Difference between OS FX & AX ABL
 

Can someone tell me the diff. between this two config?
I want to buy a .46 and have this two options:
FX H-Ringed
AX ABL
The SX is slighty expensive.

RE: Difference between OS FX & AX ABL
 

I own 2-OS 46 FXs and 2-46 AXs-all 4 engines start easy and run great. The AXs have slightly better transition and a little more power-FXs are about 3 years old and AXs are less than 1 year-for the money I would get the AX-take baffle out of muffler, and expect
13000 rpm with APC 11/6 prop on 15% nitro. With Tower discount that puts the AX at about $100, not bad for a reliable engine.

RE: Difference between OS FX & AX ABL
 

The "H" engines are for helicopter use. They have the big heat sink head. You probably wouldn't want one of those in a regular airplane.

The OS .46AX is the follow on engine to the .46FX. It has a slightly different crankshaft, wider forward transfer port which led to a 4-bolt head instead of a 6-bolt. This led to a different design cylinder and head. It also has a separate needle valve assembly instead of the cast-on one on the FX.