Here are some questions that came in as comments on other stories:
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Frank Stephenson writes:
“While there will be many different results, I am wondering what the average time before overhaul may be. Also what are we looking at cost wise for one of these engines and the average cost of an engine mount? I am considering selling my current conventional geared C-172 with a C-O300B engine and buying or building something a bit smaller and more efficient. I really don’t know anything about Corvair engines other than I know of several folks who have utilized them, but I don’t really know anything about their results. I have found, in general, that automotive engines don’t make really good aircraft engines, but some VW engines I have known of are an exception and apparently the Corvair engines may be an exception.”
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Frank, the minimum time between overhauls on a well built engine is 1,500 hours. Ten years ago we listed 1,000 hours as a very conservative figure, since then, improvements like using valve rotators have driven the life span up significantly. The Overhaul cost on the engine is very low, on the order of $2,000 to replace almost all moving parts or recondition them. You can lean more at this link: Basic Corvair information I understand that many automotive engine engines have a poor record, but I have been doing this for 25 years, and we have earned an excellent one. You can read this link: Planes flying on Corvair Power, and see many examples. For the cost of motor mounts, just look at out catalog,http://www.flycorvair.com/, and page down to Group 4200, it lists the price of every mount we make.
I know VW engines have worked for many people, but I will put the track record for reliability, power and TBO of our work with Corvairs against any VW based engine. There is a lot of information on our main webpage, http://www.flycorvair.com/. I understand that it looks overwhelming, but better too much than to little.
Here is an important point: I don’t think efficiency is a good enough reason to move to homebuilding. Lets say your Cessna does 110mph on 8 gallons an hour. There are several Corvair powered planes that can do that on 5 gallons an hour, even some on 3 gallons an hour. But even if you were to cut your fuel costs on flying 200 hours a year from $8,000 to $4,000 per year, I don’t think it is enough motivation to send a guy to the shop for 1,500 building hours. The only people that consistently succeed at homebuilding are the people who inherently would rather fly something the personally built, and people motivate by the desire to learn new skills. I have met very few people motivated just to fly less expensively who thought in the long run that homebuilding was worth it. Consider this carefully, you may have a better time staying airborne in the plane you have.
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Steve Spears
“Sir, I am currently building a RW26 Special ll and I would like to use the Corvair engine. However, some people are telling me that it is to heavy for the aircraft. What are your thoughts and do you know of anyone who has used a Corvair engine in the Rag Wing aircraft? I read what you wrote about the Pietenpol and am encouraged that I can use the engine”
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Steve, I looked at this pretty closely for an hour the other night. I tend to think that a Corvair is too big to the R-26. The 912 appears to be as large an engine as people use. Several of Rodger Mann’s designs have flown with Corvairs, but I wouldn’t call any of them an ideal match. I am guessing that a Rotax 503 is really the optimum engine for many of his designs. For a comparison of how heavy duty a Pietenpol is built, the longerons in the fuselage are one inch square spruce from the firewall to the tail post. I am pretty sure the R-26 is lighter than that.
