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Mark, Tracy,
Remember we put a 22K ohm resister and zener in the CAS circuit to
drop the voltage and allow for higher rpms. My notes say 8.1V peak to peak
at 6300 rpms with this arrangement. The higher the resister value the higher the
rpms you could run. If I remember correctly changing the CAS bracket to
aluminum (possibly changed gap ) allow you to go to 7500 rpm+. We never did look
at the signal after you changed the CAS bracket.
Bobby
Your's must be spot on Mark. I finally got mine well centered and it
worked fine but it was a pain to get it there. Took me an hour and several
tries before I got it close enough to run at WOT.
While this does work, I'm not happy with how touchy this
Renesis sensor and trigger wheel is when used with the EC2. The EC2 was
designed for the RX-7 sensor since that was what was available at the time.
I think a change is needed for the RX-8 sensor in order to be Plug n' Play
like I want it to be.
My first experiment in that direction was to put a
simple voltage clamp across the sensor (in addition to the 1000 ohm
resistor I mentioned before) and this seemed to work well. I'm still
testing this to make sure it covers all the bases.
Now that I can run consistently at full throttle, 20B testing
continues. Since the wings (and fuel tanks) are not on the RV-8 yet, I'm
feeding the engine from a small gas can. It is amazing how
fast a 20B at maximum power will empty a 2 1/2 gallon can!
Tracy
On Feb 5, 2008 2:27 PM, Mark Steitle < msteitle@gmail.com> wrote:
Tracy,
I had wondered if a slight off-center of the trigger wheel could cause
problems. So, I tried my best to get it dead on. To answer your
question, I left the trigger wheel alone and just changed the sensor
mount. I'll check the runout again just to be sure it is
within spec. Since I can see up to 7500 rpm on initial
takeoff run, I doubt that the trigger wheel is off center by any
significant amount.
Mark
(Locally I'm known as the flying
chainsaw.)
On 2/5/08, Tracy
Crook <tracy@rotaryaviation.com> wrote:
OK Mark. Also take note of my last message on centering the
trigger wheel. Nearly drove me nuts figuring that one out last
week. Yours must have centered up OK when you installing it.
BTW, did you happen to remove and re-install the trigger wheel when you
changed CAS mounts? That could have accounted for the different
results.
Tracy
On Feb 4, 2008 8:12 AM, Mark Steitle <msteitle@gmail.com>
wrote:
Tracy,
I'm reluctant to change anything now that its running like it
should. My engine always starts right up with very little
priming. Since I still have the 4130 bracket, I may reinstall it
along with the 1k ohm resistor and see how it runs. I'll let you
know if it helps or hurts.
Mark
On 2/3/08, Tracy
Crook <tracy@rotaryaviation.com> wrote:
I did the 9.7 CR rotors in mine but have never done a front to back
comparison with the stock 9.0s. It does run strong with the 9.7s
though!
BTW, all builders using the Renesis Crank sensors take note:
I had a lot of trouble starting my 20B with Renesis CAS
installed. Just yesterday I found out why. The Renesis CAS
is a much higher impedance sensor than the RX-7 CAS and this makes it
much more sensitive to noise pickup, especially when the starter is
running. It needs a load resistor across it to avoid this
problem. Install a 1000 ohm (1/4 or 1/2 watt is
fine) across the leads of the sensor either at the sensor or
near the EC2.
After installing one on mine it went from very difficult to instant
starting.
I'm not sure why I have not seen this problem on my RV-4 with
Renesis engine but one other Renesis user has seen the problem and the
resistor fixed it immediately.
Mark S., you should definitely do this on your 20B / Renesis setup
as well. I am starting to suspect that this is why your earlier
steel mount (for CAS) did not work. A very small difference in how
the CAS is mounted affects the noise characteristics a lot. Either
mount would probably have worked fine with the resistor
installed.
Future EC2s for Renesis engines will have this installed
internally.
Tracy
On Feb 3, 2008 4:44 PM, bob.kaufmann < bob.kaufmann@cox.net> wrote:
Gang
I
have a 20B that I have taken the turbos off and will be using it in
an
aircraft, a RV-10. A friend of mine said that I should use
the 9.7
compression rotors instead of the turbo rotors. What
say you all?
I have pulled the engine off to powder coat the
engine mount and if I'm
going to switch rotors, now is the time
before I hang the engine again. I
have the flat plate on
milling machine so I could make plates for the 20B if
people
wanted. I think I would be competitive. I would like to do
them in
groups of ten if people are interested.
Bob
K
Finished except all the parts aren't together yet.
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