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Bertram31.com General Bulletin Board
Diesel Horsepower
Posted By: Bill
Date: Tuesday, 4 January 2005, at 9:27 a.m.
I had an interesting discussion with Tom at Demann Marine Power yesterday regarding potential engine selection. My choice of power was the Cummins QSB 300 HP. Tom is trying to convince me that the 380 HP QSB may be the way to go.
His reasoning being that the price difference between the 300 HP and the 380 HP QSB is only $1100 and that the 380 HP engine would give the same performance at much lower rpm's and gph's. The strain on the engine would be less thus increasing the life of the engine. The lower gph fuel consumption certainly justifies the extra $1100 per side in engine cost.
I asked a bunch of question regarding strain on the running gear and engine mounts and Tom seemed confident that an increase to 1.5" shafts and the aluminum reinforcement and cross bracing on the engine beds would be adequate.
Other than the engine mounts and running gear the aaditional strain on the hull concerns me a little. The boat is torn down to the stringers right now and I have considered reinforcing the stringers with a couple extra layers of glass regardless of what engines I end up with just to be on the safe side. Won't have the ooportunity to do it in the future once things start getting added back onto the boat.
Everything I have read on this board seems to contradict 380 HP engines and that anything over 300 HP is not neccessary. I know you rarely get to run much over 25 knots in the ocean but on those great days it would be nice to get 30-32 knots. Everytime I think I have a decision made someone comes up with some additional food for thought. Tom certainly is well respected, has repowered a good number of 31's, and my friend at Cummins Atlantic as well as a bunch of people on this board highly recommend him.
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