Return-Path: Received: from [65.54.169.115] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.2b2) with ESMTP id 3207692 for flyrotary@lancaironline.net; Wed, 05 May 2004 16:12:01 -0400 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Wed, 5 May 2004 13:12:00 -0700 Received: from 4.174.5.40 by BAY3-DAV85.phx.gbl with DAV; Wed, 05 May 2004 20:12:00 +0000 X-Originating-IP: [4.174.5.40] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Date: Wed, 5 May 2004 16:11:58 -0400 MIME-Version: 1.0 X-Mailer: MSN Explorer 7.02.0011.2700 Content-Type: multipart/alternative; boundary="----=_NextPart_001_0002_01C432BB.B1119850" Message-ID: X-OriginalArrivalTime: 05 May 2004 20:12:00.0624 (UTC) FILETIME=[39735F00:01C432DD] ------=_NextPart_001_0002_01C432BB.B1119850 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable This is all starting to make sense now. You have a combination of facto= rs that are making it hard to tune at low throttle/idle. 1. Higher than normal fuel pressure (stock is about 33 - 34 at idle) 2. Big injectors (turbo) 3. Long runner between injector & port (I think?) This combination (especially first two) is causing the injectors to be ru= n at or below the minimum operational pulse width. This is the point whe= re they can't deliver a consistent fuel pulse. =20 Sounds like you are taking the first (and easiest) logical step and reduc= ing the fuel pressure. This may be enough to =20 fix it but if not, continue down the list (after being sure you have do= ne all the EC2 tweaking possible). =20 Also be aware that the stock NA injectors (440 cc/min I think) are plen= ty big enough to deliver 220 HP on a turbo engine. If you happen to have= a set, try them. The big turbo injectors are only required to prevent d= amage to engine when racer wannabes rev the engine to 8500+ at boost. En= gine doesn't really make more power there (in stock form) but the engine = would detonate if the engine didn't get more fuel. Over-revving abuse ca= n't happen on an airplane. Tracy ----- Original Message ----- From: daveleonard@cox.net Sent: Wednesday, May 05, 2004 2:51 PM To: Rotary motors in aircraft Subject: [FlyRotary] =20 Hi all, I spent a couple of hours the other day gathering clues to my ro= ugh running problems. First the facts, then my theories. I=E2=80=99m lo= oking for any input. Description of the problem: The problem is really more of a surging rath= er than rough running. At less than about 2200 RPM the engine will begin= to surge. It gets worse the more I lower the RPM. Each time I make a = change to the throttle setting I adjust the manual mixture knob to find t= he leanest point where the engine does not surge. I have Tracy=E2=80=99s= standard mixture monitor. Each cycle of the surging takes a little over 1 sec. RPM surges buy 300-= 400 RPM. Manifold pressure fluctuates by 2-3 inches, and the mixture mon= itor fluctuates the full range of its scale. At this point I can manually increase the mixture up to the first red bar= This is over rich and the engine runs a little rough and the RPM drops= a couple of hundred. It will smoke a little more, but at least the surg= ing stops. If I lean down into the amber area the surging starts again. = The surging gets very bad if I lean down into the middle of the scale. = This is what happens around 2000 RPM and 15in MAP. If I further close the throttle, the surging is similar but to a great sc= ale. In order to stop the surging I have to increase the mixture beyond = the top of the scale. Here it will be running rough from an overly rich = condition but still surging a little too. Down around 1000 RPM it is st= ill surging but so rich it will barely run. Beyond that point, either th= e richness kills the engine, or the surging kills the engine. Assorted clues: Several additional clues may shed some light on the situ= ation. Mostly centering around the Fuel Pump. I have noticed that if th= e engine is running rough from being too rich (wont run leaner because of= the surging) and I turn the engine off (by shutting off the fuel pump) t= he will run perfectly smoothly for several seconds before it stops. In o= ther words, as the fuel pressure drops below 10 psi the mixture is lean e= nough for the engine to run well and it purrs for a couple of seconds wit= hout surging until the fuel pressure reaches zero. In an attempt to track this down more I ran a couple of experiments. I n= ormally run 45 psi of fuel pressure. I have the TWM adjustable with mani= fold compensation. First I turned down the fuel pressure to 40 ( as low = as mine goes) and possibly saw a slight improvement. Then I turned up th= e fuel pressure to 55psi and the surging definitely got worse. The cycle= time was faster, it was harder to get it to go away by enriching and the= problem continued up to about 2800 RPM. =20 So it wants a lower fuel pressure. But why? More experiments: 1. Did my best to match the mixture between the two rotors, but with the = turbo I only have a single common EGT. I noticed a slight improvement. 2. Unplugged the turbo air inlet (engine now running n.a.) =E2=80=93 no c= hange. 3. Disconnected the MAP line from the fuel pressure regulator =E2=80=93 n= o change. 4. Had my EGR passages welded closed (in case they were leaking) =E2=80=93= no change. 5. Tried assorted arrangements of where to sample MAP - no change. 6. Run engine on either the primary injectors (stock turbo in the engine = block) or the 52 lb secondaries in the Throttle body =E2=80=93 no change. 7. Run on leading or trailing coils. =E2=80=93 no change. 8. adjust timing with light =E2=80=93 no change. Other findings. I had previously that turning off my alternator caused m= y engine to stop. I turns out that turning off the alternator just makes= the mixture leaner. The effect is smaller if running on only one set of= coils, and exaggerated if there is a high amp load. But this situation = is always fixed simply by enriching the mixture (about 110 deg turn of th= e knob). The buss voltage =20 Summary: So it seems that installation is particularly sensitive to chan= ges in fuel pressure. My next step will probably be to buy a lower pres= sure fuel regulator. The thought is that maybe running 35 PSI will stabi= lize everything (i.e. maybe with only having to hold 35 psi the pump will= no be as affected by changes in fuel flow or system voltage. I will hav= e my injectors checked and cleaned although I don=E2=80=99t imagine that = will help. Any other thoughts? =20 Thanks ahead of time for any input I may get. Dave Leonard >> Homepage: http://www.flyrotary.com/ >> Archive: http://lancaironline.net/lists/flyrotary/List.html ------=_NextPart_001_0002_01C432BB.B1119850 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable
This is all st= arting to make sense now.   You have a combination of factors t= hat are making it hard to tune at low throttle/idle.
 
