Heisler gear ratio?

[Flare]

I'm wondering if anyone knows what the piston-to-wheel gear ratio is on the On30 Heislers?

My sound module's default chuff rate is close to 1:1 but I know most Heislers drive shafts make 2 to two and a half revolutions per wheel revolution, and I'd rather not risk voiding the warranty on my new loco to count the teeth in the trucks.

[Yorel]

There are 2 cylinders. Each cycle of each piston produces one chuff. Gear ratio has NOTHING to do with chuff rate. Crankshaft rotation does.

[Hunt]

Flare - Presume you asked for gear ratio because of the following,

CV 116 Engine Exhaust Control
The correct synchronization rate may be computed as: 
      CV Value = 115.9 X SPD÷DIA
Where SPD is the locomotive's speed in scale miles-per-hour at maximum throttle and DIA is the locomotive's driver wheel diameter in scale inches. For geared engines, the CV value should also be multiplied by the locomotive's gear ratio.

I have put away most of my Bachmann technical notes and that is sometime I do not recall.