is the 496 mag a crappy base motor?
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is the 496 mag a crappy base motor?

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    Senior Member BigQ's Avatar
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    Default is the 496 mag a crappy base motor?

    I have not read up on this lately, but can you add power to the mag 375 motor or would you need to pull it and just add something else?

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    New here Beer:30's Avatar
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    Quote Originally Posted by BigQ View Post
    I have not read up on this lately, but can you add power to the mag 375 motor or would you need to pull it and just add something else?
    The only differences between the Mag and Mag HO are the cam and ECM programming. You could probably find someone on here with a stock HO cam, as some have put on Raylar kits. The rest of the rotating assembly is exactly the same.

    You can gain 8hp in a matter of minutes by pulling out your turbulators. Take the riser off of each exhaust manifold and remove the stainless plate in the middle. It has a hole in the middle that is about 2.5". After removing this, it will have a full 3.5" to breath through. Remove the plate only and re-use both gaskets on each side. Full Throttle Marine dyno tested this at 7-8hp.

    I put the K&N filter on mine. Supposed to be 5hp, but I didn't notice a thing. My only reason for putting it on is better filtration. Some say there is no need for a filter at all on boats, since there is no dust on the water. I understand this theory, but the motor is not IN the water. The air that it breathes is ABOVE the water and has significant dust. Also, when towing, the road debris - as well as interior debris, upholstery, carpet - flys around and into the engine compartment. Also underway when the air is being pushed from all of those dirty areas right into the intake screen. When I removed my stock screen, there was a layer of crap all around the butterfly of the throttlebody. So much for that theory.

    It depends on how much you want to add. The initial weak part is the piston(s). They are cast - which is not necessarily the entire problem; since there are several other cast pistons that will take plenty of power. These specifically have the top ring very close the the top of the piston. The first thing to go is a chunk of that thin area. This usually only happens with supercharging. So, if you want to get into the 600hp category - you are either building this motor up or building another.

    The 8100 gen-VII (496) is still a big-block Chevy. It will still respond just as well to upgrades. I have a set of Lightning headers coming for mine - which will free up 20-25hp. I feel this is the first area someone would want to update, as any other modification will want better exhaust.

    I also have a full set of 1.75:1 Scorpion roller rockers and new springs for the valvetrain. It will take a bit of massaging to make them work with the stock valve covers, but I have that handled. The 1.75s will raise the (HO) valve lift from .510 to .525. Much more and the valves start getting close to the pistons. The reduced friction and weight of the rollers and new beehive springs (with a tad more pressure to close the valves better) should be a conservative 20-25hp.

    Whipple Supercharging has the only rights to the software that reprograms our ECMs. Their site has Stage-1 and Stage-2 programming that raises HP each time. One is basically for 87 octane and the other is 91. This in particular would benefit you two-fold, since it would squash your Mag programming in favor of "beyond HO" programming. The cam would still be holding the engine back, though.

    I would hope each of these mods would add more than this, but I am being realistic.

    The next step would be pulling the heads and having them worked. The replicated intake ports are quite good already (similar to new LS small blocks) but the valves are small, springs are weak, and the exhaust needs work. A few people here have worked stock heads and found them to be quite powerful. I found a guy that has stock heads and intake he wants to get rid of. After the headers I will snag these so I can have the heads worked and then just swap them out. Minimal time down.
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

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    Senior Member BigQ's Avatar
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    Nice thanks for the information. I thought the crank and block was different in the two. So theoretically one should be able to put in an after market cam and valve train have the ECU programmed and would be as much power or more it sounds like.

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    New here Beer:30's Avatar
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    Quote Originally Posted by BigQ View Post
    Nice thanks for the information. I thought the crank and block was different in the two. So theoretically one should be able to put in an after market cam and valve train have the ECU programmed and would be as much power or more it sounds like.
    Very few aftermarket cams for gen-VII motors. Comp has a handful, but more geared for street vehicles. Crane has (had) some for marine, but had pretty big lift numbers. Would take different pistons with larger valve reliefs.

    However, if Comp has any cam listed for a motor, they will make custom grind cams for no additional charge. So, yes, if you were going to go through the effort of changing cams - you might as well go aftermarket. Raylar has a couple of cams that work with stock pistons also.
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

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    21 Daytona Outlaw's Avatar
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    placecraft just installed a raylar kit on his check it out
    http://www.performanceboats.com//showthread.php?t=20876
    #55

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    New here Beer:30's Avatar
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    Quote Originally Posted by Outlaw View Post
    placecraft just installed a raylar kit on his check it out
    http://www.performanceboats.com//showthread.php?t=20876
    I believe he just ended up with crank, rods (maybe) and pistons from them. Not sure, though. I know he went custom cam, kept stock heads (not Raylar) and no Raylar intake - via Whipple.
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

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