PR280z Posted February 4, 2012 Share Posted February 4, 2012 I JUST FOUND THIS VID OF AN RX8. Thought it`s kinda neat how it`s setup. Quote Link to comment Share on other sites More sharing options...
Cannonball89 Posted February 4, 2012 Share Posted February 4, 2012 (edited) "Kinda neat"??? It's flippin awesome dude lol. Four rotors are amazing. And the stand-off injectors are just icing on the cake. When I have accumulated a comfortable amount of wealth I plan on building one some day. I just don't know what kind of car I want to put it into... Edited February 4, 2012 by Cannonball89 Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted February 4, 2012 Share Posted February 4, 2012 I have always wanted to get 2 13b motors at pick&pull and see what it would take to put them together.On a track day at thunderhill there was a fd model rx7 with a 20b 3 rotor running and that engine sounded like a F1 engine-it had plenty of power with no turbo.In southern california the sand rail guys use turboed 20b's in 1800lb sand rails-600 hp no problem.The length of the z car engine compartment makes engine swaps easy. Quote Link to comment Share on other sites More sharing options...
Cannonball89 Posted February 4, 2012 Share Posted February 4, 2012 I have always wanted to get 2 13b motors at pick&pull and see what it would take to put them together.On a track day at thunderhill there was a fd model rx7 with a 20b 3 rotor running and that engine sounded like a F1 engine-it had plenty of power with no turbo.In southern california the sand rail guys use turboed 20b's in 1800lb sand rails-600 hp no problem.The length of the z car engine compartment makes engine swaps easy. If you search around (I can't remember if it was on this site or another, maybe a mazda site) There is a guy who I think was doing tractor pulls who simply welded the eccentric shafts of two 13b motors together and had the motors mounted one in front of the other. But since the 13b has it's firing order phased 180 degrees apart, you would have to mount one engine "on it's side" in order to recreate the 90 degrees of seperation between ignition events that true four rotors have. It would certainly be an interesting project. You can also buy four rotor eccentric shafts for around $5000 USD last time I checked. I wouldn't want to put a four rotor in a Z for personal reasons that may sound stupid to some of you. I just think that the L6 engines have their own unique and awesome sound (especially in N/A form with headers) and have enough potential power with proper modifications to the cylinder head and camshaft etc. that I couldn't see putting anything else into a Z. If I was going to do a four rotor it would have to be into either some kind of Mazda, or into a prototype-style racecar that I would design from the ground up (another one of my dreams). Quote Link to comment Share on other sites More sharing options...
bradyzq Posted February 4, 2012 Share Posted February 4, 2012 Since he welded the cranks anyways, can't you just turn one 90 degrees? Quote Link to comment Share on other sites More sharing options...
roger280zx Posted February 5, 2012 Share Posted February 5, 2012 (edited) Since he welded the cranks anyways, can't you just turn one 90 degrees? I'm not a rotary guy, but quite simply no. Because rotary engines have no cams, or valves for that matter, the timing is entirely controlled by the position of the ports on the block (excuse me if my terminology is not correct); therefore, just turning the crank will not create the desired effect. Edited February 5, 2012 by roger280zx Quote Link to comment Share on other sites More sharing options...
mutantZ Posted February 5, 2012 Share Posted February 5, 2012 Wouldn't this technically be a 12 cylinder engine? Quote Link to comment Share on other sites More sharing options...
