Ok, let's see if I can make this short and simple. I am planning on installing a Mazda RX-7 (13B) rotary engine in my aircraft. The reason is very simple--cost. I was interested in Jan Eggenfellner's Subaru firewall forward package, because I really wanted to get away from the aircraft engines with their high initial cost and expensive parts. Also, I liked the marketing hype on Jan's website about the benefits of a modern auto engine (water cooling means no shock cooling, more modern and reliable ignition, smooth operation, near FADEC control, etc.) However, after following the Yahoo SubaruAircraft list for the last year, it was apparent that the cheaper auto engine was steadily rising above $36,000. This is more than I could reasonably put on a credit card, so it looked like I would have to get a loan in order to complete the project.
Then, George McQueen got me to look at Tracy Crooks website, again. I had seen Tracy's website before, but back then, I was more interested in a firewall forward package. After doing some research, I am convinced that a 150-160Hp rotary installation can be done for between $12,000 and $15,000. Now, maybe that firewall forward package is not such a requirement. In fact, I think the challenge will be a lot of fun. I am really excited about taking this on.
Of course, this is going to take a lot more work, require some experimentation, and maybe even have some more risks, but I think saving $10,000 - $25,000 is worth it. Did I mention how much fun this is going to be?
There are a lot of other reasons to use the rotary engine, but instead of just rehashing what a lot of other people have already written, I will refer you to Todd Bartrim's website, which pretty much sums up the benefits of the rotary. Also, look at Ed Anderson's Summary of Design Adaptations for Mazda Wankel 13B Engine Aircraft Use, and John Slade's Cozy . Both of these websites have great information. I should note, that I have never driven a rotary, so I cannot attest to the claims. However, the physics behind the rotary does seem to make sense--either you're a believer or you're not.
Here's a look at the Mazda 13B numbers:
| Item | Low | High |
| Engine | $2500 | $3500 |
| Propeller | $1000 | $2000 |
| PSRU | $2500 | $3000 |
| Engine mount | $1500 | $1500 |
| Intake system | $ 500 | $1000 |
| Exhaust system | $ 500 | $1500 |
| Plumbing | $ 500 | $1000 |
| Cooling | $ 500 | $2000 |
| Ignition | $1500 | $2000 |
| Engine monitor | $1000 | $2000 |
| ------ | ------ | |
| $12000 | $19500 |
I promised to include some links for rotary information, so I have added a number of links to my links page. The best place to start is Tracy Crook's website. That will get you to just about everything else.