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Message
I've come to the point where I need to set up the expansion /
overflow system. My engine guy is saying I can just have an overflow reservoir
since the pressure cap is at the top of the engine. I've read that some 13B
flyers (if not all) have expansion chambers which, in turn, have their own
overflow reservoirs.
Hi
John,
The later RX-7's (not
sure when they started it) used an Air Separator Tank (AST), and an overflow
jug. The AST only has to be a small tank, maybe a pint, and must have a
pressure cap on it. Mazda actually used a plastic tank on the FD, though
most folks end up replacing it with an aluminum one. The cars also have a
fill port at the high point in the system, which is a plain cap (no relief
valve).
I copied this system,
with the exception of not having room for a fill cap, which means I have to
remove the top hose to fill the engine. That will be corrected in rev-2
btw. If you have room for a large 1.5 qt or so pressurized tank, such
that the top half or so of the tank is above the high point
of the engine, I would bet that it would make a dandy AST,
and overflow tank.
On the other hand, lots
of FD guys just remove the AST, and move the pressure cap to the fill port,
effectively doing just what your engine guy suggested. This is always
a hot debate, and it probably isn't ideal, but it seems to work just fine
as long as you burp the system properly to get the air out. I may do
this myself on rev-2, just to eliminate some
clutter.
Cheers,
Rusty (actively job
hunting)
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