Tossing factory EGT, replacing with JPI or similar

Marc J. Zeitlin wrote:

Still better than ROP, but I don't think that Lycoming's got a perfect
induction system tuning going :-). If I ever have a few thousand $$ fall
on my head, I'll install injection and GAMI's. But that's after the
Lightspeed electronic ignition.

Tom Sixkiller replied:

Lightspeed? I've heard of headphones under that name but not electronic
ignition.

Klaus Savier's company.
http://www.lsecorp.com/

How does it vary from PRISM? http://www.gami.com/prism.html

Uh, by being available for experimentals now? :-)
Seriously, GAMI's PRISM is cool and is expected for STC/377 in the (near?)
future. I don't think it's shipping yet. I believe that Light Speed
Engineering's ignition is intended for the experimental market only (no plan
to pursue any FAA certification).

So, different target markets.

Russell Kent

Tom Sixkiller wrote:

[snip]

CMIIW but Lycoming's have tuned INDUCTION, not tuned injectors.

This is manifestly not true with _all_ Lycomings, but it may be true for
four bangers (but even then perhaps more as a function of marketing spin
than concerted engineering effort).

Tuning an intake system usually implies two goals: Near identical
mixture distribution and tweaks to manipulate the torque curve. For
engines that do not use port or direct injection the former more or less
requires identical runner lengths, something that may be a happy
accident on four bangers but certainly isn't the case on my O-540.
Manipulating the torque curve consists of futzing with the length and
diameter of the runners such that one of the pressure peaks in the gas
column (the gas column has inertia but is perpetually being asked to
stop and start as the intake valve opens and closes, resulting in
standing waves in the gas column) coincides with the intake valve at the
time the valve is open for a particular engine speed, such that there is
a relative overpressure during some portion of the intake valve being
open. I _might_ believe some of that was done, but lacking intake
balance pipes and other weird juju I'd be skeptical of the efficacy of
same -- and even then it wouldn't contribute to mixture distribution.

Don't even get me started on Lycoming plumbing the intake runners
through the oil pan to "improve" the mixture. If the runner design is
so bad that the intake manifold needs to be heated to assure that the
mixture from the carb remains vaporized the only reasonable conclusion
is that the runners are too long or have too many kinks and that the
overall intake system blows hairy goats. It's the mechanical
engineering answer to documenting a bug and calling it a feature.

Tom Sixkiller wrote:

What's intersting is the
data the the folks at GAMI got from their test bed contradicts so much
"conventional wisdom".

Yeah, a recent article in AOPA Pilot about that contained the statement "In fairness
to both Lycoming and Teledyne Continental Motors, the engine-operating instructions
in POHs … appear to have been the result of marketing decisions taking precedence
over engineering recommendations." I wrote back that it would have been more
accurately phrased as "In fairness to both Lycoming and Teledyne Continental Motors,
their engineers are competent, but the companies apparently lie through their teeth
to get you to trash your engine and buy a new one sooner." They didn't print the
letter.

CMIIW, but a good induction system can be wasted if the QC on the injectors
sucks?

True. That wouldn't apply to carburetors, however, so we still should be able to pull
some of Deakin's tricks with them (and, apparently, one poster is doing that).

In the 70's...or the 60's? By 72' all the pollution equipment threw it all
in the dumper, TMWOT.

Not in the South, it didn't. About the only piece of anti-pollution gear you had to
leave on the car was the PCV valve. Holley was still doing a good business in tuned
intake manifolds and Shelby's exhaust systems were still in demand in 1980. Then I
sort of lost track of it for a while (went back to school). A guy I worked with in
'72 actually rodded a new Vega. He got unbelievable performance out of it for a
while, but the engine only lasted about 6 months.

George Patterson
This marriage is off to a shaky start. The groom just asked the band to
play "Your cheatin' heart", and the bride just requested "Don't come home
a'drinkin' with lovin' on your mind".

Doc,

GAMI doesn't claim, and never did, to even EGT's. Further, on a flat engine,
they don't. Deakin, with whom I have flown, would NEVER say they even EGTs.
They do even the fuel flows to each cylinder and even the horsepower
developed by each cylinder. EGTs will vary, due to the geometry and
installation of a flat engine.
Karl
"Curator" N185KG


"Viperdoc" wrote in message
...
GAMI injectors are a great addition for the big Continentals, but I'm not
so
sure if the same is true for Lycomings. My Lycoming AEIO 540 has a lot
more
even temperatures across the board than the IO-470's in my Baron that's
equipped with GAMI injectors.

