Hello all,
I found this in my travels on the rx7club.com site. It has some
interesting takes on porting along with oil metering problems and
potential/actual fixes for the warranty issues that mazda has had with
rx-8 engines. Also this is not a prod at the p-port but I think that if
anyone is serious about using a rx-8 engine, such as myself in my
Starlet, it would be best served to read about this for potential mods
because until I see an actual dyno graph of a the p-port setup with
injection working correctly I will leave it under the "nice idea but
lets see some results" section which Paul has stated at some point he
was looking to rectify when he has the time/money. Its worth signing
into the rx7club.com site to read this because it has some interesting
points. That is if he is accurate as well. I am always a skeptic unless
i see concrete results in form of data. That is what I do as a vehicle
calibrator for Delphi. Enjoy. I keep finding these little nuggets of
info:)
http://www.rx7club.com/showthread.php?t=766697
Paul,
The four NASA papers that I have are big (11 to 30M) and I dont know
where I got them from. I can email you the document numbers tonight when
I get home from work today or I can toss the actual papers at you. Do
you have an ftp site I can dump on?
Rob Woods
From:
http://www.rx7club.com/showthread.php?t=766697
"Whatever you do, ALWAYS premix on a Renesis! I mean that for everyone
who owns a pre 09 model RX-8 too. Mazda messed up with the oil metering
system and it is why so many of those engines have been dying. They have
2 oil metering jets per rotor. Nothing out of the ordinary there. They
are
both on the rotor housings now though instead of just 1 per rotor on the
housings. They are pointed towards the corners of the housings though as
they are trying to get oil to the corner seals now. This leaves the
center
of the apex seal inadequately lubricated though. If you could see a chart
of seal temperatures you'd see that the center of the apex seal gets
hottest.
That's where the oil metering is most important. This is the area of
least
lubrication on the Renesis. Seals warp, compression goes down, wear
increases.
This explains everything from inconsistent dyno numbers on RX-8's, low
power
numbers, and even explains why Mazda has gone through so many ecu
reflashes
on the car. They figured it out through and the 09 model cars now have
a 3rd
oil injector per rotor! Mazda knows they messed up as they've extended
the
engine warranty on all RX-8's to 100K miles. It's retroactive for those
who
had already had their warranties expire. Mazda has not publicly admitted
that the oil metering was flawed in design. They are just fixing the
issue
slowly and are trying to be quiet about it. Some of us figured it out
though!
Use premix!" rotarygod
This is good advise about premix but I think this gentlemen is mis
applying
information
on apex seal temperature he learned from the 13B data. One reason the
13B apex
seal
runs hot is because of the peripheral exhaust port. The RX8 engine
apex seal
may NOT run as hot. I have seen no data so far on actual temperature
measurements
on RX8 apex seals.
Mazda has a powerful incentive to cut down the amount of apex seal oil
used to
reduce hc. BTW one of the main functions of the apex seal oil is to
cool the
seal and not just to lubricate it. Mazda recently sent out a video and
reiterated
the no synthetic oil policy due to lack of testing on their part. In
the mean
time
Castrol Syntec is one of the sponsors of the SpeedSource RX8. IMHO
Mazda could
spend some time testing synthetic oils and recommending one of the
them. I mean
....what is wrong about Idemitsu Rotary Engine oil? I personally and
others have
used Mobile One for years with excellent results. Both in rotary cars
and in
rotary powered airplanes. Mobile one break down temperature is at
least twice
as high as regular motor oil. I am currently using Idemitsu in my RX8.
If you are bothered about it use silicon nitride seals from Francisco
or Sven :)
There are a lot of Mazda rotary engines in junk yards because Mazda
uses cheap
nylon lines
to carry oil to the apex seals. After about five or ten years these
lines get
brittle
and crack. So they must be frequently inspected and replaced. IMHO
they should
have used steel lines for this critical function.
BTW we have had over 4,000 hits on our youtube video on how to p-port
the RX8
engine. So far I have nothing from anybody on why it won't work :)
IMHO porting the RX8 rotary engine is not worth the cost. It is about
the same
cost
to p-port it and you get 25% more power at 7500 RPM. Mazda has every
incentive
to cut down the cast iron wall thickness to cut the weight of the engine.
By now somebody somewhere has put one on a dyno besides my self :)
Rob, I don't know how to set up my site to ftp to.
If you send the titles I'll try to download them.
Some I may already have.
--
Paul Lamar ...No rotor no motor.
Paul,
Thats all I want to see is a dyno graph of an actual run with corrected
factors and such. I am not saying it wont work. What I am saying 4000
hits and no complaints in no way constitutes a claim of extra power.
Lets try to get some one to show some actual results here. There are
dumb asses that buy 10 dollar tornado air cleaners and claim 5 extra mpg
when it takes millions of dollars in work to get 1 or 2 mpg each year.
The proof is in the pudding. Also did you notice that he was saying 185
ft-lbs in another part of that post. I have emailed him asking for the
same as I asked from you.
Rob Woods
We got a dyno run at Mazdatrix using a Weber carb but Dave told me later
there was a problem with the dyno calibration. There is no reason in my
mind
why a p-port RX8 should be any different than a p-port 13B.
We have some dyno sheets on the 13B p-port with the same runner lengths,
diameters and port timing.
The Rx8 has a higher compression ratio and 17% more exhaust port
area.
The BSFC was all over the map indicating to me the the mixture was
all over the map. In an aircraft application you adjust the mixture
for the RPM and load.
I plan on taking the same engine and mounting it on my prop
dyno using the 555 EFI I am working on.
300 HP p-port 13B's have been around since the 80's.
Paul Lamar ...No rotor no motor.
Paul,
This is a small aside, I don't believe that the Renesis apex seal will
be the hottest at the center. Since they exhaust through the SIDE. I
would believe that Renesis seals would be hotter at the corners since
the exhaust exits through the side plates. The 13B exits directly over
the center of the seal. That being said, I still believe that permix is
better for most high-power applications.
Bill Jepson
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