News

For Rob or anyone who knows MAZDA Rotary

Discussion in 'Other Off Topic Forum' started by writerguy, Feb 26, 2004.

  1. writerguy

    writerguy F1 Veteran

    Sep 30, 2003
    6,786
    NewRotic
    Full Name:
    Otto
    Ok
    I have been driving the RX8 for 4 days now (media car) and I have noticed something that I don't know if it is typical due to limited exposure to Rotary.

    This is a VERY free spinning engine

    ENGINE






    Type RENESIS 13B twin rotor

    Displacement 1.3L

    Bore x Stroke N/A

    Compression Ratio 10.0:1

    Output (SAE net) 4AT:* 197 hp @ 7200 rpm*
    6MT:* 238 hp @ 8500 rpm

    Torque (SAE net) 4AT:* 164 lb-ft @ 5000 rpm

    6MT:* 159 lb-ft @ 5500 rpm

    Redline 4AT:* 7500 rpm, 6MT:* 9000 rpm

    Transmissions
    Type Rear-wheel drive
    Transmission 6MT 4EC-AT


    Now The 6 speed Manual I am driving seems to have, well almost a two stroke power band.. It does not seem to have a BIG seat of the pants Tourque pull like the 350z or others but it winds up to 5500 rpm and seems to really come alive all the way to the 8500 area.

    the question is.
    Is this typical of a Rotary or am I feeling something that is not there but just in my brain......
     
  2. To remove this ad click here.

  3. dan360

    dan360 F1 Rookie

    Feb 18, 2003
    2,669
    Boston
    Yep - typically rotary kind of attribute. Apparently the Auto is tuned for more torque (as per your note). I drove an RX-8 6-speed at the weekend (thought I might get one as a day to day car) and i really liked it, obviously not much torque but if you like the revvy nature of a 360, then an RX-8 has that appealing red line. The dash is great - not a bad buy for 30K!
     
  4. writerguy

    writerguy F1 Veteran

    Sep 30, 2003
    6,786
    NewRotic
    Full Name:
    Otto
    I agree with everything you said just not used to it and where I end up with so many different vehicles it is a change I wanted to confirm with others.

    Usually my "seat of the Pants" is pretty well adjusted but it seemed odd so THANKS for the input.
     
  5. rob lay

    rob lay Administrator
    Staff Member Admin Social Subscribed Miami 2018 Owner

    Dec 1, 2000
    50,985
    Southlake, TX
    Full Name:
    Rob Lay
    My 12A rotary has torque numbers almost with the HP. I think my #6 has 117 RWHP and 103-105 torque. I'll have to look at the dyno chart again, but the power is there above 5k all the way up to how far you want to go. You can't blow these engines by reving them, but you can overheat them easily.

    How a rotary works...

    http://www.geocities.com/MotorCity/Garage/7365/docs/how.html
     
  6. writerguy

    writerguy F1 Veteran

    Sep 30, 2003
    6,786
    NewRotic
    Full Name:
    Otto
    Thanks Rob You the man
     
  7. To remove this ad click here.

  8. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    7,058
    What you are seeing is a combination of things:

    1) The wankle engine has taken a thermodynamic process of a 4 stroke engine and compressed the 4 strokes into a single rotation. In effect, this makes the engine have HP numbers more like a 2-stroke engine than like a 4-stroke engine of the same displacement.

    2) Without the reciprocation of pistons and valves, there is little power consumed in simply rotating the engine over and over. Heck the valve train basically doesn't move! (*) Then it is half the size of a reciprocating engine of similar power levels, so it has the rotational inertia of a very small engine.

    3) the only drawbacks of the wankle are: A) large piston surface area make emissions harder than piston engines, B) the seal between the sides of the piston and the chamber wall adds friction, C) the intake and exhaust ports are timed by rotation and can't be altered easily (like changing the cams), D) compact design makes it hard to adequately cool the internals in high output conditions.

    (*) the vavle train moves by changing port size to match the flow characterietics of the intake ports to the rotating piston. The valve train does not open and close like a reciprocating engine valve train moves.
     
  9. writerguy

    writerguy F1 Veteran

    Sep 30, 2003
    6,786
    NewRotic
    Full Name:
    Otto
    Thanks Mitch....


