| T O P I C R E V I E W |
| picodroid |
Posted - Feb 07 2014 : 04:17:12 AM
Hey Aaron, and anyone else that may venture upon this post.
I've been familiar with rotaries for a long time, but only knew very basics. I was looking for some more details and felt this a suiting place to ask. So here's a list of some questions I have.
1. What's the general range, in degrees, for the intake, compression, combustion, and exhaust cycles on a rotary? Such as intake during 10 degrees to 40 degrees, etc. I understand it's not always the same and port size and easily vary this, but a general range would be nice for each stage.
2. In a perfectly ideal situation, how many degrees after the point of combustion would you still be making decent power to the crank from the rotor? That is, let's say it combusts at 90 degrees, would power drop off enough at 200 degrees, or could you push it to 220, etc?
3. What are the pros and cons of using side ports vs peripheral ports for intake and exhaust?
4. Has anyone ever done side intake and exhaust ports, along with peripheral ports on both the outer irons and center iron? It seems to be side ports, peripheral ports, or side and peripheral from the center iron only.
Any info provided on this stuff would be really appreciated. And if you see this Aaron, I watched all of your build videos for your Cosmo in the past two days and I'm looking forward to watching your progress. You do excellent work and I'm envious of all the tools and skills at your disposal! |
| 2 L A T E S T R E P L I E S (Newest First) |
| picodroid |
Posted - Feb 11 2014 : 06:28:58 AM
Awesome, thanks for those great links and your input!
Thinking back to your video on porting your engine for the Cosmo, I can see why the full peripheral plus side ports would only be good at high RPMs. |
| Aaron Cake |
Posted - Feb 08 2014 : 10:29:03 AM
quote:
Originally posted by picodroid
1. What's the general range, in degrees, for the intake, compression, combustion, and exhaust cycles on a rotary? Such as intake during 10 degrees to 40 degrees, etc. I understand it's not always the same and port size and easily vary this, but a general range would be nice for each stage.
http://www.tmp.rotaryengineillustrated.com/re101/ports.php
That covers opening and closing port timings.
quote:
2. In a perfectly ideal situation, how many degrees after the point of combustion would you still be making decent power to the crank from the rotor? That is, let's say it combusts at 90 degrees, would power drop off enough at 200 degrees, or could you push it to 220, etc?
There is no ideal. It depends on the geometry of the engine, porting, mixture, load, etc.
Mazda has an extensive set of SAE paper detailing their research which is probably the best place to start for all these gritty details.
http://www.sae.org/search/?content-type=%28%22PAPER%22%29&qt=mazda+rotary&x=10&y=5
quote:
3. What are the pros and cons of using side ports vs peripheral ports for intake and exhaust?
http://www.mazdarotary.net/porting.htm
quote:
4. Has anyone ever done side intake and exhaust ports, along with peripheral ports on both the outer irons and center iron? It seems to be side ports, peripheral ports, or side and peripheral from the center iron only.
Yes. This configuration is sometimes used in high HP racing engines. Or sometimes smaller peripheral ports in combination with side ports are used for street applications (semi-peripheral).
Semi-peripheral engines act much like bridgeported enignes, through a bit more well behaved.
Full peripheral w/side ports essentially act entirely like peripheral ported engines. There is so much port area that these engines are high RPM only.
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