Return-Path: Received: from mail01.syd.optusnet.com.au ([211.29.132.182] verified) by logan.com (CommuniGate Pro SMTP 4.2.8) with ESMTP-TLS id 616991 for flyrotary@lancaironline.net; Fri, 21 Jan 2005 19:18:24 -0500 Received-SPF: none receiver=logan.com; client-ip=211.29.132.182; envelope-from=lendich@optusnet.com.au Received: from george (d220-236-26-139.dsl.nsw.optusnet.com.au [220.236.26.139] (may be forged)) by mail01.syd.optusnet.com.au (8.12.11/8.12.11) with SMTP id j0M0HpBT011041 for ; Sat, 22 Jan 2005 11:17:52 +1100 Message-ID: <014d01c50018$12358680$8b1aecdc@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Fuel Injector Sizing Date: Sat, 22 Jan 2005 10:19:43 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_014A_01C5006B.E39CC550" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 This is a multi-part message in MIME format. ------=_NextPart_000_014A_01C5006B.E39CC550 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Thanks Ed, More info than I asked for but not more than I need. George (down under) ----- Original Message -----=20 From: Ed Anderson=20 To: Rotary motors in aircraft=20 Sent: Saturday, January 22, 2005 9:37 AM Subject: [FlyRotary] Re: Fuel Injector Sizing George, my fuel pressure gauge reads between 40 and 43 psi depending = on whether I have one or both pumps on. I fly with 40 psi (one pump). = My pump (with no flow) will give a pressure of 80 psi, but a regulator = keeps it at 40-43 psi. I generally check my pumps for their no-flow = pressure and have noticed over the 6 years that the pressure of the main = pump has decreased from 80 psi to 60 psi - so getting near replacement = time. The spare pump still produces 80 psi - less wear as it is = normally only on for take off and landing. Ed A ----- Original Message -----=20 From: George Lendich=20 To: Rotary motors in aircraft=20 Sent: Friday, January 21, 2005 5:52 PM Subject: [FlyRotary] Re: Fuel Injector Sizing Ken and Ed Anderson. Your info and advice is well recieved and timely for me - I didn't = know what to use, now at least I can talk with some knowledge to = suppliers. One small question if I may - what is the fuel rail pressure = usually? Thanks again! George ( down under) Hi Jerry and George, The debate over the optimal injector size has been going on for = years. I personally plan to use 400cc/38 lb or 440cc/42 lb Ford = injectors. According to = http://www.maxcooper.com/rx7/how-to/fuel_system/calcs.html 38 lb = injectors at 80% duty cycle / 43 lb / .5 BSFC pressure are good for 242 = HP. The 440cc/42 lb injecors are good for 267 HP. =20 Also check out RC Engineering which is the most accepted expert = that I know of (http://www.rceng.com/technical.htm#WORKSHEET). Using = the same assumptions the 38 lb injectors are good for 242 HP and the 42 = lb injectors are also good for 267 HP. Looks like these guys are using = the same formulas - good to see consistency from 2 different sources. Lastly, note that injectors should not be run continuously over = 80% duty cycle or they will overheat and fail. A smaller is better when = it comes to idle control. DO NOT forget this part of the equation. = Lastly, at cruise altitudes the injector cycle rate decreases as the HP = requirement decreases so at 8000 ft the duty cycle of the injectors will = only be 60 % which is very safe for sustained operation. Call me if you = want to discuss this. Go play with the calculators posted above (which = George has already done). =20 Ken Powell=20 Bryant, Arkansas=20 501-847-4721 ------=_NextPart_000_014A_01C5006B.E39CC550 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Thanks Ed,
More info than I asked for but not more = than I=20 need.
George (down under)
----- Original Message -----
From:=20 Ed=20 Anderson
Sent: Saturday, January 22, = 2005 9:37=20 AM
Subject: [FlyRotary] Re: Fuel = Injector=20 Sizing

George, my fuel pressure gauge reads = between 40=20 and 43 psi depending on whether I have one or both pumps on.  I = fly with=20 40 psi (one pump).   My pump (with no flow) will give a = pressure of=20 80 psi, but a regulator keeps it at 40-43 psi.  I generally check = my=20 pumps for their no-flow pressure and have noticed over the 6 years = that the=20 pressure of the main pump has decreased from 80 psi to 60 psi - so = getting=20 near replacement time.  The spare pump still produces 80 psi - = less wear=20 as it is normally only on for take off and landing.
 
Ed A
----- Original Message -----
From:=20 George Lendich
To: Rotary motors in = aircraft=20
Sent: Friday, January 21, = 2005 5:52=20 PM
Subject: [FlyRotary] Re: Fuel = Injector=20 Sizing

 
Ken and Ed Anderson.
Your info and advice is well = recieved and=20 timely for me - I didn't know what to use, now at least = I can=20 talk with some knowledge to suppliers.
One small question if I may - what = is the=20 fuel rail pressure usually?
Thanks again!
George ( down under)
 
Hi Jerry and George,
The debate over the optimal injector size has been going on = for=20 years.  I personally plan to use 400cc/38 lb or 440cc/42 lb = Ford=20 injectors.  According to http:= //www.maxcooper.com/rx7/how-to/fuel_system/calcs.html 38=20 lb injectors at 80% duty cycle / 43 lb / .5 BSFC pressure are = good=20 for 242 HP.  The 440cc/42 lb injecors are good for 267 = HP. =20
 
Also check out RC Engineering which is the most accepted = expert that=20 I know of (http://www.rceng.co= m/technical.htm#WORKSHEET). =20 Using the same assumptions the 38 lb injectors are good for 242 HP = and the=20 42 lb injectors are also good for 267 HP.  Looks like these = guys are=20 using the same formulas - good to see consistency from 2 different = sources.
 
Lastly, note that injectors should not be run continuously = over 80%=20 duty cycle or they will overheat and fail.  A smaller is = better when=20 it comes to idle control.  DO NOT forget this part of the=20 equation.  Lastly, at cruise altitudes the injector cycle = rate=20 decreases as the HP requirement decreases so at 8000 ft the duty = cycle of=20 the injectors will only be 60 % which is very safe for sustained=20 operation.  Call me if you want to discuss this.  Go = play with=20 the calculators posted above (which George has already=20 done).   

Ken Powell
Bryant, Arkansas
501-847-4721
=
 
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