part of the mold tool that forms the cooling jacket to be removed cleanly after casting. Permanent mold casting tools are used for high production rates, allow use of high-strength hypereutectic aluminum alloys that cannot be sand cast, and allow block castings with thinner sections that can be lighter. The drawback is that the open deck block design is structurally weaker.

The closed deck design is used when the block is sand cast. The sand casting process allows the use of integral cooling jackets around the cylinder liner that cannot be produced with other casting techniques. Lower strength hypoeutectic aluminum alloys are the only aluminum suitable for sand casting. And the section thicknesses of a sand cast part must be thicker than a part produced from a permanent mold tool. However, the closed deck design with an integral liner is a stronger structure than the open deck design.

Many F1 engines use what is mostly a closed deck design, but they have separate liners. The open liner coolant jackets allow the block to be 100% machined from billet, maximizing strength and minimizing weight. Very similar to that Top Fuel block picture that Ciro posted. So I guess that technically does not make them truly a closed deck block design.

Modern F1 engines have linerless blocks with a closed deck. Cast using a non permanent mold - usually investment casting or sand casting.