snipes:

The airplane operating requirements are relatively simple
compared to
that of a performance car like a Corvette. In the
Corvette, they want
good throttle response at all RPM, and good fuel economy
with very
minimal driver involvement - one lever. On the other hand,
the
airplane really has only a couple of requirements.. It
can't quit.
It can't burn too much fuel in cruise. It has to make
the peak
horsepower afforded by the mechanical limits of the engine.
That's
not too bad by comparison. The airplane engine doesn't
have to idle
all that well as long as it doesn't actually quit. It
can have a
separate lever for controlling power vs. economy. All of
this makes
the tunability of the airplane easier to accomplish by
comparison.

As far as running the engine on the dyno, I think that was
a p-port,
and it was being run with the manifold pressure tap located
at the
wrong place on the engine for good readings. It would be
interesting
to hop on the dyno with the mp tap installed in the housing
and see
how the tuning goes.


Regards,

Matt-

Looks fixed to me. This looks fine.

Paul Lamar


Wonderful response Bill. I would add that the choice
between carb, mech
fi,
efi, distributor, dis, etc boils down to not only
simplicity but also
cost.
This wouldn't be the case in the certified market but
since we don't
have
to
jump hops for the FAA, we can choose our options based on
more than
just a
certificate. With regards to fuel delivery, it seems like
the only two
cost
effective options are the Holley and custom efi (555,
Tracy's,
Megasquirt.)
If someone could find a better carb in terms of function
and cost, that
would be cool but at this point that seems very unlikely.
Mech fi
would be
a
very good feature if it wasn't SO expensive. For $2900
I could buy a
Motec
(read $$$) and still have money left for dyno tuning. While
custom efi
would
be the holy grail of performance and flexibility, how many
people
really
need it? The turbocharged and the aerobatic (are there any
using
Mazda's?)
could genuinely use them, for everyone else, seems
unlikely.
Vlad
--


My problem with electronic FI is in the systems support..
Requires
independent, redundant power (dual alternators), and high
pressure
fuel. Not insurmountable by any means, but I'm not
convinced the
payoff is worth it for what I want to be flying.


Matt-

It's part of the risk that one must accept when
building or flying an
experimental aircraft or using a non-certified engine. Am
I against
making
the systems safer and less likely to cause a catastrophic
failure, no.
But
I'm not asking an engine from a car to be as redundant
and rudimentary
(read
safe) in design as a $25k+ aero engine. Would I fly an efi
rotary with a
single alternator, battery, ecu, etc., yes. If I was that
concerned about
safety, I would get a certified slug and call it a day.
Vlad

To interject a disrupting thought. I have a Bosch CIS fuel
injection
running on a rotary in an airplane. Al thought the plane
has not flown(
a problem with me not the plane), the injection was
extensively tested
on the ground on a test stand. The CIS is a mass flow
sensor with
automatic mixture adjustment. In addition the mixture can
be
modified to any level from too rich to run to too lean to
run. All the
hard work of air verses fuel has been done at time of
manufacture of the
unit.
The units are very inexpensive from a junk yard. I have
several that I
have used on cars that were no where worn out. A little
clean up and
they work perfectly.
However they are not without problems.
1. Size is a problem.
2. High pressure fuel.
3.Weight might be a problem. They are not light because of
the cast iron
fuel distributor.

C Smale

I was going through my records, the MAF I purchased new from Rock Auto was
$61, ('02 5.4l V8) didn't have to hunt through junk yard, just type on
keyboard, no time spent removing, or driving to junk yard, or cleaning and
reconditioning. ABS sensors, $22 ea, same conditions, with added benefit of
not laying on my back in the mud or getting crud in my face removing them.

Time spent researching part numbers and tracking down flow data for suitable
injectors so far I've put in maybe 4-5 hrs. I have decided it is easier to
just buy some 42 lb ford racing injectors(known qualities), set of 8 for
$210, that's $26.25 ea. free shipping. Anyone want the other 4?
That's under $300 so far. I figure, maybe another $200 for the rest of the
electronic 555 parts and circuit boards. Fuel runner and regulator, haven't
priced yet, can't be that much.
I figure the rest of the intake stuff like tubes and slide throttle would be
necessary no matter how you skinned the P-Port cat, so those costs are
comparably the same.

Because of differences in the MAF and injectors anyone decides to use(or
carburators, and differences in how you make your induction setup), I agree
that anyone choosing to go rotary should be prepared to put in tuning time.
Everyone has to do it, so it is not a differentiating factor. I REALLY like
the FI systems resistance to icing.
I dont think hardening the electronics is going to be difficult, I plan on
using an appropriately sized MOV and LM-150K (proven and reliable,
inexpensive) in front of the control circuitry.
I really can't see any substantial cost difference in either approach.
Your results may vary.
C. Smith