Lets clear some myths up...

Discussion in '2002 Mazda RX-8' started by venomGTR, Aug 10, 2002.

  1. First, the torque issue, rotarys do have torque and bogs of it.

    If you know anyhting at all about rotarys you'd know how a rotary makes more power than a piston engine at the same engine speed... hmmm engine speed x torque = horsepower.
    Work it out.
    They make much more torque than a piston engine, about twice, and can make very long flat torque curves a wide wide rev range. The RX-8 is 1300cc and makes 220Nm, about the same as a ford 2.5 V6.

    Second myth, lack of bottom end torque.

    The RX-8 revs to 10000rpm, yet according to the mazda website it makes over 180Nm of torque from as low as 2000rpm to over 9000rpm.
    It does this without the kind of camshaft switching a s2000 might use to do the same thing. Not just the RX-8 but older rotarys are good at that too. the s6 Rx-7 has 255 of 300Nm torque available from under 2000rpm.

    Reliablity.
    With a fraction of the moving parts of a piston engine its a no brainer. Modern rotarys are being used more and more in aircraft because of sheer longevity.

    Emissions
    Moller's sky car is going to be using super reliable rotary engines that produce about 4% the emissions of a piston engine. Good design is all that was lacking in the rotarys 20-30 years ago

    Mazda site also says they will be doing a special 380hp triple rotor RX-8.

    Don't get my wrong i drive a piston powered GTR and love it but you gotta have some respect for the superiority of the wankel.

     
  2. Re: Lets clear some myths up...

    u all got to admit it, ROTARY RULES!
    itŽs just a matter of time, they will reign the races (they have already won a Le Mans race)<!-- Signature -->
     
  3. Re: Lets clear some myths up...

    finally a good informative post. thanks for the info venomGTR. now i learned more about rotary engines and not readin other bs threads on this forum (ie: that thread about that one jackass kid who says he owns a RX-8 or sumthin).<!-- Signature -->
     
  4. Re: Lets clear some myths up...

    Allow me to correct you on something you said.

    "a rotary makes more power than a piston engine at the same engine speed"

    There is only one possible way it could make more power at the (same) engine speed, and that's if it's making more torque at equal RPM. This particular engine torque peaks at 160 ft/lbs, which is hardly enough to challenge most piston engines. It may make more torque than a 1.3 liter piston engine would. But that would be a rediculous comparison. There aren't any 1.3 liter piston engines that I know about, certainly not any that are focused on performance.

    What it does provide is an ultra lightweight starting point with very high RPM. But to say it generates more power than piston engines at the "same engine speeds" is false.
     
  5. Re: Lets clear some myths up...

    Seansvette said:

    Allow me to correct you on something you said.

    "a rotary makes more power than a piston engine at the same engine speed"

    There is only one possible way it could make more power at the (same) engine speed, and that's if it's making more torque at equal RPM. This particular engine torque peaks at 160 ft/lbs, which is hardly enough to challenge most piston engines. It may make more torque than a 1.3 liter piston engine would. But that would be a rediculous comparison. There aren't any 1.3 liter piston engines that I know about, certainly not any that are focused on performance.

    What it does provide is an ultra lightweight starting point with very high RPM. But to say it generates more power than piston engines at the "same engine speeds" is false.


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    actually you are both wrong. Funny thing is that is that the Rotorys RPM rating is actually 3 times faster than it really is. This has to do with the 270 degree combustion process compared to the 180. So technically the RX8 creates only goes up to about 3333 RPMs. It is rated the other way inorder to try to conform.

    Thanks.

    p.s. there is actually a really long drawn out explanation and this is only a piece of it.

    93 RX7 Twin Turbo 1/4 mile eta 11 sec.
     
  6. Re: Lets clear some myths up...

    That cannot be correct. If the torque specs are correct and the engine only maxes out at 3000 RPM, then the horsepower would be extremely low. Perhaps what they're referring to is the RPM of the rotor itself. But it could only manage that performance with only 163 ft/lbs of torque if the driveline RPM is correct.
     
  7. Re: Lets clear some myths up...

    That cannot be correct. If the torque specs are correct and the engine only maxes out at 3000 RPM, then the horsepower would be extremely low. Perhaps what they're referring to is the RPM of the rotor itself. But it could only manage that performance with only 163 ft/lbs of torque if the driveline RPM is correct.
     
  8. Re: Lets clear some myths up...

    Where does it say there will be a 380hp Rx-8. I believe you, I just want to see the site. A 380hp rotary engine would hopefully convince some other manufacturers to seriously consider a rotary. Imagine if they put that in the Miata ...
     
  9. Re: Lets clear some myths up...

    Rotary's have three combustion phases per rev. Four stroke only one every two. Thats where it rotarys make there power.
     
  10. Re: Lets clear some myths up...

    rotaryŽs dont just get good power and torque. And the power dont just comes from the rpm, in the conventional engines the pistons first goes down, stops and then go up, this change of direction generates a lose of power, in rotaryŽs theres no change of direction, they just go round and round.

    RotaryŽs also are lighter and smaler. This helps to lower the center of gravity, increasing the handling and stability (in the RX8 the engine has the same height that the gear box).
     
  11. Re: Lets clear some myths up...

    the flywheel spins 3 time faster than the "piston". U use the flywheel RPM to calculate power since thats the thing attached to the transmission.

