> Mikuni HRS48 is looking good. I'll mount the carbs close to  the
    engine
     > for good idle and low profile and use a 25 inch long stack.
     > Mikuni claims 120 HP per carb which is perfect for our use.
     > If a Mikuni can live on a hog it can live on a rotary.
     >
     > If this works it is a major breakthrough for the rotary in   general.
     > I would not be a bit surprised if it finds it way into car   racing.
     >
     > Mikuni is in my neck of the woods so perhaps I will hit
     > them up for some test 48 mm carb loaners.
     >
     > Paul Lamar ...No rotor no motor.

    Hello Paul,
    How are you going. I have been of the list for some time now   but dave
    has passed on your email. I have mounted two Mikuni on the   renises for
    my Mustang. I did not need to go to the bigger ones for this.   the best
    price I found was from www.easternperformance.com.
    all the flow rates are at another site.
    What ignition are you going to use? i was looking at using  the  same
    system as the Jabiru uses on this. I have a Harley direct drive
    alternator to mount also.
    I have been working on the lightning with the 8 5100 Jabiru   engine in
    of late but will go back to the Mustang again. I am a lot   happier now
    that I have descended with the high pressure fuel supply.
    I have also had this project on hold as the RAA in Australia   get its
    new regs in place to include the Mustang
    Regards Don

    --
    Best regards,
    ddunbar WA


    We are doing fine Don. We just got a new Golden puppy.
    BTW Robin and I might visit next month. I would like
    to explore WA some more.

    Yes I know. Here are some old pictures you sent.

    Don't expect a lot of power if your using the Mikuni with the
    side port RX8 motor. The hot tip is a p-port engine.
    I would swap these for the 48's and p-port the engine. It is   real easy
    now that Mark Steitle has figured out how to tig weld them in.
    This is a piece of cake for the highly skilled people you  have  over
    there.

    You don't have to use the power and fuel burn if you don't  need  it.
    Also the extra power will pay off big time when cruising at
    10,000 feet because you are down to about 60% power anyway.
    In other words starting with 240 HP at sea level you will
    have 144 HP at 10,000 feet where the aerodynamic drag is
    much much lower. Mount the 48's close to the block for a
    better idle. Don't fool around :) Jump in! The water is fine :)

    Ignition:
    A multi spark capacitor discharge ignition one per spark plug
    has an advantage for a rotary as it will fire through a fouled
    spark plug. If you burn any 100LL the plugs foul sooner  rather  than
    later.
    If you use one per plug the RPM at which they fail to fire
    multiple times is doubled as that number (about 4,000 RPM) is   given
    for a four
    cylinder engine that fires twice as often as a one rotor engine.
    It will also fire a leaner mixture so you can cruise with a lower
    fuel burn. MSD Part number 6200. Don't worry about the total
    power consumption as each unit is using half the power as a four
    cylinder
    unit single unit would be using.

    The easy and simple way to trigger it is use two mag pick ups   mounted
    180 degrees from each other and make a new steel trigger wheel.
    Mount the new trigger on the outside of the RX8 e-shaft pulley
    as it is easier to fabricate brackets and clear the belts.
    Thanks again to Mark Steitle for this tip.

    Fire leading and trailing plugs at the same time around 20 to 30
    degrees BTDC.

    http://www.msdignition.com/ignition_4_6200.htm

    Paul Lamar ...No rotor no motor.

    Paul,

    I don't think the MSD is going to fire more than one spark above
    3000 rpm, which is what it says in its literature.

    Even with one box per rotor (or even one box per spark spark   plug),
    there is not enough time for multiple sparks. The fact that  you  have
    less cylinders to fire does not change that.

    Let's say the engine is running 6000 rpm. That's 100   revolutions per
    second, or 360 degrees of rotation every 10 milliseconds.

    The spark duration from the MSD is 20 degrees, or 1 /18'th of a
    revolution. That works out to 10 milliseconds divided by 18  equals
    0.5 milliseconds for the spark itself. Trying to cram in multiple
    sparks in that short a time would only be counterproductive   because
    you are shortening the time that spark is present.

