X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imr-db03.mx.aol.com ([205.188.91.97] verified) by logan.com (CommuniGate Pro SMTP 5.4c2a) with ESMTP id 4822910 for flyrotary@lancaironline.net; Sat, 22 Jan 2011 13:22:27 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.188.91.97; envelope-from=Lehanover@aol.com Received: from imo-da02.mx.aol.com (imo-da02.mx.aol.com [205.188.169.200]) by imr-db03.mx.aol.com (8.14.1/8.14.1) with ESMTP id p0MILjdS014633 for ; Sat, 22 Jan 2011 13:21:45 -0500 Received: from Lehanover@aol.com by imo-da02.mx.aol.com (mail_out_v42.9.) id q.d5b.646b7ad6 (55761) for ; Sat, 22 Jan 2011 13:21:41 -0500 (EST) Received: from magic-m23.mail.aol.com (magic-m23.mail.aol.com [172.20.22.196]) by cia-md05.mx.aol.com (v129.7) with ESMTP id MAILCIAMD052-d9d14d3b203442; Sat, 22 Jan 2011 13:21:41 -0500 From: Lehanover@aol.com Message-ID: <62a68.2b79afdc.3a6c7a34@aol.com> Date: Sat, 22 Jan 2011 13:21:40 EST Subject: Re: [FlyRotary] Re: Charge Air Pre-Heat To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_62a68.2b79afdc.3a6c7a34_boundary" X-Mailer: 9.0 Security Edition for Windows sub 5382 X-AOL-IP: 72.187.199.116 X-Spam-Flag:NO X-AOL-SENDER: Lehanover@aol.com --part1_62a68.2b79afdc.3a6c7a34_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 1/22/2011 11:54:33 A.M. Eastern Standard Time, eanderson@carolina.rr.com writes: I'm not certain what heating the air would do but further reduce the air density which would theoretically mean you would need less fuel to maintain the same air/fuel ratio - so that might reduce the risk (to a piston engine) of running tool lean - but would still cut down the fuel consumption by permitting less fuel and yet maintain the same air/fuel ratio. The only down side I have notice in flying WOT (at cruise altitudes) with reduced air/fuel ratio is that the engine occasionally will miss - not enough to worry about (unless you worry about things like that {:>), generally just enriched the fuel mixture a bit stops it. Having said that - I have never compared operating at reduced throttle setting to WOT so can't say how much (if any) difference it makes - theoretically, it should make some difference. FWIW that's my $0.02 Ed Everything Ed said, and: A) Wide open throttle keeps cylinder filling closer to 100% which means effective compression ratio stays higher, which means that more heat of compression is available to maintain vaporization which means more of the available fuel gets burned. B) Adding heat to the intake air raises heat of compression and improves vaporization and allows for an even leaner mixture to burn completely. C) Although detonation is charge temperature dependant, super lean mixtures produce slower flame front speeds and mimic ultra high octane fuels, so detonation should not be a factor. This is not at all damaging to the engine. Less fuel per revolution means lower temperatures and less stress. All big radial engines were run well lean of peak EGT. Lest TWA would never have made it across the Atlantic. Lest the P-38s would never have made the round trip to kill Yamamoto. Even works on supercharged and turbo charged engines. Lynn E. Hanover --part1_62a68.2b79afdc.3a6c7a34_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 1/22/2011 11:54:33 A.M. Eastern Standard Time,=20 eanderson@carolina.rr.com writes:

I'm not certain what heating the air woul= d do but=20 further reduce the air density which would theoretically mean you would= need=20 less fuel to maintain the same air/fuel ratio - so that might reduce the= risk=20 (to a piston engine) of running tool lean - but would still cut down the= fuel=20 consumption by permitting less fuel and yet maintain the same air/fuel= =20 ratio.

The only down side I have notice in f= lying=20 WOT (at cruise altitudes) with reduced air/fuel ratio is that the engine= =20 occasionally will miss - not enough to worry about (unless you worry abo= ut=20 things like that {:>), generally just enriched the fuel mixture a bit= stops=20 it.

Having said that - I have never compared operati= ng at=20 reduced throttle setting to WOT so can't say how much (if any) differenc= e it=20 makes - theoretically, it should make some difference.

FWIW that's my $0.02

Ed

Everything Ed said, and:

A) Wide open throttle keeps cylinder filling closer to 100% which mea= ns=20 effective compression ratio stays higher, which means that more heat of=20 compression is available to maintain vaporization which means more of the= =20 available fuel gets burned.

B) Adding heat to the intake air raises heat of compression and impro= ves=20 vaporization and allows for an even leaner mixture to burn completely.

C) Although detonation is charge temperature dependant, super lean mi= xtures=20 produce slower flame front speeds and mimic ultra high octane fuels, so=20 detonation should not be a factor.

This is not at all damaging to the engine. Less fuel per revolution= means=20 lower temperatures and less stress.

All big radial engines were run well lean of peak EGT. Lest TWA would= never=20 have made it across the Atlantic. Lest the P-38s would never have made the= round=20 trip to kill Yamamoto. Even works on supercharged and turbo charged=20 engines.

Lynn E. Hanover

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