X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 21 Jan 2008 10:05:44 -0500 Message-ID: X-Original-Return-Path: Received: from ironport5.liveoakmail.com ([216.110.12.21] verified) by logan.com (CommuniGate Pro SMTP 5.2c4) with ESMTP id 2681843 for lml@lancaironline.net; Mon, 21 Jan 2008 09:42:44 -0500 Received-SPF: none receiver=logan.com; client-ip=216.110.12.21; envelope-from=walter@advancedpilot.com X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Aq4HAAc+lEdAMf4V/2dsb2JhbACCOTaBb40OmQw X-IronPort-AV: E=Sophos;i="4.25,227,1199685600"; d="scan'208,217";a="43334982" Received: from rs5.liveoakhosting.com (HELO secure5.liveoakhosting.com) ([64.49.254.21]) by ironport5.liveoakmail.com with ESMTP; 21 Jan 2008 08:42:03 -0600 Received: (qmail 3397 invoked from network); 21 Jan 2008 08:42:03 -0600 Received: from ip12-197-248-25.networkusa.com (HELO ?10.0.1.4?) (12.197.248.25) by rs5.liveoakhosting.com with (AES128-SHA encrypted) SMTP; 21 Jan 2008 08:42:03 -0600 Mime-Version: 1.0 (Apple Message framework v753) In-Reply-To: References: Content-Type: multipart/alternative; boundary=Apple-Mail-2--718977632 X-Original-Message-Id: <3D0FE7C5-1327-411A-99E2-6A6BE91E9FE6@advancedpilot.com> From: Walter Atkinson Subject: Re: [LML] Re: Pressurized Injectors X-Original-Date: Mon, 21 Jan 2008 08:42:01 -0600 X-Original-To: "Lancair Mailing List" X-Mailer: Apple Mail (2.753) --Apple-Mail-2--718977632 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Scott: Nice summary. In addition, if he is using the air pressure under the cowl to push air into the injector (through the screen on the NA injector), the addition of RAM air to the induction increases the MP to the point that he no longer might have enough upper deck cowl pressure differential to result in anything more than a pencil stream in the FF. That alone--even with excellent F:A ratios could result in rough running as the fuel would be more liquid than vapor. That's what I understood his message to be about. If my interpretation were correct, then he's right about adding upper deck pressure to the injectors to increase the differential pressure between MP and cowl pressure into the injector. Of course, I could have misunderstood his message. Walter On Jan 20, 2008, at 6:22 PM, Sky2high@aol.com wrote: In a message dated 1/20/2008 12:49:20 P.M. Central Standard Time, douglasbrunner@earthlink.net writes: A while ago there was a thread on the effect of pressurized injectors on fuel atomization. It was suggested that pressurizing the injectors improves fuel atomization and leads to a smoother running engine LOP at high altitudes. Recently, we ran tests to see what effect the use of Ram Air had on smoothness of operation at high altitude. Engine: IO-550N, 10:1 compression, ram air, magnetos, GAMI injectors, GAMI spread of .2 gallons Conditions: Altitude = 17,500, OAT = 1 C Without Ram Air (MAP = 15.2) the engine ran smoothly down to about 60 deg LOP or 8.8 gal/hr With Ram Air (MAP = 16.3) the engine only ran smoothly to Peak or 11.2 gal/hr The only difference between these two settings (that I can think of) is that in the first, ambient air pressure is probably slightly above manifold pressure (accounting for the filter) - which means the injector is pressurized very slightly. In the second, ambient pressure is probably about 1.0 less than manifold pressure (accounting for ram effect) so pressurization of the injector is reversed. This would seem to confirm the fact that unpressurized injectors reduces fuel atomization and makes for a rougher running engine LOP at altitude. I would like to run smoothly LOP at altitude using ram air. It seems to me that I can go ahead and pressurize my injectors by running tubes off the ram air tube to the injectors and using turbo injectors. (Is Mike Mahar still selling this setup?) Not sure that I want to go to the time, trouble and expense to do this though. I am also wondering if using a "hotter" spark from