Fuel Injection and Variable Timing

"Allen" wrote in message
. net...

"Robert M. Gary" wrote in message
ups.com...
I would say that the advantage of direct port injection is that the
computer puts exactly the right amount of fuel in that cylinder at the
exact right time. The injectors on my Mooney are running all the time,
the injectors on my Saturn only run (actually pulse) when on the intake
stroke. I've never seen aircraft injectors that had computer wires
going to them.

-Robert

Robert,

Check out the Liberty with the TCM IOF-240. It has pulsed injectors just
like (well, similar to) your Saturn.

Allen
And I forgot to add: computer controlled variable ignition timing. No
magnetos.

http://www.libertyaircraft.com/libertyxl2/engine.php

Allen

"karl gruber" wrote in message
...

For the most part, only diesel engines have direct injection.

Karl
ATP, CFI, Etc.
"Curator" N185KG


But there are a few new gasoline engines that do use direct injection. The
Mitsu/Volvo engine is one.
http://www3.bc.sympatico.ca/Volvo_Books/engine6.html

GM has several DI engines also:
http://www.greencarcongress.com/2006...ertrain_u.html
I believe one of these engines is used in the Saturn Sky roadster.

It would be nice to see this technology transferred to aero engines as it
looks like it improves fuel economy and gets more power for the same size
engine. Well, don't hold your breath....unless you jump over to
rec.aviation.homebuilt

Regards,
John Severyn @KLVK

"J. Severyn" wrote in message
...

"karl gruber" wrote in message
...

For the most part, only diesel engines have direct injection.

...
But there are a few new gasoline engines that do use direct injection. The
...
It would be nice to see this technology transferred to aero engines as it
looks like it improves fuel economy and gets more power for the same size
engine. Well, don't hold your breath....unless you jump over to
rec.aviation.homebuilt

The fuel economy improvements are seen at lighter loads. At aircraft type
loads (60+%) and at altitude you can't run lean and/or stratified so you
don't gain much economy.

The improvment in power from the increased volumetric effciency and charge
cooling would still apply.


Geoff.

Check out the Liberty with the TCM IOF-240. It has pulsed injectors just
like (well, similar to) your Saturn.


Allen
...

Thanks for the info. It is about time the major aircraft engine makers
got out of the stone age.

Ben
www.haaspowerair.com

: The fuel economy improvements are seen at lighter loads. At aircraft type
: loads (60+%) and at altitude you can't run lean and/or stratified so you
: don't gain much economy.

: The improvment in power from the increased volumetric effciency and charge
: cooling would still apply.


The "stone-age" of aviation engines which many people gripe about do not appreciably affect the
steady-state operational efficiency save one: air-cooling and octane requirements. Magnetos, fixed timing,
carbs, etc all work rather well in the fixed operating regime of cruise power. A few percent might be
obtainable with variable timing or direct injection, but a BSFC of 0.42 lb/hp*hr (typical for LyContosaurus)
is pretty good for a spark-ignition gasoline engine. If the same engine were to be liquid-cooled and run 12:1
on the 100LL like the automotive counterparts (or 87 AKI "crapgas" on 8.5:1 like their automotive
counterparts), that's more to the tune of 10% efficiency gain. Point-maintainence and ham-fisted-leaning
aside, the old-school works well for efficiency if properly used... just takes more care and feeding to keep
it there.

-Cory


--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

wrote in message
oups.com...
Check out the Liberty with the TCM IOF-240. It has pulsed injectors just
like (well, similar to) your Saturn.


Thanks for the info. It is about time the major aircraft engine makers
got out of the stone age.

Even some of the stone age stuff is improving.

http://www.radialengines.com/fuel_injection/index.htm

"Robert M. Gary" wrote in message
ups.com...
I would say that the advantage of direct port injection is that the
computer puts exactly the right amount of fuel in that cylinder at the
exact right time. The injectors on my Mooney are running all the time,
the injectors on my Saturn only run (actually pulse) when on the intake
stroke. I've never seen aircraft injectors that had computer wires
going to them.

-Robert

I also own a couple of 96 S1 series Saturns and am very happy with their
economy and utility, however I think you are mistaken regarding the fuel
injection.

AFAIK the 91-94 SOHC engines used a single electric injector mounted in the
throttle body. The 95 and all DOHC engines use one injector per cylinder
located in the port close to the valve, however while this is called
sequential port injection the injectors pulse once per revolution (@60
degrees BTDC) or twice per cycle so are actually pulsing on both the intake
and exhaust cycle. It seems counter-intuitive to me, but it works well so
the Saturn engineers must know something we don't. The ignition is also a
waste spark type that simultaneously fires two cylinders, one near the top
of the compression stroke and one near the top of the exhaust stroke.

Matt wrote "


Even some of the stone age stuff is improving.

http://www.radialengines.com/fuel_injection/index.htm


Thanks Matt, I always wonder why it takes sooo long for a simple idea
to get put into motion. 11,000 - 12,000 grand seems high but The "FAA"
blessing accounts for more then half of it I bet.

Ben
www.haaspowerair.com

In article _EOdg.194434$P01.165735@pd7tw3no,
Private wrote:


AFAIK the 91-94 SOHC engines used a single electric injector mounted in the
throttle body. The 95 and all DOHC engines use one injector per cylinder
located in the port close to the valve, however while this is called
sequential port injection the injectors pulse once per revolution (@60
degrees BTDC) or twice per cycle so are actually pulsing on both the intake
and exhaust cycle. It seems counter-intuitive to me, but it works well so
the Saturn engineers must know something we don't. The ignition is also a
waste spark type that simultaneously fires two cylinders, one near the top
of the compression stroke and one near the top of the exhaust stroke.



Your engine is multiport but not sequential. Seq-multiport inyection fire
each injector individually and only when the valve is open. It improves
idle and part throttle economy. At medium to high loads injector are
open most of the time anyway, so when they open is not as critical
so the advantages of sequential are not important..



--
Eduardo K. |
http://www.carfun.cl | Freedom's just another word
http://e.nn.cl | for nothing left to lose.
|

In article ,
Aaron Coolidge wrote:

I have yet to see a fuel-injected car that fires its injectors at exactly
the right time as the intake valve opens. The injector is a little solenoid,
and has ~5 mS response time opening - longer when closing. A 3600 RPM car
engine is running at 60 Hz, ie, one revolution per 16.67 mS.

On my analog fuel injection car (1977), all the injectors run in parallel.
Pulse width is varied according to RPM. The airflow meter biases the pulse
width a tiny bit. The injectors create a little cloud of finely atomized
gasoline which gets sucked into the cylinder as the intake valve opens.
Interestingly enough, although it's port FI, there is a single injector
in the intake manifold just aft of the throttle body. It turns on at full
throttle to further enrichen the mix, and also gives a shot of fuel when
starting the engine presumably for priming (there is no choke, of course).
It's the height of 70's technology which the Japanese licensed from the
Germans (Hitachi copy of L-Jetronic).


Bosch Motronic cars fire the inyectors individually so they are open while
the intake valve is. You are correct that at a mid to upper range
injectors are open more that what the intake valve is open. It just poodles
behind it.


--
Eduardo K. |
http://www.carfun.cl | Freedom's just another word
http://e.nn.cl | for nothing left to lose.
|