Sources: Choosing a displacement.

This is part three in the ‘new sources’ series.



The second decision to be made when building an engine is which displacement to use. The Corvairs Pistons, Rods and Cylinders are covered in Group 1300 and Group 1400 in the conversion manual. Here are the ‘Common’ displacement choices for builders: 2,700 cc’s,  2,850 cc’s and 3,000 cc’s.

( Additionally there are two other displacements on the availability horizon, 2,775 cc’s and 3,300 cc’s. )


The conversion manual covers the choices in great detail, and we have links below the pictures to specific stories for builders who would like to read more in detail. To stay focused here, I want to concentrate on where a builder goes to get the parts for each of the Groups involved.


2,700 cc: Traditionally, these parts are ordered from Clarks Corvairs in MA. ( ) . Clarks offers two brands of forged pistons, and all the specific part numbers are contained in the conversion manual. We have always guided builders directly to readily available source rather than trying to ‘middle man’ these parts.


2,850 cc: We have been selling these kits for a number of years, and they are flying on a large number of aircraft . In the last 24 months, we have had trouble getting the proprietary new cylinder that these kits are based on. This has caused delays in deliveries. We can still get them in a trickle, but in the long run I am working to replace this option with the 2,775 cc kit, which is based on the original 1965-69 GM cylinder. The 2,850 kit pricing is on our page :


3,000 cc: The person who originated this displacement and kit is Dan Weseman. Not only did he place the original piston order with R&D costs, it was his particular experience base and flight testing that refined the design and set the displacement. Although I have sold 3,000 cc kits, and I have used the same machine shops here in Florida for the work, I am now steering builders buying a 3,000 cc kit to get it directly from Dan Weseman at his site: .  He has invested to buy a great number of piston sets, several hundred cylinders, and he is the source for new billet connecting rods. He also has on the shelf, exchange cases pre-machined to the 3,000 cc cylinder size. The pay off is that any builder can now just buy the parts right off the shelf.  I will still be building complete production 3,000 cc engines, but when I need the parts to assemble one I will just get the from Dan, just like builders .


As a courtesy while he was focused on developing the Panther aircraft, Dan Weseman allowed Mark at Falcon and Roy’s Garage to order the piston sets off his original design card. In order to insure interchangeable parts, Dan, Mark and Roy agreed to a set of dimensions for the machine work on the cylinders, but each of them had cylinders made at a different location. Although it would have made more sense for Mark and Roy to try to get caught up on their backorders on heads and 5th bearings respectively, they didn’t choose that path. In the end, they, as one person shops were spread too thin to do any of the jobs well, and they don’t have the resources to stockpile parts and kits on the shelf. Thus, any builder who wants to build his own 3,000 cc engine without long delays should just get all the Group 1300 and Group 1400 parts from Dan Weseman.




Above, Dan Weseman and I at the test run of his 3,000 cc Panther engine. No person flies a Corvair harder than Dan. His engine has performed flawlessly through a full 18 months of aerobatics. To Learn more about 3,000 cc engines read these links: Why Not the Panther engine? and The Panther’s engine, worlds strongest Corvair flight engine.




Above, a 2,850 in my front yard. I built this particular engine around a Weseman billet crank, thus,the only used parts in this engine are the case halves, the head castings, the oil case casting, the distributor body and some misc. hardware. The rest, including the cylinders, pistons rods, crank, and all conversion parts are brand new. Read more here: New 2850cc / 110hp Corvair in photos. to read a bout the first 2,850cc engine, now with hundreds of flight hours, read this: Woody’s 2,850cc Corvair/601XL hits 400 hours.


 Above, Dan and Rachel stand on either side of their 3.3 engine at Oshkosh.  Read the story at this link: SPA / Weseman 3.3 Liter Corvair now running



Above, our 601XL pictured at Brodhead WI in 2004. The first 200 flight hours on the plane were done with a 2,775 cc Corvair that we specifically built to test the displacement.  The combination offers a slight power increase over a 2700 cc engine, but is specifically aimed at using standard automotive gasoline. We are bringing this combination back to an off the shelf kit in 2015.




About William Wynne
I have been continuously building, testing and flying Corvair engines since 1989. Information, parts and components that we developed and tested are now flying on several hundred Corvair powered aircraft. I earned a Bachelor of Science in Professional Aeronautics and an A&P license from Embry-Riddle Aeronautical University, and have a proven 20 year track record of effectively teaching homebuilders how to create and fly their own Corvair powered planes. Much of this is chronicled at and in more than 50 magazine articles.

One Response to Sources: Choosing a displacement.

  1. Larry Nelson says:

    Glad I choose the Dan bearing. Just finished the install and getting ready for the college at zenith.

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