Mail Sack, 10-11-12…..Cleanex notes


On the topic of Intakes and the Internet,

West Coast Pietenpol builder Pete Kozachik writes:

Thanks for the informative (and very entertaining!) piece on vapor-expertise vs. real-world expertise. That rear alternator mount looks great! Have been waiting to see it since you described it some time ago. How does it test out?

Pete, Dan and I are still working out manufacturing details, and then are going to stick it on a test bed aircraft. We want to affirm that the unit spins fast enough and runs cool enough in an actual engine compartment. We will have all the parts at Corvair College #24.-ww

500 hour Zenith Corvair builder/pilot Andy Elliot writes:

“For anyone who would like to learn more about the truly amazing development of piston engine technology during WWII, I wholeheartedly recommend the book “Allied Aircraft Piston Engines of World War II”, by Graham White. It is published by the Society of Automotive Engineers (SAE) and is available on their web site ( for only $60.
The development of the V-1710 is covered in detail, from the first 650 HP version built for the Navy in 1931, through the development of the “ram’s horn” intake manifold in 1935 which resulted in the 1000 HP -C8 version in 1937, through to the G model which made 2200 HP (with ADI) at 3200 RPM, but never saw large production as the war ended. (They are used at Reno, though.)
As is well described and documented, the V-1710 was ahead of the Merlin throughout most of its life, but suffered for its single-stage engine-driven supercharger when Rolls-Royce added the 2-stage, 2-speed, intercooled/aftercooled supercharger with the -60 series Merlins.
Allison introduced the -199 version of the V-1710 for the XP-51J, the fastest of all the Mustangs. It used a 2-stage supercharger with a liquid-cooled aftercooler and was the first to meter fuel directly into the supercharger without a carburetor. It produced 1700 HP, at 3200 RPM ** at 21000 ft! **
Another very good book, specifically about the V-1710 is “Vees For Victory!: The Story of the Allison V-1710 Aircraft Engine 1929-1948″, by Dan Whitney, who provided engineering support for Reno air racers for many years. Available on Amazon for $50. Interestingly enough, if you check out the presentation at, you’ll find about 1/2-way through, a picture of Graham White at Reno in 2002, working with Pete Law, who is more or less the “godfather” of racing engines at Reno! -Andy “


On Cleanexes, builder Jackson Ordean writes:

I’m amazed there aren’t more Sonex powered by Corvair? Beats Aerovee by any measure, not to mention Jab. Anyway, just keep up the awesome work – hope you guys are blessed doing it.

Jackson, Different engines for different people. We try to just present the appeal of the Corvair without getting in to debates about merits. Over the years I have found that guys who just want a by-it-in-a-box  imported engine have very little interest in Corvairs, and people who really want to know every nut and bolt on their airframe and engine will find little satisfaction in engines from companies that are focused on selling a consumer good rather than an educational mission. This is the most important division in engine choices. A guy who really wants to be self-reliant and his own mechanic, but buys a Rotax 912 because its lighter than a Corvair, isn’t likely to be happy in the long run. Neither is a guy whose sole interest in Corvairs is because they are comparatively inexpensive. This is why I spend a lot of time speaking about philosophy and motivation, these are important things to understand before people start shelling out money.

At Oshkosh last year, a nice enough guy, new to homebuilding showed me a spread sheet he had made with every possible 100-120 hp engine on the market. A lot of the data was brochure stuff like liquid cooled engines weighed without water and fuel burns a Cox .049 couldn’t match. This guy even invented new concepts like engine weight divided by dollar cost, not a particularly useful value. I tried to get him to switch gears and think differently by pointing out that his marriage works because he and his wife are a good philosophical match, not because her height x weight divided by her gross income is in some target range on values. I think he understood the point, but I suspect he went home and graphed out the last equation.

On the subject of Cleanexes, There are a lot of photos of them on Dan’s site Hard to believe, but Dans plane has been flying for seven years. Time waits for no one. In the first years, Dans plane was followed quickly by Chris Smiths “son of Cleanex.” At the time there was debate about what the ‘right’ engine was, or how well the Corvair worked in the sonex airframe, mostly driven by people who spent a lot of time on the net and had never seen a Corvair or Dans plane. 

In the foreground Dan’s Cleanex, behind, Chris in the “son of Cleanex.”

In 2009 Dan and Chris flew up to the Crossville fly in for Sonexes. Chris later told me that he and Dan, who fly together a lot, did a full power, formation flyby at 5 feet, 180mph, 3,500 rpm and 12 cylinders, followed by a sharp pull up and a clean break. Chris said after the came back around and landed it was like Lindbergh landing in Paris, they were mobbed and questioned by people who had only heard from internet experts that the Corvair was a heavy, oily, old American engine that made no power. After one look at reality, opinions change. Today there are about 14 Cleanexes flying. many of these were built by people who were present at the Crossville moment, and they cite the sound and the power as the decision maker. All of them report that the performance had been astounding, partially because the internet experts, people who had never seen the Combination fly, had them expecting much less. One of these successful Cleanex builders whose mind was made at Crossville is already regestered to fly his creation into Corvair College #24-ww

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