Electronic Ignition would improve the problem. (I would try to use an Electronic Ignition system that had the same advance as mags) Your thoughts? Doug, Well, you asked, so................. Let's try to get a common understanding of the contribution of components first. Remember that good combustion is a result of the right amount of air and fuel (A/F ratio) and something to ignite the mixture. Work is performed at a reasonable time in the combustion cycle by having the combustion event reach some appropriate state of completion( good pressure) at a certain range of motion of the piston after TDC, say around 16 degrees. Each time you change one of the combustion components, it affects the rest. Higher compression ration, fuel octane, spark effectiveness, timing, yada, yada, yada. At some point, after the engine was broken in, the baffling was set and ram system built, a Gami lean test was performed and used to get injectors that were sized to deliver A/F ratios so that each cylinder was receiving the fuel, air and spark that resulted in delivering fairly equal amounts of power as measured by reaching peak within a narrow fuel delivery range. Thus, LOP the engine ran smoothly. Now, a component was changed without recording all the data necessary to analyze the results. It would be useful to run the GAMI lean test again, with and without RAM air, since it appears that the smoothness is gone because the cylinders are producing different power. One thing that the ram set-up may do is cause an unusual flow thru the throttle body, thus altering the A/F in some cylinders. Perhaps the airflow is altered in the cooling plenum that provides air to the injectors and there could be some effect. The major benefit of providing controlled air equally to all the injectors reduces the possible effect of peculiar air flow in the cooling chamber on atomization. Be careful - the GAMI injectors were tuned to your engine as it was operating when the GAMI lean test was performed. Changing to shrouded injector bodies may again change atomization and the A/F ratio in each cylinder and not result in an improvement. The benefit of supplying air to the injector at or above the MAP (I don't know what you mean by ambient pressure) is that there is no detriment to atomization. Electronic ignitions do not just provide a "hotter" spark. They also provide a spark every time it is needed (some mags miss although you wouldn't notice it merely by feel), a longer more powerful spark to insure the mixture is ignited even if it isn't the best mixture for ignition and, they can adjust the timing to deliver the same power for less fuel (or more power for the same fuel) at different power settings as determined by RPM and MAP. Electronic ignitions may help your engine be inherently smoother, depending. Without the timing adjustments, you are assuming the mag timing is right even though you have increased the CR by quite a bit. High power performance might be improved by using less than 25 DBTDC. You have started to experiment with ram air to achieve better performance (for free) from an engine upon which you spent many dollars for high CR pistons and GAMI injectors to get a high level of performance. You have to be willing to spend more money and time on the further experimentation necessary to keep things moving towards more optimal performance. It seems you had a good configuration where everything was reasonably optimal (filtered air, GAMI, etc.) and the next step (free ram air) seemed simple except that the balance in your engine has been upset. Welcome to the world of tweaking, resulting in effects similar to those of the snowball at the top of the avalanche area. Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) Pilot not TSO'd, Certificated score only > 70%. Start the year off right. Easy ways to stay in shape in the new year. --Apple-Mail-2--718977632 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=ISO-8859-1 Scott:

