12a's and revving to 8 grand: Does it really hurt the engine?
 

Well, A few times of needed power I ignored the buzzer. It seems my buzzer sometimes comes on at only 6.5k rpm, so I don't heed it completely. Well, looked down and saw the tach going quickly to 8k, so I shifted even thought the engine was smooth and still building power.
Ok, so I revved to (almost?) 8k a few times. If the engine is smooth and still building more power cxlose to 8k rpm, why is it damaging the engine? I guess I am torn- torn between pampering my ol rex for curvey roads, and torn bewteen wringing the power from my 12a for personal enjoyment- because I can always rebuild it (and it is close to needing it based on miles)- right?


And Bills' (the po) record are right. In almost 2k miles, it has only used 1/2 quart. I don't have much (any) personal experience with rotary engines, but that seems great for even a 175k mile piston engine that doesn't inject oil. Does that mean the engine may last way beyond 200k if I pamper it more? Or is 200k a magic number of destruction for 12a's? I now have an extra 12a, so I might rebuild it for backup. But if you wait until an apex seal goes, you may have serious housing or roto damage?

If you're mixtures and timing are right 8000rpm is fine IMO. My unported 12A made peak power at 7800rpm last dyno run and was beginning to lean out so it could have made power higher. You are pushing the mechanical limits of the engine once you are 9000rpm plus, which is fine cos unless you have a BP, you are not make any more power up there. The 12As are quite a bit more rev happy than 13Bs of the same era as well. Stick to 8000rpm as a nice limit.

PS....you can change when in the rev range the buzzer kicks in

What happens is the apex seals chatter against the rotor housing and nick up the Chromium plating. The Chromium plating is what allows the seals to slide againt the Aluminium without tearing it up... The seals are made of Iron.

Occasional revving is okay, but constant revving does damage... If you are building an engine, and you intend for it to be a race only high revving engine, replace the stock Iron seals for Carbon ones... They are lighter, so they wont chatter... The problem is that they are lighter, so at low RPM's they dont weigh as much, hence the centrifugal force pulling them against the housing isnt as great,and they don't seal well.. Therefore they are only good at High RPM's. They are also soft carbon, so they wear out faster.

Also, 1/2 quart of oil for 2000 Miles seems a bit low compared to my experience. I thought it was supposed to be 1 quart per 2000 miles... Double check your Oil metering pump linkage and maybe do the test as described in the Haynes manual...

The pump is located on the side of the engine, opposite the spark plugs, near the bottom to the front.

Not to mention the fact that at the higher rpms the stock lubricating system becomes inadequate. That's why race motors typically run a higher pressure. There is also the danger of breaking the stationary gears if the motor is over-revved. And I agree, 1 pint/2000 miles is TOO low. I'd check that out.

Should you choose to use carbon seals, use two cycle oil, it makes them last much longer then the OMP. Also, always drive moderately hard to very hard with carbon apex seals, it keeps them sealing good and prevents carbon build up which wouldn't occur as much with steel seals.

Pele's completely right on the chatter issue with steel seals. Occational 8000rpm is fine, but every shift is not so good. Don't drive it light all the time either. That is also bad. Before I did a rebuild, I found out how bad 8000rpm is for housings making them chatter up and get more flaking which makes them less good for making power as they will always have blowby those flaking spots.

Ok, alot of opinions on expected Metering Oil Pump oil consumption. Well, 100k miles of record show consistent 1/2 quart oil consumption on my 175k mile 12a. Hmmm, if it is too low, wouldn't it need a rebuild by now>?:confused:
My experience with engines is limited to what I have owned. Mazda piston engines use oil with any miles. But in order for the oil to lubricate the engine> and the rings, oil gaps must be there- which also allows for oil to get in the cylinders. As long as the oil consumption is consistent (no matter what engine), then I feel completely comfortable with the engine. So why should rotary engines be different????

I know for a fact that stock 12a's can handle at least 10,500rpm once in a long wile... 8K is nothing. As long as you keep the revs below 9k and dont go up there all the time you will be fine. Also, rip off that OMP and just add some 2-cycle oil to the gas every fill up :)

so im curious , any 2 cycle oil, and how much for a 1980 tank if it makes a difference, how much oil to gas if i am puting in a full tank?

use marvel mystery oil its the shiznit!!

shitnizzlenet.. yea.. i think 2-cycle err 2 stroke oil for liek boat motors or watever is a safe bet

Your buzzer is always working at redline. If your tach isnt at redline when you hear the buzzer, your tach isn't fully operational yet.

