Yeah, I figured someone would bring that up...I think the issue there is that the piston speed is monumentally slow. There's no need to worry about how fast your flame is traveling when the piston is moving at glacial speeds. Also I think that one was for a boat, where engine size and weight are less critical. Maybe you could choke down a chevy 502 and run it at 500 RPM, but then it would only be suitable for moving a Geo Metro.

I was wondering about the flame speeds for hydrogen and LNG simply because if they burn faster, then the disadvantage of a large combustion area becomes less meaningful...I would think. (Is there an SAE chart somewhere that shows flame speed for various fuels?) In other words, let's find a fuel that burns faster than gasoline. Or skip the problem altogether and have a compression ignition rotary, or is that even possible?

 

RG already mentioned that if you increase compression by removing the dishes in the rotors, you loose the ability to contain and channel the charge. Therefore, even diesel rotaries used some form of plug AFAIK.

 

Ingersoll made a 2 rotor engine that produced over 1000Hp. The total displacement from the 2 chambers was over 80 liters and produced a record holding 41000 hours of service without overhaul.

Surely MAZDA can adopt this...

 

Ha, it ain't in no car. Its not a rotary either. http://www.bath.ac.uk/~ccsshb/12cyl/

John Deere built a rotary with a 31500 cc rotor, and of course the 21A was 1046 cc per rotor and the 22A (which I don't think was ever built) was planed to be 1169 cc per rotor.

I'm not convinced that a 15% increase in displacement will choke off the engine, even if the port area stayed the same. Redline would probably be down, but peak flow would probably go up at least some, due to increased velocity. Maybe it won't make 273 hp, but Mazda may be more concerned about increasing torque at lower rpms right now, depending on what their plans are for the engine. The rotary failed in the Amati applications not because it wasn't silky smooth, but because it has no low-end torque.

The other thing that people are missing is that the Renesis engine was developed for roughly 15 million dollars; that's not a lot. I suspect the reason Ford lets the guys at Mazda play with their wacky engines is that they do it cheaply. I believe the Renesis costs about $2000 / engine for Mazda to make. And as another poster mentioned, there's only 1 vehicle right now to amortize the R&D. I think everyone (including Mazda) realizes that more rotors would make for a better engine, but they simply don't have the cash to do that right now. I imagine a significant chunk of their R&D budget is devoted towards hydrogen.

 

What about a 1.5L, three rotor with displacement on demand? What I'm thinking is that one of the housings (probably the middle one) would need a valve system that would close the intake and exhaust ports to provide an air spring effect. The outer housings could have the side ports of the Renesis. More displacement, more power, better cruise mileage. BRILLIANT!

Maybe I should patent this....

~ Matt

 

you should because mazda is on record saying they are not goin ganywhere near DOD for rotaries.

 

Awww, I think that would be awesome if they did. Do you happen to remember why they didn't want to do it?

 

President of MNAO was asked as a result of a thread on this forum-

If a larger displacement twin rotor or triple rotor is in the future of the RENESIS and fuel consumption is a concern, can Displacement On Demand (expected in the C6 Vette) be implemented in the rotary engine?

His answer-
No

follow up i believe said they were going in a different direction. And since they had been showing hybrid rotaries before then and since then hydrogen engines and dual fuel hydrogen/gasoline hybrid cars i think we can see that direction clearly.
http://rotarynews.com/node/view/193

 

GM had a 6.4L 4-rotor with 420hp in 1973

 

I may be a bit out of line, but I'd so love to see the 20B or an iteration of a 20B with side ports (like the renesis) pushing "true" 260hp and at least 200LBs torque without a turbo, think about it, no lag, instant 260hp, marvelous I think, a 20B iteration in a production car, I mean why can't they do this?

if pontiac is able to churn out 175hp and 205LB torque from a poorly designed, heavy chunk of a 3.4L v6... and market it in every car from a montecarlo to a grand am... and have people love it... come on? mazda... I don't want to offer comparisons... but mitsubishi knew they made a mistake with the 3rd generation eclipse... this is why the 4th generation pushes 264hp! they listened! for mazda's flagship car to be weak is bad for business I think... and I love my RX-8, I only wished it had a bit more oomph!

