X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 08 Mar 2006 00:55:44 -0500 Message-ID: X-Original-Return-Path: Received: from HQEMGATE02.nvidia.com ([216.228.112.143] verified) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTP id 1025320 for lml@lancaironline.net; Tue, 07 Mar 2006 01:00:11 -0500 Received-SPF: none receiver=logan.com; client-ip=216.228.112.143; envelope-from=colyncase@earthlink.net Received: from hqemfe02.nvidia.com (Not Verified[172.16.227.92]) by HQEMGATE02.nvidia.com id ; Mon, 06 Mar 2006 22:00:22 -0800 Received: from ccaselt ([172.16.228.84]) by hqemfe02.nvidia.com with Microsoft SMTPSVC(6.0.3790.1830); Mon, 6 Mar 2006 21:59:05 -0800 X-Original-Message-ID: <003501c641ac$3d887050$c1321f0a@nvidia.com> From: "colyncase on earthlink" X-Original-To: "Lancair Mailing List" , References: Subject: Re: [LML] TSIO550 differences X-Original-Date: Mon, 6 Mar 2006 21:59:04 -0800 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0032_01C64169.2F2CBB30" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Original-Return-Path: colyncase@earthlink.net X-OriginalArrivalTime: 07 Mar 2006 05:59:05.0721 (UTC) FILETIME=[3E031E90:01C641AC] This is a multi-part message in MIME format. ------=_NextPart_000_0032_01C64169.2F2CBB30 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I noted their numbers for the TSIO-550-N. The=20 compression ratio is 8.5:1 and the oil capacity is 8 quarts.=20 Robert, I don't know what a TSIO-550-N is for sure but if memory serves, Columbia flat rated their engine down to 310hp to get the longer = TBO. ...so that may relate to their choice of compression ratios, if it is = not a misprint. At any rate, there are more than a few TSIO-550's flying now with the = higher compression ratio. The advantages of that are: 1) lower CHT's due to = the fact that the greater expansion factor takes more heat away and 2) 5% or better improvement in fuel economy. Personal belief is that you get to run at higher power settings at high = alt. cruise because you aren't temp limited. If I had to do it over again I would certainly use a 8.5:1 setup. I think the 7.x:1 idea was that if you mismanage your mixture you have a little more margin at 7.x:1 than at a higher compression ratio. But the impact of mismanagement on internal cylinder pressure is so much higher than the impact of a slightly higher compression ratio, I=20 don't see the sense in keeping the lower compression ratio. If you = would blow up your engine at 8.5:1 you would probably blow it up at 7.x:1 = also. Colyn ------=_NextPart_000_0032_01C64169.2F2CBB30 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

I noted their numbers for the = TSIO-550-N. =20 The
compression ratio is 8.5:1 and the oil capacity is 8=20 quarts.

Robert,

I don't know what a = TSIO-550-N=20 is for sure but if memory

serves, Columbia flat rated their = engine down to=20 310hp to get the longer TBO.

...so that may relate to their choice = of=20 compression ratios, if it is not a misprint.

At any rate, there are more than a few = TSIO-550's=20 flying now with the higher

compression ratio. The = advantages of=20 that are: 1) lower CHT's due to the

fact that the greater expansion factor = takes more=20 heat away and 2) 5% or

better improvement in fuel = economy.

Personal belief is that you get to run = at higher=20 power settings at high alt.

cruise because you aren't temp=20 limited.

If I had to do it over again I would = certainly use=20 a 8.5:1 setup.

I think the 7.x:1 idea was that if you = mismanage=20 your mixture you have

a little more margin at 7.x:1 than at a = higher=20 compression ratio.

But the impact of mismanagement on = internal=20 cylinder pressure is so

much higher than the impact of a = slightly higher=20 compression ratio, I

don't see the sense in keeping the = lower=20 compression ratio. If you would

blow up your engine at 8.5:1 you would = probably=20 blow it up at 7.x:1 also.

Colyn

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