Return-Path: Sender: (Marvin Kaye) To: lml@lancaironline.net Date: Mon, 17 May 2004 21:05:19 -0400 Message-ID: X-Original-Return-Path: Received: from mail.indian-creek.net ([209.176.40.9] verified) by logan.com (CommuniGate Pro SMTP 4.2b3) with ESMTP id 3237962 for lml@lancaironline.net; Mon, 17 May 2004 20:56:26 -0400 Received: from VAIO (sl14.du.indian-creek.net [209.176.40.30] toucan@78055.com) by mail.indian-creek.net with SMTP (IOA-IPAD 4.02) id 5WDHR00 for ; Mon, 17 May 2004 19:56:18 -0500 X-Original-Message-ID: <000901c43c72$ec062320$1e28b0d1@VAIO> From: "Jim Cameron" X-Original-To: "Lancair Mailing List" Subject: Ram air, LOP & the Legacy X-Original-Date: Mon, 17 May 2004 19:55:33 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0006_01C43C48.EA014480" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2720.3000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2739.300 This is a multi-part message in MIME format. ------=_NextPart_000_0006_01C43C48.EA014480 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Here's another tidbit from the New Braunfels fly-in that I forgot to = include in my earlier posting: Tim Ong passed along a recent experience with the ram air in a = Legacy (can't remember whose). They had the ram air pulled (on) at = altitude, and started to pull the mixture back toward the right (lean) = side of the hump. When they got there, the engine abruptly quit! = Apparently this was reproducible, and led to considerable = head-scratching in their debrief. The conclusion is that when manifold pressure starts to exceed the = ambient pressure, i.e., the pressure in the cooling plenum, the venturi = effect that provides atomization of the fuel charge in the injector = nozzles quits. When the pressure gets "upside down," air is no longer = drawn into the fuel charge, and this is apparently rather upsetting to = the engine, which displays its pique (sorry, bad pun) by going very = quiet. This is similar to the situation in the TSIO-xxx, and the fix will = be the same, also. That is, a different shroud is used over the = injectors, and air, instead of being pulled in from the ambient air, is = ducted to each injector shroud from the intake manifold. One could = either add the shrouds and rails from the TSIO parts catalog, or build = up something similar. My A&P tells me that the injector bodies on my = IO550 are the same as what's on the TSIO-550. There is a second O-ring = on the injector body, not installed in the normally aspirated engine, = that will be needed for the new setup. Tim said he was thinking about putting together a retrofit kit, but = wasn't sure when it would happen, as he's leaving town shortly for some = weeks. Meanwhile, it looks as if the choices are either ROP + ram air, = or LOP and no ram air. It would be interesting to know if any others are flying Legacy's = with the ram air added, and what happens when LOP operation is = attempted. Jim Cameron Legacy N121J ------=_NextPart_000_0006_01C43C48.EA014480 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Here's another = tidbit from the=20 New Braunfels fly-in that I forgot to include in my earlier=20 posting:

Tim Ong passed along = a recent=20 experience with the ram air in a Legacy (can't remember whose). = They had=20 the ram air pulled (on) at altitude, and started to pull the mixture = back toward=20 the right (lean) side of the hump. When they got there, the engine = abruptly quit! Apparently this was reproducible, and led to = considerable=20 head-scratching in their debrief.

The conclusion is = that when=20 manifold pressure starts to exceed the ambient pressure, i.e., the = pressure in=20 the cooling plenum, the venturi effect that provides atomization of the = fuel=20 charge in the injector nozzles quits. When the pressure gets = "upside=20 down," air is no longer drawn into the fuel charge, and this is = apparently=20 rather upsetting to the engine, which displays its pique (sorry, bad = pun) by=20 going very quiet.

This is similar to = the situation=20 in the TSIO-xxx, and the fix will be the same, also. That is, a = different=20 shroud is used over the injectors, and air, instead of being pulled in = from the=20 ambient air, is ducted to each injector shroud from the intake = manifold. =20 One could either add the shrouds and rails from the TSIO parts catalog, = or build=20 up something similar. My A&P tells me that the injector bodies = on my=20 IO550 are the same as what's on the TSIO-550. There is a second = O-ring on=20 the injector body, not installed in the normally aspirated engine, that = will be=20 needed for the new setup.

Tim said he was = thinking about=20 putting together a retrofit kit, but wasn't sure when it would happen, = as he's=20 leaving town shortly for some weeks. Meanwhile, it looks as if the = choices=20 are either ROP + ram air, or LOP and no ram air.

It would be = interesting to know=20 if any others are flying Legacy's with the ram air added, and what = happens when=20 LOP operation is attempted.

Jim Cameron

Legacy N121J

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