X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 23 Jan 2008 07:47:05 -0500 Message-ID: X-Original-Return-Path: Received: from imo-m27.mx.aol.com ([64.12.137.8] verified) by logan.com (CommuniGate Pro SMTP 5.2c4) with ESMTP id 2685287 for lml@lancaironline.net; Tue, 22 Jan 2008 21:45:41 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.8; envelope-from=PJHWFD@aol.com Received: from PJHWFD@aol.com by imo-m27.mx.aol.com (mail_out_v38_r9.3.) id q.c90.21971ab5 (65100) for ; Tue, 22 Jan 2008 21:44:55 -0500 (EST) From: PJHWFD@aol.com X-Original-Message-ID: X-Original-Date: Tue, 22 Jan 2008 21:44:54 EST Subject: Re: [LML] Re: Pressurized Injectors X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1201056294" X-Mailer: Unknown sub 36 X-Spam-Flag: NO -------------------------------1201056294 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Doug and all, I have a performance engine with Mike's injector pressurization feed off the ram air. I can run very smoothly at 100 degrees LOP with the ram. One question I had was old Bernoulli's theorem as it relates to taking a feed off the intake. I ended up bending a tab down to scoop the feed air as I was unsure if high velocity low pressure air would move things the wrong way. I also built a carbon scoop to take air directly from the intake because taking air near the intake seemed to be a crap shot at getting high pressure ram predictably. The whole system works well for me. In a message dated 1/22/2008 10:42:48 A.M. Eastern Standard Time, douglasbrunner@earthlink.net writes: 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 reversal of pressure through the screen) makes the engine run rough (at high altitude, LOP) - as you suggested. 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 ----- From: _Walter Atkinson_ (mailto:walter@advancedpilot.com) To: _lml@lancaironline.net_ (mailto:lml@lancaironline.net) 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_ (mailto:Sky2high@aol.com) wrote: In a message dated 1/20/2008 12:49:20 P.M. Central Standard Time, _douglasbrunner@earthlink.net_ (mailto: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_ (http://body.aol.com/fitness/winter-exercise?NCID=aolcmp00300000002489) in the new year. **************Start the year off right. Easy ways to stay in shape. http://body.aol.com/fitness/winter-exercise?NCID=aolcmp00300000002489 -------------------------------1201056294 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
Doug and all,
I have a performance engine with Mike's injector pressurization feed of= f=20 the ram air.  I can run very smoothly at 100 degrees LOP with the=20 ram.  One question I had was old Bernoulli's  theorem as it relate= s to=20 taking a feed off the intake.  I ended up bending a tab down to scoop t= he=20 feed air as I was unsure if high velocity low pressure air would move things= the=20 wrong way.  I also built a carbon scoop to take air directly from the=20 intake because taking air near the intake seemed to be a crap shot at gettin= g=20 high pressure ram predictably. The whole system works well for me.
 
In a message dated 1/22/2008 10:42:48 A.M. Eastern Standard Time,=20 douglasbrunner@earthlink.net writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
Walter,
 
You understood me correctly.
 
The test was designed to determine how sm= oothly=20 the engine runs at high altitude, lean of peak in two difference=20 situations:
1)  NO RAM AIR - air pressure inside= the=20 cowl exceeds the pressure of the induction system (usual for a normally=20 aspirated engine)
2)  RAM AIR - air pressure inside th= e cowl=20 is less than the pressure of the induction system.
 
It appears that using ram air (with the r= esultant=20 reversal of pressure through the screen) makes the engine run rough (at hi= gh=20 altitude, LOP) - as you suggested. 
 
GAMI lean test has already been performed= using=20 ram air (at a lower altitude) with very good results (.2 spread).  Of= =20 course I can repeat GAMI lean test, but if we assume that the spread remai= ns=20 low then improper fuel distribution is not the problem and lack of fuel=20 atomization may be.
 
Mike Mahar sells a system to pressurize t= he=20 injectors - has anyone tried it and what were the results?
 
D. Brunner
 
D. Brunner
 
 
----- Original Message -----
Fr= om:=20 Walter Atkinson
To: lml@lancaironline.net
Sent: Monday, January 21, 2008 10= :05=20 AM
Subject: [LML] Re: Pressurized=20 Injectors

Scott:=20

Nice summary.  In addition, if he is using the air pressure un= der=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=20= 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=20 running as the fuel would be more liquid than vapor.  That's what I= =20 understood his message to be about.  If my interpretation were corr= ect,=20 then he's right about adding upper deck pressure to the injectors to=20 increase the differential pressure between MP and cowl pressure into the= =20 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, <= A=20 title=3Dmailto:douglasbrunner@earthlink.net=20 href=3D"mailto:douglasbrunner@earthlink.net">douglasbrunner@earthlink.ne= t=20 writes:
A  while ago there was a thread=20= on the=20 effect of pressurized injectors on fuel atomization.  It was=20 suggested that pressurizing the injectors improves fuel atomization an= d=20 leads to a smoother running engine LOP at high altitudes.
 
