engines: size and efficiency

[DaveB]

Hi folks,

I've got a friend who's in the market for a new boat... a 25-28' cuddy which will have a fairly large i/o... some dealers are trying to talk him into a larger engine and I'm not sure about the trade offs. My impression is that a larger engine would:
-provide more power -> more speed and acceleration
-be less loaded at a given power output, and possibly last longer (i/o's are based on car blocks... as cars typically operate at less than 2000 rpm this might be significant)
-consume more fuel for a given power output.

Are these generalizations reasonable?
(I appreciate that there are likely exceptions)

Thanks for reading,

Dave

[KCook]

I don't have any data to pin this down. But as for "consume more fuel for a given power output" - I think that was a concern from carburetor days. With fuel injection I wouldn't expect much difference. Stronger motor makes more sense (up to a point). Bigger question is when you opt for twin engines as the means to greater total power. Twins will burn more fuel.

Kelly Cook

[Corpus Skipper]

Always go for the larger engine. It won't have to work as hard, therfore will last longer, and as far as fuel burn goes, horsepower is horsepower. A 4 banger running wide open will consume as much fuel as a big block loping along at 2500 RPM. KCook is right also, twins will burn more fuel even if the total HP is the same due to drag from the drives and increased weight.

[stevel]

I've never heard a powerboater complain about too much power