X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [201.225.225.169] (HELO cwpanama.net) by logan.com (CommuniGate Pro SMTP 5.1c.4) with ESMTP id 1416031 for flyrotary@lancaironline.net; Fri, 22 Sep 2006 19:33:05 -0400 Received-SPF: none receiver=logan.com; client-ip=201.225.225.169; envelope-from=rijakits@cwpanama.net Received: from [201.224.93.110] (HELO usuario5ebe209) by frontend3.cwpanama.net (CommuniGate Pro SMTP 4.2.10) with SMTP id 78116425 for flyrotary@lancaironline.net; Fri, 22 Sep 2006 19:11:23 -0500 Message-ID: <007001c6de9f$50135b50$6e5de0c9@usuario5ebe209> From: "Thomas y Reina Jakits" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Fuel Pressure Regulator Vacuum or Boost?? Date: Fri, 22 Sep 2006 18:32:01 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_006D_01C6DE75.6543CD40" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2869 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 This is a multi-part message in MIME format. ------=_NextPart_000_006D_01C6DE75.6543CD40 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi guys, thanks for all the details! Got the idea! Ed, I thought the EC2 needs a fuel-P sensor anyway! Surprised it = doesn't! So the whole manifold referenced fuel-P thing is basically a means to = broaden the absolute injector range.... Thomas J. ----- Original Message -----=20 From: wrjjrs@aol.com=20 To: Rotary motors in aircraft=20 Sent: Friday, September 22, 2006 9:52 AM Subject: [FlyRotary] Re: Fuel Pressure Regulator Vacuum or Boost?? Blake, Using a vacuum referenced pressure regulator isn't manditory, but = should help you tune the system. If you run a constant fuel pressure you = must do a complete re-mapping of the needed pulse width (lets just say = rich or lean for the non-techno types among us) The system would be rich = at idle and lean at WOT if it functions as we would expect. Mapping the = other situations where the throttle opening doesn't match exactly could = be much harder. Like WOT at idle (sudden acelleration) or closed = throttle at high RPM (decent or deceleration) and what I consider the = toughest for most people transitions through tuning zones. An = explaination is most engines rotaries included have RPMs where the = combination of overlap, intake tuning, and exhaust tuning cause = reversions in the intake or lean mixtures. I had one engine that I tuned = that had a weird cam/overlap tuning situation where closing the throttle = and then opening it at a medium RPM could cause the engine to just stop! = This engine would just scream straight to red line if you opened it up = at idle, go figure. Point is there are enough problems to handle, using = a MP referenced FP regulator will help you get through the problems. But = you will probably still have some problem areas. Bill Jepson =20 -----Original Message----- From: echristley@nc.rr.com To: flyrotary@lancaironline.net Sent: Fri, 22 Sep 2006 6:23 AM Subject: [FlyRotary] Re: Fuel Pressure Regulator Vacuum or Boost?? Blake Lewis wrote:=20 =20 > I am just learning this stuff. This is my line of thoughts on the > = subject.=20 >=20 > The amount of fuel that will flow through the injector during a=20 > pulse width, is proportional to the pressure differential across the = > injector.=20 > (Delta Pressure) * (Pulse Time) =3D constant * Volume=20 > Without the "Vacuum Regulator", at Idle when you have a vacuum=20 > (less pressure) the Delta Pressure would be bigger, flowing more = fuel=20 > per pulse time.=20 > I guess the computer wants a constant flow rate.=20 =20 Not really. The computer has a lookup table that matches injector open = time to manifold pressure. The issue is, "How much adjustment range does = the computer have for modifying the open time?"=20 =20 Pulling some numbers from the air:=20 =20 You need 1GPH to get a good idle. But not just any 1GPH, you need a = nice steady 1GPH. The computer has to do this by commanding a 10% duty = cycle on the injectors. But in the real world, there is no way to = perfectly maintain a steady 10% cycle with all the electromechanical = stuff going on. Sometimes it wanders to 11 and sometimes it drops to 9. = That 1 point change is a tenth of the whole duty cycle. What you get is = a rough idle. The problem is even worse if you're turboed, and injectors = are sized to flow enough fuel at full boost. By the time you get to = idle, those injectors may have to drop to a 5% duty cycle to get down to = 1GPH.=20 =20 Now, if the computer could command a 15 or even 20% duty cycle to get = that 1GPH, then the wandering would be much less of the total open time. = How could we make the computer have to use a longer duty cycle? How = about we drop the delta pressure across the injector opening? Good = solution. Enter the vacuum referenced pressure regulator. As manifold = pressure goes down, so does the fuel pressure. The injectors have to = stay open longer.=20 =20 Is that the only solution? We could accept the rough idle as the cost = of a simpler solution. We could use a much smaller injector for the = primary which will be used at idle. The primaries could be sized to need = a 30% cycle to get that 1GPH, and monster secondaries would insure that = there is enough flow for WOT. That complicates the software, but the = hardware remains essentially the same. There is the option of higher = quality injectors that will wander less (Oops! That's sounding = expensive. Sorry I mentioned that one.)=20 =20 There may be other solutions, but given Ed's experience with nothing = more than a rough idle, I think staged injectors and the acceptance of a = little roughness at idle will let you use any pressure regulator you = choose.=20 =20 -- ,|"|"|, Ernest Christley |=20 ----=3D=3D=3D<{{(oQo)}}>=3D=3D=3D---- Dyke Delta Builder |=20 o| d |o http://ernest.isa-geek.org |=20 =20 --=20 Homepage: http://www.flyrotary.com/=20 Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/=20 -------------------------------------------------------------------------= ----- Check out the new AOL. Most comprehensive set of free safety and = security tools, free access to millions of high-quality videos from = across the web, free AOL Mail and more. ------=_NextPart_000_006D_01C6DE75.6543CD40 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi guys,
 
thanks for all the details! Got the = idea!
 
