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View Full Version : 502/454 mag versus 496 mag HO



CJ Skier
07-10-2006, 05:57 PM
Other than the 40 extra horses is there any reason I should lean towards a 496 mag HO versus a 454 mag? What about the 502 ? I have seen a couple older (1997-8) :) 25 foot boats with 454 mags or 502's and very low hours. Does the 496 have better or worse internal components?
Thanks
Christopher

GRUNION
07-10-2006, 06:26 PM
Other than the 40 extra horses is there any reason I should lean towards a 496 mag HO versus a 454 mag? What about the 502 ? I have seen a couple older (1997-8) :) 25 foot boats with 454 mags or 502's and very low hours. Does the 496 have better or worse internal components?
Thanks
Christopher
496 has worse internals

Beer-30
07-10-2006, 06:55 PM
Really, the only weak points on the 496 (either) are the pistons and the weaky valve springs. The block, crank, and rods are all pretty industrial. Meant for long service. So are the pistons - if it's a stock motor. Raising cylinder pressure has been breaking pistons.
The cylinder heads flow well, to .500", then they fall off. The replicated ports (intake) need very little, if any, work. Bigger valves and some exh port work make for nice power. Matching springs, of course.
The intake tends to dip the intake runners right into the hot valley oil. Two other intakes that don't do this, are available.
Plenty of aftermarket cams.
Coil-per-cylinder ignition with crank/cam sensors is state of the art for efficiency and reliability.
454/502 (mags) have stouter rotating assemblies. More parts are available for immediate bolt on. Ignition is weaker, but can be upgraded. EFI intake is a nice part.
With the right bolt-on parts and head work, 1hp per c.i. is easily obtainable on any of them.

a catered life
07-10-2006, 10:29 PM
Really, the only weak points on the 496 (either) are the pistons and the weaky valve springs. The block, crank, and rods are all pretty industrial. Meant for long service. So are the pistons - if it's a stock motor. Raising cylinder pressure has been breaking pistons.
The cylinder heads flow well, to .500", then they fall off. The replicated ports (intake) need very little, if any, work. Bigger valves and some exh port work make for nice power. Matching springs, of course.
The intake tends to dip the intake runners right into the hot valley oil. Two other intakes that don't do this, are available.
Plenty of aftermarket cams.
Coil-per-cylinder ignition with crank/cam sensors is state of the art for efficiency and reliability.
454/502 (mags) have stouter rotating assemblies. More parts are available for immediate bolt on. Ignition is weaker, but can be upgraded. EFI intake is a nice part.
With the right bolt-on parts and head work, 1hp per c.i. is easily obtainable on any of them.
could you please retype that in english :p

Kilrtoy
07-10-2006, 10:31 PM
you can hop up the 454 and the 502, if you try and do anything to the 496
BANG

jbone
07-10-2006, 10:41 PM
Go 502. Easier to diagnose and work on. They are bullet proof, once you work out the bugs if any. Plus they look better.
http://www.***boat.com/image_center/data/520/3295engine2.jpg
J

franky
07-11-2006, 05:17 AM
you can hop up the 454 and the 502, if you try and do anything to the 496
BANG
Thats a very generalized (bandwagon) statement.
I have a 496 HO that I put a Mag cam in, installed an ASM manifold and throttle body, stripped off all the water flush crap, put a bigger oil cooler on it, a dyno programmed MEFI-4 computer and have a very turnkey, reliable and strong running motor.
BTW, you cannot beat a closed loop cooling system, which is one of the nice features of the 496, for efficient engine temps.

Raylar
07-11-2006, 08:31 AM
I will agree with Franky here. There are thousands and thousands of 496's out there running hard all the time and only a small few have had bang problems both stock and modified 496 motors. I can speak from expierence when I say we have hundreds out there with our upgrades 525Hp to 600HP and none have gone bang. A few small problems with small parts but no catistrophic loses. I think the claim that 454-502's are stronger is not a fair and objective statement. Any high performance marine engine is subject to a lot of stress and hard use and when you study the actual numbers you can see that the 496 series in just 5 years have one of the best service lifes of any marine engine ever released.
Ray @ Raylar

riverracerx
07-11-2006, 08:38 AM
I love my stock 502! :cool:

ChumpChange
07-11-2006, 08:42 AM
I love my 502. 517hp with a carb. If it breaks, much easier to fix without needing a computer to do it.