    Also, I'm not clear on whether you are proposing to use one  MSD  box
    per spark plug, or one box per rotor. I would think you could use
    one box per rotor and use a coil with two towers two fire  both  spark
    plugs in a rotor at the same time.

    Btw, this would also work with my flywheel magneto. Just use two
    charging coils on the stator -- one each going to an MSD box. Use
    two magnetic triggers 180 degrees apart to trigger the boxes. And
    use two of those twin-tower coils.

    You could do the same thing with two sets of points and not  bother
    with the MSD boxes. I still like this method better because its
    simpler, less stuff to fail and you will get a very hot spark.

    The point of CDI is to get a big jolt of voltage to the coil   primary
    side very quickly. The charging coils on the flywheel magneto  will
    put out higher voltage the faster the engine spins -- like  any  magneto.

    Depending on the number of windings on the stator coils, you  could
    easily get 400 volts at 6000 rpm, which is what the CDI box   puts out.

    The other point of CDI is to get that voltage to the primary
    windings of the spark coil very quickly. Here again, my scheme is
    just as good because the dwell time (points closed) is so long.

    The points only are open for 20 degrees of  revolution. The   rest of
    the time current is flowing from the charging coil on the   stator to
    the primary winding on the spark coil -- 340 degrees. At 6000 rpm
    that is 9.5 milliseconds. So the primary has all the time it  needs
    to be fully charged with high voltage.

    There is zero advantage to the CDI system. The CDI system is good
    when you have multiple cylinders and the time gets very short for
    the primaries to charge up. Plus -- unless you have a magneto   -- you
    only have a piddly 12 volts going to the primaries.

    This is not the case here. You have high voltage going to the
    primaries and a very long duration time.


    Regards,

    Gordon.

BTW the chart I uploaded was wrong on the duration of the
spark. It came from Heinz Heisler's book and there
are frequent errors in the illustrations. The decimal
point was missing. Heisler had it correct in the text
but the illustration was wrong. Here is the corrected version. I
double checked the Bosch Automotive Handbook for the corrections.
Sorry about that I misled you. It is getting so I have to check
everything in Heislers book.

"I don't think the MSD is going to fire more than one spark above
 3000 rpm, which is what it says in its literature."

It depends on the size of the capacitor and the output resistance
of the power supply charging the capacitor. The traditional
value for the capacitor is is one micro farad with 400 volts charging
it. That is the capacitor used in this third chart yielding
a .35 ms spark duration.


As I recall and if memory serves me correctly the energy is
proportional To voltage squared times 1/2 capacity. E = 1/2 x C x V^2
which gives 80 mj.

It is possible MSD is using a smaller, faster charging capacitor.
MSD uses 460 to 480 volts. 470 squared is 220,900 while 400 squared
is 160,000 of course. MSD claims 100 mj and 12 sparks maximum per
firing event.

However it is also possible to design a high RPM MSD
ignition system using multiple smaller capacitors that are charged
in parallel and fired in sequence with .1 ms or shorter spacing.   The pulse
transformer coil must be designed accordingly. I can't say
for sure MSD are doing that as I have never ever seen inside of
one of their boxes let alone the skematic.

I was thinking of one MSD unit per rotor to keep the cost reasonable
but Racing Beat is using one per spark plug.
    

 Paul Lamar ...No rotor no motor.

Mikuni slide carbs and capacitor discharge ignition---I  have the
feeling that we (the rotary movement) have taken a very long and
tortured path to get to this simple and elegant combination.  I know
I can get comfortable with this set up.    Jerry

Don't get too comfortable. I just checked on the price
at my local motor cycle shop and the Mikuni 48 mm are $500 each :)

If I had a dyno I would still be working on the slide throttle carb.
If I can promote the loan of a couple of Mikuni's I'll test those
on this P-port RX8 engine go around.

Maybe Bill Jepson knows somebody and he can get a discount.

Paul Lamar ...No rotor no motor.

Given the price of any intake system, a $1000.00 bucks for two carbs
is just fine.  You can save that by not buying an engine
controller.   Can these carbs be gravity fed?     Jerry

Probably. I think they are low pressure. A high wing tank should
work fine.