1.  Higher than normal fuel pressure   (sto= ck is about 33 - 34 at idle)
2.  Big injectors= (turbo)
3.  Long runner between injector & port = ; (I think?)
 
This combination (especially fi= rst two) is causing the injectors to be run at or below the minimum = operational pulse width.  This is the point where they can't deliver= a consistent fuel pulse. 
 
Sounds like = you are taking the first (and easiest) logical step and reducing the fuel= pressure.  This may be enough to
fix it  but if no= t, continue down the list  (after being sure you have done all the E= C2 tweaking possible). 
 
 Also be a= ware that the stock NA injectors (440 cc/min I think)  are plen= ty big enough to deliver 220 HP on a turbo engine.  If you happen to= have a set, try them.  The big turbo injectors are only required to= prevent damage to engine when racer wannabes rev the engine to 8500+ at = boost.  Engine doesn't really make more power there (in stock f= orm) but the engine would detonate if the engine didn't get more fuel.&nb= sp; Over-revving abuse can't happen on an airplane.
 = ;
Tracy
----- Original Message -----
= From: daveleonard@cox.net
Se= nt: Wednesday, May 05, 2004 2:51 PM
To: Rotary motors in aircraft
Subject: [FlyRotary]
 
Hi all,  = I spent a couple of hours the other day gathering clues to my rough runni= ng problems.  First the facts, then my theories.  I=E2=80=99m l= ooking for any input.

Description of the problem:  The proble= m is really more of a surging rather than rough running.  At less th= an about 2200 RPM the engine will begin to surge.   It gets wor= se the more I lower the RPM.  Each time I make a change to the throt= tle setting I adjust the manual mixture knob to find the leanest point wh= ere the engine does not surge.  I have Tracy=E2=80=99s standard mixt= ure monitor.