Ed, I thought the EC2 needs a fuel-P sensor = anyway!=20 Surprised it doesn't!
 
So the whole manifold referenced fuel-P thing is = basically=20 a means to broaden the absolute injector range....
 
Thomas J.
----- Original Message -----
From:=20 wrjjrs@aol.com
Sent: Friday, September 22, = 2006 9:52=20 AM
Subject: [FlyRotary] Re: Fuel = Pressure=20 Regulator Vacuum or Boost??

Blake,
Using a vacuum referenced pressure regulator isn't manditory, but = should=20 help you tune the system. If you run a constant fuel pressure you = must do=20 a complete re-mapping of the needed pulse width (lets just say = rich or=20 lean for the non-techno types among us) The system would be rich at = idle and=20 lean at WOT if it functions as we would expect. Mapping the other = situations where the throttle opening doesn't match exactly could be = much=20 harder. Like WOT at idle (sudden acelleration) or closed throttle = at high=20 RPM (decent or deceleration) and what I consider the toughest for most = people=20 transitions through tuning zones. An explaination is most = engines=20 rotaries included have RPMs where the combination of overlap, intake = tuning,=20 and exhaust tuning cause reversions in the intake or lean mixtures. I = had one=20 engine that I tuned that had a weird cam/overlap tuning situation = where=20 closing the throttle and then opening it at a medium RPM could cause = the=20 engine to just stop! This engine would just scream straight to red = line if you=20 opened it up at idle, go figure. Point is there are enough problems to = handle,=20 using a MP referenced FP regulator will help you get through the = problems. But=20 you will probably still have some problem areas.
Bill Jepson
 
 
-----Original Message-----
From:=20 echristley@nc.rr.com
To: flyrotary@lancaironline.net
Sent: Fri, = 22 Sep=20 2006 6:23 AM
Subject: [FlyRotary] Re: Fuel Pressure Regulator = Vacuum or=20 Boost??

Blake Lewis=20 wrote: 
 
> I am just learning this stuff. This is = my line=20 of thoughts on the > subject. 
> 
> The = amount of=20 fuel that will flow through the injector during a 
> pulse = width,=20 is proportional to the pressure differential across the 
>=20 injector. 
> (Delta Pressure) * (Pulse Time) =3D constant * = Volume 
> Without the "Vacuum Regulator", at Idle when you = have a=20 vacuum 
> (less pressure) the Delta Pressure would be = bigger,=20 flowing more fuel 
> per pulse time. 
> I guess = the=20 computer wants a constant flow rate. 
 
Not really. = The=20 computer has a lookup table that matches injector open time to = manifold=20 pressure. The issue is, "How much adjustment range does the computer = have for=20 modifying the open time?" 
 
Pulling some numbers from = the=20 air: 
 
You need 1GPH to get a good idle. But not just = any=20 1GPH, you need a nice steady 1GPH. The computer has to do this by = commanding a=20 10% duty cycle on the injectors. But in the real world, there is no = way to=20 perfectly maintain a steady 10% cycle with all the electromechanical = stuff=20 going on. Sometimes it wanders to 11 and sometimes it drops to 9. That = 1 point=20 change is a tenth of the whole duty cycle. What you get is a rough = idle. The=20 problem is even worse if you're turboed, and injectors are sized to = flow=20 enough fuel at full boost. By the time you get to idle, those = injectors may=20 have to drop to a 5% duty cycle to get down to = 1GPH. 
 
Now,=20 if the computer could command a 15 or even 20% duty cycle to get that = 1GPH,=20 then the wandering would be much less of the total open time. How = could we=20 make the computer have to use a longer duty cycle? How about we drop = the delta=20 pressure across the injector opening? Good solution. Enter the vacuum=20 referenced pressure regulator. As manifold pressure goes down, so does = the=20 fuel pressure. The injectors have to stay open = longer. 
 
Is=20 that the only solution? We could accept the rough idle as the cost of = a=20 simpler solution. We could use a much smaller injector for the primary = which=20 will be used at idle. The primaries could be sized to need a 30% cycle = to get=20 that 1GPH, and monster secondaries would insure that there is enough = flow for=20 WOT. That complicates the software, but the hardware remains = essentially the=20 same. There is the option of higher quality injectors that will wander = less=20 (Oops! That's sounding expensive. Sorry I mentioned that=20 one.) 
 
There may be other solutions, but given Ed's=20 experience with nothing more than a rough idle, I think staged = injectors and=20 the acceptance of a little roughness at idle will let you use any = pressure=20 regulator you choose. 
 
--   ,|"|"|, Ernest = Christley=20 | 
----=3D=3D=3D<{{(oQo)}}>=3D=3D=3D---- Dyke Delta = Builder=20 | 
  o| d |o http://ernest.isa-geek.org=20 | 
 
-- 
Homepage: http://www.flyrotary.com/ 
Archive and = UnSub: http://mail.lancaironline.net/lists/flyrotary/ <= BR>
Check out the new AOL. Most comprehensive = set of free=20 safety and security tools, free access to millions of high-quality = videos from=20 across the web, free AOL Mail and = more.
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