anyone have the official Specs on the 5.7, 6.2 all flavors ?



Hp at what RPM's , HP to Torque Curves ?

Merc keeps hp and torque curves confidential. Dustin Whipple is probably the best source for this info.

That seems like a silly thing to do. If someone really wanted to get the info, they could throw it on a dyno. Seems like Merc would just publish it and save their customers the trouble. I could understand if it was a super secret and the average person couldn't pay a few hundred and figure it out. But why should they have to...

Chris

Not enough hp and not enough torque

I would be willing to bet that the Merc. 350mag is the same base engine as a the 330/350 HO crate engine GM sells. Also, the 6.2 is likely a version of the 383HT crate engine. If I'm right the 6.2 does have quite a bit more torque, like some 60lbf...
Speaking of crate engines, What do you all think of the new ZZ383/425HP??? I bet that baby would make my little Superboat talk...

Not a 383....377 mag is a destroked 400 smallblock. basicly a 400 with a 350 crank and modified rods and pistons. I don't know mecruisers specs, but theoretically,
with the larger bore size it would produce a higher tourque curve. Mercruiser was thinking longevity, rather
than HP. 377 is a well balanced engine and handles the
high rpm marine application as well as a 350, and much better than the stroked 350 "383"

350 = 4.000" x 3.48" (Gen.I, 5.7" rod)
350 = 4.000" x 3.48" ('96-'01, Gen. I, Vortec, 5.7" rod)
350 = 3.900" x 3.66" ('89-'95, "LT5", in "ZR1" Corvette 32-valve DOHC, 5.74" rod)
364 = 4.000" x 3.622" ('99-later, Gen.III, "LQ4" 6.0 Liter Vortec, 6.098" rod)
383 = 4.000" x 3.80" ('00, "HT 383", Gen.I truck crate motor) (5.7" rod)
400 = 4.125" x 3.75" (Gen.I, 5.565" rod)

and merc specs the 377 as 4.000 x 3.75

so is it really just a 350 block? not a 400 AthORiTAH
looks like they just use a special crank & rods

so is bore is resposible for higher tourque curve?

Author,

See other thread.
6.2 Merc is a 350 bore size and a 400 stroke length. A stroker motor.

While increased displacement will always = more output if all variables otherwise remain the same, for a given displacement, longer stroke length holds a clear mechanical advantage over bore diameter.

Apples to apples, a long stroke 377 will be torquier than a big bore 377.

And a stroked 383 (which is a .030 over longstroke 377) will hold up just as well at the rpms we consider to be "normal" for a moderate marine performance motor (4500-5000 rpm).