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Lynn,
The second part:
do you have oil pressure data at 3,000RPM?Reference
value PSI....50.8 @3000 RPM Series 1
RX-8, 72.5 @ 3000 RPM Series II RX-8..at 100c
I believe I have a series 1 engine. My book shows the 50.8 @ 3000 rpm , 212F. and I have verified this before. I
never see 72 psi at the stock oil filter pad. Early on I was seeing oil
pressure between 95-115 psi measured a few inches after the pump outlet
and before the oil cooler. I moved both my oil senders to the oil pad on the
engine. I will verify again today and talk with Bruce T or Racingbeat about
a solution.
Thanks,
Bobby
In a message dated 11/6/2009 9:02:47 P.M. Eastern Standard Time, bhughes@qnsi.net writes:
Thanks Lynn. What's
your opinion with the 56-60 psi range I see in flight? Seems low compared to
others.
Bobby
All of the pressure relief valves from Mazda open at 71.1 PSI. Through 92.
This valve is screwed into the rear iron at the bottom, and has a jamb nut on
it. The twin turbo engines 93-95 have that relief set at 110-115 PSI.
I have no data on the Renesis at all.
In any case the relief only determines the peak pressure. Or "cracking"
pressure for safety valve fans.
At lower RPM the totals of all of the oil leak rates can outrun pump volume
out, and the pressure will be some number below the cracking pressure. However
once the RPM comes up along with pump volume, then you should see the oil
pressure stop rising at that cracking pressure, and stay there even when more
RPM are added. So that valve has only to do with peak oil pressure and nothing
else.
If this is the case, say the pressure peaks at 70 pounds when at startup,
then fades to 55 at operating temperature, it is usually oil foaming that
is the cause. The effect of foaming is to leave the suction side of the
pump pulling in some air and oil mixture. The air compresses and uses up pump
volume, in effect making the pump smaller. So pressure goes down as pump volume
out goes down.
This a page from the RX-8 club. The second bit has data on relief pressures
for two models (ididn't know that).......... And after you read that, it looks
like your oil pressure is OK for a series one engine, but they had wear
problems, so in the series two engines they went nuts on oil pressure. Probably
gets them pump wear problems.
Renesis OIL PRESSURE Discussion with Dealer Tech
Just got back from a face to face talk with my
Mazda Dealers Service Head Tech, I sent him the pics of the Internal UK
RENESIS Engine Damage/Wear for comment
yesterday.
**********
Simply put there are two reasons why
the back bearing is wearing the way it is and that is "Oil Pressure" and
to a lesser extent oil viscosity.
The RENESIS 1 has the same Oil
Pressure... Oil Pump Rotors, Oil By Pass Valve and Eccentric Bearings as
Mazda's last NA Rotary, the 13B FC RX-7 .
Back when this model was around the recommendation
for engine oil was 15W40 (here).
Because of this higher Viscosity Oil,
Oil Pressure and Bearing Wear was not an issue like we see at the moment
in some S1 RX-8's.
When the RENESIS RX-8 came out the recommendation
(because of Fuel MPG and Emission targets) was a 5W20 or 30.
While
there is nothing wrong with these oils, what was occurring over oil
use/age was a lower engine oil pressure value
therefore not enough oil
getting to the Rear Stationary Gear Bearing for
lubrication....particularly at start ups.
**********
In the
Series II (09~) Oil Pressure was almost doubled, but the same oil grade
recommended??
I asked why the large increase in Oil Pressure
Values.
60% is there to supply the two new EMOP's Lubrication System
for the Apex Seals, with the other 40% for engine oil supply,
particularly all the Rotor and Stationary Gear Bearings and improved
oil flow through oil coolers.
He believes the 5W20-30 weight oils
for the S2's are fine because of the engines higher oil
pressure.
***********
So, my next question was what can
RENNY 1 owners do about the oil pressure, (unofficially official)
.....to use a higher viscosity grade of engine oil which will help
increase the engines oil pressure at the "critical" locations.
In
other words a higher oil viscosity will equate to Oil Pressure values like
the NA 13B RX-7 which has the same oil pump and related parts and values
as the S1 RX-8.
**********
I also asked him about the use of
Magnets on Oil filers and or sump drain plugs...his word was DO IT....it
is all good.
Then what to do about middle Apex Seal wear, and we
know the "unofficial" answer to that one, and it goes in your gas
tank...
**********
So, there you have it, I know it is
not all Groundbreaking or Revolutionary news, I thought it deserved it's
own thread.
What was interesting to hear is the lower oil pressure
because of the lighter (thinner) weight oils, which is what some members
discussed.
RG also mentioned the Bearing Wear was due to a lack of
engine oil getting there.
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The second part:
do you have oil pressure data at 3,000RPM?Reference value PSI....50.8 @3000
RPM Series 1 RX-8, 72.5 @ 3000 RPM Series II RX-8..at 100c If the NA RX-7
has the same Oil Pump, chain, rotors and Oil Pressure By Pass Valve then the
values have to be the same, give or take a few PSI.... The RX-8's Opening
Pressure regulator for the Oil Pumps.. S1..64-71 PSI S2..156.6
PSI RX-8's Oil Filter By Pass Open.. S1..11.4-17.1
PSI S2..20.3-26.1 PSI
__________________
Some of this problem may be due to the extra bearing clearance of the
Renesis, and the tapered rear main on the shaft. This allows for shaft flex when
screaming the engines,
So the 64-71 PSI is not all that far off of your pressure. Any early relief
may be disassembled and a few washers dropped in under the spring to
bring the cracking pressure up. You can check that with the shop air supply
regulator. Or you can buy one from Racing beat as the street high performance
regulator (80-85 PSI cracking pressure) as part number 11810. Now you have to
call them and ask if this will work on the model of Renesis you have. The series
2 engines have the relief valve in the pump and don't use this style of relief.
It is also possible to improve pressure by changing viscosity and you can
minimize foaming by using a racing oil. They have more anti foaming agents
and more anti scuffing compounds (Zink). If cold weather starting is not a
problem, try a straight weight oil in 30 or 40 weight. Under fill the sump by
1/2 quart.
You can install a baffle plate between the engine and pan to allow bubbles
to burst before the oil falls into the pan.
Racing Beat has all of the catalogs on line for free download. Worth the
paper.
Lynn E. Hanover
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