Return-Path: Received: from [65.54.168.123] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.3c2) with ESMTP id 763311 for flyrotary@lancaironline.net; Mon, 28 Feb 2005 15:35:46 -0500 Received-SPF: pass receiver=logan.com; client-ip=65.54.168.123; envelope-from=lors01@msn.com Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Mon, 28 Feb 2005 12:35:00 -0800 Message-ID: Received: from 4.174.0.238 by BAY3-DAV19.phx.gbl with DAV; Mon, 28 Feb 2005 20:34:09 +0000 X-Originating-IP: [4.174.0.238] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: injector life and reliability Date: Mon, 28 Feb 2005 15:34:08 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0052_01C51DAA.F190C650" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: MSN 9 Seal-Send-Time: Mon, 28 Feb 2005 15:34:08 -0500 X-MimeOLE: Produced By MSN MimeOLE V9.10.0011.1703 X-OriginalArrivalTime: 28 Feb 2005 20:35:00.0334 (UTC) FILETIME=[F955A8E0:01C51DD4] This is a multi-part message in MIME format. ------=_NextPart_000_0052_01C51DAA.F190C650 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Correct on all points Ed. Except that I changed the injector drivers to = a higher current version about 6 years ago. This was after a couple of = "peak & hold injectors connected as saturated" incidents. Now the = injector gives up first. But I think it still takes a long time to kill = an injector this way. Tracy Subject: [FlyRotary] Re: injector life and reliability Bernie, Your injectors should be fine, the drivers won't hurt the injectors - however, the injectors can hurt the drivers. Because a saturation = driver is expecting more resistance (less current requirement) from a saturated = type injector of around 12-16 ohms. If you stick a Peak and Hold (around = 2.5 ohms) in a circuit designed for saturation injectors, they (Peak and = hold) will draw considerably more current and may exceed the design limit of = the saturation injector driver thereby damaging it. On the other hand, if = the designer "over-designed" the driver it may cause no damage at all. If you put a saturation injectors in a circuit designed for Peak and = Hold, you will not damage the drivers because the saturation injector will = never exceed the current draw the P&H circuit was designed for - but, you = may not get very good injection especially at the lower rpms. So if anything could have been damaged - it would have been the EC2, = but Tracy has done a good job of providing a bit of margin there as well. = I don't doubt you had a bad injectors ( I have had several - they are = just getting old), but I doubt it was caused by the lack of resistors. Tracy, of course, will correct any incorrect reference to his design = work {:>) Ed A ------=_NextPart_000_0052_01C51DAA.F190C650 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
Correct on all points Ed.  Except that I changed the injector = drivers=20 to a higher current version about 6 years ago.  This was after a = couple of=20 "peak & hold injectors connected as saturated" incidents.  Now = the=20 injector gives up first.  But I think it still takes a long time to = kill an=20 injector this way.
 
Tracy
 
Subject: [FlyRotary] Re: injector life and reliability

Bernie,

Your injectors should be fine, the = drivers won't=20 hurt the injectors -
however, the injectors can hurt the = drivers. =20 Because a saturation driver is
expecting more resistance (less = current=20 requirement) from a saturated type
injector of around 12-16 = ohms.  If=20 you stick a Peak and Hold (around 2.5
ohms) in a circuit designed = for=20 saturation injectors,  they (Peak and hold)
will draw = considerably=20 more current and may exceed the design limit of = the
saturation =20 injector driver thereby damaging it. On the other hand, if = the
designer=20 "over-designed" the driver it may cause no damage at all.

If = you put a=20 saturation injectors in a circuit designed for Peak and Hold,
you = will not=20 damage the drivers because the saturation injector will = never
exceed the=20 current draw the P&H circuit was designed for - but, you may = not
get=20 very good injection especially at the lower rpms.

So if = anything could=20 have been damaged - it would have been the EC2, but
Tracy has done = a good=20 job of providing a bit of margin there as well.  I
don't doubt = you had=20 a bad injectors ( I have had several - they are just
getting old), = but I=20 doubt it was caused by the lack of resistors.

Tracy, of course, = will=20 correct any incorrect reference to his design = work
{:>)

Ed=20 A


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