    SeansVette, an extremely high-performance example of a 1.3 reciprocating engine would be the Hayabusa motorbike. 175hp, 102lbft - its slightly unfair to compare that to the RX8 since the RX8 isnt as highly tuned, but the Mazda still has 1.6 times more torque. Compare the RX8 to an average 1.3-litre car engine and it will be over twice the torque at the same RPM

    racing rotaries are about 3 times better than normal engines
     
  12. Re: Lets clear some myths up...

    racing rotaries are about 3 times better than normal engines

    Preach it what happened to the 4 rotor it lemans oh wait it ws banned becouse it was to damn fast
     
  13. Re: Lets clear some myths up...

    Let's clear another myth, that the rx7's 1.3 litres = 1.3 litres of piston. 1.3 litres of rotary = 2.6 litres of piston engine. The reason is because the rotary combustion champer fires every revolution and not every other revolution, thus makeing displacement comparison with the piston engine uneven. So is the displacement of a 2-stroke comparable to the displacement of a 4-stroke piston engine. Nope.

    so a 2.5 litre v6 compared to a rotary would have 1.25 litres.
     
  14. Re: Lets clear some myths up...

    Is that why the an ls1 v8 swap into an rx7 does not change the weight of the car? No the 2rotary + turbos is not lighter then the aluminum v8.
     
  15. Re: Lets clear some myths up...

    i dont know for sure if that information ur posting is true, but lets say its posible. But ALSO consider the posibility of an aluminium rotary. u would be able to lift that without any kind of help.

    So we go back to this part of the advantages that a rotary has over a piston engine, LIGTHER, REV HAPPY, SMALLER(this includes the posiblity to fit the engine in a better place for the stability and others, for example behind the front axel, just were the renesis is in the rx8), MORE HP/LTR, and going, and going...

    so please, cut that v8 muscle engine crap, those are powerfull engines, but they arent good engines (in technical aspects), as a 1300 cc rotary can be.

     
  16. Re: Lets clear some myths up...

    No no no. I know its a point of contention for a lot of people but you can't just double the displacement of the engine. Its still 1.3 liters any way you shove it. End of story. You can talk about combustion cycles, and RPMs, but you can't just double the displacement.
     
  17. Re: Lets clear some myths up...

    Now i have to ask the stupid qustion, i do understand how it all workes, but the crankshaft, how abouts does it transfer the power to the flywheel, how does it spin? (same or opposite direction.) yes i know it is a dumb qustion, but i would really like to know, if i don't i will go stircrazy thinking of it and how it would do it.
     
  18. #18 stewacide, Mar 28, 2003
    Last edited by a moderator: Apr 25, 2016
  19. Re: Lets clear some myths up...

    Yeah i am, thanks for the site, it is clearing it up so far.
     
  20. Re: Lets clear some myths up...

    I know the 20b (3 rotor engine used in i think cosmos in austurala) is real, but does anyone here think that it is possible to fit that in to this car? becouse i have also heard rumours that they may make a us spec. for this car.
     
  21. Re: Lets clear some myths up...

    Rotary engines done have a flat torque curve... the torque curves are very steep. That greatly limited their use in rally racing (at least this is what i have found from my research of use of RX-7s in rallying). The cars would begin with too little power at low RPMs, but would spin their tires as the engine reved up to speed. One solution, i cant remember who did it, but the did it with help from Mazda of Japan, re-geared their car so that it would top out at 100 mph. Im just rambling now... later.
     
  22. Re: Lets clear some myths up...

    check the pix
     
  23. Re: Lets clear some myths up...

    ok to clear up the confusion..... lol

    i always thought a wankel made two power strokes power output shaft/flywheel rotation.....
    so relatively speaking it displaces 1306cc, but is equivelent is 2612cc in piston terms.....

    The rotary actually makes three power strokes for two rotations of the eccentric shaft.

    Or is it two power strokes per 0.75 rotation of the eccentric shaft?

    Then again people talk about the 180 degree cycle versus the 270, thus there must be 1.5 power strokes per eccentric shaft rotation?

    Wankel confuses me
     
  24. Re: Lets clear some myths up...

    k this is a really dumb question but i barely know anything about cars. My cousin believes a new car (2004 viper) will have a v18 engine. Is it possible to estimate how many liters that wud be? I'm telling him there's no way it wud even fit but he says the front is wider now.
     
  25. Re: Lets clear some myths up...

    Anyone who thought that the RX-8 will be the next generation rotary sports car of Mazda replacing the legendary RX-7, forget about it. They are TOTALLY different, and there is a clear reason why RX-8 is not the next version of the RX-7.

    The concept of RX-8 is a sports car that can load 4 male adults. It is designed to give comfort and reliability, not to give performance of a pure rotary rocket. You can easily find that RX-7 had two generations before the 3rd version. If the RX-8 is truly the next version of RX-7, there is no reason for Mazda to do so; they could simply make it the 4th generation RX-7.

    The purpose of RX-8 is to make the rotary engine more common to the public, and at the same time, to notice the public about Mazda's new rotary engine, RENESIS. RX-8 was never a true successor of the RX-7 even during the design process. I don't think RX-8 will ever have a Mazda stock turbo kit.

    But we could probably wait: Although it is an unofficial news, Mazda already revealed a plan to release the 4th generation RX-7 at the near future. (hopefully the year 2005) Japanese otaku(an expert fan) groups had already got a silouette of the new RX-7's mechanism; it will be a twin turbo RENESIS. (There was a rumor that a 3-rotor RENESIS will be placed on the engine room of 4th gen RX-7. But that's not true. Mazda revealed that due to the new mechanism of the RENESIS engine, it is impossible to add an extra rotor)

    So cool down and wait; the Legendary Rotary Rocket RX-7 will return in the new form of 4th generation, hopefully a twin turbo.
     

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