SonexBuilders.net

After seeing the unusual engine mount on Rhetts post in the sonex build status thread, I investigated his build page to see that he is installing a corvair engine.

Thats something that I have not heard much about, so I thought that a corvair engine thread would make for some good discussion.

How many corvair powered sonex airframes are flying?

What is the typical weight of the engine?

How much horsepower?

Is there any documented performance numbers for the corvair?

Does one build a corvair from an old core or is there a place to purchase a running/kit corvair engine (along the lines of the vw revmaster aerovee great plains engines)?

What are the costs associated with building or buying if possible, a corvair engine?

What are some advantages or disadvantages of building a corvair? I'm guessing cost and possibly power as an advantage with less support/no support from sonex as a disadvantage.

Any other thoughts about using corvair engines?

This is an interesting topic of conversation. I'll freely admit my knowledge is pretty limited but from what I've gathered Sonex does not support the Corvair based mostly on engine weight. I wish I knew how much it weighs but I do know it's over the 200 lb recommendation by the factory.

That being said, I know that several builders have installed and are very happy with their Corvair engine. Most have claimed that it's powerful and a very smooth running engine. The cowling requires modification as well as the engine mount.

A lot of these engines are being used on the Zenith 601 XL airframes and seem to be well liked. Back when I was looking at that airframe most Corvair users were happy with their choice.

I also seem to remember the nickname "Cleanex" being used to describe Sonexes with a Corvair... If you google hit you can easily find a lot more info.

You can find a lot of info on Sonex/Corvair combinations here:
http://www.flycorvair.com/corvair.html#Sonex

Also, these guys make full Sonex firewall forward kits for their own Corvair conversion engine (incl. Cowling & Mount):
http://www.aeromaxaviation.com/

(BTW: they also make wing tanks for the Sonex)

MichaelFarley56 wrote:This is an interesting topic of conversation. I'll freely admit my knowledge is pretty limited but from what I've gathered Sonex does not support the Corvair based mostly on engine weight. I wish I knew how much it weighs but I do know it's over the 200 lb recommendation by the factory.

That's really the only big strike against the Corvair. I think it's 210-220lb. I've seen various packages giving power from 90-115hp. At those power levels and weights you will not get Jabiru 3300 performace, but it will be much better than the Aerovee and only about $8K or so. I'm too much of a wimp to go against the factory recommendations on FWF weight, but otherwise it looks like a neat option for the more adventurous types.

Chris, since I am building a Corvair powered Sonex, I have done quite a bit of research myself, but most of it through internet and speaking with the builders.

How many corvair powered sonex airframes are flying? Dan Wesemen, the builder of the original "Cleanex" mentioned there were 7 flying , 2 years ago. I would be willing to guess there is over a dozen easily now, based on turnouts to William Wynne's Corvair Colleges.

What is the typical weight of the engine? FWF weights can be 210 to 240 lbs. The 3100cc Big Boy being the lightest of the conversions.

How much horsepower? William Wynne states 100 hp for a stock Corvair 2650cc engine. 110hp for the 2850cc, 120hp for the 3100cc Big Boy engine. The 3100CC Big Boy engine is lighter (about 12-15 lbs) than the standard Corvair because of the additional material removed when boring out the block and heads for larger 94mm cylinders.Based on speaking with pilots that have flown the 3100cc Sonex planes, I believe the Corvair may have more available power than the Jabiru, and can certainly run at full power longer than the Jabiru 3300, which is rated for 107 hp and 120hp intermittantly.


Is there any documented performance numbers for the corvair? These are From Dan Weseman's FlyCleanex.com website:

ALT (AGL) RPM GPS (MPH) FPM GPH
7500 wot 3410 174 6
7500 3350 168 5.8
2500 wot 3460 174
2500 3250 155 (nrml "low alt" cruise) 5.5
200 wot 3540 178 7.2
CLIMB
1000 wot 3050 80 1750
1000 wot 3110 115 1150

Does one build a corvair from an old core or is there a place to purchase a running/kit corvair engine (along the lines of the vw revmaster aerovee great plains engines)? Yes, One needs to locate a core engine to build. The majority of the engine parts in the conversion are new with minimum block, crank, heads and some miscellaneous parts reused. William Wynne sells conversion parts or completely converted engines also.

What are the costs associated with building or buying if possible, a corvair engine? My estimate for building is $6500 to $9500

What are some advantages or disadvantages of building a corvair? I'm guessing cost and possibly power as an advantage with less support/no support from sonex as a disadvantage. Sonex will not provide technical support for the Corvair engine installation, and requests that those planes that do not have one of the 3 approved engines by Sonex, not be registered as under the Sonex name, hence where the name Cleanes, Son of Cleanex, Corvair, Sonair, etc.. comes from. Since many builders call their planes many different names, and since it is not an approved combination, Cleanex type aircraft are like step children and fly and exist under the table so to speak, without a lot of hoorah and fanfare. But there is plenty of support and help for Corvair installations from William Wynne and other builders. My main reason for choosing the Corvair, is that it is a simple and dependable engine that is not stressed in its role as an Aero Conversion engine, and very inexpensive to repair or rebuild, A typical rebuild will be $1000 or less compared to an aircraft engine of several thousand dollars. That fit my philosophy of inexpensive to build and maintain. And Last but not least, it is an American made product. Our economy can use all of the help it can get right now, so it is nice that the dollars spent stay in the USA.

Any other thoughts about using corvair engines? The more and more I have researched and learned about the Corvair, the more I believe I made the right choice for me. This engine was originally designed by Chevrolet to be an aircraft engine, for Aviation contract they were trying to win. When they did not recieve the contract, They decided to use the engine in the automotive market to compete with the mid and rear engine European sports cars. So it, like the VW actually started off as an aircraft engine and was then converted for use in Automobiles.

That is the short version.... I could talk about Corvairs for days!! :)

Correction to the engine displacements in the above post:

2850cc is 100hp
3000cc or 3.0liter is 110hp
3100cc is 120hp

Thanks for the corvair info Vic. Very helpful. Looking forward to seeing the how the 2 sone...err... I mean corvex or cleanex's on this site progress. Keep us updated.

I just noticed the Aeromax aviation website is not online anymore (http://www.aeromaxaviation.com/). Have they gone out of business? Anybody know anything?

Info about the Aeromax Corvair conversion can still be found on this site though http://www.lightsportaircraftpilot.com/ ... index.html

Yes, Aeromax is out of business, as well as Magnificent Machines, that had the Carbon fiber valve covers and oil pans as well as light weight corvair engine.

Hi Chris,

I noticed you mentioned the photo of my engine mount and thought I would chime in.

The best place for information regarding the Corvair engine is at www.flycorvair.com, www.flycorvair.net, and www.roysgarage.com

Everything you need to know is at those sites.