about the whole rotary reliability thing

Discussion in '1991 Mazda 787B' started by erwin, Aug 10, 2002.

  1. Re: about the whole rotary reliability thing

    <!-- QUOTE --><center><hr width="90%"></center><blockquote><i>Quote from Paragon Racer</i>
    <b>Wow, you are asking a lot. jk. Well, my father and i have well over 100 hours over the past four years on our 12A in IT-7 (a class in SCCA). To put that in perspective, I have heard of some guys who run preludes and z-cars that tear down their motors every 60 hours. typical red line for it is arround 9,000 to 9,500 rpm. Additionally, i have seen 10,000 but it really quit breathin on me. Granted we do have a fully balanced 12A with a 90psi oil pump, and we do change the oil between each weekend (some times more than once a weekend depending on how it looks). However, we do run all stock components straight from mazda competition parts department, but they are just basically factory parts that have been balanced (that is stipulated by the rules).

    In a piston engine, the redline is limited by the valve train, not the crank or rods. valve spring just can't keep up at higher rpms. Therefore, seeing as rotaries don't have valves and they do have much less moving parts, they are much more durrable when properly takin care of. The apex seal is the week link in the rotary. For that reason, Mazda upgraded them again on J-spec efini's after they stopped importing them over here. On stock 3rd gen's and even the single turbo 2nd gens, apex seals are typically the first to go, especially when not properlly maintained. Never the less, i have heard of 3rd gens with 200,000 miles on the clock with oringinal everything. Personally, I would wanna pick up a 3rd gen with more than 60,000 miles though. Anyone, who says that the rotary is an unreliable engine though, has no idea what they are talkin about.

    About temps., well, i have personally seen stainless steel headers glow red and then yellow in color. I am told that it is some where near 1800 F. As far as i know, as long as the apex seals are kept lubricated, ie some 2-cycle in the gas tank, they can handle the stress.

    Hope, i helped clear somethings up. Any other questions, feel free to ask.</b></blockquote><center><hr width="90%"></center><!-- END QUOTE -->

    Hey someone who know's a rotary, FINALLY! well stock rotaries, with proper servicing should last bout, what 160000 miles, then you may need a major overhaul, pending on how the car was treated. Well I hope soon more rotary cars come out, they are better then pistons I tell ya! Apex seals are the weak point, but soon wont be a problem, if you get Ceremic ones, you can rev higher, like to bout 10-11 grand (pending on engine) and they will last forever almost, but they do cost about the same as a new engine <IMG SRC="http://www.supercars.net/servlets/cMsg/html/emoticons/smile.gif">

    In short rotaries are more reliable than piston engines IF serviced by a trained mechanic/ anyone who knows about a rotary engine.<!-- Signature -->
     
  2. Re: about the whole rotary reliability thing

    Yep, damn apex seals. Main cause for them being known as shit reliability is idiots modifying them w/ no idea what they are doing.
    You can't go too lean on a rotary.
    N/A's will last for ever and a day most of the times, think of how many FB3S's are running around w/ 200k+ miles on them, stock engine, and most else stock.
    But the ceramics cost $600 each i think (maybe $300 a pop but i forget), and you need 3 each rotor, so most of the time you'd need 6. Which is way over the engine, but the ceramics will last longer, and are self lubricating. But if they ever go, they take the engine and alot of times the ceramic shards go into the turbo and destroy that too.
    <!-- Signature -->
     
  3. Re: about the whole rotary reliability thing

    rotary engines are much more tunable than others, it rules all engines... thank the german guy that invented it... you know it was originaly made as airplane engines..
     
  4. Re: about the whole rotary reliability thing

    It was actually used many years before in medieval times as water pumps.
     
  5. hey to answer kenmclarens question since he's been looking for someone worthy to answer it. well this is how i see it. i love the rx-7 and i absolutely love the rotary engine. i'm about to get myself an rx-7 in a few months and for the last few years or so all i've been doing is engulfing myself on information about the car adn its amazing engine. but to answer the question, the only reason it has not been reliable is because no one knows how to use the engine. face it some people don't even kno how a rotary works or even what a rotary is. i don't blame them, 90% of the people in this world are used to the piston type engine and some people even get scared when they see something new or different like the rotary. and all they do is make up somethin like its not reliable enough so it sucks. i mean the every engine is reliable its just who takes good care of the engine. i can say most cars or engines that join le mans break down one time or the other i don't kno why its such a big deal when one of the 3 787's engines break down all of a sudden, i mean come on this is the greatest and hardest race on earth, and your pushing a car beyond its limit of course its gonna break down somehow. but there are the exceptional that push the limit and go beyond such is the case with this 787. so to leave it, i say some people just don't understand the rotary and its as reliable as every other car, it all matters on who's taking care of it.


