X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 09 Jan 2008 21:10:24 -0500 Message-ID: X-Original-Return-Path: Received: from ironport5.liveoakmail.com ([216.110.12.21] verified) by logan.com (CommuniGate Pro SMTP 5.2c4) with ESMTP id 2638248 for lml@lancaironline.net; Wed, 09 Jan 2008 16:41:36 -0500 Received-SPF: none receiver=logan.com; client-ip=216.110.12.21; envelope-from=walter@advancedpilot.com X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AgAAAHbOhEdAMf4VjGdsb2JhbACCb40uAQEBgU+Xfw X-IronPort-AV: E=Sophos;i="4.24,264,1196661600"; d="scan'208,217";a="41856314" Received: from rs5.liveoakhosting.com (HELO secure5.liveoakhosting.com) ([64.49.254.21]) by ironport5.liveoakmail.com with ESMTP; 09 Jan 2008 15:40:54 -0600 Received: (qmail 26352 invoked from network); 9 Jan 2008 15:40:54 -0600 Received: from 216-107-97-170.static.networktel.net (HELO ?10.0.1.4?) (216.107.97.170) by rs5.liveoakhosting.com with (AES128-SHA encrypted) SMTP; 9 Jan 2008 15:40:54 -0600 Mime-Version: 1.0 (Apple Message framework v753) In-Reply-To: References: Content-Type: multipart/alternative; boundary=Apple-Mail-2-416835041 X-Original-Message-Id: From: Walter Atkinson Subject: Re: [LML] Re: One mag, One electronic ignition X-Original-Date: Wed, 9 Jan 2008 15:40:50 -0600 X-Original-To: "Lancair Mailing List" X-Mailer: Apple Mail (2.753) --Apple-Mail-2-416835041 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Scott: I would be hard-pressed to improve on your excellent summary of the issues at hand. Nicely done. I cannot honestly give more details for two reasons, 1) I don't know them all, and 2) This was an R&D run on a NA TCM engine set up like TCM wants it set up with only the one difference of advancing the timing 2 degrees. The resultant ICPs were 1130-1140psi and it was not at max power or at max ICP mixture! It could easily have been made worse--and it wasn't even TC'd. My point, Scott, is that we see folks diddling with timing changes who have no hard ICP data--only what they *think* will be the result or some *calculation* and we now know, from hard data, that that decision tree in this instance could be flawed--with nasty results. Some of the guys who who have seen this data and were common choice builders of engines for the exp. market will no longer build/warrant an engine on which the owner plans to use EI. I find that telling. My current position on EIs is that the jury is still out on what's being done by some folks who are doing so without hard ICP data--and as far as I can tell, that's most of them. Walter On Jan 9, 2008, at 12:37 PM, Sky2high@aol.com wrote: Walter, Would you care to give us more complete information? For any given combustion event in a piston 4-cycle engine with certain compression ratio, A/F ratio, fuel octane, # of ignition points,valve count, piston head and chamber shape there is an optimal timing to deliver appropriate pressure during the power stroke. If the timing is changed, the pressure delivery range is changed. Some of the ways to change the timing of the combustion events would be to change the A/F (lean or rich), the octane, and uncommanded ignition events (pre ignition, detonation). If the event is late, the best pressure applied to piston power stroke may be less effective because there is little work for the piston to do. If the event is too early, the pressure may work against the purpose of the engine - the piston may still be on the compression stroke or too early in the power stroke where the rod angle isn't in a position to smoothly deliver the power to the crankshaft, both causing more stress on the engine than is desirable. The fixed timing compromise delivers less than optimal power under conditions outside the engine design range specified by the designer. One of the negative ways to change the timing of the combustion event is to diddle with the mixture so that the engine is operating 20-30F ROP under high power - this can place abnormally high pressure on the piston/chamber and at the wrong time. When all the engine parameters are appropriately controlled, including ignition timing and A/F ratio, the engine can smoothly and efficiently deliver the power within its design and engineering. Thanks for keeping us within the bounds of reason. Scott Krueger Green efficiency thru the use of appropriate timing. If I could only get my stock market timing right........................... . In a message dated 1/9/2008 8:14:42 A.M. Central Standard Time, walter@advancedpilot.com writes: I think what is happening is that the thetaPP is changed less by the loss of the mag than by the loss of the EI. This had little to do with the amount of fuel being burned. BTW, I just looked at the thetaPP data on a set-up where the timing was changed by as little as 2 degrees, advanced. The thetaPP was advanced to 10dATDC and the peak pressures were above 1100 psi. This is not a good thing. You guys do as you please, but that's not something I want to do to my engine. Spark plugs begin to be blasted out of cylinders at 1200psi--by imperical experience. These are observations of hard data. Start the year off right. Easy ways to stay in shape in the new year. --Apple-Mail-2-416835041 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=ISO-8859-1 Scott:

