SonexBuilders.net

I am a fairly new forum member and the proud owner of a Waiex that I recently purchased from a friend and fellow forum member. First thing I did was remove the turbo aerovee and order a CAMit 3300 to replace it. I now have a brand new motor that is unsupported due to CAMit's recent insolvency and am trying to decide whether to install it and hope for the best or sell it and go with a Corvair. My mission is a 300 mile range with reserve and I need to go 140 to 150 mph. High fuel flow and slow speed with the aerovee made that impossible. I would like some input on performance (speeds/fuel flow), ease of installation (cowling fabrication specifically) and weight/balance differences with the Corvair installation. I also considered the UL 350 series but decided that it would stretch the budget too far. Any and all input (good and bad) will be GREATLY appreciated. Regards, Mark

Mark,
Is the BSFC (i.e fuel burn per HP) significantly different between the Corvair, the turbo Aerovee, the CAMit, or any other options? I'm not talking about the claims of companies or fans, I'm talking real-world numbers. My guess would be that it is not, that any air cooled recip engine will burn the "standard" .45 - .48 lb/hr/HP for this type of engine. That's what Lycomings get, Continentals get, VWs get--any air-cooled reciprocating engine. If this is correct, then you may find that, if you need to go 150 MPH TAS and do it for 2 hours and have fuel in reserve, then you'll need to carry more gas than a standard Waiex tank holds. Is installing/carrying an aux tank incompatible with your mission (i.e. would carrying 5 extra gallons cut into your required payload too much?)

For consideration: I can go 125 MPH with my standard Aerovee and go 300 miles on one tank, with reserve (if no unfavorable winds). And I'm sure my plane is not the fastest Sonex with a stock Aerovee. The difference in flight time between 125 MPH and 150 MPH cruise speed for a 300 mile trip (disregarding climb, descent,etc) is about 24 minutes, in the real world it would be even less. Obviously, it is your call and everyone is different, but if I did the math on the number of dollars spent for every minute saved, I'd probably settle for a slightly lower cruise speed and save the $10K+ spent in changing the original engine. Heck, just the increased fuel burn will cost about $1 for every minute I would have saved on that 300 mile trip (if the diff is 4 gallons of 100LL). That's if cruise speed is the only factor I'm considering. But, again, everyone has unique priorities.

In the situation you are in right now (money spent already for the new CAMIT that has probably decreased in value by a bit, a perfectly good Turbo Aerovee with prop still on hand), I'm not sure which way I'd go. But I'm sure I'd think really hard before buying yet another engine.

If it were me, I'd stick that CAMIT on the nose and enjoy the heck out of it.

Hi Mark

Since you already have the Camit that's a pretty tempting direction. My Corvair build has been a lot of fun and a lot of great learning, met some really good people along the way too.

I'm proud of my short supply chain too, dang near every part is made in America. As in currently in production in America.

As far as power per fuel flow, I think the earlier poster is correct. A normally aspirated air cooled engine is going to fall into a very narrow bsfc no matter who makes it. Depending on the mission of the day, throttle up go fast and burn the gas, or climb higher, slow down, and get the range.

Whatever way you go, get the thing back in the air. See you up there soon,

Gordon

I upgraded to the turbo and I can cruise at 4000 feet at 30 in. map at 142 mph true airspeed. and burn about 5.45 to 6 gph. I added an auxiliary fuel tank behind the seat that adds 7 gallons. That gives me a range 2 3/4 to 3 hour range and about 400 mile range. I usually flight plan for 300 mile legs to ensure a good fuel reserve in case of higher headwinds etc.

I think you already have the engine that will get you close to the performance you are after. As far as I can tell, a Camit is just a Jabiru engine with a few tweeks. I did a recent long trip and got the following figures with my Jab 3300 Sonex.

