Real World Solutions, Inc
Home of RA Classic Apex Seals and RA Super Seals
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We welcome any & all questions and will make every effort to answer them here. If you are seriously contemplating installing a rotary in your airplane, we recommend that you get our “Aviator’s Guide to Mazda Rotary Conversion.” It will probably answer questions many of your questions. For questions specific to the Aviation Parts (EC2/EC3/EM2/EM3/PSRU) please click HERE. What year oil pan is best to use? What spark plugs do you recommend? HELP! I installed your O ring kit (or overhaul kit) and I have extra O rings. What did I do wrong? Any suggestions regarding fabrication of the Renesis intake manifold? I removed the oil injector pump per your suggestion. What do I do with with holes left behind? I want to use the Renesis engine.
What model should I get? What accessories should I ask for? Why is our rotary RV-8 project going so SLOWLY? What is an RVotter and why is that the name of Tracy's rotary powered RV-4?? Q. Many states are adding ETHANOL to all but high octane MoGas. Does this impact the fuel pumps you sell? What other considerations are there surrounding ethanol in MOGas for aviation use? A. The fuel pumps we sell are commonly used in cars and trucks. Because of this, we assume that they will not be damaged by ethanol. However, we do NOT manufacture the pumps so we cannot give 100% assurance that this is the case. Note that we DO fly the pumps in our own planes, for what that is worth. On the topic of ethanol, it needs to be said that there are other issues surrounding the addition of ethanol to fuel for aviation use. Ethanol by itself is NOT corrosive. However the WATER it attracts IS corrosive. Ethanol is hydroscopic and absorbs water from the air (and your fuel system is vented so there is air in the system). One issue of this is that if you are flying at high altitudes OR whenever operating in freezing temperatures, the water in the fuel system could freeze. This IS (obviously) a serious concern. By the way, you can write your congressman and thank him/her for imposing this insanity on you. Adding the ethanol helps NOTHING. The original intent of ethanol was as an oxygenate which is no longer required by todays EFI systems. Now the claim is that the use of ethanol will allow the USA to be more fuel self sufficient which, for MANY reasons, it does not. It takes about as much energy in fossil fuels to make the ethanol as the ethanol delivers when burned. Does this make sense to you? Much information is available on the web about this topic if interested. Q. HELP! I installed your o ring kit (or overhaul kit) and I have EXTRA O RINGS left over. What did I do wrong? A. The O ring kit (which is included in the Overhaul kits) are UNIVERSAL (to fit 1986- 1995 engines). Because of this, we include 2 different oil cross over rings. You only need to use the ONE that fits your engine year. Also, we include the INJECTOR DIFFUSER O rings and CRANK ANGLE SENSOR o rings in the kit. Many builder's forget to replace these O rings and are a common cause of "extra" O rings. Q. Do the fuel pumps you sell have a check valve? How do you recommend routing the fuel system? Do I need to have a 6-way valve or electric lock out valves? A. The fuel pumps we well DO have a check valve. However, before designing your fuel system using 6 way valves, electric lock out valves, etc. please consider the following design that Tracy uses: Tracy always DRAWS and RETURNS to the same fuel tank. He has the 2nd fuel tank plumbed in to the RETURN LINE of the primary tank. When he needs more fuel in the primary tank, he turns on a small, low pressure transfer pump and transfers fuel from the secondary tank to the primary tank. I already know the next question - what if the transfer pump fails? He ALWAYS transfers fuel with at least 1 hour of fuel left in the primary tank, allowing him to land at an alternative location in the event of transfer pump failure. Of course he leaves a large margin of safety if flying in remote or hazardous terrain. He also has an alert set up on his EM2 to remind him to check the fuel in the primary tank AND he has an alarm to remind him to turn off the transfer pump. All in all it is a simple and lightweight solution to the fuel design problem. Q. I want to use the Renesis. What model should I get? What accessories should I ask for? A. Tracy recommends the 4 port Renesis (from a RX-8 with an automatic transmission). The reason for this is: - it allows for a simpler manifold design - it will already have the automatic transmission counterweight (which is required for all our gear reduction drives). If