SonexBuilders.net

After nearly a year hiatus from working on my nearly-finished Waiex (primarily due to the procurement and arrival of a new member to my family!) I returned to the Hangar last week to start dusting off the project for the final push to completion.

In doing so, I performed an engine test run on my still-never-flown Aerovee Turbo. Remarkably after sitting for several months without being run (I'm never dong that again), it fired right up within a few turns. I warmed it up, and tried a short powered test runup, which at full throttle gave me the following numbers:

~27" Manifold pressure
~2700-2800 RPM (Sensinech turbo-aerovee climb prop.)

Since I had already read (but not yet performed) the Turbo Service bulletin, I immediately knew where my issue was. After shutdown and cooldown, I removed the intake manifold to the turbo, and felt with my finger that the impeller was very resistant to movement (this procedure is detailed in the SB.) Still, I was able to get it to start turning with my finger, and after about several rotations it suddenly freed up substantially, after which it seemed to spin freely.

I then performed another engine runup and was greeted with 40"+ MAP and 3300+ RPM.

So, chalk me up as another Turbo owner who had a siezed turbo that was easily detectable during a ground run. Per the SB, the reason for my seizure was extremely likely to be a low-time turbo that had sat for several months allowing rust deposits to form (rather than oil coking.) I doubt the power generated would be enough to even take off (due to the coarse prop), but a siezed turbo putting out 27" manifold pressure should be enough for level flight I would imagine. I will be performing the SB in its entirety and will never let my engine sit for so long again.

Welcome back!

I also want to say - glad you are building again (and congrats about the tyke). I love your build log. ;-)

Hi ryan,
Great news!! I was wondering what happened to you. I hadnt seen any posts in a year. Congrats on your child, and getting back to the waiex. Lots of catch up reading here.

WaiexN143NM
Michael

after sitting for the last several weeks I had low rpm at full power and aborted a take off due to only seeing about 27 in. MAP. I taxied back and tried again and this time got over 43 inches MAP and had to throttle back to prevent an over boost situation. The turbo needs to be flown regularly to keep it going. If you have a hangar queen then the turbo is probably not your engine, but the normally aspirated AeroVee probably is.

I'm 10 x hours into my second turbo and starting to find the new turbo is starting to bind again like the first one. All service bulletins done and meticulous about idle time after flight before shutdown. Question is after spending hours on the net trying to find helpful info
- why is the turbo in the kit a water cooled turbo obviously and not water cooled.
- most bb turbos specify a synthetic oil only, why cant the Aerovee run synthetic oil? Lots of vw sites recommend a sythetic oil for air cooled vw engines.

Brett

While I have no answers to your questions, I can say my turbo gave me enough issues that I removed it. To say I am disappointed in the product and the factory is an understatement. When I removed it, I also had problems with my MOFOCO heads. I asked the factory about both products. They said to contact the manufacturer about the heads as far as a replacement, but did not answer when asked about the turbo manufacturer.

If Sonex won't stand behind their products it speaks volumes about them.

Brett wrote:- why is the turbo in the kit a water cooled turbo obviously and not water cooled.
- most bb turbos specify a synthetic oil only, why cant the Aerovee run synthetic oil? Lots of vw sites recommend a sythetic oil for air cooled vw engines.

Please take these answers for what they're worth...I'll give you the same answers the factory gave me when my turbo started to seize up and I had to send it back in for a rebuild.

- The turbo itself is meant to be liquid cooled due to it being automotive in nature, but given the relatively low power that we produce, the shop that prepares the turbo felt confident that oil cooling alone would be sufficient. That assumption is debatable as we now know.

- Synthetic oil would be a much better option for us to use in our airplanes, but the problem we face is actually the 100LL fuel. You can't use synthetic oils with 100LL fuels; I'm not a chemical engineer but the lead byproduct in the fuel is basically incompatible with fully synthetic oil, and we would run into big issues with trying it. That's why the Brad Penn (semi-synthetic) oils are still okay, but a full synthetic can't be used.

I'm sorry to hear about your problems Brett. You're not the first person I've heard about who is running into issues with their "second" turbo (after rebuild). I wish I had advice to offer here but I really don't know what to tell you. All I can say is, good luck!

The AeroVee Turbo Nightmare.

There seems to be a 'black cloud' hanging over the Turbo users.....is there any good news regarding this setup?

As I understand it Robbie..........you have removed your Turbo/VW setup and are going with the Corvair? This sounds like a much better option than what you had if you need more power.

As a long time RV builder/flyer, when it comes to horsepower, more is always better. It can get you out of a compromising situation that you likely should have avoided but some extra horsepower just saved your butt.

I hope I don't regret jumping into my Onex project with the 85 hp Hummel 2400. I think the airplane is basically a good airplane but it is underpowered as are all the Sonex's with only 80 hp.........that's my opinion any way.

Carl Eldridge from Texas has the 130 hp UL Power Onex and that makes a nice performing airplane. Of course the 6 cylinder Jabiru is another answer for both the Onex and the Sonex but it comes with its own set of problems. Also you can't discard the fact that both these engines are quite pricey.

With the increased prices of the 'B' model and then you add in the Rotax or UL engine you are approaching the cost of a low end RV-7...........and you won't have anywhere near the "re-sale value" of the Van's airplane.

There's no easy answer to this issue. I DO love the sound of that 6 cylinder Corvair, the price is in the right ball park although it is a bit on the heavy side. I guess we need to see more of them flying and see how they stand up after some higher flight times.

Gordon..........Onex.......Hummel 2400

Gordon wrote:As I understand it Robbie..........you have removed your Turbo/VW setup and are going with the Corvair? This sounds like a much better option than what you had if you need more power.

I believe that may be a future plan for Robbie, but for now he simply pulled the turbo and associated accessories and rebuilt his AeroVee to run as a non turbo engine. I know Robbie has been flying his Sonex this way and seems to be happy with the outcome of the modification. I did the same thing on my Waiex and have been flying behind my non turbo AeroVee for almost a year as well.