Renesis ignition?

Discussion in 'Mazda Rotary' started by DLrocket89, Jan 27, 2011.

Help Support HomeBuiltAirplanes Forum by donating:

  1. Jan 27, 2011 #1

    DLrocket89

    DLrocket89

    DLrocket89

    Well-Known Member

    Joined:
    Aug 10, 2009
    Messages:
    249
    Likes Received:
    1
    Location:
    Janesville, Wi
    Hi everyone,

    Does anyone out there make a self-sustaining ignition unit for the Renesis, much like a magneto that doesn't need electrical power to keep working? I'm considering using mechanical fuel injection for my Renesis (the Rotec TBI) that can work gravity fed if need be, so if I found an ignition unit that was self-powering (like a P-mag or a magneto), that would be awesome.

    The goal is to maximize the time that I can stay up in the event of a complete electrical failure.

    Thanks!

    Dustin
     
  2. Jan 27, 2011 #2

    DLrocket89

    DLrocket89

    DLrocket89

    Well-Known Member

    Joined:
    Aug 10, 2009
    Messages:
    249
    Likes Received:
    1
    Location:
    Janesville, Wi
    I was thinking about this more, and am realizing that it's probably an impossibility. So, what do I use for an ignition module, and how do I get two of them to work together?

    There are bunches of ignition modules, ECUs, etc available. I want ignition only, as fuel injection won't be an issue. For redundancy, I'd have two. How do I switch between them? Should I have some sort of a 4PDT switch to switch outputs going to the coils, or should I just have one feeding 1 set of plugs (1 on each rotor) and the second feeding the second set, and then live with less power if one goes down?
     
  3. Jan 29, 2011 #3

    DLrocket89

    DLrocket89

    DLrocket89

    Well-Known Member

    Joined:
    Aug 10, 2009
    Messages:
    249
    Likes Received:
    1
    Location:
    Janesville, Wi
    After spending some time on a Mazda forum, I think what I'm going to do is to buy to aftermarket, automotive ignition units and then build a circuit to switch between them. Have the board professionally made by someone like pad2pad.com or whatnot, should work pretty well.
     
  4. Jan 29, 2011 #4

    skeeter_ca

    skeeter_ca

    skeeter_ca

    Well-Known Member

    Joined:
    Jun 29, 2005
    Messages:
    1,026
    Likes Received:
    50
    Location:
    Yucaipa, Ca
    Try taking a look at Tracy Crook's EC3. It has redundant computer built in. Just a flip of a switch and your using the backup computer. Some of the sensors can also be made redundant.

    EC3 EFI
     
  5. Jan 30, 2011 #5

    DLrocket89

    DLrocket89

    DLrocket89

    Well-Known Member

    Joined:
    Aug 10, 2009
    Messages:
    249
    Likes Received:
    1
    Location:
    Janesville, Wi
    Yeah, I've seen it. There are a couple of things that I don't like about it...not that they're deal breakers, I'm just looking around to see what else is there.
     
  6. Feb 1, 2011 #6

    Monty

    Monty

    Monty

    Well-Known Member

    Joined:
    Jul 15, 2010
    Messages:
    1,283
    Likes Received:
    478
    Location:
    Fayetteville, AR / USA
    Do a search on the Fly Rotary List.

    Lynn Hanover has posted several designs using inexpensive components.

    One thing you can do is use waste spark on the leading plugs (I think. I can't remember whether the leading or trailing plugs must have a separate spark) Anyway, you use two pickups and have both pickups trigger one ignition, and only one pickup trigger the second. Use the second for the set of plugs that can't use waste spark. That way you get true redundancy. You would treat it just like a mag check before takeoff and you would get an rpm drop if any component fails so you know to check on it. I would have a backup battery as well in case you have either an alternator or primary battery failure.
     
  7. Feb 1, 2011 #7

    DLrocket89

    DLrocket89

    DLrocket89

    Well-Known Member

    Joined:
    Aug 10, 2009
    Messages:
    249
    Likes Received:
    1
    Location:
    Janesville, Wi
  8. Feb 28, 2011 #8

    dave2336

    dave2336

    dave2336

    Member

    Joined:
    Feb 28, 2011
    Messages:
    6
    Likes Received:
    0
    Location:
    fort smith,ar
    I have one of these jewels in one of my cars. It is very reliable. Much more so than I had thought. It is also priceless to be able to record all information coming into and leaving the ECU. However, it is NOT easy. You are soldering a computer together from parts, very small parts. Making one mistake can release the magic blue smoke. Then, you have to wire install it. That turns out to be the most difficult part. Then, you have load the firmware and start programming it. Programming the engine parameters is painful. You'll learn more than you ever wanted to know about IC engines. After spending weeks, maybe 100+ frustrating man hours just to get the motor to start, you discover that there is this thing called 'noise'. All the important sensors pick that up and you get to find a way to deal with it. Fortunately for me I have access to some EEs who helped me.

