X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 15 Nov 2010 07:30:42 -0500 Message-ID: X-Original-Return-Path: Received: from elasmtp-curtail.atl.sa.earthlink.net ([209.86.89.64] verified) by logan.com (CommuniGate Pro SMTP 5.3.10) with ESMTP id 4577166 for lml@lancaironline.net; Fri, 12 Nov 2010 17:51:52 -0500 Received-SPF: none receiver=logan.com; client-ip=209.86.89.64; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=SLLXScDVupE1HIHUPMb/xTTXM6lDOqClIJyRy5AbtdnO0pKyEAx0it3Ghye5htRD; h=Received:From:Mime-Version:Content-Type:Subject:Date:In-Reply-To:To:References:Message-Id:X-Mailer:X-ELNK-Trace:X-Originating-IP; Received: from [216.57.118.85] (helo=[192.168.1.100]) by elasmtp-curtail.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1PH2Sj-0005nW-9T for lml@lancaironline.net; Fri, 12 Nov 2010 17:51:17 -0500 From: Colyn Case Mime-Version: 1.0 (Apple Message framework v1081) Content-Type: multipart/alternative; boundary=Apple-Mail-147--90053233 Subject: Re: [LML] Re: LNC2 Legacy Performance questions X-Original-Date: Fri, 12 Nov 2010 17:51:15 -0500 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: <8008C145-6875-4A99-9D78-31300FDABBFB@earthlink.net> X-Mailer: Apple Mail (2.1081) X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da940159147b9b0c2bd6a4428a85a4e7a915c350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 216.57.118.85 --Apple-Mail-147--90053233 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Craig, I believe GAMI puts the HP difference in the 5-7% range between at 7.5:1 = and a 8.5:1. I've never been able to get more out of them than "it's = diminishing returns" for higher than 8.5:1. That said, there's another advantage to higher compression in turbo'd = engine and that is that the turbine inlet temperature will be lower at a = given power setting with the higher compression engine. In my = installation, TIT is the limiting factor to how rich I can take the = mixture when LOP. (I have a 7.5:1 engine). So if I had a turbo and I was doing the engine from scratch, I would = definitely get at least 8.5:1. If I didn't have a turbo I would say = the advantage is marginal. I also wouldn't own a 10:1 engine or any turbo engine without going to = APS. Colyn On Nov 12, 2010, at 7:33 AM, Craig Jimenez wrote: > What's the group's general opinion about 10:1 compression? I like = the idea (higher efficiency). I found that raising the compression on = my old Grumman AA5 from 7.x to 8.5 vastly improved the climb and high = altitude performance. I'd be interested in your practical experiences = of going to 9 or 10:1. > =20 > If I understood correctly, when running LOP, you can expect more power = for any fuel flow at higher compressions: > Comp HP/gph > 7.5 12.7 > 8.5 13.9 > 9.0 ? > 10.0 ? > =20 --Apple-Mail-147--90053233 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii

That said, there's another advantage to = higher compression in turbo'd engine and that is that the turbine inlet = temperature will be lower at a given power setting with the higher = compression engine. In my installation, TIT is the limiting factor = to how rich I can take the mixture when LOP. (I have a 7.5:1 = engine).

So if I had a turbo and I was doing = the engine from scratch, I would definitely get at least 8.5:1. = If I didn't have a turbo I would say the advantage is = marginal.

I also wouldn't own a 10:1 engine or = any turbo engine without going to = APS.

Colyn

On Nov 12, 2010, at 7:33 AM, Craig Jimenez wrote:

What's = the group's general opinion about 10:1 compression?   I like = the idea (higher efficiency). I found that raising the compression = on my old Grumman AA5 from 7.x to 8.5 vastly improved the climb and high = altitude performance. I'd be interested in your practical = experiences of going to 9 or 10:1.

If I understood correctly, when running LOP, you can expect more = power for any fuel flow at higher compressions:

Comp HP/gph

7.5      12.7

8.5      13.9

9.0        ?

10.0       ?

= --Apple-Mail-147--90053233--