The Zenith 650 Corvair engine of Jim and Patty Raab.


The second engine to hit the run stand at Corvair Finishing School #2 was Jim and Patty Raab’s 3,000 cc /120HP engine destined for their Quick build Zenith 650, which will take to the air next year.  They did some of the assembly at home, but came to the Finishing School well prepped to finish, run and learn more about their power plant.


The engine was on the stand early Saturday and put down a good break in run. We made some small adjustments, but the smaller nature of the Finishing School gave a more relaxed pace than a traditional Corvair College. By the end of the afternoon, they had a great running engine, their confidence as skilled builders and operators was confirmed, and we all headed off to our local small town bar and grill for a dinner in high sprits.



Above, Jim and Patty with their engine on the run stand. They are priming the oil system for 15 minutes before the first start. The red drip pans on the heads allow the visual confirmation that oil is reaching every single location in the engine. All Corvairs have hydraulic lifters and high strength head studs, neither of which ever need adjustment during the life span of the motor.


Something fun about working with the Raab’s: Jim is skilled with tools, but earns his living as a nurse. On the other hand Patty spent 20 years in the USAF, working ordinance on strike aircraft. Not only is she the safety wiring guru in the family, she is well versed in following literature and procedures.  When your day job in aviation is installing guidance units and fuses in bombs that weigh more than a light sport aircraft, it contributes to making you picky about methods and practices.




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.

5 Responses to The Zenith 650 Corvair engine of Jim and Patty Raab.

  1. michael mckosky says:

    I am a bit confused. I thought the 3000cc, or 3.0L, engine developed 115hp, and the 3300cc, or 3.3L engine, developed 119hp plus. This from previous writings and I think from the flywithspa website. What am I missing???

  2. michael mckosky says:

    Wait, my error! I did re-read the sales info etc. and indeed the 3.0L is supposed to generate 120HP. Isn’t there a 3.3L version, and what HP does it generate?

  3. Tim Hansen says:

    The 3.3 make 125HP at 3200rpm (119HP at 2700rpm). A lot more detail is available, there have been several stories on this site following the development. For a recent story follow this link:

    It has links to further stories about the first run, and the detailed specs of how the power was increased.

    Obviously, Dan and William themselves are the go-to source for any additional info.

    • michael mckosky says:

      I did read the article before but I didn’t put it together, so thanks for pointing out this article. It seems essentially to be a 3000cc engine but with the billet crankshaft giving a larger displacement to 3300cc (ignoring all the other improved features). According to Rachel the 3000cc engine will deliver 115HP at 3300 and the 3300cc 125HP at 3300 and 119HP at 2800.
      Rachel said that the figures were obtained on a dyno.

      • Tim Hansen says:

        I think you’ll find that the variations in the numbers given are due to not specifying which compression ratios were used, and fuel type, cam, and timing can also influence output. The 3.3 was a clean sheet designed billet crankshaft with increased stroke, and it requires custom rods, pistons and cylinders, along with ‘new’ everything else, EXCEPT for main case castings, head castings, rear case, which are modified/machined/inspected. The 3000cc has the ability to recondition some additional parts, but can optionally have new and improved versions used. The exact breakdown is listed in the manual and elsewhere on this site. (I am sure their dyno info is accurate as tested, just wanted to help complete the picture.) -tim

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