 

read the link i gave on why no 3 rotor.

eclipse- 264hp and its still slow

 

Faster than our car :p Engine designs for Rotary have maybe .1% of all the R and D of piston engines. I think Mazda did a kick *** job with this engine, and it will only get better from here. It takes time to improve things, look at the piston engine and how pathetic it was 40-50 years ago. Advances will be on the way over the years.

 

Shoot, the Eclipse isn't THAT much faster, for having all that power. It's so damn heavy, and it's front-wheel-torque-steering drive. If I won the lottery, say, 60-75 mil or so, I'd donate 7 or 9 to Mazda for some R & D. I'd like to see a three-rotor, but I don't think the demand would justify the costs to develop it. But who knows?

 

My personal opinion is that if we see a 1.5L 2 rotor Renesis, it will not have any more power than the current engine as it has no more port area. How could it make any more power? Power is determined by airflow not displacement. It would just be an engine that doesn't rev as high due to airflow restrictions. It might have more low end torque though. People would be pissed off that you would have a larger engine that didn't rev as high and didn't make any more power and probably got less gas mileage. Everyone would feel ripped off and cry about their "missing power". The car isn't even missing any power now.

Not saying a 1.5L 2 rotor won't happen, but it doesn't make as much sense as a 1.5L 3 rotor that could have the necessary intake area and could run smoother. If complexity was really the issue, Mazda wouldn't have ever made a 3 rotor instead of abandoning the 15A and 21A concepts and they wouldn't have ever replaced 1 turbo with 2 smaller more complex and less reliable ones in the RX-7. A 1.5L 2 rotor can not breathe any more than a 1.3L 2 rotor. People only care about peak power. They don't even care about real world performance as long as the power number on paper is high enough. That's what will sell.

 

there is an easy way to make more port area, you only need to make a 4 port engine with aux peripheral ports mazda has done this in the past, the engine works as a 4 side port engine to lets say 5000 rpm and as a peripheral port engine to 10000 rpm, maybe the same way in the exaust side?

what do you guys think?

 

for 7-9 mill you could design your own damn engine.....

 

I'd need more than that. Those engineers are damned expensive...

 

I'm not buying the port size limitation arguments. In the LS7 engine, each cylinder is 875 cc's, and the intake valve size is 56mm, and the lift is 15mm. This gives a max of 2637 sq. mm of intake area. This means it has 3.014 sq mm. of intake area per cc of displacement. So a Renesis with the same airflow requirements should have 1974 sq mm of intake port area per rotor, and a 1.5 Renesis should have 2260.5 sq mm of intake area.

Granted the intake area is a bit deceptive in a rotary due to opening constraints, but is the airflow really all that choked off? I'm finding it hard to believe that a 1.5 would really be that starved for flow with the existing ports.

 

so let me see if I undertand, in essense the 15l wold use 13b renesis street port side housing

I think peripheral aux ports are a better solution even in the 13b renesis and direct inyecccion.

 

We are never going to see peripheral ports appear again due to emissions reasons and their inferiority in this regards.

 

This engine is probably going to be the one that is installed in the future 7 that is supposed to be released in 07

 

...and the fact that the Renesis is that highest output N/A two rotor engine out of the factory (race engines excluded obviously). It nearly puts out as much power as the 13B-REW from the FD. Direct injection will likely improve fuel economy, emissions and may even give the engine a slight boost in power. Who needs peripheral ports?

 

With the new MazdaSpeed 6 out this fall with all wheel drive and over 270 turbocharged hp and Mazda developing a 1.5 Rotory for it's RX, I can't believe they would come out with a new rotory under 300 hp. IMO that just wouldn't make sense. They can't have their family sedan faster than their sports car. The car mags say new RX-7 out as an 07 model predicted 300 hp using the same chasis as the RX-8 and Miata, oops MX-5. No reason not to put it in the 8 too. I also read somewhere that although three rotors was prefered for torque, they couldn't make it pass emissions without the sideport. Hence the Renisis design.

 

Direct Injection also helps with torque (more notibly low end torque) in piston engines... hopefully it will help rotaries as well.

 

Adding horsepower isn't the only way to make the car faster. If they made the Mazdaspeed RX-8 with maybe 250hp and 300lb. lighter, it would be fast...and way faster than the Mazdaspeed 6.