Exhaust hanger on Superior IO-360

[KiloFoxtrot]

Can you guys shed some light on an exhaust hanger installation.

I have a Vetterman trombone exhaust with mufflers installed on a Superior IO-360 with the cold induction. Between the header and muffler/tail pipe is a ball type socket. I assume this is primarily for movement absorption.

As the pipes exit the cowl keeping a good airgap for spacing, I tried to install the hangars to the back of the engine, and I can't get a straight shot, so I mocked up this installation. I would like to get some opinions of experience from you.

Am I going to run into problems doing it this way?

If you have an IO-360 with a Vetterman trombone exhaust, how did you do it?

Thanks

 

[rv8ch]

Keep in mind that the engine will shake like a wet dog from time to time, which means it rotates along the same axis as the crankshaft. If your hangers allow for this rotation, which is substantial, then the mounting method is probably fine.

The "best" way is to fix the exhaust pipes to the engine, then they rotate together. If you can't do that, make sure your method allows for this movement.

Hopefully someone with the same engine mount (RV-7A) can chime in with a better solution. On the RV-8 it's easy to use the method described in the Vetterman documentation since there is no nose gear mount tubing to get in the way.

 

[wawrzynskivp]

Funny, just made this comment on another post

For that specific installation I imagine the adel clamp loaded along the engine mount tubing as very prone to slipping. I would try something to fix it in place IRT to tension. It's tricky but I found a way to get those hangar attach points onto the engine for all of the good reasons to do that. Otherwise I think what you have it will work. If you can, maximize rubber length and minimize steel tube length?

It's been mentioned before, but a rehash is always good:

The tubing that forms the hanging support for the ends of the exhaust tubes is prone to slipping (hose slipping on small steel tube).

In my mind a rolled bead at each end of each tube would be the perfect solution so that the hose clamp could be mounted just above the roll and lock everything in place.

I didn't have that tool and used a very slight flare instead, works great. Others have had success with knurling or just roughing up the surface with a stone to give it some tooth.

It's probably going to get oily eventually so consider that now.

 

[pilotkms]

I have a Vetterman 4 into 2. So mine is different. But in case no one with your setup responds, my thoughts having replaced those tubes supplied by Vetterman:
U have the pipes supported by the motor mount tubes. I don’t think that is recommended. The engine will shake/vibrate differently than the mount. Attach to the engine (I used the sump bolts) so that the pipes move with the engine.

And if u want to head off additional maintenance issues, search for MOVING EXHAUST PIPES here on VAF. Several suggestions on modifying or replacing those tubes.

 

[KiloFoxtrot]

Guys,
Thank you all for your responses. I mocked this up just as a test, but I now can visualize what you are saying about rotating around the crankshaft. Allowing for more play in the rubber tube is good recommendation. I will also check the other posts.

Sometimes I look at it too long and it becomes analysis paralysis. Then it's time for VAF.

Another question came to mind. I read in some of the posts that the torques for the aviation bolts used on our planes can be different for the same size bolts which are used on engines. True or False?

So what is the torque of the bolts that go around the perimeter of the oil pan?
Would that be a dry torque or a lubricated?

Thanks much for sharing your experience!

 

[pilotstev]

Hey there.

I too have a superior XP IO 360, cold air sump, and the trombone. I think a few of us got excited about previous builders experimenting with this rabbit hole and we jumped in. I originally wanted the airflow performance servo because it had a 3” hole. When I attempted to hook up vans mixing bracket to the servo for throttle, it didn’t work. I ended up sending my cross under exhaust back to Vetterman, and got the trombone. This allowed me to run my throttle and mixture directly to the servo without the mixing bracket. It works great, but one mod turned into 4.

I have flown the plane 5 times. I have a very small vibe in the frame. I feel it in the stick and pedals. It’s really small…. But my experience tells me it shouldn’t be what it is. I have been working through troubleshooting along with engine break in temps as usual. A dynamic prop balance is in my future once break in is complete, but my next move is to disconnect the lateral hangers from the exhaust and just leave the vertical supports which are bolted to a rear sump case bolt… not the flange pass thru bolt.

My next plan is to tie the two exhausts together and see if the vibration is gone as the exhaust will be totally isolated to the engine. I have some A&P types looking at things with me trying to come up with a good and safe troubleshoot plan.

I also feel the need to say I have thoroughly examined the engine and the data from my flights with Savvy to make sure I don’t have an engine issue causing the vibe. All systems are good from that standpoint.

Short answer, you can get access to the rear sump bolt on the case with superior 360 with cold air sump. You have to do a little massaging of the angle brackets provided and cut the length correctly.

Now, how late am I to this issue. Looks like this thread may have gone cold. If so, are you flying? And what was the result for my own learning.

Cheers. Happy Osh

 

[D-Dubya]

The instructions for the Vetterman exhausts are generally pretty good and should be followed. There are a lot of them out there and they work well. Not sure how the exhaust pipes would be causing the vibration you're describing, so you may have separate issues going on.

In general, for the older models (e.g. RV-6, 7, 8), the exhaust hanger supports should be attached to a bolt on the engine case. This keeps the exhaust moving in unison with the engine when it goes through its "wet dog" routine. While the run of the pipe has a jointed connection in it, it's only flexible to a point. Fo all intents and purposes, it's a rigid pipe run. Some of the newer Van's models with the larger engines (e.g. RV-10 & 14) have spring-loaded flex joints on the exhaust pipes--so the pipes attached to the engine move with it, and the downstream portions of the pipes are attached to the engine mounts and move less. The spring loaded joints should allow some movement and prevent cracking of the pipes.

Which do you have? Some pics might be helpful.

 

[pilotstev]

The instructions for the Vetterman exhausts are generally pretty good and should be followed. There are a lot of them out there and they work well. Not sure how the exhaust pipes would be causing the vibration you're describing, so you may have separate issues going on.

In general, for the older models (e.g. RV-6, 7, 8), the exhaust hanger supports should be attached to a bolt on the engine case. This keeps the exhaust moving in unison with the engine when it goes through its "wet dog" routine. While the run of the pipe has a jointed connection in it, it's only flexible to a point. Fo all intents and purposes, it's a rigid pipe run. Some of the newer Van's models with the larger engines (e.g. RV-10 & 14) have spring-loaded flex joints on the exhaust pipes--so the pipes attached to the engine move with it, and the downstream portions of the pipes are attached to the engine mounts and move less. The spring loaded joints should allow some movement and prevent cracking of the pipes.

Which do you have? Some pics might be helpful.

Hey thanks for the response! I’ll get some pictures tomorrow.

I think one of the big hurdles is the new elastomer nose gear on my RV-7A. It changes the engine mount geometry. The support clamp and bracket supplied to mount to the sump on my Superior motor is tight. The cross brace to the motor mount is not a good alignment for me. That’s not the reason I want to delete it, but it isn’t a plug and play with the Trombone system intended for the older nose gear arrangement.

I hope the vibration isn’t something more complex, but it does seem to be directly related to RPM. It’s either a contact issue or power plant.

Also, I have the spring loaded ball type joints just prior to the muffler.

I’ll get some pictures tomorrow.

 

[pilotstev]

I have the lateral support removed. Looking for options. Thanks!