In a message dated 5/12/2006 12:15:39 A.M. Eastern Daylight Time,
keltro@att.net writes:
Lynn,
This is a little late but after rereading your answer to Bob
Mears I wondered how
you would eliminate the front relief valve opening and case to iron "O"
ring ??
Kelly Troyer
This an answer to that question I did from the "Nopistons"
list. Very big list. Often very informative.
Well I just had my secondary relief valve
partially fail. this utterly destroyed my engine in just 50 miles from the
rebuild. My shop blames the plastic coating guys, since the front cover on
my FD may have been warped.
anyway, the plunger was badly scored,
scratched and mangled and I saw it being pulled out.
This cost me
all bearings, oil pump, side seals, e shaft and rear iron.....
So I had in mind of eliminating the
valve from that position, and have a relief valve set up under the oil filter
housing. this gives me access to regulate the oil pressure, and also keep my
original front face, but avoid the use of that valve.
I know I saw
some one here produced a CNC product but I just cant find it.
Do you think its a good idea, and do you think that it would be a
reliability mod?will it effect the safety of my engine having the relieved oil
back into the sump using the under oil filter housing passage? or can I use
the rear turbo oil return drain (rear iron)? I am going single
turbo.... so that drain for the rear turbo will just be blocked...
Thanks
for reading and your time...
George
Was the plunger assembly installed while some plastic
coating was being done? I don't understand the plastic comment.
Anyway
the "O" ring junction where oil leaves the front iron and enters the front cover
has killed thousands of rotaries. The Japs won't admit that but then they won't
admit the rape of Nanking either.
The front relief valve opens to prevent
oil cooler damage and keep the "O" ring from popping out on cold startup. But
the front cover is so flexible that if you try it a few times, you can pop out
the "O" ring anyway.
Street racers jamb up the front relief pressure
spring with washers, when they want more oil pressure from the installation
of a higher value rear relief valve (100 to 115 PSI). So that makes it more
likely that the "O" ring will pop out.
What to do? If you have to use
the stock pump, and the engine is apart, I would put a thick steel disc in the
"O" ring hole so as to block all oil from leaving the engine. Then drill out the
end of the lateral Gallery that runs past the faulty opening in the front iron.
Install a dash 10 by "O" ring boss fitting in the end of that gallery. Now there
is no "O" ring to blow out. If you are shaky on the "O" ring boss deal take the
fitting and front iron to a machine shop and have them bore the hole out and
plane the surface flat with a 45 at the mouth of the hole for the "O" ring to
seal against. This the same sealing method used in hydraulics and on dry sump
pumps.
Or, you might make a steel or soft copper "O" ring that is
thicker than the stock "O" ring and just use that. If it is steel it cannot pop
out can it? (the "O" ring deforms badly) It is then a situation where part of
the ring is clamped between the aluminum and the boss in the iron and cannot
return to its stock location. This makes for a big hole in the pressure side and
oil pressure goes way down. The only cure is to remove the front cover and
replace the "O" ring. A giant pain in the a__.
As a joke on the round
eyes they added a plastic washer around the outside of the "O" ring to add pre
load to the boss area. None of this would be needed if they had added a stud
nearby the boss location to account for the flexible front cover lifting off
under high oil pressure.
Do not use a tapered pipe fitting. The boss in
the iron is too small and will crack out when you tighten the fitting.
The valving in the oil cooler is a temperature operated diverter valve
that allows cold oil to run through the cooler rather than through the cooling
channels for rapid warm-up. It also prevents a big pressure drop in the cooler.
Actual (maximum) oil pressure is controlled by the relief valve at the bottom of
the rear iron.
For operation below 8,000 RPM the stock relief valve is
fine (around 80 PSI) for racing at 8,000 plus RPM then an early relief valve
shimmed up to 95 to 100 PSI is enough. For all out road or rally where operation
above 9,000 RPM for extended periods is planned, 110 from a stock turbo relief
or 115 from a Racing Beat relief should be used. I use a dry sump system with
the maximum oil pressure set at 100 PSI and no bearing problems.
There
you go, problem solved.
Lynn E. Hanover
In road racing, we use an external pump. Either a complete dry sump system,
so there is no oil pan at all, just a flat plate, or a wet sump with an external
oil pump. I have both styles.
In both cases, the galleries used for the stock pump are not used.
Pressurized cooled and filtered oil enters the engine through the inner most
hole on the filter stand in the rear iron. The outer most hole goes to the stock
relief valve at the bottom of the iron, and is not used.
A dash 10 line from an adaptor block on the filter stand is run to the
front main bearing through the second lateral drilling to provide two paths to
the front main. The stock path is through the upper dowel gallery, and the
inside of those dowels is tapped with threads, so removal is easy. Not a good
flow situation.
If you disable the "O" ring failure mode, you can run a stock gasket in the
front cover/ front iron junction, and avoid any oil leaks there. Leaving out the
.025" gasket is one of the gags used to help get more pre-load on the "O" ring
junction.
Lynn E. Hanover