Recently, we ran tests to see what ef= fect the=20 use of Ram Air had on smoothness of operation at high=20 altitude.
 
Engine: IO-550N, 10:1 compressio= n, 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 en= gine ran=20 smoothly down to about 60 deg LOP or 8.8 gal/hr
 
With Ram Air (MAP =3D 16.3) the engin= e only=20 ran smoothly to Peak or 11.2 gal/hr
 
The only difference between thes= e two=20 settings (that I can think of)  is that in the first, ambien= t=20 air pressure is probably slightly above manifold pressure=20 (accounting for the filter) - which means the injector is pressurized=20= very=20 slightly. In the second, ambient pressure is probably about = 1.0=20 less than manifold pressure (accounting for ram effect) so pressurizat= ion=20 of the injector is reversed.  This would seem to confirm the fact= =20 that unpressurized injectors reduces fuel atomization and ma= kes=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=20 pressurize my injectors by running tubes off the ram air tube to the=20 injectors and using turbo injectors.  (Is Mike Mahar still=20 selling this setup?)  Not sure that I want to go to the time, tro= uble=20 and expense to do this though.
 
I am also wondering if using a "hotte= r" 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=20 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= =20 right amount of air and fuel (A/F ratio) and something to ignite the=20 mixture.  Work is performed at a reasonable time in the=20 combustion cycle by having the combustion event reach some appropri= ate=20 state of completion( good pressure) at a certain range of motion of the=20 piston after TDC, say around 16 degrees.  Each time you change one=20= of=20 the combustion components, it affects the rest. Higher compression=20 ration, fuel octane, spark effectiveness, 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=20 get injectors that were sized to deliver A/F ratios so that each=20 cylinder was receiving the fuel, air and spark that resulted in deliveri= ng=20 fairly equal amounts of power as measured by reaching peak within a narr= ow=20 fuel delivery 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 GA= MI=20 lean test again, with and without RAM air, since it appears that the=20 smoothness is gone because the cylinders are producing different=20 power.  One thing that the ram set-up may do is cause an unusual fl= ow=20 thru the throttle body, thus altering the A/F in some cylinders. &n= bsp;=20 Perhaps the airflow is altered in the cooling plenum that provides air t= o=20 the injectors and there could be some effect.
 
The major benefit of providing controlled air equally to all t= he=20 injectors reduces the possible effect of peculiar air flow in the coolin= g=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.&n= bsp;=20 Changing to shrouded injector bodies may again change atomization=20 and the A/F ratio in each cylinder and not result in an=20 improvement.  The benefit of supplying air to the injector at or ab= ove=20 the MAP (I don't know what you mean by ambient pressure) is that there i= s no=20 detriment to atomization.
 
Electronic ignitions do not just provide a "hotter" spark.  Th= ey=20 also provide a spark every time it is needed (some mags miss although yo= u=20 wouldn't notice it merely by feel), a longer more powerful spark to insu= re=20 the mixture is ignited even if it isn't the best mixture for igniti= on=20 and, they can adjust the timing to deliver the same power for less=20= fuel=20 (or more power for the same fuel) at different power settings as determi= ned=20 by RPM and MAP.  Electronic ignitions may help your engine&nbs= p;be=20 inherently smoother, depending.  Without the timing adjustments, yo= u=20 are assuming the mag timing is right even though you have increased the=20= CR=20 by quite a bit.  High power performance might be improved by using=20= less=20 than 25 DBTDC.
 
You have started to experiment with ram air to achieve better=20 performance (for free) from an engine upon which you spent man= y=20 dollars for high CR pistons and GAMI injectors to get a high level=20= of=20 performance. You have to be willing to spend more money and=20 time on the further experimentation necessary to keep things moving= =20 towards more optimal performance.  It seems you had a good=20 configuration where everything was reasonably optimal (filtered air, GAM= I,=20 etc.) and the next step (free ram air) seemed simple except that th= e=20 balance in your engine has been upset. 
 
Welcome to the world of tweaking, resulting in effects similar to t= hose=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




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