Mercruiser hp rating correction factors
Just curious, does Merc use the STD/STP or the SAE correction factor when rating their engines?
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That is a tough one...
They are all over the place in relation to stated horsepower. A typical 525 makes north of 540 horsepower. My 600sci made 587 horsepower stock A couple of 700sci's made 679 horsepower on Dustin Whipples dyno On the same dyno... a 1075 made 1103 horsepower stock All of these were standard SAE correction So... who knows??? Chris |
What probably needs to be remembered is the stern drives will be rated at the prop shaft. The dyno pull with no drive attached is bound to show greater HP than advertised.
A 10% +/- of the advertised HP is normally acceptable. Not sure whats going on though with those 600 and 700sci's? |
If I recall the blue motors are rated crankshaft HP and the black motors propshaft HP.
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Originally Posted by Back4More
(Post 3184379)
If I recall the blue motors are rated crankshaft HP and the black motors propshaft HP.
I know most performance companies use the STD/STP correction factor and I would assume it's because it shows more hp. But I don't know if Merc uses SAE or STD/STP when they rate their motors. |
Got that backwards! Merc Racing engines are rated at the prop and Mercruiser engines are rated at the crankshaft.
I believe Mercury Racing and Mercruiser both use SAE standards when measuring HP and torque on their dynos and this is pretty much the standard for the reliable marine engine manufacturers. We use SAE on our tests and we make sure the dyno has a recent recalibration, proper correction factors and is on the "stingy" side on outputs for specific engine packages. Regards, Ray @ Raylar |
Originally Posted by Raylar
(Post 3185974)
Got that backwards! Merc Racing engines are rated at the prop and Mercruiser engines are rated at the crankshaft.
Regards, Ray @ Raylar Mercruiser sterndrive examples: 502 Mag - 415hp at the prop 454 Mag - 385hp at the prop 350 Mag - 300hp at the prop Merc Racing examples: HP500 - 500 at the crank HP575 - 575 at the crank Scorpion 377 - 377 at the crank HP525 - 525 at the crank I think the confusion comes into play because the 525 is always WAY more than 525 hp. Either way I was curious as to if Merc used SAE. Thanks |
I was always under the assumtion that the HP engines
were rated at the crank, due the the fact that they could be had with different drive types ( bravo/ssm) which would net different p/s hp. |
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