[QUOTE=yoyo;426063]When there are 2 engines on the back in your case adding up to 100hp it is said that there is only about 2/3 of the power of a single 100hp engine due to the addition drag of the second engine etc. This means that you would actally be increasing the power on your RIB by aprox 15hp only
......Another option would be to sell your original 50hp engine and buy a larger single engine 90-100hp.
Search for "twins drag cube" and my ID. I'm fed up typing this........
Twins on a 5.4, not a huge problem, unless you have a transom cut- out? Twin 4- stroke 50s you'd best fill the rear toob sections with helium! Weight will be your biggest issue with that setup. Kev on here also had a Twin 40 setup, and could tell you more about it. Did I see twin 40s on sale in the bits'n'bobs section?