I would be = hard-pressed to improve on your excellent summary of the issues at hand. = =A0Nicely done.

I cannot honestly give = more details for two reasons, 1) I don't know them all, and 2) This was = an R&D run on a NA TCM engine set up like TCM wants it set up with = only the one difference of advancing the timing 2 degrees. =A0The = resultant ICPs were 1130-1140psi and it was not at max power or at max = ICP mixture! =A0It could easily have been made worse--and it wasn't even = TC'd.

My = point, Scott, is that we see folks diddling with timing changes who have = no hard ICP data--only what they *think* will be the result or some = *calculation* and we now know, from hard data, that that decision tree = in this instance could be flawed--with nasty results. =A0Some of the = guys who who have seen this data and were common choice builders of = engines for the exp. market will no longer build/warrant an engine on = which the owner plans to use EI. =A0I find that telling.

My current position on EIs = is that the jury is still out on what's being done by some folks who are = doing so without hard ICP data--and as far as I can tell, that's most of = them.

Walter



On Jan 9, = 2008, at 12:37 PM, Sky2high@aol.com wrote:

Walter,
=
=A0
Would you care to give us more complete = information?=A0 For any given combustion event in a piston 4-cycle = engine with certain compression ratio, A/F ratio, fuel octane, #=A0of = ignition points,valve count, piston head and chamber shape there is an = optimal timing to deliver appropriate pressure during the power stroke.=A0= If the timing is changed, the pressure delivery=A0range is = changed.=A0=A0Some=A0of the ways to change the timing of the combustion = events would be to change the A/F (lean or rich), the octane, and = uncommanded ignition events (pre ignition, detonation).=A0 If the event = is late, the best pressure applied to piston power stroke may be less = effective because there is little work for the piston to do.=A0 If the = event is too early, the pressure may work against the purpose of the = engine - the piston may still be on the compression stroke or too early = in the power stroke where the rod angle isn't in a position to smoothly = deliver the power to the crankshaft, both causing more stress on the = engine than is desirable.
=A0
The fixed timing = compromise delivers less than optimal power under conditions outside = the=A0engine design=A0range specified by the designer.=A0 One of the = negative ways to change the=A0 timing of the combustion event is to = diddle with the mixture so that the engine is operating 20-30F ROP under = high power - this can place abnormally high pressure on the = piston/chamber and at the wrong time.
=A0
When all = the engine parameters are appropriately controlled, including ignition = timing and A/F ratio, the engine can smoothly and efficiently=A0deliver = the power=A0within its design and engineering.
=A0
=
Thanks for keeping us within the bounds of reason.
=
=A0
Scott Krueger
Green efficiency thru the = use of appropriate timing. If I could only get my stock market timing = right...........................
=A0
.=A0
=
In a message dated 1/9/2008 8:14:42 A.M. Central Standard = Time, walter@advancedpilot.com = writes:
I think = what is happening is that the thetaPP is changed less by the loss of = the mag than by the loss of the EI. =A0This had little to do with the = amount of fuel being burned.

BTW, I just looked at = the thetaPP data on a set-up where the timing was changed by as little = as 2 degrees, advanced. =A0The thetaPP was advanced to 10dATDC and the = peak pressures were above 1100 psi. =A0This is not a good thing. =A0You = guys do as you please, but that's not something I want to do to my = engine. =A0Spark plugs begin to be blasted out of cylinders at = 1200psi--by imperical experience.

These are observations = of hard data. =
=A0



Start the year off right. Easy ways to stay in shape in the new year. =

= --Apple-Mail-2-416835041--