Closed Deck Versus Open Deck
Posted: Sun Nov 19, 2000 3:19 pm
An open deck engine is cheaper to manufacture, as the water jackets
around the cylinders are made by inserting a die that can be slid
straight out the top when the casting has cooled. When the head is off
of an open deck engine, you can see right down into the water jackets
all around the cylinders. This means that the cylinders are standing up
like cans, with little to support them. For highly modified Hondas,
they sell aftermarket blanking plates that fill all the open spaces at
the top of the cylinders serve to brace them from swaying and expanding.
A closed-deck Subary engine is made using the "lost styrofoam" (similar
to lost wax method) technique. When the head is off, you can see that
all the space between the cylinders is sealed off by a solid deck with
holes for the coolant passages, but otherwise solid. This method does
not allow for a casting die that can be retracted from the finished
casting and it requires a bunch of costly machining to achieve a
suitable mating surface for the heads.
The Subaru engines that were designed to be turbocharged have a number
of "bulletproofing features", such as an under piston oil spray system,
extra bracing of the crankshaft bearing areas, etc.etc. My son has a 98
Impreza RS with a Minnam Stage II kit and 5psi boost. He has already
lost a cylinder liner, because his 2.5 open deck engine was not built to
take the strain. That is one reason why I'm not interested in selling
one of my EJ20G engines, he will probably need one soon.
Bill Robinson
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around the cylinders are made by inserting a die that can be slid
straight out the top when the casting has cooled. When the head is off
of an open deck engine, you can see right down into the water jackets
all around the cylinders. This means that the cylinders are standing up
like cans, with little to support them. For highly modified Hondas,
they sell aftermarket blanking plates that fill all the open spaces at
the top of the cylinders serve to brace them from swaying and expanding.
A closed-deck Subary engine is made using the "lost styrofoam" (similar
to lost wax method) technique. When the head is off, you can see that
all the space between the cylinders is sealed off by a solid deck with
holes for the coolant passages, but otherwise solid. This method does
not allow for a casting die that can be retracted from the finished
casting and it requires a bunch of costly machining to achieve a
suitable mating surface for the heads.
The Subaru engines that were designed to be turbocharged have a number
of "bulletproofing features", such as an under piston oil spray system,
extra bracing of the crankshaft bearing areas, etc.etc. My son has a 98
Impreza RS with a Minnam Stage II kit and 5psi boost. He has already
lost a cylinder liner, because his 2.5 open deck engine was not built to
take the strain. That is one reason why I'm not interested in selling
one of my EJ20G engines, he will probably need one soon.
Bill Robinson
-------------------------- eGroups Sponsor -------------------------~-~>
eGroups eLerts
It's Easy. It's Fun. Best of All, it's Free!
http://click.egroups.com/1/9698/1/_/_/_/974665151/
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