From: "Charlie England" <flyrotary@lancaironline.net>
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Date: Thu, 03 Jul 2014 16:04:10 -0500
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: What to do with this Mazda
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On 7/3/2014 2:38 PM, Randy Smith wrote:
> See my responses below...
>
> On 07/03/2014 11:58 AM, Charlie England wrote:
>> 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!
>
> Thank you.  I wanted to drive over to visit with everyone at the 
> slobovia event, but after I looked at how far it was and the time 
> involved,  I decided to save my vacation time for another time. :-(  I 
> understand I missed a good time.
>>
>> 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 will need between 180-200 hp.  I want to keep the engine as close to 
> stock as I can so perhaps this isn't the engine I need.
>>
>>
>> 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.
>
> Good advice.  I can certainly wait on both and hope for the 16X.
>>
>>
>> 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$$.
> Is there a difference between boosting an engine to get more power and 
> boosting to maintain sea level pressure up to a point so that higher 
> altitude operation is possible?
>>
>> Charlie
>> (It's a shame you're not considering an RV-x; there's a great group 
>> of RV builders in Columbia.)
> Yeah, I briefly hung out at the local EAA hangar and found out real 
> fast that most of them were building RVs.  Great bunch of people, just 
> not a lot of glass experience.
>
>
You definitely can 'turbo-normalize' to maintain sea level power at 
altitude. But it's still much more $complicated$ than adding 
displacement, even with a rotary. Having said that, I couldn't afford to 
feed 200 hp continuously.
(200 hp * .55 lbs per hp per hour)/6 lbs per gallon = ~18.3 gallons per hour

Too rich for my blood.

I spent a few days (for work) in Columbia several years ago. Loved the 
town (I'm crazy about university towns), & had a great time hanging out 
with some of the RV guys at the downtown airport.

Get to know the RV guys; maybe one of them will get a wild hair & decide 
to bring you to the next rotary event for gas money. :-)

Charlie