The International Cessna 170 Association

There is no difference between a muffler system for a C-145 or any model of 0-300. Assuming one wants to find a Hanlon-Wilson system, here is what they would be looking for depending on what year/serial number 170 they have.

If you have a '52 serial 25372 or prior, the right and left muffler assemblies which includes all the clamps, exhaust inlets, heat shroud and hardware, are exact duplicates. There is a different left and right exhaust stack however.

If you have a '53 serial 25373 or later, the entire muffler system is the same as that for serial 25372 and prior except for the right hand muffler and head shroud parts.

An entire muffler system from a 172 serials 28000 to 47746, if it uses the original part numbered parts, is the same system as that in a '53, serial 25373 and later 170B. Muffler systems found on 172s after serial 47746 are not the same as the earlier system in that the diameter of the muffler cans are bigger and as reported by Canav8 quoted below, the exhaust stack diameter is bigger and perhaps some other differences which might interfere with direct installation on any model of 170.

canav8 wrote:The 172 Hanlon Wilson cans are larger exit port. They are 2.25 diameter instead of 2 inch. Different part numbers. No they are not higher performance either. D

Moderator Note- Most of this info was originally gathered and posted in a TradeMart post. As TradeMart posts are deleted in 6 months the info would be lost, thus I've posted it here as well as directed that any further comment about muffler systems be directed to this thread.

To help clarify, The early “pancake” style of exhaust system is sometimes hard to maintain due to diminished availability. Conversion to the “Hanlon-Wilson” system is recommended.

Note: The ENTIRE system must be replaced when upgrading to the H-W system. NO PARTIAL CONVERSIONS are approved. Both sides must be accomplished.

IF you are converting from pancakes to H-W a 170 or 170-A you will want TWO LEFT MUFFLERS and Shrouds. Otherwise, the remaining “risers” and “tailpipes” are “handed” as left/right.

However, LATER B-MODELS subsequent to the ‘53 year models which have the larger/improved cabin heat systems will utilize the parts as-illustrated below for the left and right systems. Note that the ‘53 and later B-models ONLY use the illustrated items 8, 9, and 10 shroud parts and the muffler with the “shroud rings” depicted in item 1, PN 0550157-9 .

All earlier 170 models, pre SN 25373 use two LEFT MUFFLERS AND SHROUDS.

The following illustration is from our supporter AWI: https://awi-ami.com/