Each cycle of the surging takes a little over 1 sec.&= nbsp; RPM surges buy 300-400 RPM.  Manifold pressure fluctuates by 2= -3 inches, and the mixture monitor fluctuates the full range of its scale=

At this point I can manually increase the mixture up to the firs= t red bar.  This is over rich and the engine runs a little rough and= the RPM drops a couple of hundred.  It will smoke a little more, bu= t at least the surging stops.  If I lean down into the amber area th= e surging starts again.  The surging gets very bad if I lean down in= to the middle of the scale.  This is what happens around 2000 RPM an= d 15in MAP.

If I further close the throttle, the surging is simila= r but to a great scale.  In order to stop the surging I have to incr= ease the mixture beyond the top of the scale.  Here it will be runni= ng rough from an overly rich condition but still surging a little too.&nb= sp;  Down around 1000 RPM it is still surging but so rich it will ba= rely run.  Beyond that point, either the richness kills the engine, = or the surging kills the engine.

Assorted clues:  Several add= itional clues may shed some light on the situation.  Mostly centerin= g around the Fuel Pump.  I have noticed that if the engine is runnin= g rough from being too rich (wont run leaner because of the surging) and = I turn the engine off (by shutting off the fuel pump) the will run perfec= tly smoothly for several seconds before it stops.  In other words, a= s the fuel pressure drops below 10 psi the mixture is lean enough for the= engine to run well and it purrs for a couple of seconds without surging = until the fuel pressure reaches zero.

In an attempt to track this = down more I ran a couple of experiments.  I normally run 45 psi of f= uel pressure.  I have the TWM adjustable with manifold compensation.=   First I turned down the fuel pressure to 40 ( as low as mine goes)= and possibly saw a slight improvement.  Then I turned up the fuel p= ressure to 55psi and the surging definitely got worse.  The cycle ti= me was faster, it was harder to get it to go away by enriching and the pr= oblem continued up to about 2800 RPM.

So it wants a lower fuel pr= essure.  But why?  More experiments:
1. Did my best to match= the mixture between the two rotors, but with the turbo I only have a sin= gle common EGT.  I noticed a slight improvement.
2. Unplugged the= turbo air inlet (engine now running n.a.) =E2=80=93 no change.
3. Dis= connected the MAP line from the fuel pressure regulator =E2=80=93 no chan= ge.
4. Had my EGR passages welded closed (in case they were leaking) =E2= =80=93 no change.
5. Tried assorted arrangements of where to sample MA= P  -  no change.
6. Run engine on either the primary injecto= rs (stock turbo in the engine block) or the 52 lb secondaries in the Thro= ttle body =E2=80=93 no change.
7. Run on leading or trailing coils. =E2= =80=93 no change.
8. adjust timing with light =E2=80=93 no change.
=
Other findings.  I had previously that turning off my alternator= caused my engine to stop.  I turns out that turning off the alterna= tor just makes the mixture leaner.  The effect is smaller if running= on only one set of coils, and exaggerated if there is a high amp load.&n= bsp; But this situation is always fixed simply by enriching the mixture (= about 110 deg turn of the knob).  The buss voltage

Summary:&= nbsp; So it seems that installation is particularly sensitive to changes = in fuel pressure.  My next  step will probably be to buy a lowe= r pressure fuel regulator.  The thought is that maybe running 35 PSI= will stabilize everything (i.e. maybe with only having to hold 35 psi th= e pump will no be as affected by changes in fuel flow or system voltage.&= nbsp; I will have my injectors checked and cleaned although I don=E2=80=99= t imagine that will help.

Any other thoughts? 

Thanks= ahead of time for any input I may get.

Dave Leonard


>>  Homepage:  http://www.flyrotary.com/
>>&nb= sp; Archive:   http://lancaironline.net/lists/flyrotary/List.ht= ml
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