you plan to use our gear drive, you also need a fly wheel (also called a flex plate) from an RX-7 car 1986-1991 model years. If you decide to get a 6 port engine, you will need to REMOVE the manual transmission fly wheel and install an automatic transmission counter weight from a 4 port/automatic RX-8. You also need to get the RX-7 1986-1991 fly wheel (flex plate). Note: As of the 2007 model year ALL RX-8 cars (both automatic and manual) will have 6 port engines. If you acquire a 2007 or later engine, try to get an AUTOMATIC transmission engine as it will already have the required automatic transmission counter weight. Accessories Try to get the Renesis coils, injectors and fuel rails. The 6 port engine comes with 6 injectors - 4 yellow and 2 red. Tracy suggests using only FOUR of the 6 injectors - the 4 YELLOW injectors. You can use the stock fuel rail to fabricate the fuel rails for your installation. You can use the Renesis coils on the plane. If you do not get them with the engine, they are very expensive to purchase so.. instead, use the AC Delco LS1 coils. They cost less and are a little lighter. Q. What horsepower can I expect to get from the Mazda rotary? A. A relatively stock 13B two-rotor engine used in the RX-7 will deliver from 150-200 hp in aircraft service. You may hear stories about 400 hp or more from other sources. When modified, this kind of power can be had for racing and other short duration uses but it has no relevance if you want to fly with this engine. When turbocharged, up to 275 hp could be used for take-off & initial climb but continuous power should be limited to around 170. The exact horsepower you get will depend on your choice of intake systems. A very simple manifold like the one I originally used with three Mikuni motorcycle carbs will produce about 160 hp at 6000 rpm. The somewhat better tuned manifold I now use with the EC2 EFI system produces about 180 hp at the same speed. Construction of this manifold (built from pieces of the stock system) was covered in our newsletter, “Rotary Aviation News.” An optimally tuned manifold will get you close to 200 hp. By using an RD-1C gear drive and increasing engine rpm to 7200, I was able to get about 200 hp for the Sun 100 race in 2004. Exhaust tuning is not as critical as the intake system on the rotary. Any low restriction type system will work adequately. I do recommend a muffler as the exhaust note from the rotary at full song can be un-nerving. I originally built a simple muffler using a 15 inch length of 6 inch diameter pipe which makes my RV-4 quieter that the Lycoming powered version. Details of manifold & exhaust construction are in the conversion guide we publish. All rotary exhaust systems should be constructed from 321 stainless tubing (or better) due to the higher EGT of the rotary. Don’t use the massive (18 pound) cast iron exhaust manifold from the car. Update 7/31/04: I eventually built a tuned header exhaust system and gained about 6 hp and fuel economy improved a bit as well. If you need more than 200 hp, you should look to the Mazda 20B three-rotor engine. These are more expensive and harder to find but they will make 240 to 300 reliable hp when normally aspirated. Update 7/31/04: The availability of the Renesis (RX8) engine provides another option if you need slightly over 200 hp. This the engine I am installing on the RV-4 and I expect around 225 hp. Note! Our power estimates are based on “as installed” test results comparing the rotary powered RV-4 with other RV-4s powered with 150 to 180 hp Lycomings. None of our engines have even been near a dynamometer. BACK TO TOP. Q. What is the highest time on a rotary in aircraft service? A. I have the highest time in an airplane that I know of. (1400+ hours as of 07/31/2004) Jim Mayfield had about 2500 total hours on a rotary powered gyrocopter. BACK TO TOP. Q. How much does the rotary weigh? A. Weight was one of the primary reasons I chose this engine. The only thing that really counts is what the total system with re-drive, cooling systems, engine mount, etc weighs. This is called firewall forward (FWF) weight. In my case, this is about 345 pounds. From my research, it appeared to be the only auto engine available which would equal the weight, power and reliability of the O-320 or O-360 Lycoming. ANY automotive V6 piston engine will be much heavier. Update 7/31/04: By careful attention to details, I have reduced the FWF weight by about 30 lbs in the Renesis installation. Here is the breakdown of system weights in my airplane. This list is a bit out of date because it does not reflect many changes I have made (like the EFI system) but will give you a good idea of what you can expect.