Gollum Posted February 6, 2012 Share Posted February 6, 2012 Actually rotating the crank will change the timing as the timing of events is based on the ROTOR in relation to the HOUSING. since the crank is tired to the rotors at a 3:1 ratio then spinning the cranks away from either 60 degrees would give you a net effect of being in sync. If you wanted the timing separated you'd want a 30 degree split, but you'd still end up with twerp rotors in sync I believe. That's something that's avoided in the custom shafts I believe. All that said, I've been saying for a while that an adapter to bolt onto the rear snout to the front pulley would be much cheaper and make more sense for that average car project... Quote Link to comment Share on other sites More sharing options...
circasurvive Posted March 6, 2012 Share Posted March 6, 2012 Wouldn't this technically be a 12 cylinder engine? I believe that is correct. 2 rotors are equivalent to a 6 cylinder from what I was told. So I guess a four rotor is equivalent to 12. Absolutely love the sound of an NA rotary Quote Link to comment Share on other sites More sharing options...
zgeezer Posted March 6, 2012 Share Posted March 6, 2012 I have always wanted to get 2 13b motors at pick&pull and see what it would take to put them together.On a track day at thunderhill there was a fd model rx7 with a 20b 3 rotor running and that engine sounded like a F1 engine-it had plenty of power with no turbo.In southern california the sand rail guys use turboed 20b's in 1800lb sand rails-600 hp no problem.The length of the z car engine compartment makes engine swaps easy. Not a problem, here's the kit. Not quite cheap, but fun back in the day: 1 RX100 + 13B+ 5sp manual + Racing Beat intake, matched headers, exhaust port plugs, light flywheel and bridgeporting = 195 hp (or so) out of 1.3 liters. There is NOTHING in this world that sounds like an uncorked rotary at about 8,000 rpm and climbing. I'm sure a four rotor could break windows at 1/2 mile. The problem at the time was keeping them together for anything over 50,000 miles. Gas mileage was something you could write home about.....something along the lines of that 440 Monaco cruiser the CHP was using. g Quote Link to comment Share on other sites More sharing options...
Gollum Posted March 6, 2012 Share Posted March 6, 2012 Not a problem, here's the kit. Not quite cheap, but fun back in the day: 1 RX100 + 13B+ 5sp manual + Racing Beat intake, matched headers, exhaust port plugs, light flywheel and bridgeporting = 195 hp (or so) out of 2.6 liters. There is NOTHING in this world that sounds like an uncorked rotary at about 8,000 rpm and climbing. I'm sure a four rotor could break windows at 1/2 mile. The problem at the time was keeping them together for anything over 50,000 miles. Gas mileage was something you could write home about.....something along the lines of that 440 Monaco cruiser the CHP was using. g Correction in bold. Pretty much all racing bodies call it a 2.6 liter, as that's the actual displacement that is displaced during 720 desgrees of rotation. If you're comparing the rotary to a 2 stroke, then yes, you can call it a 1.3 liter, but then it still starts to look like an only "average" HP per liter motor, which it generally is. Quote Link to comment Share on other sites More sharing options...
Nizm0Zed Posted March 6, 2012 Share Posted March 6, 2012 (edited) iirc, once you start getting high power 3 rotor and 4 or more rotors, you have a LOT of trouble controlling the twist of the motor. Probably need to start bracing them externally. Having said that, watching Mad Mike (from New Zealand) in his quad rotor RX7 drifting Eastern Creek Raceway during the World Time Attack Challenge was absolutely epic. And my god, the sound.... Edited March 6, 2012 by Nizm0Zed Quote Link to comment Share on other sites More sharing options...
zgeezer Posted March 7, 2012 Share Posted March 7, 2012 Correction in bold. Pretty much all racing bodies call it a 2.6 liter, as that's the actual displacement that is displaced during 720 desgrees of rotation. If you're comparing the rotary to a 2 stroke, then yes, you can call it a 1.3 liter, but then it still starts to look like an only "average" HP per liter motor, which it generally is. Hmmm, and I thought that was just a ploy by various racing bodies to legislate the rotary out of contention. I remember Vacaville quite well... lived there for a number of years just off Main and Kentucky, taught school at Vanden, racked up 300 hours puddle jumping from Nut Tree Airport to dirt strips in Dixon and Rio Vista, and got absolutely wacked at Putah creek (now, that is an interesting name and spelling). Stop by every now and then to eat at Murillos. Just like we used to in the early '70's. Still in business, no change in seating and still great food. Good place to live, I can envy you. G Quote Link to comment Share on other sites More sharing options...
