X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 22 Jan 2008 10:41:43 -0500 Message-ID: X-Original-Return-Path: Received: from elasmtp-galgo.atl.sa.earthlink.net ([209.86.89.61] verified) by logan.com (CommuniGate Pro SMTP 5.2c4) with ESMTP id 2682241 for lml@lancaironline.net; Mon, 21 Jan 2008 14:24:50 -0500 Received-SPF: none receiver=logan.com; client-ip=209.86.89.61; envelope-from=douglasbrunner@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=JO8nJPqihCvWyNib00SNm3PHr9wXQ28HX3vNtthimyKQ9KCKULvAzyS3ujYnl5Ry; h=Received:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MIMEOLE:X-ELNK-Trace:X-Originating-IP; Received: from [68.204.156.17] (helo=DFWK3391) by elasmtp-galgo.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1JH2Fh-0006Wq-S5 for lml@lancaironline.net; Mon, 21 Jan 2008 14:24:14 -0500 X-Original-Message-ID: <002a01c85c63$35b08e20$6d00a8c0@DFWK3391> From: "Douglas Brunner" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Re: Pressurized Injectors X-Original-Date: Mon, 21 Jan 2008 14:24:14 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0027_01C85C39.4C73FC20" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 X-ELNK-Trace: ad85a799c4f5de37c2eb1477c196d22294f5150ab1c16ac04d04932202c5b85b12a0b501542dd387d0b75bcb38c0fc08350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 68.204.156.17 This is a multi-part message in MIME format. ------=_NextPart_000_0027_01C85C39.4C73FC20 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Walter, You understood me correctly. The test was designed to determine how smoothly the engine runs at high = altitude, lean of peak in two difference situations: 1) NO RAM AIR - air pressure inside the cowl exceeds the pressure of = the induction system (usual for a normally aspirated engine) 2) RAM AIR - air pressure inside the cowl is less than the pressure of = the induction system. It appears that using ram air (with the resultant reveral of pressure = through the screen) makes the engine run rough (at high altitude, LOP) - = as you suggested. =20 GAMI lean test has already been performed using ram air (at a lower = altitude) with very good results (.2 spread). Of course I can repeat = GAMI lean test, but if we assume that the spread remains low then = improper fuel distribution is not the problem and lack of fuel = atomization may be. Mike Mahar sells a system to pressurize the injectors - has anyone tried = it and what were the results? D. Brunner D. Brunner ----- Original Message -----=20 From: Walter Atkinson=20 To: lml@lancaironline.net=20 Sent: Monday, January 21, 2008 10:05 AM Subject: [LML] Re: Pressurized Injectors 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 =3D 17,500, OAT =3D 1 C Without Ram Air (MAP =3D 15.2) the engine ran smoothly down to about = 60 deg LOP or 8.8 gal/hr With Ram Air (MAP =3D 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. =20 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.=20 ------=_NextPart_000_0027_01C85C39.4C73FC20 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Walter,
 
You understood me = correctly.
 
The test was designed to determine how = smoothly the=20 engine runs at high altitude, lean of peak in two difference=20 situations:
1)  NO RAM AIR - air pressure = inside the cowl=20 exceeds the pressure of the induction system (usual for a normally = aspirated=20 engine)
2)  RAM AIR - air pressure inside = the cowl is=20 less than the pressure of the induction system.
 
It appears that using ram air (with the = resultant=20 reveral of pressure through the screen) makes the engine run rough (at = high=20 altitude, LOP) - as you suggested. 
 
GAMI lean test has already been = performed using ram=20 air (at a lower altitude) with very good results (.2 spread).  Of = course I=20 can repeat GAMI lean test, but if we assume that the spread remains low = then=20 improper fuel distribution is not the problem and lack of fuel = atomization may=20 be.
 
Mike Mahar sells a system to pressurize = the=20 injectors - has anyone tried it and what were the results?
 
D. Brunner
 
D. Brunner
 
 
----- Original Message -----
From:=20 Walter Atkinson
Sent: Monday, January 21, 2008 = 10:05=20 AM
Subject: [LML] Re: Pressurized=20 Injectors

Scott:

Nice summary.  In addition, if he is using the air pressure = under=20 the cowl to push air into the injector (through the screen on the NA=20 injector), the addition of RAM air to the induction increases the MP = to the=20 point that he no longer might have enough upper deck cowl pressure=20 differential to result in anything more than a pencil stream in the = FF.=20  That alone--even with excellent F:A ratios could result in rough = running=20 as the fuel would be more liquid than vapor.  That's what I = understood=20 his message to be about.  If my interpretation were correct, then = he's=20 right about adding upper deck pressure to the injectors to increase = the=20 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= =20 writes:
A  while ago there was a = thread on the=20 effect of pressurized injectors on fuel atomization.  It was = suggested=20 that pressurizing the injectors improves fuel atomization and leads = to a=20 smoother running engine LOP at high altitudes.
 
