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Oil pressure relief valve, was oil pressure gauge
Posted: Wed May 22, 2002 8:50 am
by Bullwinkle
Barney, Bill, Chip, Lawrie, Skip, and all other racers and mechanic
freaks:
<<>>
my MGA lost oil pressure completely at about 7000 rpm because
the oil pump was cavitating.
<<>>
Okay, that comment has me thinking, terrible thought that is.
Where does the excess oil from the relief valve go to? Into the sump or
back into the pump? On the B series engine where does it go? On the
XPAG engine where does it go?
Was the effect of raising the oil pressure on racing engines actually to
decrease the flow rate at high RPM's and therefore reduce the oil
cavitation problem in the pump? This question of course depends on
where the excess oil from the pressure relief valve goes.
Blake
Re: Oil pressure relief valve, was oil pressure gauge
Posted: Wed May 22, 2002 9:19 am
by Skip Kelsey
Blake:
Are you sure that it was cavitation? Do you have a crossdrilled crank?Did
you modify the pump for more volume,per the book?
If you do not, then that could be your problem. At 7000 RPM and above you
will lose the engine for sure without crossdrilling the crank.
Skip ...................................................................At
10:50 AM 5/22/02 -0600, Bullwinkle wrote:
>Okay, that comment has me thinking, terrible thought that is.
Re: Oil pressure relief valve, was oil pressure gauge
Posted: Wed May 22, 2002 8:22 pm
by AJChalmers@aol.com
If I recall from inboard/outboard motor cavitation, the prop creates a
"cavity" in the water, therefore losing its bite in same. I guess oil pumps
can do it in oil.
Re: Oil pressure relief valve, was oil pressure gauge
Posted: Wed May 22, 2002 9:11 pm
by Jennifer and Hugh Pite
Cavitation is a result of a low pressure in the fluid caused by the moving
metal parts (propellor). If the pressure is below the vapour pressure of
the fluid the fluid vapourizes and forms a gas or, in other words, the fluid
boils without the addition of any heat. The small bubbles formed by
cavitation quickly collapse when they leave the local region of low pressure
and can cause vibrational damage to the propellor, pump, valve or
what-have-you.
Hugh Pite '48 TC 33' J-2
> If I recall from inboard/outboard motor cavitation, the prop creates a
> "cavity" in the water, therefore losing its bite in same. I guess oil
pumps