BTW Ed how's your problem? Do you have an oscilloscope to trouble shoot
those sensors? There are some relatively low cost oscilloscope out now
that use a lap top computer screen. They feed data in through the printer
port.
Paul Lamar
Ed Anderson wrote:
Hi Paul,
It appears that the fuel map for the above 5000 rpm range was set too
lean. As I had mentioned, I am using Mazda Injectors in my new intake
system instead of the ones on my previous set up. The Mazda injectors have
a 22% higher flow rate. So, not being too bright, I decided that with the
additional flow rate with these injectors, that using the fuel map I had
been using and reducing the injector timing by 20% should put me in the ball
park injector timing wise. And it apparently does at lower rpms, however,
after the "incident", I decided to put some numbers on the spreadsheet. In
talking with Tracy Crook, he informed me that his new engine static rpm was
around 5100 with my new set up I am getting 5200-5300 with same prop as
Tracy indicating to me that the engines may be producing comparable power.
Taking that assumption, I set down and figured the fuel flow rates (knowing
Tracy pulls approx 17 gph at max power ) and found out that, if comparable
with Tracy's, then my engine is now flowing approx 34% more air at high rpms
than it did previously.
This increased airflow, of course, naturally meant that I needed more
fuel flow to maintain the proper air/fuel mixture. Indeed, rather than
reducing the injector timing (even with the higher flow rate) from the old
injector timing settings, I actually needed to move it back to orginal
values and then add another 12% to the injector timing.
I have done that and intend to do some high speed taxi test this week.
Also, I am going to bite the bullet and take my exhaust header off and have
it fitted for an 02 sensor and get myself an Air/fuel mixture meter.
Yes, I have one of the handheld LED scopes which is perfect for most of
the things I need one for.
I received the propeller from Charlie England, but unfortunately (did not
think of it until I took it out of the box) its for a regular aircraft
engine and does not rotate in the desired direction. I thought that perhaps
I could flip the prop but that only had it with the trailing edge leading
and it would push rather than pull in either case. Also, Charlie's prop
hub is considerably thicker than mine so the prop bolts are too short.
Charlie was a super guy to get the prop out to me so quickly and I feel
bad about putting him to that trouble before realizing the potential
problem.
Guess the smart thing would be to pop for a test club for a Ross drive
and make it available for anyone on the list who needs one for loading the
engine.
Again, thanks for the assit, Paul. I will keep you and the list
informed
Ed
Good work Ed. Hope to see you and your airplane at Sun & Fun.
Ground adjustable test club Ed. That way we can use it on a homemade dyno
test stand. I have been threatening to go down to Tracy's and make one
of those for two years now. Tracy is so busy perhaps someone from Florida
that can weld can meet me there and we can build one without disturbing
Tracy. I am way rusty on welding since the last time I welded was in
1971 or so. While we are at it we can make the stand nod so we can test props
and PSRU shafts.
Oh and BTW the adjustable pitch prop we are working on could serve for that
test club purpose. No need to stop the engine and adjust the pitch for
another HP/RPM data point measurement.
Paul Lamar
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