    I'm not saying don't do it. I may do if I ever get to that stage of the project. But, don't under estimate the difficulty! The EC3 may actually be cheaper. It would certainly be easier.
     
  9. Mar 1, 2011 #9

    DLrocket89

    DLrocket89

    DLrocket89

    Well-Known Member

    Joined:
    Aug 10, 2009
    Messages:
    249
    Likes Received:
    1
    Location:
    Janesville, Wi
    I understand what you're talking about, I've done electronics as a hobby for quite awhile now. I'm working on a box that will do all the switching between ECUs, everything will be laid out on PCBs which will be nice. From there, the actual wiring will consist of making wire harnesses and connecting it all up. All of the harnesses will be shielded, so hopefully that will help.

    Glad to hear that you like the MS. I've been on their support forum, I'm hoping to be able to download a "base" set of parameters for an RX8 to take away a lot of the time there. Regarding soldering, not a big deal, been doing it for quite awhile now.

    And I have a sparky (who's also an ME and also a pilot) to help. :beer:
     
  10. Mar 1, 2011 #10

    dave2336

    dave2336

    dave2336

    Member

    Joined:
    Feb 28, 2011
    Messages:
    6
    Likes Received:
    0
    Location:
    fort smith,ar
    I've found that twisted pairs work better than shielded wire. It is also cheaper and easier to work with.
     
  11. Mar 2, 2011 #11

    DLrocket89

    DLrocket89

    DLrocket89

    Well-Known Member

    Joined:
    Aug 10, 2009
    Messages:
    249
    Likes Received:
    1
    Location:
    Janesville, Wi
    Good to know. Where are you getting noise? Is it outside, or is it signals within the ECU harness crosstalking? If it's external, I'm going to use something we use at work on aerospace hardware, called Cho-Shrink. Basically, it's polyolefin shrink tubing with silver deposited on the inside. Run all the wires through it, run a bare wire along the outside of the bundle so you can use it to ground the silver, and there you go...pretty much 100% EMI shielding (from external EMI that is)...
     
  12. Mar 7, 2011 #12

    dave2336

    dave2336

    dave2336

    Member

    Joined:
    Feb 28, 2011
    Messages:
    6
    Likes Received:
    0
    Location:
    fort smith,ar
    The noise I've seen was the wiring harness picking up the ignition system. I originally assumed I could move the wiring harness to avoid the noise from the coils/plugs. That was a bad assumption.
     
  13. Mar 7, 2011 #13

    DLrocket89

    DLrocket89

    DLrocket89

    Well-Known Member

    Joined:
    Aug 10, 2009
    Messages:
    249
    Likes Received:
    1
    Location:
    Janesville, Wi
    I'm planning on using LS series coils, which mount near the sparkplugs. The actual ignition signal is just a logic level +5V, the power for the coils comes straight from the battery (through a circuit breaker or fuse, but yeah).

    Would that setup help prevent what you experienced/
     
  14. Mar 8, 2011 #14

    dave2336

    dave2336

    dave2336

    Member

    Joined:
    Feb 28, 2011
    Messages:
    6
    Likes Received:
    0
    Location:
    fort smith,ar
    Not a chance. Any spark generates tons of EMF and don't forget about the radio. Just run twisted pairs. It reduced the noise across my temp sensors from literally hundreds of degrees to tenths of a degree.
     
  15. Mar 8, 2011 #15

    DLrocket89

    DLrocket89

    DLrocket89

    Well-Known Member

    Joined:
    Aug 10, 2009
    Messages:
    249
    Likes Received:
    1
    Location:
    Janesville, Wi
    :shock:

    I used to build vacuum tube guitar amps as a hobby (till I decided to build an airplane)...when you have a gain of 10,000,000 from end to end, noise reduction becomes an issue, so I know what twisted wires can do. What I didn't know was that coils/sparkplugs could do THAT. Wow.
     

Share This Page



arrow_white