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I'm also running 87 octane, but now that you mention it, I'm wondering if I should run 91. I have the stock low compression (turbo) rotors in mine, so I "assume" that 87 octane is OK. I'll be interested to see what kind of feedback you get on this.

I'm not sure what Mazda required for the 2nd gen turbo, but I would never even think about running 87 octane in a turbo rotary. I know that the FD required premium, and they weren't kidding. I'd bet that using regular 87 octane fuel probably killed more FD engines than anything else. My advice would be to immediately switch the the highest octane you can get, particularly John, since he's running higher boost levels. Also, make sure you keep the mixture quite rich during boost time.

John, since everyone's picking on your prop, I guess I'll pile on. Remind me again why you want this oversize prop? Are you trying to set max speed cruise at some low rpm like 5000? On the list of safe ways to increase power in a rotary, running higher rpms is probably number 1, and turbo charging is waaaaaaay down there. I think you'll be much safer with 7000 rpm, and minimal boost, vs 5000 rpm and lots of boost.

I believe Ed has mentioned before that you can't just look at the top power number when setting up a prop for your engine. The rotary doesn't produce a ton of power at low rpms. (Lots of made up figured follow) If you told Clark that you would be making 250 HP at 6000 rpm, then I'm sure he would be able to make the prop correctly for that amount of power. The problem is that the same prop might require 150 HP to turn at 4000. Even with a turbo, the rotary probably will have trouble making that due to the low RPM. In other words, your prop might be just right for max power, but "you just can't get there from here".

Cheers,

Rusty (probably raining out my engine run)