Total distance - 2188 miles (just direct distance from flight plan - haven't included circuits for 10 take-offs and landings)
Actual fuel used - 84.5 gallons
Total air time - 17 hours

So average speed (all air time) = 128.5 mph (If circuit distance is added average is over 130 mph)
Average fuel used = 4.97 gal/hr
Longest leg - 320 miles with safe reserve - landed with 4.5 gal.

Peter
Sonex 894
Jab 3300, 289 hours

Hi , I have just taken my Sonex #160 for its first flight with its new engine.
I have flown ZK-WBS here in New zealand for the last 13 years on a very early early (1520 Jabiru 2200.
I did over this time replace the allow con rods and fitted the newer heads. It never gave me any problems but I always had that niggle in the back of my mind. I found dealing with Jabiru CHALLENGING to say the least.
My wife and I went for a trip to Australia to visit and purchase a Camit 2200. Ian and Jenny Bent could not have been nicer. They showed us around the factory and met their staff.
2 weeks after receiving my engine they shut up shop. There is a lot more to why than has been made public.
Any way the new engine is FANTASTIC. Sounds great and pulls really well. ( only 3 hours on it so far).
I think that if you fit your Camit and keep it cool it will give you good service for years. "Camit is just a Jabiru with a few tweaks" 131 tweaks I think!!!! some just simple changes some to create a safer engine.
I feel really sorry for Ian and Jenney Bent they seem like caring people and have a great product, customer service second to none.
I have no experience or prejudice towards the Corvair ( the cars were never introduced to NZ) but 1970s technollogy against your new Camit? Camit every time. Put it in you will love it.
Bill S

Hi Mark,
I recently posted about my CAMit 3300. Search "100 hour CAMit 3300" and you will be able to tell what I think of my CAMit. It is really just an old reliable solid lifter Jabiru (the ones that are still going strong before the early hydraulic lifter models) with ALL the upgrades and improvements. I went on three cross country flights this summer with legs of 300, 290 and 324 miles and still had an hour reserve after each, including return flights. I was only able to make the 324 mile flight once with the Aerovee without stopping for fuel. I also went on a 440 mile trip stopping at two airports before I headed home. I put 3 gallons of 100LL in at the second stop to get home (I use 91 auto gas and I don't like paying for 100LL) and still had an hour reserve when I got home.
I took an Aerovee off to put the CAMit on. I did not build my plane so it took me all last Fall and Winter to install it, I spun my wheels over thinking everything.
I should have, and probably still will, put a top fuel vent line on with a Peter Anson Fuel Vent Check Valve instead of the bottom vent line. This will give you another gallon in your tank.

I would do as others have said, put it on and fly it.

Ken W
Sonex 959 438 hrs
CAMit 3300 108 hrs

Thanks to everyone for your thoughtful and insightful replies. Deep down I know (from all of the posts and some personal conversations) that the CAMit is a wonderful engine and will most likely serve me for many years to come. I think I need to quit considering a worst case scenario and assume the best. I am probably way over thinking this thing and will most likely do as most of you have said... bolt it on and enjoy!

Bill Sargent wrote:I have no experience or prejudice towards the Corvair ( the cars were never introduced to NZ) but 1970s technollogy against your new Camit? Camit every time.
Bill S

Bill, I would like to argue a different view to this statement. First, it was 1960's when the corvairs we use were being produced. However GM had arguably the best and highest budgeted engine development team in the world at that time. They were vastly bigger than the engineer team at Jabiru or Camit. GM had economy of scale and millions of engines to sell. I don't have the numbers, but would be willing to bet there were more hours put on Corvair engines in one month in 1965 than all Jabiru and Camits combined ever. Another point is that a lot of the engine is in fact new parts that have the benefit of being new technology. Many Corvair flight engines are built with nothing more than the case and heads being reused, after a major overhaul and modification to those heads. I'm not trying to say one engine is better than the other, I'll let you decide for yourself. I do think it is unfair to dismiss the Corvair only on the basis of it being born in the 1960's.