Jabaru vs Corvair

[lstinthot]

Has anyone flown in both a Jabaru 3300 and a Corvair? Looks like the price to build a Corvair has increased close to the cost to buy a Jabaru 3300. Is the performance per dollar comparable? The Corvair is moving away from off the shelf items so the cost to rebuild is comparable to that of the Jabaru I would expect as well.

For those that have flown both, which is your preference? Why?

Thanks,
Mike

[Jgibson]

I would expect similar performance from both, however the bigger difference IMHO would be the terrible reliability track record of the Jab. Research the many issues with the Jab (cam, lifters, cylinders, cooling, thru studs, 'starwheel', etc. etc.)
Probably why the builders can't give a Sonex away with a Jabiru.
I'm SURE there are Jab owners out there who have had positive experiences with the engine, and I'm SURE they will rise up to defend the motor. But facts are facts, and coupled with the Camit fiasco, I personally wouldn't touch one. But I WOULD buy one with a bad motor........to convert to a 120 hp Corvair.
There is MUCH more to an engine decision than simply price.
JMHO.

[MichaelFarley56]

Interesting topic Mike and thanks for bringing it up. I think there are a lot of people looking for maximum performance out of their Sonexes, so this is an excellent time to bring up this subject.

Personally, in the end this will be a decision based on personal preference. I’ve flown Sonexes with the Jabiru 3300 and they’re a blast to fly! I’ve flown behind Corvair’s in Zenith products (never in a Sonex) and can also agree that they’re very smooth, powerful, and sound great!

This is just my two cents of course, but there’s what I’m thinking for a pro’s and con’s list:

Jabiru 3300:

Pro’s:
- Lighter in weight (it meets the 200 lb FWF Sonex recommendation)
- Full factory support, including installation manuals and parts
- The new 4th generation 3300 is supposed to address many of the previous model’s issues
- There are still many people happily flying behind older 3300’s without issues
Con’s:
- Expensive
- Older ones have some Service Bulletins that are costly to comply with
- They have a history of potential reliability issues

Corvair:

Pro’s:
- Gaining a lot of popularity
- Seems to have good support from SPA
- Powerful, durable engine most operators really like
- Can be built for much less money as compared to a Jabiru 3300
Con’s:
- Heavy
- Limited factory support (Sonex won’t be able to help much on the installation)
- Cost seems to be rising (others can chime in on this)
- Some have a history of crankshaft failures (but I believe new cranks are available)

I know there are people on here flying behind Corvair’s and love them. I also know people who have flown behind their Jabiru 3300’s for hundreds of hours (Kip, how many hours on yours now?) and love them.

Other thoughts? Like I said, great conversation!!

[kmacht]

If you are ok with 100hp instead of 120 you can build up a corvair for about the price of an aerovee. The big price jump to 120hp is due to the custom Pistons, cylinders, and machine work to the case and head. A 100hp motor doesn't need any of that. It uses stock pistons and cylinders bored .060 over and no work needs to be done to the case or head.

Keith
#554

[MichaelFarley56]

Thanks Keith. I’m curious, would that include the SPA billet crankshaft? I think those are close to $3,000 alone so I wasn’t sure. 100 hp on 7-8K would be nice!

[samiam]

Hi Mike,

There are so many option with the Corvair, which really helps the builder to do what they want - but creates some uncertainty around what the actual costs are. Dan has said he wants to make this more straightforward for builders, but for now it remains confusing.

Regarding the crankshaft, it is $2350 for a reconditioned crank with fifth bearing, or $3700 for a new billet crank with fifth bearing, making it a net cost increase of about $1350 for the billet crank.

I really think it would be quite difficult to build a Corvair to the highest standards today for less than $10k. The costs have gone up considerably from the "old" days of Corvair, but it has always been for an increase in quality.

The biggest areas that a builder can save money on a Corvair these days is by using a reconditioned crank and by going with the 2700cc displacement. The smaller displacement will save at least $2k on the cost of the engine build.

I went with the 3.0L and the new billet crank. It's a no-expense-spared motor, but the parts that went in it are a thing a beauty. My bottom end is assembled and I hope to have a test run at my next college later this year.

For reference, I fully expect to have close to $14k into the motor and about $4k into the FWF when all is said and done. It may be a savings over a Jabiru, but it is definitely more expensive than the Aerovee.

[kmacht]

Thanks Keith. I’m curious, would that include the SPA billet crankshaft? I think those are close to $3,000 alone so I wasn’t sure. 100 hp on 7-8K would be nice!

If you search my other posts I had a breakdown of the costs to build up a 2700cc motor. It did not include the new billet crank but did include a wessman 5th bearing and having the old crank processed and reconditioned by Dan. There is some really good information on Mark Langfords site about corvair cranks. I'm comfortable with a stock crank conditioned properly for a 2700cc motor but might consider the billet crank if I were to go for a higher horsepower or wanted to turbo charge in the future.

Keith
#554

[MichaelFarley56]

Cool Thanks!

[Marrahm]

The weight of the corvair is what concerns me the most. I understand that the lightest incarnation, the 3.3, weighs about 40#s more than comparable jabinstall per the experts.

My hope (and the reason i asked for data in the other thread) is that the standard gear has a FWF weight gain of around 40#s over the TD. That way, I can talk myself into going the corvair route w/o violating the FWF weight limits since I am building a TD.

I’m also hoping the jab gen4s finally have their reliability act together as a backup...

Mike

[N111YX]

My Jabiru 3300 has been good to me (this is where I knock on something, right?).

I'm at 715 trouble free hours on serial #1637 which was manufactured in 2007 or so I believe. It has the 2nd generation hydraulic lifters that were updated just 30 serial numbers later if I recall correctly. I've replaced the caps, rotors, and plug wires twice now as preventive maintenance bit did have one coil go bad at 675 hours which is pretty good considering that I don't have blast tubes to keep them cool.

I do treat it well. I monitor every cylinder CHT and EGT and pay very close attention to both. I climb out shallow (though 1300 feet per minute is easy) and also avoid shock cooling on descents. I'm very "bonded" with this engine when I fly and that's probably not the case with many other pilots. I don't really "baby" it but I tend to operate it in a way that I feel minimizes thermal stresses. I also add a little Marvels to the fuel and oil :).

I'd like to get to 1000 hours in which case I'll probably get a new one as the latest generation looks amazing compared to mine in terms of updates. I do an oil analysis and compression check at every 25 hour oil change so I like to think that I will see something bad happening before it gets catastrophic. I do worry a bit about the flywheel bolts, however. Mine have never moved but will they shear? Hopefully only on start-up if they do!