Originally Posted by Raylar (Post 2489024)

You gentlemen need a little clarification here. First, all Mercury Racing Engines, 500EFI, HP525, HP500, etc. are hand built in Fondulac Wisconsin at the Mercury Racing Plant. They start with just parts and blocks and build the engines from the ground up. They dyno them and rate the horsepower at the PROP, not the crank! for example a Mercury Racing HP525 makes approximatly 540HP at the crankshaft and 525HP at the propshaft.

Mercruiser (black motors) Mercruiser, a different company division of Mercury receives standard GM Powertrain engines at their plant in Stillwater, Oklahoma, accessories them with Mercruiser external parts, sprays them BLACK and ships them to the builders and buyers. These GM Powertrain factory built engines are the same ones GM ships to Volvo, Crusader, etc and GM dyno's and measures the horsepower on these engines at the crankshaft! Hence, all black Mercruiser motors that come from Stillwater, Oklahoma are producing and are listed as horsepower at the crankshaft, period !!
I hope this puts this question and mis-statements to bed for the last time!

Regards,
Ray @ Raylar

Originally Posted by Raylar (Post 2498560)

Well I might as well make some money here. I've got $100 bucks here that says the stock Mercruiser 496HO does not make 425HP at the propshaft but makes 425HP at the crankshaft.
Any takers here?

This may start them naping again.

Best Regards,
Ray @ Raylar