Q. What year engine do you recommend? A. Any of the RX-7/RX-8 13B engines from 1986 through 2004 are good. The most abundant models are the years 1986-88 which have parts that are all interchangeable. Most parts are physically the same in later years but rotor and counter weights were slightly lighter and these must be matched up. Either the normally aspirated or turbocharged engine is acceptable. Even if you do not intend to turbo charge you airplane, the turbo model works well when normally aspirated. Mazda still makes the RX-7 but it is no longer sold in the US (after 1996). With the introduction of the RX-8, Mazda introduced a new generation of 13B engines called the RENESIS. IT is now available to us, and we expect 225 hp normally aspirated in aircraft service. BACK TO TOP. Q. What is the cost to install the rotary in an aircraft and how long does it take? A. It is impossible to say what any given builder will spend on their engine installation. The exact cost will depend a lot on how resourceful you are. For example, if you order custom heat exchangers from Griffon for radiators & oil coolers, you could easily spend over $2000. I used automotive air conditioner evaporator cores from the junkyard and spent $10. Intelligent use of available materials like this does not mean you are looking for trouble. I have no argument with those who insist on using the very best on their airplane. Here at Real World Solutions, we have one Guiding Principle on the subject: It is better to fly a good airplane than to dream about a perfect one. My total installation costs in 1995, was around $5000 including initial cost of the engine, redrive, engine instruments, cooling system, engine overhaul, exhaust system, etc (i.e. everything). Time-wise, I spent 4 months (almost 40 hours a week) designing, procuring parts, fabricating & debugging the installation. For another point of reference, to replicate the Renesis installation on my RV-4 would cost about $12,000. Not cheap, but a lot less then an IO-360 Lycoming at around $30,000 (July, 2004). Q. Is your redrive setup for use with constant speed (CS) propellers? A. No. CS propellers are expensive (about $7000 new) and are not simple stand–alone devices. They require a properly designed governor, which bolts to the engine. Obviously, such a thing does not exist for the Mazda rotary. We could design one and modify the gear drive to go with it but that would be an expensive venture. See Guiding Principle above. The recommended prop for our gear drive is a wood prop, either 2 or 3 blades. If you must have a CS prop, the MT electric CS is a good choice and is easily installed on the RD-1 series redrives. BACK TO TOP. Q. Would a rotary engine work on an airboat? A. Yes! Boats benefit from lower weight engines, such as the Mazda rotary, as much or more than airplanes. Lower weight helps lower the center of gravity, thereby improving stability, in airboats. Since the rotary is not well-suited to direct drive propeller applications, air boat installations should include a gear reduction drive, such as our RD-1 planetary reduction drive. If you would like a closer look at the hardware, call to schedule a visit. Real World Solutions is located at Shady Bend Airpark, adjacent to the Suwannee River in Florida, making us convenient to visitors by land, sea, or air! BACK TO TOP. 8. Why is our rotary RV-8 project going so SLOWLY? A. I guess it is because we accidentally bought the slow build, instead of the fast build, kit! Seriously, several factors have impacted this project. Most significantly is the time that Tracy devotes to RWS manufacturing. We have been fortunate to have a steady flow of EC2 and RD-1x orders for the past 4.5 years and paying customers do get top priority on the time schedule. In addition, Tracy has developed several new versions of the EC-2 and the new ratio RD-1C drive. Each product takes hundreds of hours of development effort. Add to that the lack of space in the current hanger resulting in the building of a new hangar and the difficulty in working (building) outdoors in the Florida heat, and you can start to see how the RV-8 keeps falling further and further behind. And let's not forget the never ending changes and development work on the RV-4. We'll keep plugging at it.....BACK TO TOP 9. What is an RVotter and why is that the name of Tracy's rotary powered RV-4?? A. When Tracy and I first met, he told me about a book that he read, in which man was described as the "otter of the universe" because, bottom line was that all we REALLY want to do it play. Tracy really related to this theory (contrary to the indications in question #8, above) so I started calling him Otter. BACK TO TOP When he started flying the RV-4, he said it was so much fun to fly, that we started referring to flying as "Ottering". This somehow led to perverting of the name of Van's Aircraft newsletter (the RVator) and changing it into the RVotter.. and the plane's name was born. BACK TO TOP Q. I have your Aviator's Guide. Does the information in this guide correspond to the Renesis engine? Does the Tension Bolt Service Bulletin apply to the Renesis? BACK TO TOP A. Yes, all the basic design philosphies expressed in the Avaitor's Guide still apply. Of couse, due to the mechanical and physical differences between the "regular" 13B and the Renesis 13B, some modifications in the fabrications of systems will be required. Yes, the TENSION BOLT SERVICE BULLETIN does apply to the Renesis, I removed the oil injector pump per your suggestion. What do I do with with holes left behind? BACK TO TOPA. Block the holes. You don't need them for anything. Q. Any suggestions regarding fabrication of the intake manifold for the Renesis?A. There are MANY opinions on this, but after flying 1600+ hours in a rotary plane, here is my advice: On the RENESIS engine I use 11 inch runners. They are all little short. If possible 16 inch runner length is about perfect. Keep the intake manifold CLEAN with no square corners. Bigger is NOT better.The primary runner diameter should be 1 1/8 to 1 1/4 inches diameter. The secondary runner diameter should be 1 3/8 to 1 1/2 in diameter. Q. What year oil pan is best to use? BACK to TOPA. Tracy used a modified 1986-1991 RX-7 pan. The 93-95 pan might work as well, but I have not personally used one. Q. What spark plugs do you recommend for my aviation installation? Back to Top A. Tracy uses NGK brand plugs. Part number BUR7EQ for LEADING BUR9EQ for TRAILING. He gets about 150 hours - 200 hours on these plugs when using ONLY auto fuel. If you want to spend more (and perhaps get longer plug life) an alternative is to use stock RX-8 iridium plugs.
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