I notice my tach sometimes wont work until I drive at least 5 minutes.....then it will kick in. Or......it will seem to travel slowly......and then I hear the buzzer kick in.......but, by now, I know redline by engine pitch.

So, take your rev buzzer as actual redline.....not just the tach.

There are no Cylinders in a Rotary engine... The Rotary engine has a triangular rotor with seals in it's tips. To lubricate these seals (Called Apex Seals), a small amount of oil is injected into the cumbustion chamber, usually through the intake. It is measured out by the Oil Metering Pump...

Check out several links on how the Rotary works...

http://www.rotaryengineillustrated.com
http://travel.howstuffworks.com/rotary-engine.htm
http://members.home.com/sofronov/Cars/Mazda/Rotary.html

whats the proper ratio of oil for fuel when premixing?

:rofl: I think he knows about the rotary using an OMP and not having cylinders :p: .... I hope....

I think he was just justifying the OMP's consumption by comparing it to his Piston engine'd Mazdas that burn oil because of ring gap...

i think it depends on what you use. if i remember correctly MMO is about 4 ounces to 10 gallons. not sure if different ratios apply to different oils. there should be info on the bottle you buy.

Yes, I know the my rex doesn't have pistons in the engine (doh). I was just making that old statement: If it ain't broke, why fix it? In regards to its oil consumption. If an engine makes it to 175k miles while consistently using 1/2 quart every 2k miles, why should I all of a sudden think it isn't using enough oil just because some of you guys think it should be using 1 quart every 2k miles? Have your engines made it to 175k miles? hmmm?
:)

I dont think a stock 12a makes its max hp at 7800rpm. More like 6800-6900 rpm

Go check to which setting your OMP is set.
There is 3 holes in the rod.
I place mine on the highest one,seeing that i want more oil to be injected with the fuel

Besides..if it smokes...put a "Diesel" sticker on.like a friend of mine did. 10 000 rpm diesel...haha!

Proofs in the dyno dude ;) This is where my engine made its peak power.
This is with an aussie series 3 4 port 12A which has large ports from the factory. Also, this was with a deleted water pump (water pump blanked off and belt run from e-shaft to alt), facilitated by a Davies Craig electric water pump, no air pump, and e-fans - all of which have the effect of decreasing high-rpm drag, in effect shifting torque up at high rpm values (drag torque losses relate as a cubic to rpm). The A/F curve also showed the carby was starved of fuel from around 6500rpm as it was unmodded at the time. It is modded now...and with underdrive main pulley and the new carby and timing, it should be producing power even higher (and more spread at this range too). Your exhaust design also plays a part in where you get peak power.

i think your series 3 motors, might be like the euro ones, in which case you have 10degrees more exhaust port timing

mike

My bad. I just misunderstood your other post comparing the RX-7 engine to a piston engine...

Actually mine is at 176K miles... It was there when I put the engine in the trunk of a Corolla. I think i'd still run if I changed the ignitors... I know it cranked with a lot fo compression last winter...

yea, when i went to dyno my car i did a few runs letting off at 7200 and the guy running the dyno was yelling at me to not stop because the hp curve was still shooting way up. my car makes peak hp around the exact same as KYPREO. that's usually how i beat people in street races, i keep going and usually end up shifting right after they do and i'm already ahead. WOOHOO for rotary!

i believe you are correct...for 84/85we got the larger port 4 port 12A - I believe same as Europe, Japs got the 6 port and the 12AT, and you guys got the 13B 6 port, and which 12A? You guys would know.

The one thing no one has mentioned, is if you keep the stock main pulley, the water pump will spin
too fast and not circulate the water properly. Iam not sure of the exact rpm's it start cavitating at, but is in the RB catalog. So basically speaking, dont hold high rpm's for too long because it will create hot spots in you engine! Or spend $45 and get a smaller main pulley, which works very well, unless you use an a/c then you need to figure something else, like I need to do.

Any comments on where and how to relocate a/c belt? I was thinking maybe move a/c back slightly and run the belt to the water pump pulley which originaly used for the air pump '83 Rx-7.

our s3 12a is the same as the s1/2 port timing wise, as usual if its better it didn't come to the us

mike