---------------------------------------------------------- TeamGrumman-List Digest Archive --- Total Messages Posted Thu 03/24/05: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:42 AM - Re: 02:31 AM - Re: Cylinder head temp phenomena (HalB) (Mike Lehman) 2. 11:36 PM - (TeamGrumman@AOL.COM) ________________________________ Message 1 _____________________________________ Time: 04:42:26 AM PST US From: "Mike Lehman" Subject: TeamGrumman-List: RE: 02:31 AM - Re: Cylinder head temp phenomena (HalB) --> TeamGrumman-List message posted by: "Mike Lehman" Hal B, Thank you for reporting back on that ... I would not expect that increasing airflow around the steel barrel would reduce the head temperature because this requires increased conduction from the hotter aluminum head to the barrel via the threaded joint. (Also, is there risk of distorting the barrel by increased temperature differential around the barrel?) Could bleeding off more flow via the barrel actually increase head temperature by reducing the pressure differential and airflow across the head? Available cooling air removes the most heat when cooling the hottest surfaces, i.e. the head. I look forward to hearing about your 'fix', when you find it! Mike AA-5 (without multi-cylinder instrumentation) > --> TeamGrumman-List message posted by: "HalB" > > Been there done that, I even tried opening it up to 1.5 ", with > no change, > so the mystery continues. Hal B > > > > > In a message dated 3/22/05 1:35:26 PM, halb@adelphia.net writes: > > > > > >> ut left # 4 > >> unchanged. I can not explain why but it did on my Tiger. # 4 > is still my > >> high one running about 20 deg.hotter than 1,3,4 > >> > > > > try trimming back the metal baffle strap that wraps around the > bottom of > > the > > hottest cylinder about 1 inch. > > > > Gary > > ________________________________ Message 2 _____________________________________ Time: 11:36:18 PM PST US From: TeamGrumman@AOL.COM --> TeamGrumman-List message posted by: TeamGrumman@aol.com In a message dated 3/24/05 4:43:19 AM, lehmans@sympatico.ca writes: > Could bleeding off more flow via the barrel actually increase head > temperature by reducing the pressure differential and airflow across the > head?=A0 Available cooling air removes the most heat when cooling the hottest > surfaces, i.e. the head. > Well, that is an excellent question. In fact, 3 years ago, I posed that same questions to one of my graduate advisors who is now teach at UNLV. In case your curious, type Robert Boehm into Google. The answer I got back was, "You need velocity and turbulence going past the cylinders to keep the them cool." Now, it's true that while a high pressure differential can 'potentially' create a high velocity, choking the flow to create the high delta P defeats the purpose. The objective is to change 160 mph incoming air into a flow that is ideal for cooling, create a suitable pressure drop to develop the required turbulence and velocity to cool the cylinders and yet not creat so much pressure that you increase cooling drag. It's like walking a tightrope with your eyes closed.