h a l f b a k e r yWhy not imagine it in a way that works?
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gasketless heads
Remove the gasket entirely, eliminate it's potential for failure. | |
Modern precision machining techniques should be able to create surfaces that mate with enough precision to seal liquid and pressure without the use of a gasket. It might require that the sealing surfaces, IE: head and block, be made of the same material to counter-act differential expansion.
Even
then I bet something could be worked out that would provide sealing while allowing for differential expansion. A network of concentric grooves and matching ridges for example.
This could nearly eliminate high-mileage gasket failure and reduce dramatically the incidence of overheating failure as well.
Fitting O-rings to a Pontiac
http://www.popularh...re/0307pon_ringing/
[david_scothern, May 02 2005]
[link]
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Some amazing things can be done with surface finish, but I'm betting against this one. It would probably be simpler to make the block and head one piece, but while we're waiting for the internal combustion wizards to chime in, have an oil-and-water soaked fishbone :-) |
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If they would only design cars with the engine in the passenger seat. Then we we could keep the heads cool with a handheld water spray bottle. |
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Unfortunately blocks fail too, usually they don't get the chance because the gasket goes first. I'd rather a blown gasket than a blown block. |
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Chances are wag, that there is a hairline crack between some adjacent valves in the head brought on by the over-heating. Only an ulta-violet light and powder can show it up, at a head gringing shop. The search for a used head in perfect condition, grail-like, begins. |
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In order to keep the block and head in perfect alignment, they'd not only have to be made of the same material, but they'd need to maintain uniform temperatures. If parts of the head are hotter than others, there will be warping. Since the inside will be hotter than the outside, this will be the case. |
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A gasket is much cheaper than the extreme precision machining that would be needed for a good seal, and, as stated by [wagster], a blown gasket is better than a blown block when things get ugly. |
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This is commonly done on performance engines. As long as the head is flat (ie not warped) it can be milled to a suitable finish. A ring-shaped groove is machined around the top of the cylinder bore (and correspondingly in the underside of the head) and a ring is placed in the gap created. Bolting the head down then applies most of the load through these rings, compressing them to produce a good seal. The seal across the rest of the head face is then less critical. |
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My, what a process, the copper gasket with syringe sealer applicator and it all has to be taken apart to check if the wire o-rings didn't buckle or mess up, then reassembled. |
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However, once it's fitted, you don't need to worry about your head gasket blowing (assuming you've done your sums right and are not trying to extract a million horsepower from a 1l engine). I've taken a head off, and it's not a job I'd want to do regularly. |
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I once ran a triumph spitfire engine for a while with no head gasket, i just used red goo. It worked fine, but the Spit engine is all iron. Head gaskets usually fail on alluminium heads more oftern. |
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Gasket failure can be caused by the use of bad quality parts or over tightned bolts or head overskimming or skimming with blunt cutting tools. |
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Worn out wax themostats can also cause problems. |
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To minimise risk of gasket failure don't demand full power from an engine until the car has reached operating temperature. |
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The electric thermostat idea I posted I feel would reduce head gasket consumption on troublesome engines. |
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// make the block and head one piece // |
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This is very easy on a two-stroke ..... |
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If I remember correctly in the time of Ernesto, the engines of Bugatti's were constructed with such precision that no gaskets were used in their assembly. None. No o-rings either. By today's standards their output was quite modest and they were very heavily built. |
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