    (ya gotta love Ferrari chat for being a great resource of information)

    You guys ROCK
     
  10. Dale

    Dale F1 Veteran

    Oct 7, 2003
    5,211
    uk
    Full Name:
    Dale Juan
    Hi all,we use'd to service a couple of rx7 turbo 2's,yep they will rev up a treat
    just the cornering ability was somthing to be desired NOT,
    Im sure mazda's rx8 is now much better from what ive read,havent had the chance to drive one yet,

    Dale.
     
  11. rob lay

    rob lay Administrator
    Staff Member Admin Social Subscribed Miami 2018 Owner

    Dec 1, 2000
    50,985
    Southlake, TX
    Full Name:
    Rob Lay
    Those are the 2nd gens, right? The 3rd gens handled amazingly well, they won several national autocross titles in Super Stock. However, 3rd gens had quite a few engine problems. No engine should require rebuilds every 40-50k miles on the street.
     
  12. To remove this ad click here.

  13. Dale

    Dale F1 Veteran

    Oct 7, 2003
    5,211
    uk
    Full Name:
    Dale Juan
    Hi Rob,bit of a story on the engine side Rob,one of our cutomers who had a 7 turbo 2 filled up with petrol went to pay came out would'nt start,got it feched in totaly locked up,we couldnt belive it the rotor had just split in half,
    how wierd is that drove on for gas went to pay split rotor no go,we dont do rotory engines so the job was done by somone else,nice engine though love the high rpm,

    Dale.
     
  14. Johnny Bravo

    Johnny Bravo Formula Junior

    Jul 22, 2003
    532
    DC Metro/MD
    Full Name:
    Ben
    I'm a self confessed rotorhead :D and have owned a 3rd gen twin turbo RX-7 in the recent past (I'm still looking for an elusive Series V 2nd gen GTUs). The natural simplicity of the Wankel designed rotary engine is much of the reason why it's so smooth and "free spinning" as you experienced. In a basic 2 rotor engine there are essentially only 3 moving parts (2 rotors and the eccentric shaft) and as they're going in an elliptical motion the vibrations caused by the up & down motion of the reciprocating piston engine aren't really there. I suppose technically a rotary engine, if designed properly and strong enough, could rev almost unlimited. There are some single rotor industrial applications that if I recall correctly can run upwards of 30,000rpms. Even a monster ported, bridge ported, or peripheral ported 12A or 13B (which some Spec 7 run) can turn upwards of 10,000rpm. The downside to this major port work though is that there is a drastic decrease in torque & reliability. From my limited understanding of the RENESIS (I just haven't been reading up on it as much as I would like to due to time constraints) is that its more or less like a peripheral ported rotary, but it's hard to relate the two as the rotor housings in the RENESIS are of a new design and not quite like the "old" rotary design although not entirey dissimilar either (um, if that makes any sense :)) I'm just hoping Mazda, if they decide to continue developing the RENESIS, brings back a 3 rotor version of the engine such as they had in the JC Cosmo's or at least slap a turbo or supercharger on the current 2 rotor RENESIS. Multi-rotor (erm, well more than 2 rotors that is) engines are really gaining big popularity in places like Australia so hopefully Mazda will get the hint that people like big horsepower AND torque. Just as long as they work the bugs out of the system and train their mechanics before unleashing a complicated sports car on the public like the did with the 3rd gen RX-7.
     
  15. rob lay

    rob lay Administrator
    Staff Member Admin Social Subscribed Miami 2018 Owner

    Dec 1, 2000
    50,985
    Southlake, TX
    Full Name:
    Rob Lay
    Dealer told me there will be a turbo version of RX-8 after they turbo the Miata, then in a few years they'll have a new RX-7 with more HP than the 8. Can anyone confirm?
     
  16. sherpa23

    sherpa23 F1 Veteran
    Silver Subscribed Owner

    May 28, 2003
    9,501
    Colorado
    Full Name:
    Bastuna
    I remember one of the car magazines last year had artist renditions of the next gen RX-7 due out in Japan in 2006. It looked awesome. Nothing like the Rx-8.

    Rob, that was an awesome website. I never understood how those things worked.
     
  17. writerguy

    writerguy F1 Veteran

    Sep 30, 2003
    6,786
    NewRotic
    Full Name:
    Otto
    Yeah Rob that site put the "knowledge" into a pretty easy to under stand fashion. It was great.
     

Share This Page