Nice = summary. =A0In addition, if he is using the air pressure under the cowl = to push air into the injector (through the screen on the NA injector), = the addition of RAM air to the induction increases the MP to the point = that he no longer might have enough upper deck cowl pressure = differential to result in anything more than a pencil stream in the FF. = =A0That alone--even with excellent F:A ratios could result in rough = running as the fuel would be more liquid than vapor. =A0That's what I = understood his message to be about. =A0If my interpretation were = correct, then he's right about adding upper deck pressure to the = injectors to increase the differential pressure between MP and cowl = pressure into the injector.

Of course, I could have = misunderstood his message.

Walter


On Jan 20, = 2008, at 6:22 PM, Sky2high@aol.com= wrote:

=
=A0
=A0
In a message dated 1/20/2008 12:49:20 = P.M. Central Standard Time, douglasbrunner@earthlink.net<= /a> writes:
A=A0 while ago there was a thread on the = effect of pressurized injectors on fuel atomization.=A0 It was suggested = that pressurizing the injectors improves fuel atomization and leads to = a smoother running engine LOP at high altitudes.
=
=A0
Recently, we ran tests to see what effect the = use of Ram Air had on smoothness of operation at high = altitude.
=A0
=
Engine:=A0IO-550N, 10:1 = compression, ram air, magnetos, GAMI injectors, GAMI spread of .2 = gallons
Conditions: Altitude = =3D=A017,500, OAT=A0=3D 1 = C
=A0
=
Without Ram Air (MAP =3D 15.2) the = engine ran smoothly down to about 60 deg LOP or 8.8 = gal/hr
=A0
=
With Ram Air (MAP =3D 16.3) the = engine only ran=A0smoothly to Peak or 11.2 gal/hr
=
=A0
The only=A0difference between these two = settings (that I can think of)=A0=A0is that in the first, ambient air = pressure is probably=A0slightly=A0above manifold pressure (accounting = for the filter) - which means the injector is pressurized very = slightly.=A0In the second, ambient pressure is probably about=A01.0 less = than manifold pressure (accounting for ram effect) so pressurization = of the injector is reversed.=A0 This would seem to confirm the fact = that=A0unpressurized injectors reduces=A0fuel atomization and makes for = a rougher running engine LOP at altitude.
=A0
I would like to run smoothly=A0LOP at altitude using ram = air.=A0 It seems to me that I can go ahead and pressurize my injectors = by running tubes off the ram air tube to the injectors and using turbo = injectors.=A0 (Is=A0Mike Mahar still selling this setup?)=A0 Not sure = that I want to go to the time, trouble and expense=A0to do this = though.
=A0
I am also wondering if using a = "hotter" spark from Electronic Ignition would improve the problem.=A0 = (I would try to use an Electronic Ignition system that had the same = advance as mags)
=A0
Your = thoughts?
Doug,
=A0
=
Well, you asked, so.................
=A0
=
Let's try to get a common understanding of=A0the contribution of = components first.=A0 Remember that good combustion is a result of the = right amount of air and fuel (A/F ratio) and something to ignite the = mixture.=A0 Work is performed at a reasonable time in the = combustion=A0cycle by having the combustion event reach some appropriate = state of completion( good pressure) at a certain range of motion of the = piston after TDC, say around 16 degrees.=A0 Each time you change one of = the combustion=A0components, it affects the rest. Higher compression = ration, fuel octane, spark effectiveness, timing, yada, yada, = yada.
=A0
At some point, after the engine was = broken in, the baffling was set and ram system built, a=A0Gami lean test = was performed and used=A0to get=A0injectors that were sized to deliver = A/F ratios so that each cylinder was receiving the fuel, air and spark = that resulted in delivering fairly equal amounts of power as measured by = reaching peak within a narrow fuel delivery range.=A0 Thus, LOP the = engine ran smoothly.
=A0
Now, a component was = changed without=A0recording all the data necessary to analyze the = results.=A0 It would be useful to run the GAMI lean test again, with and = without RAM air, since it appears that the smoothness is gone because = the cylinders are producing different power.=A0 One thing that the ram = set-up may do is cause an unusual flow thru the throttle body, thus = altering the A/F in some cylinders.=A0=A0 Perhaps the airflow is altered = in the cooling plenum that provides air to the injectors and there could = be some effect.
=A0
The major benefit of providing = controlled air equally to all=A0the injectors reduces the possible = effect of peculiar air flow in the cooling chamber on atomization.=A0 Be = careful - the GAMI injectors were tuned to your engine as it was = operating when the GAMI lean test was performed.=A0 Changing to shrouded = injector bodies may again change atomization and=A0the A/F ratio in each = cylinder and not result in an improvement.=A0 The benefit of supplying = air to the injector at or above the MAP (I don't know what you mean by = ambient pressure) is that there is no detriment to atomization.
=
=A0
Electronic ignitions do not just provide a "hotter" = spark.=A0 They also provide a spark every time it is needed (some mags = miss although you wouldn't notice it merely by feel), a longer more = powerful spark to insure the mixture is ignited even if it isn't the = best mixture=A0for ignition and, they=A0can adjust the timing to deliver = the same power for less fuel (or more power for the same fuel) at = different power settings as determined by RPM and MAP.=A0 Electronic = ignitions may=A0help your engine=A0be inherently smoother, depending.=A0 = Without the timing adjustments, you are assuming the mag timing is right = even though you have increased the CR by quite a bit.=A0 High power = performance might be improved by using less than 25 DBTDC.
=
=A0
You have started to experiment with ram air to = achieve better performance (for free)=A0from an engine upon which=A0you = spent many dollars=A0for high CR pistons and GAMI injectors to get a = high level of performance.=A0You have to be willing to spend more money = and time=A0on the further experimentation necessary to keep things = moving towards more=A0optimal performance.=A0 It seems you had a good = configuration where everything was reasonably optimal (filtered air, = GAMI, etc.) and=A0the next step (free ram air) seemed simple except that = the balance in your engine has been upset.=A0
=A0
=
Welcome to the world of tweaking, resulting in effects similar to = those of the snowball at the top of the avalanche area.
=
=A0
Scott Krueger AKA Grayhawk
Lancair = N92EX IO320 SB 89/96
Aurora, IL (KARR)

Pilot not TSO'd, = Certificated score only > = 70%.




= --Apple-Mail-2--718977632--