Gollum Posted March 7, 2012 Share Posted March 7, 2012 Yea I'm downtown too, just one block off main st towards the high school. I've been here a year and a half and I really like it. I'm originally from Richmond from the bay area, then Benicia for a short while, and now Vacaville. Quote Link to comment Share on other sites More sharing options...
stony Posted March 9, 2012 Share Posted March 9, 2012 Correction in bold. Pretty much all racing bodies call it a 2.6 liter, as that's the actual displacement that is displaced during 720 desgrees of rotation. If you're comparing the rotary to a 2 stroke, then yes, you can call it a 1.3 liter, but then it still starts to look like an only "average" HP per liter motor, which it generally is. Isn't it 2.9 since 1.3 is one side of each rotor? 1.3+1.3+1.3= 2.9. Quote Link to comment Share on other sites More sharing options...
Nizm0Zed Posted March 9, 2012 Share Posted March 9, 2012 (edited) so where did you go to school? 1.3 + 1.3 + 1.3 = 3.9 1.3 + 1.3 = 2.6 This is a really crude way to explain it, but, bear with me. The rotor has 3 combustion chambers for each rotor. For a 13B they are 654cc for EACH chamber. the combustion chamber is the machined hollow in the face of the rotor. 2 rotors equal 6 in total. The engine is a 4 stroke motor, so at any given time when running, (talking about a twin rotor now) you'll have 2 combustion chambers in induction, drawing a fuel/air mix in, 2 chambers compressing and igniting the fuel/air mixture and the last 2 chambers exhausting the burned remains (and sounding like a pack of angry wasps) In a complete rotation (720 degrees, like a 4 stroke petrol motor) the engine will only use 2 of its 3 combustion chambers per rotor. So, looking at that, there are only ever 4 combustion chambers with any fuel/air in them at any given time in a 720 degree engine cycle. 4 chambers at 654cc = 2616cc understand? Like i said, very crude. Edited March 9, 2012 by Nizm0Zed Quote Link to comment Share on other sites More sharing options...
Nizm0Zed Posted March 9, 2012 Share Posted March 9, 2012 That may help you to visualize it. Quote Link to comment Share on other sites More sharing options...
stony Posted March 9, 2012 Share Posted March 9, 2012 HAHA That was obviously a typo. Thanks for the crude explanation. Quote Link to comment Share on other sites More sharing options...
Gollum Posted March 9, 2012 Share Posted March 9, 2012 Apparently Stony needs to stick to RBs... And actually, the Wankel operates more like a two stroke, especially if you consider the fact it needs oil mixed into the fuel for chamber lubrication, just like most 2 strokes. Where the whole things comes crashing down in comparisons between typical 4 stroke piston engines and the wankel is that the wankel is internally geared down in how the rotor spins the "crank". It's geared 3:1, so for every one rotation of the rotor you have three rotations of crank (eccentric shaft, but using the term crank for us piston heads). Mazda could have geared this anyway they wanted, and if it were 1:1 we wouldn't think of the 13B/renesis as a "high revving motor" like we do. Mazda could have also geared it 5:1 and we'd be looking at their 1.3 liter as the most torque less motor in the world as you'd have to wind it up to 3k to get it off the line in 1st. So if you wanted to get really picky, the motors should be calculated per each rotor surface, but then most aspects of the motor wouldn't "add up" to specs that make any sense. This is just because they really are apples to oranges. Quote Link to comment Share on other sites More sharing options...
stony Posted March 9, 2012 Share Posted March 9, 2012 (edited) All i know about rotaries is they sound really cool and they blow up really easy ..... blew up 3 of them before my rb days ;> Edited March 9, 2012 by stony Quote Link to comment Share on other sites More sharing options...
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