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I am installing the aluminum baffles on the 3300. The aluminum sheet is a single piece mounted to all three cylinders. There is no provision for individual cylinder movement. Seems to me this is a recipe for cracked baffles down the road. Has cracked baffles been a problem to anyone?

The baffles on my O-320 have a slip joint between the cylinders. I could do the same but I would rather not have the extra work if it is not needed.

RIck Caldwell
CAMit 3300 in Xenos 0057

I have seen at least one 3300 with the sonex baffles that have cracked between the cylinders, that being said once you have the baffle kit it wouldn't be to hard to make replacements from the broken baffles or to make modification to the baffles to account for cylinder movement

Yes mine are crackd and cracked even after doubling aluminum. I agree some kind of slip joint maybe with a flexible fiber between the cylinders would benefit you down the road

Thanks for the replies. That is what I was afraid of. I'll copy the design of the slip joint used on the Van's baffles for mine on the 3300. I am making my own set which is different from the one Sonex supplied. I am just using it as a template to trace out the rocker box cut outs. Once I get mine done, I'll sell the Sonex baffle set as they are in as delivered condition.

I moved the prop forward with a spacer so I have more room in there for inlet ducts. The oil cooler shroud from the kit will be replaced with a fiberglass duct since the shroud does not come close to the cowl.

Rick Caldwell
CAMit 3300 #0088

A better question might be has anyone Not had the plenum sides crack on a 3300 installation. Was warned about this when building 10 years ago, split mine part way up the sides, to a large hole drilled as a stop hole. covered the slit with a patch riveted to one side only, and they still cracked.

David A.

After the second baffle crack repair. I used and modified the Jabiru supplied Fibreglass baffles making them the same volume as the metal ones. Fibreglass seems to be a better material to use in this application. No more cracks in the last 200 hrs.
Steve
Sonex 892

sonex892. wrote:After the second baffle crack repair. I used and modified the Jabiru supplied Fibreglass baffles making them the same volume as the metal ones. Fibreglass seems to be a better material to use in this application. No more cracks in the last 200 hrs.
Steve
Sonex 892

Agreed. My engine came with the Jabiru fiberglass ducts (which are not as large as the Sonex supplied aluminum ducts). This was before Sonex ever came out with their first version of the aluminum ducts. To the fiberglass ducts, I riveted on a continuous aluminum strip along the bottom to extend the ducts downward a bit and to capture the rocker cover screws. So even though this "hybrid" version runs aluminum from cylinder to cylinder, there has been no cracking in over 700 hours.

Art,,,,,,,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,,,,Jabiru 3300 #261

I think it's actually unusual if these baffles don't crack. Mine definitely did. When I converted by 2n'd gen hydraulic to internal oil distribution to the heads (removed the external oil tubes), I remade all my baffles to remove the inter-cylinder slot for theoil tubes. The new baffles haven't cracked yet and I've got over 200 hours on them. The previous ones were cracked by about 80 hours.
Lorin

This is the slip joint I made to account for cylinder movement.

Rick Caldwell
Xenos 0057

I've added doublers and the cracks go right through them.

I've also had the cracks split the solid rivets of the doublers in half. Cracks don't care.