Recently, we ran tests to see what = effect the=20 use of Ram Air had on smoothness of operation at high = altitude.
 
Engine: IO-550N, 10:1 = compression, ram=20 air, magnetos, GAMI injectors, GAMI spread of .2=20 gallons
Conditions: Altitude =3D 17,500, OAT =3D 1=20 C
 
Without Ram Air (MAP =3D 15.2) the = engine ran=20 smoothly down to about 60 deg LOP or 8.8 gal/hr
 
With Ram Air (MAP =3D 16.3) the = engine only=20 ran smoothly to Peak or 11.2 gal/hr
 
The only difference between = these two=20 settings (that I can think of)  is that in the first, = ambient air=20 pressure is probably slightly above manifold pressure = (accounting=20 for the filter) - which means the injector is pressurized very=20 slightly. In the second, ambient pressure is probably = about 1.0=20 less than manifold pressure (accounting for ram effect) so = pressurization of=20 the injector is reversed.  This would seem to confirm the fact=20 that unpressurized injectors reduces fuel atomization and = makes=20 for a rougher running engine LOP at altitude.
 
I would like to run = smoothly LOP at=20 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=20 this setup?)  Not sure that I want to go to the time, trouble = and=20 expense to do this though.
 
I am also wondering if using a = "hotter" spark=20 from Electronic Ignition would improve the problem.  (I would = try to=20 use an Electronic Ignition system that had the same advance as=20 mags)
 
Your = thoughts?
Doug,
 
Well, you asked, so.................
 
Let's try to get a common understanding of the contribution = of=20 components first.  Remember that good combustion is a result of = the right=20 amount of air and fuel (A/F ratio) and something to ignite the = mixture. =20 Work is performed at a reasonable time in the combustion cycle by = having=20 the combustion event reach some appropriate state of completion( good=20 pressure) at a certain range of motion of the piston after TDC, say = around 16=20 degrees.  Each time you change one of the = combustion components, it=20 affects the rest. Higher compression ration, fuel octane, spark = effectiveness,=20 timing, yada, yada, yada.
 
At some point, after the engine was broken in, the baffling was = set and=20 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=20 was receiving the fuel, air and spark that resulted in delivering = fairly equal=20 amounts of power as measured by reaching peak within a narrow fuel = delivery=20 range.  Thus, LOP the engine ran smoothly.
 
Now, a component was changed without recording all the data=20 necessary to analyze the results.  It would be useful to run the = GAMI=20 lean test again, with and without RAM air, since it appears that the=20 smoothness is gone because the cylinders are producing different = power. =20 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=20 the airflow is altered in the cooling plenum that provides air to the=20 injectors and there could be some effect.
 
The major benefit of providing controlled air equally to = all the=20 injectors reduces the possible effect of peculiar air flow in the = cooling=20 chamber on atomization.  Be careful - the GAMI injectors were = tuned to=20 your engine as it was operating when the GAMI lean test was = performed. =20 Changing to shrouded injector bodies may again change atomization = and the=20 A/F ratio in each cylinder and not result in an improvement.  The = benefit=20 of supplying air to the injector at or above the MAP (I don't know = what you=20 mean by ambient pressure) is that there is no detriment to = atomization.
 
Electronic ignitions do not just provide a "hotter" spark.  = They=20 also provide a spark every time it is needed (some mags miss although = you=20 wouldn't notice it merely by feel), a longer more powerful spark to = insure the=20 mixture is ignited even if it isn't the best mixture for ignition = and,=20 they can adjust the timing to deliver the same power for less = fuel (or=20 more power for the same fuel) at different power settings as = determined by RPM=20 and MAP.  Electronic ignitions may help your engine be=20 inherently smoother, depending.  Without the timing adjustments, = you are=20 assuming the mag timing is right even though you have increased the CR = by=20 quite a bit.  High power performance might be improved by using = less than=20 25 DBTDC.
 
You have started to experiment with ram air to achieve better = performance=20 (for free) from an engine upon which you spent many = dollars for=20 high CR pistons and GAMI injectors to get a high level of=20 performance. You have to be willing to spend more money and = time on=20 the further experimentation necessary to keep things moving towards=20 more optimal performance.  It seems you had a good = configuration=20 where everything was reasonably optimal (filtered air, GAMI, etc.)=20 and the next step (free ram air) seemed simple except that the = balance in=20 your engine has been upset. 
 
Welcome to the world of tweaking, resulting in effects similar to = those=20 of the snowball at the top of the avalanche area.
 
Scott=20 Krueger AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL=20 (KARR)

Pilot not TSO'd, Certificated score only >=20 70%.



Start the year off right. Easy ways to stay in shape in the new year.=20

------=_NextPart_000_0027_01C85C39.4C73FC20--