Powerquest_Baby!!

Your not getting it. Your statement doesnt make any sense. Your saying you have never seen a 502 with 415 hp outperform a 496 mag ho with 425 hp. All Im saying is why would it? Im not debating hp ratings at the prop or crank--just the fact that the 496 is rated 10 hp more than the 502 therefore it should be able to outperform the 502.
Your logic isnt making sense.

American Thunder

Im still painting mine blue..just in case
will keep u informed if i pick up mph

88242LS

Sooooooooooooooooooooooo I always thought after 89 they were measured at the prop shaft, but what do I know,

Sooooooooooooooooooooooooo

my 93 502 carb was what at the propshaft?

potential new boat 94 502 EFI is what at the propshaft???


after we figure that all out when and if I get it I'll yank the motors go down to the hardware store and buy some blue paint

onesickpantera

iTrader: (1)

While I agree that the propshaft hp number from Merc are optimistic, the original post asked what the RATINGS were. And they are 390 and 415.

endeavour32

iTrader: (4)

What is odd about the black engines is that Merc rates the 502 mag at 425 at the prop yet OMC rated the 502 at 425 crank and 385 prop. The OMC engine is the exact same engine! Plus I really doubt that the 454 mag carb is going to go from 365 crank to 385 prop with the addition of fuel injection and a slightly different cam. I'm with Raylar that its marketing hype vs reality. Look at a Merc manual for example, the cam specs are all over the place.

MILD THUNDER

iTrader: (3)

http://www.fullthrottlemarine.com/49...%20Article.htm

Raylar

When you get to the hardware store you might want to remember that Superman's cape was RED!



Best Regards,
Ray @ Raylar

ROTAX454

Ray, I remember seeing the Merc Racing specs on the HP500 carb motor and it stated: 470HP at the prop. So therefore, they were rating it 500HP at the crank.

Is this correct?

onesickpantera

iTrader: (1)

Yes the 500EFI and 500HP were rated at 500hp at the crank and 470hp at the prop.

Mercruiser(black engines) are rated at the prop.

Mercury Racing(blue engines) are rated at the crank.

Note I said RATED.

stevesxm

well... just a couple of observations...

first going from 365 to 385 with injection and cam work is a piece of cake...

second my factory workshop manual for my late 502 says
425 and they make no mention where but the presumption has to be at the flywheel...

why would it make any sense to measure it thru a drive ? losses thru various drives would differ and just add a variable that would make the number meaningless in general... the spec would have to read " 425 hp at the prop thru a bravo 1 at 365 deg temp using 65wt saemc gear oil "

huh ?

i know its just bench racing... but it has to make sense to some degree...

and a 496 vs a 502 w/ a 10 hp dif " outperform " one another ? what does "outperform" mean ? accelleration ? top speed ? on paper you might think the one with more hp would have to be better but the shape of the curve vs the shape of the hull and the drag profile might mean that the higher hp motor never makes the revs necessary to get to where the hp is made because it can't push thru the drag to get there... in one hull one motor might be MUCH better and in another hull the opposite would be true...

and do they actually say " at the prop after the drive" or do they say " shaft hp" because shaft hp could easily be crank hp. when you dyno a specific car on a chassis dyno you might say ' at the rear wheels" but you can't then say that as a standard that motor makes that power at the rear wheels of EVERY car you put it in... just that one type and spec


just to fan the flames of discontent...