Mercury 565 Actual HP?
 

Has anyone dyno'd a Mercury Racing 565? Anyone know what the actual HP is close to? A 525 usually dynos closer to 540 so just wondering if the 565 is also under-rated.

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I've got a dyno someone just needs to bring a 565

Not under rated, just measured at the prop.
Don't know the number, but it would be higher at the flywheel

So the 525 and the new 565 are both measured at the prop?
I'm seeing speed increase claims much higher than I'd expect with only 40 more hp.

Yes, change to the prop (NMMA - National Marine Manufactures Assocation) was done years ago. As example, manual 23 for a 502 MPI the MCM list 415hp and the MIE list 400hp

Don't know about the claims

It says 565HP crankshaft rated.
https://mercuryracing-prod.azurewebs...engines/565-2/

Is that the front of the crank or the back?(joking) Whatever it is I want one!

OK, wonder what the manual list the hp is, because that would be with drive?
The 6.2 MPI list 350 hp as a bobtail, in a boat Merc list as 320hp in manual 31

Yep, it sure does. I looked in my 525 service manual and it also says 525 hp rated at crankshaft. Hmmm.

Could be your Lucky day Eddie. I'm considering selling my twin 565's and replacing with bigger power

But, the 525s are known to be closer to 540hp, so probably actual close to 525 at the prop through a bravo.

The difference is due correction factors being different depending on the standard used.

Mercs are rated at a more conservative standard than your normal aftermarket Dyno shop. And that’s assuming the Dyno operator even uses those corrections properly. The difference is 4-7% I believe, I don’t remember exactly.

A 565 likely makes 600 on a normal aftermarket engine Dyno test.

600 hp sounds about right to me. It's 533 CID with dual throttle bodies. I don't know what other differences there are between the 525 and 565.

I've heard Mercury takes the #8 spark plug wire off during dyno.....