Okay, this is something that I've been wondering. I've seen computational models to approximately simulate the airflow through a boinger given such things as valve events and whatnot... and from this approximately calculate horsepower.

I'm just wondering if anyone has such a model for a rotary, or has heard of such a thing. I'm working on delving as deeply into various SAE papers as I can in the hopes of making such a thing (eventually!) but has anyone heard of anyone else publishing such a thing? It seems to me that the geometry is well known, so it should be possible to calculate the flow through the ports at various configurations. I mean, the port timing and location of corner / oil seals directly dictates the shape of the ports, so it should be possible to have a model where you can plug in port timings and get approximate volumetric efficiencies at various RPMs.

Anyway. As I said, has anyone heard of such a thing for rotaries, or am I going to have to make it myself?

 

This would be sooooo cool if it exists.

 

I believe a friend i knew back in san antonio that he worked at Soutwest Research Institute and they did a test of how a rotary intake flow and got numbers using radiation. They threw the motors away when they were done because of the radiation. Maybe you can find some info from them, if this guy was telling the truth

 

Well, that's sorta like the other end of things, really. What I want to do is come up with a way to test unconventional porting configurations and come up with a simulated dyno that's somewhere vaguely close to what it would really do. It sounds like they were trying a more practical solution.

Sounds like I might be making a visit to the engineering library again.

 

I've looked pretty hard for one and have asked in another forum to no avail. If one exits I haven't been able to find it. People seem to kind of blow it off, I think due to the perceived complexity when thinking of all of the variables.

I'm like you in thinking it shouldn't be that hard to do. You would be doing the rotary community a huge favor if you came up with one. It would help out in a big way when trying to figure out what turbo to run. Giving you can get the maps for the turbos you're looking at.

Once developed it seems like you could compare it to the real world if you could get someone that has kept good records to give them to you along with dyno #s.

Go for it. If you want something done right, you've got to do it yourself.

 

I did come across a very detailed spreadsheet for clculating output from a rotary but its far from a full engine model. it does not allow for varying port sizes, shapes and timeing

i will post it here if i can find it

 

Hee hee... yeah, that last is probably going to turn out to be true. At first, it's probably just going to be an NA model, as that's pretty much the basis for everything else. As to comparing it to the real world... well, this thought occurs to me. See, I'm working on a degree in Mechanical Engineering (automotive reall,y but here they're basicially the same) and it seems to me that it would be a neat senior project. IE, come up with the best mathematical model I can, and then use the machine shop on campus (hee hee hee) to get various ports cut, including peripheral. And then dynoing the engines to see how accurate the model is.

... but that may be a bit beyond the scope of an undergrad senior project. Would look pretty impressive to a lot of people that I'd want to work for later tho.

You're right though, I hadn't even thought of combining this with a way of calculating turbochargers! Wow... hee hee hee.


Okay, so I basicially want to single-handedly advance aspects of rotary engine tuning. Yeah, I might be being a bit ambitious. There's probably good reasons why nobody's done what I want to (or maybe Mazda has and just hasn't published). But... well hell. It's good to have goals, right?