---------------------------------------------------------- Engines-List Digest Archive --- Total Messages Posted Mon 03/19/07: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:00 AM - Re: Lycoming Cylinder question (Gary Casey) ________________________________ Message 1 _____________________________________ Time: 06:00:45 AM PST US From: Gary Casey Subject: Engines-List: Re: Lycoming Cylinder question I'm not "the" Lycoming expert, but as far as I can tell everything with a power rating of 300 or more has the angle-valve cylinders. A sure-fire way to tell is to look at the Lycoming spec sheet on their website and the parallel-valve engines are narrower. Other than that the model numbers don't give much of a clue unless you just know which is which. As Bill said, the angle-valve heads flow better. The naturally-aspirated versions have a 8.7 compression ratio vs. the 8.5 of the parallel-valve engine, and that also helps to produce slightly more power. With more space between the valves the angle- valve engine requires less pressure drop for cooling, theoretically reducing cooling drag. But they are heavier, to the tune of 4 or 5 pounds per cylinder and the angle-valve engines don't have the same reputation for longevity as the parallel-valve engines. An expert told me that there is nothing to be gained by porting and polishing the angle-valve cylinder, while the parallel-valve version can be ported to achieve almost the same airflow as the angle-valve cylinder. Gary Casey Parallel-valve IO-540 with 10:1 compression dyno tested at 305 hp > From: Dan Rogers > Subject: Engines-List: Lycoming Cylinder question > > > I have some questions about Lycoming Cylinders. I understand that all > their 360 and 540 engines use the same size cylinders. Also that > there > are 2 types of cylinders: Straight valve and Angle valve. I know what > the cylinders look like and can easily tell the difference but what > are > the differences in engine application? How can you know whether a > IO540 > L (for example, if there is such a thing) has one or the other type of > cyl? Do the high HP engines have one type and the Lower hp the other > type? Is one type of cylinder newer than the other? > > Thanks, > > Dan ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message engines-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Engines-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/engines-list Browse Digests http://www.matronics.com/digest/engines-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.