Alpiners,
I have a modified adjustable pressure relief valve on my 1725.
I adjusted it to dump at 80PSI.
If gives me 75 PSI when the motor is hot.
The motor only develops about 30PSI at a hot idle, and the pressure can
drop as low as 20PSI after some very spirited driving. The pressure
does come up to 70+ PSI at around 2000 RPM however.
The volume of oil pumped is porportional to the RPM of the motor, and
thus the pressure developed is dependant upon the RPM. This is only
true until the relief valve dumps off the additional oil, and the
pressure is regulated. Additional RPMs will have only a small effect on
the oil pressure.
An importtant thing to know here is that even with the relief valve is
set to a very high pressure, the volume of the oil pump and the engine
clearances will determine the actual oil pressure, in cases where the
pumps capacity is less than that to overcome the oil losses.
If you are running an early "3 main" engine, it is possible to use a
later "5 main" pump.
The 5 main pump has a larger rotor, and thus has a higher capacity.
This will require some modification, but nothing too major.
As John says, the relief valve can be modified to give more pressure,
but if the motor is really tired, this will only delay the inevitable.
I would say that if your hot idle pressure is below 15PSI, find out why,
otherwise have fun.
Jarrid Gross
----------
From: frodo4(at)ix.netcom.com
To: Chris.S.Mottram/AMPAC/ECCI(at)ecc.com
Cc: alpines(at)autox.team.net
Subject: Re: Alpine Oil Pressure
Date: Monday, March 17, 1997 12:12PM
You wrote:
>
>
> What is the "normal" oil pressure for a series 5. The guy I have
> working on my car thinks that it is low compared to an MGB. Now I
am
> concerned. Also what is the normal operating temperature. I am at
about
> 100c, which seems a bit warm for 70 degree days in Atlanta (sorry to
you
> guys up north).
>
> Thanks,
> Chris Mottram
>
>
100c is a bit hot. Check the thermostat - there are available 160 and
180f versions.
Normal pressure - hot and at about 3000rpm. Must be at least 40psi, but
happier at 55 psi (ish). The pressure relief valve can be dismantled
and the spring shimmed to get that little extra if the rest of the
engine is tight enough.
What are you getting now. What are you getting at idle, hot.
John
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