    --------------------------------------------------------------------------------
    either way the sun will still shine <!-- Signature -->
     
  6. Re: about the whole rotary reliability thing

    Lada, some of these dimwits are just keyboard mechanics, I wouldn't worry about it all. Read my response in "What do you think??" to KenMclaren's question. C yas!! Mafs!!<!-- Signature -->
     
  7. a few questions

    from what i know the rotary should theoretically be more reliable in one resepect because there are fewer moving parts and no accelerating up and down of pistons. does anyone have any factual info on the reliablity of rotaries - avg milage etc?
    and i read in another forum that they run hotter than reciprocating piston eng. is this true? if so how much hotter? (it does seem as though theres a lot of talk about knocking with rotaries)

    and could someone explain to me how apex seals could last any reasonable time considering they experience tremendous amount of stress?

     
  8. Re: about the whole rotary reliability thing

    Wow, you are asking a lot. jk. Well, my father and i have well over 100 hours over the past four years on our 12A in IT-7 (a class in SCCA). To put that in perspective, I have heard of some guys who run preludes and z-cars that tear down their motors every 60 hours. typical red line for it is arround 9,000 to 9,500 rpm. Additionally, i have seen 10,000 but it really quit breathin on me. Granted we do have a fully balanced 12A with a 90psi oil pump, and we do change the oil between each weekend (some times more than once a weekend depending on how it looks). However, we do run all stock components straight from mazda competition parts department, but they are just basically factory parts that have been balanced (that is stipulated by the rules).

    In a piston engine, the redline is limited by the valve train, not the crank or rods. valve spring just can't keep up at higher rpms. Therefore, seeing as rotaries don't have valves and they do have much less moving parts, they are much more durrable when properly takin care of. The apex seal is the week link in the rotary. For that reason, Mazda upgraded them again on J-spec efini's after they stopped importing them over here. On stock 3rd gen's and even the single turbo 2nd gens, apex seals are typically the first to go, especially when not properlly maintained. Never the less, i have heard of 3rd gens with 200,000 miles on the clock with oringinal everything. Personally, I would wanna pick up a 3rd gen with more than 60,000 miles though. Anyone, who says that the rotary is an unreliable engine though, has no idea what they are talkin about.

    About temps., well, i have personally seen stainless steel headers glow red and then yellow in color. I am told that it is some where near 1800 F. As far as i know, as long as the apex seals are kept lubricated, ie some 2-cycle in the gas tank, they can handle the stress.

    Hope, i helped clear somethings up. Any other questions, feel free to ask.<!-- Signature -->
     
  9. Re: about the whole rotary reliability thing

    thanks for the info
     
  10. Re: about the whole rotary reliability thing

    see, the engine's in RX7's are so poorly cooled that they aren't very reliable in heat, otherwise they are good.<!-- Signature -->
     
  11. Re: about the whole rotary reliability thing

    I have but one question. How does it work? The engine intrestes me.<!-- Signature -->
     
  12. Re: about the whole rotary reliability thing

    check out mr rotary's avatar.
     
  13. Re: about the whole rotary reliability thing

    The ceramic seals are very good but I was told that when these seals are used you tend to get more ware on the housings cus ceramic is harder than the normal seals.

    And as for the rotor motor being crap as in reliability, look at it this way, you use less energy going round and round than up and down!!
     
  14. Re: about the whole rotary reliability thing

    Rotary = Efficient & Trouble with seals
     
  15. Re: about the whole rotary reliability thing

    wankel?
     
  16. Re: about the whole rotary reliability thing

    The biggest problem with the current crankshaft/rod/piston engine set up is that you have to overcome a lot of moving inertia. The crankshaft has to mechanically reverse the direction of the piston 4000 times at idle (Assuming idle at 2000 rpm). The beauty of a rotary engine is that everything continues to cycle in the same direction. It's also essentially like having 3 pistons per rotor because you have different phases of the combustion cycle happening at the same time. With that logic, the 787's 4 rotor is equivelant to a 12cylinder engine.
     
  17. Re: about the whole rotary reliability thing

    Actually, most early water pumps more closely resemble a roots type blower. A wankel rotor and a roots blower do serve practically the same purpose however; move a medium from one place to the next.
     

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