Oscar, I am building a VW engine also. Consider this, anywhere you place the probe you are going to read a different temperature. Regardless of its location, I believe the intent is to get a idea of when the engine is getting to hot. My experience in R&D engine testing has been that we place the probe in a location that represents the hot spot relative to the component being tested while monitoring other locations to see where the heat is migrating. You may then set the limits of operation. The locations are important but should be read with knowledge of where its positioned. Probe it at different locations to gain knowledge to understand how the engine is being cooled. Maybe use multiple probes with a exhaust gas probe. Them I would place it at the hottest point to foreworn you of cooling problems.
KRRon ----- Original Message ----- From: "Oscar Zuniga" <taildr...@hotmail.com> To: <kr...@mylist.net> Sent: Monday, December 22, 2003 11:47 AM Subject: KR>CHT sensor location on VW > Howdy, Netters- > > I got my "Beetle Flyer" (from Great Plains Aircraft Supply) over the weekend > and took notice of a tech tip on locating your CHT sensor on the VW engine > ( down the page, at http://www.greatplainsas.com/bf20032.html ). Standard > practice is to install it under a spark plug, but Steve Bennett points out > that your CHT temps will read high if you do this... by as much as 150F. He > recommends installing it under a head stud (location is given in the text in > the Flyer, but not as clear as it could be). Long and short of it is that > if you're running a VW and have your CHT sensor under a spark plug, you may > not be getting readings that reflect what you're really interested in. > > If Bob Hoover is still monitoring this list, maybe he would care to chime > in? If Steve is monitoring this list, maybe he would care to elaborate more > clearly on the preferred location? The picture in the Flyer identifies a > boss that is used for fuel injection temp. probe, but doesn't say this is > the recommended spot (and doesn't seem to be a good spot anyway). The idea > is to respect the metallurgy of the head castings by not allowing the CHT to > exceed recommended temperature... bad and irreversible damage can result if > the metal gets too hot. > > Oh, and somewhat timely and related to Mark Jones and Mark Langford's two > different approaches to cooling plenum on the Corvair, the Beetle Flyer also > addresses cooling plenum design for the VW on the above-referenced webpage. > > Happy holidays! > > Oscar Zuniga > San Antonio, TX > mailto: taildr...@hotmail.com > website at http://www.flysquirrel.net > > _________________________________________________________________ > It?s our best dial-up Internet access offer: 6 months @$9.95/month. Get it > now! http://join.msn.com/?page=dept/dialup > > > _______________________________________________ > see KRnet list details at http://www.krnet.org/instructions.html >
