Flexible baffles - Innies or Outies?

[N3322G]

The Twin's flexible engine baffles need work. The flexible part is currently attached as an Outie - the flexible part is attached on the outside of the metal part of the baffle.

In the past after they'd been replaced at engine overhaul time, I'd been told by LoPresti that they were on backwards - in other words, they should be Innies - attached on the inside of the metal part of the baffles. LoPresti did some work and the engines temps dropped 20 degrees as measured by JPI.

Since the baffles were pulled for the prop strike engine IRAN, all of LoPresti's custom work was lost and I'm getting ready to have it done again.

There are so many holes and gaps that the ability to direct airflow and therefore the cooling effectiveness is dramatically reduced - as shown by the higher fuel flows needed to cool the engines - real noticeable when you fly from CA to TX and then to OH and back to TX - range shortening fuel flows.

So what is your experience and opinion - should the flexible baffles by Innies or Outies?

[steen]

Hi, Pat.
Innies, definitely! Think like an air molecule and you will find the ability to leak past the metal is much better with the flexible outside than with it inside, right?
Continuing to think like a molecule the flexible should be bent forward into the airflow against the inside of the cowling for the same reason.
As you have already stated, the difference these small details can have on the overall operating efficiencies is huge.
Steen

[N3322G]

[Michael]

[Bruce Thumann]