Didn't Deakin's articles pretty much say the same?

"Russell Kent" wrote in message
...

How does it vary from PRISM? http://www.gami.com/prism.html

Uh, by being available for experimentals now? :-)
Seriously, GAMI's PRISM is cool and is expected for STC/377 in the (near?)
future. I don't think it's shipping yet. I believe that Light Speed
Engineering's ignition is intended for the experimental market only (no
plan
to pursue any FAA certification).

So, different target markets.

I was speaking of _operationally_.

"Viperdoc" wrote in message
...
GAMI injectors are a great addition for the big Continentals, but I'm not
so
sure if the same is true for Lycomings. My Lycoming AEIO 540 has a lot
more
even temperatures across the board than the IO-470's in my Baron that's
equipped with GAMI injectors.

Didn't Deakin's articles pretty much say the same?

I don't think so (IMW), but GAMI's are not the only factor in even CHT's one
way or another. (I "assume" you're referring to CHT's when you speak of
temperatures.

Tom Sixkiller wrote:

"Russell Kent" wrote in message
...

How does it vary from PRISM? http://www.gami.com/prism.html

Uh, by being available for experimentals now? :-)
Seriously, GAMI's PRISM is cool and is expected for STC/377 in the (near?)
future. I don't think it's shipping yet. I believe that Light Speed
Engineering's ignition is intended for the experimental market only (no
plan
to pursue any FAA certification).

So, different target markets.

I was speaking of _operationally_.

Both systems use capacitive discharge systems to make longer duration, hotter
sparks. The GAMI PRISM system uses a pressure sensor in the cylinder (part of
the spark plug assembly I believe) to measure the cylinder pressure during the
combustion event. It uses that information to alter the timing of the spark for
best performance. This also makes it compatible with varying grades of fuel.
The LSE Light Speed has no such pressure feedback, but does use manifold
pressure and RPM to affect the timing and duration of the spark. I do not know
if the PRISM uses MAP or RPM for timing curve manipulation.

Russell Kent

"Russell Kent" wrote in message
...
Tom Sixkiller wrote:

"Russell Kent" wrote in message
...

How does it vary from PRISM? http://www.gami.com/prism.html

I was speaking of _operationally_.

Both systems use capacitive discharge systems to make longer duration,
hotter
sparks. The GAMI PRISM system uses a pressure sensor in the cylinder
(part of
the spark plug assembly I believe) to measure the cylinder pressure during
the
combustion event. It uses that information to alter the timing of the
spark for
best performance. This also makes it compatible with varying grades of
fuel.
The LSE Light Speed has no such pressure feedback, but does use manifold
pressure and RPM to affect the timing and duration of the spark. I do not
know
if the PRISM uses MAP or RPM for timing curve manipulation.

Thanks...that increased my knowledge of ignition system immensely!!

I notice that GAMI's PRISM system offers/recommends a digital tach, so it
may be (guessing) that it's based on RPM.

I've heard that STC certifications are running wayyyy behind, so it may be
over a year.

"Tom Sixkiller" wrote in
:

I notice that GAMI's PRISM system offers/recommends a digital tach, so
it may be (guessing) that it's based on RPM.

I've heard that STC certifications are running wayyyy behind, so it
may be over a year.

PRISM went through several variations of the algorithms during the
design cycle, as you would expect, learning what was needed (and a
surprising amount of stuff that wasn't needed). I believe you will find
that it is not quite described by either of the typical MAP or RPM
approaches. It's inputs are the cylinder timing (TDC) and the cylinder
pressure *curve*, plus those things that can be derived from TDC (like
RPM). The timing of the spark is adjusted to produce the desired
pressure curve relative to TDC, further adjusted to offset any
unacceptable variation in the curve shape itself (i.e. stop any
detonation before it happens).

Works amazingly well, and is independent of fuel - in that if (for
example) you switch tanks in flight and the octane rating of the fuel in
one tank is lower than the other, the PRISM system notices the changes
in the combustion pressure curves and moves the timing to compensate.
You, the pilot, may notice a slight change in the "sound" of the engine,
and a slight change in power output, but otherwise it just keeps humming
along.

Certification -- ah, there's the rub. Anyone got the schematics for a
good electric FAA-prod? Maybe two years ago when the Light Sport Plane
proposal is approved. {:(

-----------------------------------------------
James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
-----------------------------------------------