Return-Path: Received: from mail18.syd.optusnet.com.au ([211.29.132.199] verified) by logan.com (CommuniGate Pro SMTP 4.2.8) with ESMTP-TLS id 616862 for flyrotary@lancaironline.net; Fri, 21 Jan 2005 17:51:36 -0500 Received-SPF: none receiver=logan.com; client-ip=211.29.132.199; 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 mail18.syd.optusnet.com.au (8.12.11/8.12.11) with SMTP id j0LMp2vf030286 for ; Sat, 22 Jan 2005 09:51:03 +1100 Message-ID: <008301c5000b$f1767640$8b1aecdc@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Fuel Injector Sizing Date: Sat, 22 Jan 2005 08:52:53 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0080_01C5005F.C2BC2350" 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_0080_01C5005F.C2BC2350 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable 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_0080_01C5005F.C2BC2350 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Ken and Ed Anderson.

Your info and advice is well recieved = and timely=20 for me - I didn't know what to use, now at least I can talk = with=20 some knowledge to suppliers.

One small question if I may - what is = the fuel=20 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 for=20 242 HP. The 440cc/42 lb injecors are good for 267 HP. =

Also check out RC Engineering which is the most accepted expert = that I=20 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 42=20 lb injectors are also good for 267 HP. Looks like these guys are = using=20 the same formulas - good to see consistency from 2 different = sources.

Lastly, note that injectors should not be run continuously over = 80% duty=20 cycle or they will overheat and fail. A smaller is better when = it comes=20 to idle control. DO NOT forget this part of the equation. = Lastly,=20 at cruise altitudes the injector cycle rate decreases as the HP = requirement=20 decreases so at 8000 ft the duty cycle of the injectors will only be = 60 %=20 which is very safe for sustained operation. Call me if you want = to=20 discuss this. Go play with the calculators posted above (which = George=20 has already done).

Ken Powell
Bryant, Arkansas
501-847-4721

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