502 mpi vs 496
 

all i know is one is old style and one is new style . if you have plan's on upgrading the power the 502 mite work better . if you want relability and you are not going to do anything to the motor i would say 496 ho. all the way . i have had 2 boat's with the 496 ho motor's and they are great motor's for there intended use .

my 2 cent's
mike

The 502 should come with all forged internals whereas only older 496 HO models came with forged internals. I'm not sure of what year the changeover was from forged to cast. On the 496 your performance options are relatively limited. I think the only people that really specialize in 496 performance is Raylar. Their stuff is killer for sure! You definitely have more options with a 502 though.

Stock for stock, it's probably even money. I imagine that if you treated a 502 and 496 in the same manner, you'd get pretty even hours and reliability out of them.

Pro of the 496 is it has closed cooling. Its a little higher tech than the 502mpi. Personally, I prefer the 502. More standard and upgrade parts available. Many proven kits to bump up the HP. 502mpi's do tend to use oil.

500's are 502.

I'd go with the 502 because it's easier to upgrade and there are more aftermarket parts. You don't see mercury racing using 496's. I really haven't seen anything the 496 does that the 502 can't.

500efi's made after about 2001 also had Manley rods and were better.