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rotary into a miata

Old 03-23-2009, 12:20 AM
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Join Date: Jan 2009
Location: Knoxville, TN
Posts: 5

Hi guys! New to this forum and glad to be here. I'm somewhat new to rotaries but not to tinkering with cars, and I'm eagerly awaiting my 13b from an 88 rx7 to arrive. Let me give you some background as to why I decided on a 13b. My miata currently has the stock 1.8L four-banger, and its just not satisfying me. Even with cams, ITB's, and a standalone megasquirt, it's only putting out a measly 140whp or so. Also, my engine is getting high in mileage and I just can't **** kick it with confidence anymore.

so, knowing that a good N/A rebuild for that engine would cost $3k+ if I want it to be in the 180whp range, I realized that I could damn near complete a rotary swap and rebuild just by selling my current aftermarket engine parts. Also, no timing belt or valve train just seems so refreshingly simple!

keeping in the spirit of my previous engine, I want to go N/A, at least for now. I'm pretty well versed with messing with ITB's and building megasquirts, so I'd definitely go the EFI route instead of the popular weber carb setup.

So anyway, let me get to the point of this post. I'm getting my whole motorset for around $150 and the engine 'runs but needs a rebuild.' I plan on rebuilding it from the ground up, with the help of a rotary buddy. When it comes to starting an N/A rebuild, what do you rotary gurus have for ideas that immediately leap to mind? important things I should keep in mind?

- what are the best (cheap) rotors to use for N/A?

- does a full bridge port kill mileage compared to a half-bridge? My rotary buddy said something about a lot of overlap killing mileage

- do ITB's kill low end torque because they eliminate the seperation of primary and secondary intake ports, or are there itb kits out there that isolate them? I apologize if this sounds like a really stupid question, I'm a pretty huge rotary noob.

My goals for this swap are:

- hopefully keeping above 16mpg or so (keep in mind miatas are really really light, mine is around 2170 pounds)

- over or around 170whp

- not obscenely loud (regular loud is fine, lol)

do you think itbs would be necessary to reach that goal, or make it a lot easier? I would kinda like to preserve low end if possible.

Thanks in advance for any input! I'll post pics soon of my progress.
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