Originally Posted by
1967brutus
Now that was a username that I would have immediately recognized as being you
Thanks for the explanation on the liner swap, so if I am getting you right, the (ABC) piston and liner of the SH 55 engine should be a possible swap into the GO GH56 with some minor and easy to execute mods like a headshim? Kewl!
I don't need one yet, but it is good to know there is an alternative/it can be done.
That's correct, however, don't expect the same level of performance as all ports are narrower and lower down the liner, the HS .55 liner/piston appear to be timed for torque rather than high RPM, that would be more suitable for a fixed wing aircraft rather than for a heli.
Interestingly the GH56 piston appears to have a hard coat of material at the top 2/3 of the piston, instead of the usual aluminum finish, probably suggesting it is a hard wearing piston/liner combination and should last for a long time. I would also guess that a piston ring from an OS 55HZ or TT Redline 56 (both 23mm) would be quite easy to modify and use if required.
The GH56 bore on the HK website say 23.35mm, that's incorrect, I have measured it to be just under 23mm.