Loading Gearbox: 1432 or 1-3-2-4 Firing Order?

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Discussion Overview

The discussion revolves around the optimal firing order for two twin cylinder engines geared together, specifically whether a 1432 or a 1-3-2-4 firing order would result in the least load on the gearbox. The focus includes considerations of dynamic loads, bearing life, and potential modifications to the engine setup.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that a 1432 firing order would evenly spread the load on the gearbox, but questions whether this would affect the main shaft bearing's lifetime.
  • Another participant proposes that the 1-3-2-4 firing order might provide better dynamic balance, indicating a preference for option B.
  • A participant mentions the possibility of using an uprated bearing and increasing oil pressure with an upgraded oil pump, while also confirming the use of journal bearings.
  • One participant references an external resource that provides information on joining engines to gearboxes, suggesting it may contain useful insights for the discussion.

Areas of Agreement / Disagreement

Participants express differing opinions on which firing order is preferable, with no consensus reached on the optimal choice. The discussion remains unresolved regarding the implications for gearbox load and bearing life.

Contextual Notes

Participants have not fully explored the assumptions regarding dynamic loads versus transmitted power, and the potential impact of modifications on the overall system has not been thoroughly analyzed.

wolram
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If 2 twin cylinder engines are geared together (90 degree cranks) and then a chain is coupled to the rear engine to a gearbox, would it be best to have a 1432 or a 1 and 3, 2 and 4 firing order,1 being front engine left 4 rear engine right ,to give least load on the gearbox, intuition tells me 1432 would be best (the load is spread) evenly, but would the main shaft bearing have a reduced life time.
 
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I assume you are talking about the dynamic loads from the engine, not the transmitted power from the shaft? An educated guess would be option B which would have more of a dynamic balance to it.

Your main shaft bearings are journal bearings, correct? I can't see how you would have reduced life unless the coupling of the two increases the radial loading. Is there an option to increase oil pressure slightly?
 
There is an option for an uprated bearing but it requires some crank case mods, so i am not sure if it is justifiable, i may be able to increase pressure with an uprated oil pump, yes they are journal bearings.
 

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