Rotary engine smoking...
Sean Reifschneider
some of my earlier postings regarding problems with my '84 RX-7 GSL-SE.
Well, I'm still having them.
I've changed the Fule Pressure Regulator, and I got a fule pressure
gauge. The pressure seems to be within spec. But now when I start up
up the engine, it smokes really badly (REALLY badly, looks like a smoke
bomb), and runs really roughly. Any idea what's causing this? Maybe the
oil metering pump? Anyone with any suggestions on this, I'd like to hear
them.
I've been thinking of rebuilding the engine, and replacing all the seals
with the carbon racing type seals, hardned stationary gears, lightened
rotors... Anyone have any comments on the difficulty of doing this.
I think I'm probably just going to mostly leave it in the garage for the
winter, and work on it next summer. Looks like I got a beater car just in
time...
Sean
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Roger Haaheim
Jon Lusky
has been sitting for a couple of weeks, go drive it and see if it doesn't.
quit smoking after about fifteeen minutes on normal driving. The park it,
and start it up the next morning to see how bad it smokes. If it smokes really
bad, its time for a rebuild. If it doesn't smoke much, you're probably okay for a while. THis is assuming that it is indeed smoke coming out, not steam.
Rx-7's are very sensitive to overheating. WHen you overheat one, the rotor
housing deform, and the o-ring between the combustion chamber and the water
jacket can't seal. The result is the egnine burning lots of water, and
pressurizing the radiator with exhaust.
I've rebuilt a 79 12-A engine before, and I probably won't do it again.
It is an absolute must that you check the rotor housings for warpage when you
do the rebuild, and there probably isn't a machine shop in the country that knows how to do it. You could do it yourself, but calipers, micrometers, and
dial guages get pretty expensive. I'd reccomend buying a complete engine
from someone like racing beat. I didn't know that there were such things as lightened rotors. It's my understanding they use stock rotors that have been
milled down a little bit so they can take long durations of greater than
8,000 rpm. Replacing the stationary gear is also generally only done for high
RPM use. I know it is cut different from the stock gear as well as being hard
ened.
Oh as far as the oil metering pump goes, even if its stuck all the way open, it doesn't put out enough oil to cause noticeable smoking (although oil consumpt
ion will be higher than usual). The best thing you can do is get another
stock engine and fitting a racing beat dellorto steup on it along with a header
and tuned exhaust.
Jon Lusky
>Is the smoke white? Is the water in your radiator extremely rusty?
Rusty water in an RX-7 radiator would be real intersting to see considering
that it uses an aluminum block...
Sean Reifschneider
That was one thing I forgot to mention. The smoke did seem to be white, as
opposed to blue/grey. I figured that it must be water vapor, but it would take
some real damage to get the water in there. The rotor housing would have to
warp pretty badly. I didn't do anything to it that would cause the housing
to warp. I just changed the fule pressure regulator.
The coolant looks like new (I flushed it a year ago). A friend of mine has
bought a couple of Honda engines from a place in CA, that buys them from
Japan. He's had good luck with them, and says they typically have 40000 miles
on them. I'm thinking of getting one of them, so I can have a spare around.
Tear one apart and get it race ready.
Sean
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From the desk of Sean Reifschneider. Isn't Amiga UUCP great? Thanks Matt.
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Myron Wintonyk
Damn, this gut is good ...
I guess those things on the end that are made of steel aren't part of
the "block". I wonder why only the rotor housing are part of the
"block" and the steel parts aren't?
Ahhh, the wonders of the rotary, aren't they neat?
Myron Wintonyk, Oheeron Racing Inc. (Rotary Performance Specialists).
Jon Lusky
>In article <40...@ut-emx.uucp>, lu...@ccwf.cc.utexas.edu (Jon Lusky) writes:
>
>Myron Wintonyk, Oheeron Racing Inc. (Rotary Performance Specialists).
Soory, got the mazda confused with my sachs... When I said block, btw, I was
referring to the side housings and rotor housing. Its been a while since I
tore down my 12A.
Jon Lusky
are seals on the rotors to keep the oil from leaking out of them when the
engine is not running. If your getting a couple of minutes of blue smoke when
you start it up, that is your problem. As long as it burns off after a couple
of minutes, I wouldn't worry too much (although you might want to remove the
catalytic converter). You might want to get a compression graph done on it.
If the car had been sittting for a while (2 weeks or so) and only smoked
really bad once, I wouldn't worry at all.
As far as building a race motor, first, I don't reccomend rebuilding a rotary
yourself, unless you're very good at checking for warpage and runout. And if
you want to stay with the 6-port engine, there isn't a whole lot you can do to the inside. You can replace the stationary gear with an MFR one (mazda factory
racing) and have the rotors race clearanced (milled down, basically), but those
mods are only to keep the engine from flying apart during extended runs at
over 8000 rpm. Best mods you can do to a 6-port are replacing the EGI and
the exhaust. I 've seen some nice carb setups for the 6-port, but I don't know
about upgraded fuel injection systems. Maybe a turbo-II injection system with
a Haltech brain?
John_Schubert
# with the carbon racing type seals, hardned stationary gears, lightened
# rotors... Anyone have any comments on the difficulty of doing this.
Generally speaking using race parts gives you a heavy duty part. Carbon apex
seals are an exception. These are designed for high rpm use (10K) and
applications where long life is not important. Unless you're planning to
tear down your engine every 15K or so to replace the apex seals, I'd use
steel seals and limit your rpm to 8500 max...
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