On 7/3/2014 9:49 AM, Randy Smith wrote:

Folks,

Charlie England wanted more traffic, so I will come out of lurk mode to introduce myself and ask a question or two.

My name is Randy Smith and I live in Columbia, SC and am trying to start building a Cozy Mk-IV.  I've had the plans for over 20 years, but three things have to line up before one can build a plane.  1. Money.  2. Time. and 3. Space.  At any one time, only 2 out of the 3 have ever been in line, but they're beginning to converge.  :-)

I plan to use a rotary in this airplane and I've been listening and learning about it from this list for several years.  A few years ago, a friend of my brother gave me an old Mazda RX-7. It's been an eyesore in my yard and shop ever since.  This car has a 12-A engine with a carb.

My questions are:

1.  Is this a suitable engine for the Cozy Mk-IV, in the horsepower department?
2.  If it is, how hard is it to convert it to fuel injection?
3.  How hard is it to add a turbo charger to it?
4.  Should I just sell the damned thing and get a newer renesis when I get closer to time to needing the engine?

Well, I've just kicked the hive, let's see what you guys think.

Thanks in advance,

-Randy

Hi Randy; welcome to the list!

The 12A will make quite a bit less power (140-160 hp is typical) than a Renesis, unless you heavily modify it. I would think that it will be harder to get parts for it, since it's been out of production for so long, and you're probably going to need parts, if it's been sitting up for years. :-)

I had both a 12A & 13B in my hangar, and bought a used Renesis for my RV-7. FWIW, you can now get a decent used Renesis for well under $2000 (possibly a lot less). That's going to be a very small percentage of the total cost of the plane. Everything around the engine (intake, exhaust, control, reduction drive, etc) will have to be fabricated anyway, so I'd start building the plane and when you get close to needing an engine, *then* start looking for a motor. Otherwise, by the time you're ready to install it, it might need an overhaul just from sitting. Plus, by the time the airframe's finished, Mazda may have the 16X in production. That engine would trump anything else available. I'll give you an example from the avionics world: A couple of years ago, I bought a used, but state of the art autopilot, for 1/2 the new price. Great deal, right? Today, it's still not mounted in the panel, and I can buy a model from the same mfgr that has more features for about the same price I paid 2 years ago for the used one. With avionics and engines, don't buy until you need them.

Converting to FI won't be an issue with any of the newer engines, but could be done on the 12A if you really want to use it.

Dave Leonard & a couple of others have managed to get boosted engines working well, but I think all will tell you that it adds a LOT to the development proce$$.

Charlie
(It's a shame you're not considering an RV-x; there's a great group of RV builders in Columbia.)