Supercharging a 496...
 

I have a 2008 277 Islander with a 496 HO, wanting more power but I really don't want to change the motor. I would really like to go with a whipple charger but all i've heard is that a 496 cant be supercharged. There has to be someone that has had good luck with one. I know the 496 has cast internals but there are other engines that can be supercharged without forged guts. What has to be done to make it work?

The pros here say that the cast pistons will not hold up. Also cast crank will not like it much either. I hear there are a also fuel sytem mods and computer programing to be done. Sorry there is no such thing as cheap HP.

I know of two 496 stock boats with superchargers on my lake, and one 330 cast 454 with a roots style blowers as well.

All have stock cast internals. All have been running for the last 3 years with no problems.

The prob with a cast piston is just a little pre ignition knock (detonation) can blow the cast piston to pieces in seconds. Forged pistons will handle a lot more "knock" but no nock is good.

When you add boost, and some timing your chances of seeing knock are a lot higher, especially in a marine engine where fuel may easily get old, or have water in it.

Its a gamle, but speaking with one of the guys on our lake he states these rules-

Always fuels on shore, 93 octane
If fuel sits for longer than 3 weeks he adds 110 race fuel to mix with 93
Changes fuel filter twice a year
Inspects fuel system and igniton twice a year
No wide open runs for more than 5 mins

I don;t know who did any of the programing or other changes, and i won't see these guys til May again.

no wide open runs for more than 5min? oh there goes all the fun, i run wide open for 20-30min all the time

No one wants to change an engine until they realize that boosting that particular engine was a mistake. If you really baby it and don't run it very hard, it will live for a while but at that point you may as well leave it alone and run it hard.

Sure, there are people that will tell you it's okay. This has been debated so many times... Looking for "one" (someone) to tell you that they had no problems?? Wouldn't you rather find several owners that all agree that spending that type of money won't send you in the "other" direction??

It really doesn't matter that there are "other" engines out there with cast internals that also have forced induction.

You're asking about the 496. If setup properly, it's great, closed cooled package allowing you to keep all of your accessory drive components etc..

If you don't want to build it to last (spend money on what you currently have), then by far the best way to handle your desire for more power would be to sell your entire engine as a take out and start over.

You can spend a lot doing it correctly. Or you can spend even more dealing with it after you went cheap (or cheaper).

I did mine and had great time with it. With that been said it is still not for everyone. PM me your number and I talk to you about my experince with it.

So would upgrading to forged internals and a boost friendly cam be a cost efficient option to a motor swap? Is there any other weak points in the motor to be addressed?

I think there are some fuel system mods and computer upgrades that should be done. The Miami boat show is coming up, some of the pro's must be really buisy right now. I'm sure they can give you more details.

Then of course there is still my favorite idea-

Take your engine out, and put it in the corner

Buy a high performance engine that will drop in, if used get it freshened first.

When you are done put the stock back in your boat, it will sell faster and most like be worth more than it would be with aftermarket mods to the stock engine.

Bonus- you have the high perf engine left to sell outright or use in your next project

Very well said +1