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Nap time? NAP TIME did you say? Boy,do
I ever wish it were. You ever get to the 90% point and think you are
about through - oh, Yeah, Rusty - never mind, rhetorical question for you
{:>).
I had planned to go out today to put my new digital
Electronic Fuel Monitoring system in the aircraft and fire up the engine (sans
prop) to see it work. Well, I needed to make one little bitsy cable to
interface the board with the aircraft. First thing after making the cable,
I hook it up to my homemade PWM generator to make certain all the leads actually
do what they are suppose to. Well, it doesn't work any longer. After
hours of checking leads and getting indication of good connections, I can't
understand why my gadget no longer shows fuel flow (or any other fuel related
values) in response to the pulse train. I check leads, I check the
board, I check everything thing. I even hook up the oscilloscope to the
PWM generator to confirm I have a pulse train. Yep! Everything
else is working just fine - except the *&^#^ does no longer
work!!
Get to bed at 1 Am problem still unresolved.
This morning, I start fresh, got PWM pulses, Pulses getting to chip, pulses on
chip - chip doesn't do a thing with the pulses. Reload program into chip in case
a cosmic ray had flipped a bit. (I admit getting disparate), no
joy.
I check the out put of the PWM with scope again,
yep! nice pulse train swinging 1.5 volts peak to peak ........WHAT! it suppose
to be swinging a minimum of 5 volts - no wonder, I have a clamping circuit to
bring the 14 volts injector pulse train in the aircraft down to the CMOS 5 volts
level. Of course, the 1.5 volts never make it through the clamp!
Something strange is wrong with my PWM pulse generator.
Hey, I may be old but creative still (at
times). I had been reading about the PIC chip I am using capability to
generate a PWM pulse train. I read up on, simply it seems and the Compiler
I have even has a basic PWM function in its library. So a little bit of
programming and sure enough I can get the chip on my development board to
generate a pulse train at 5.0 volts (close enough). So I hook up a wire to
carry the signal to the chip on my new board.
Here I get the signal to the new board and
then hook up the cable from the mother board I use to program the chip on
my EFI board and plug it in. I reload a fresh program and viola - the chip and
LCD are working again. But, the EFI chip is getting power through the
programming cable, so I unplug the programming cable and hook up my power cables
from a separate supply and check with the scope that the pulse are still to the
chip (and the are) .......but, the *&^#*# chip and program won't
function. I try the second board I built same scenario - I am going
bonkers!
A couple of hours later ( or more I won't admit how
many ), I finally realized what the problem was! Always before
my homemade PWM generator had been hooked up to the same separate power supply
as I am using for my EFI chip. THAT connection provided the ground return
path for the signal from the EFI chip - but since I had disconnected the
malfunctioning PWM generator there was no longer a signal ground (once I
removed the programming cable) and the chip would refuse to process the signal!!
AAAAHHHGGGG!
So there, nuff said. All is working and I am
going to bed, test the thing tomorrow.
Nap Time! You young
whippersnapper.
Ed A
----- Original Message -----
Sent: Wednesday, March 23, 2005 9:26
PM
Subject: [FlyRotary] Re: New to the list,
and some questions.
planning stages of building a Van's RV-7, and the current
powerplant plan is to use a 6-port Renesis on a Conversion Concepts
mount. I want to get a nice, easygoing 200hp out of the Renesis so I can
be at the top end of the power recommendations for the RV-7 without having to
plumb turbos and intercoolers and to keep it generally as simple as
possible.
Welcome John.
Excellent plan.
One, is the oilpan bolt pattern on the Renesis the same as
the 13b?
No. I think the front cover is
all that's different though.
Will the Conversion Concepts mount work for the Renesis without
modification, and if not, what mods are necessary?
Best to talk to Fred about
that. I'm sure he's either got a new mount, or will have one soon that
works for the Renesis.
Two, (big newbie question here),
where do you actually GET
a Renesis? Is there a crate version
available, and from
whom? Latest price?
You can buy one direct from Mazda,
but I'd recommend calling Bruce Turrentine instead. Last I talked to
him, he was selling the engines for $5700, which includes having him
personally go through the engine. If I were starting over, that's
probably the way I'd go.
(On this list and the Canard Aviation forum, it's been between $5700-$6200)
Has the RX8 been out long enough to make it worthwhile sourcing one from auto
wreckers, or are they being snapped up by speed shops and racers?
I've seen some used engines for sale,
but they aren't necessarily a bargain. Eventually, there will be more
deals out there though.
Is the Renesis overkill? Can i get
200hp out of a n/a
13b without a lot of exotic modification? (I've
been
reading the posts on injectors, intake tuning,
turbocharging,
etc).
Truth be told, I don't think the
Renesis will really outrun the 13B in our rpm range. I think Mazda just
made a better intake, and turned up the rpms. There are certainly some
improvements in the Renesis, but it's not light years ahead in
performance. It's absolutely possible to get 200 HP from a 13B at
less than 7500 rpm, with nothing more than a street port, and a decent intake
and exhaust. Tracy was doing it, and I expect to be as
well. All that being said, the Renesis is clearly the future of the
rotary, and there's no downside with the exception of a bit higher price
at the moment. I think the Renesis is a slam-dunk choice for folks
starting out now.
Cheers,
Rusty (must be Ed's nap time)
Mazda 13B rotary powered RV-3
(flying)
Kolb Slingshot (Mazda single rotor
project)
Sonerai-IIL (next project in
line)
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