Offshoreonly.com - From mild to wild! Building a 540 or 572?

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Quote:

Originally Posted by snapmorgan (Post 3496672)

I have a 540 with the stock intake and fuel injection setup off a 454 mag mpi(should be the same as yours) makes 575hp. I have talked to 3 of the top engine guys on this site and they have all said the same thing, that is all that the intake will flow. All have recommended ditching the stock intake and installing a Holley or FAST efi setup. They claim a 50hp gain just by changing intakes. I plan to swap mine out this winter.

Mine runs great and is a HUGE improvement over the 454mag, but will only turn 5200 rpm no matter what prop i put on it. Something to consider.

I have a 540 with 502 mpi intake system,bored out throttle body, better injectors, ported/modified base intake, stock plenum. Made 1115 hp blowing thru it with a procharger, 657 hp normally aspirated. I don't believe their is a "wall" at 575 hp (closer to 650)where hp ends IF you take the time to modify the intake but there is definitely easier solutions!!!~! Smitty

My intake , throttle body and injectors are bone stock as delivered from Merc. I think in the long run it will be better to upgrade as opposed to doing all of the work to the existing setup.

I intentionally kept my 540 very mild because i also am running a stock Bravo 1. I have since purchased an XR upper and am IMCO lower, so i am not afraid to make a little more power. I hate to rip my fresh(20hr) engine back apart, but you have to do what you have to do.

[QUOTE

Mine runs great and is a HUGE improvement over the 454mag, but will only turn 5200 rpm no matter what prop i put on it. Something to consider.[/QUOTE]

Sure you're not hitting the stock rev limiter?

Rev limiter set at 5800, final tune done by Eddie Young.

Quote:

Originally Posted by snapmorgan (Post 3497438)

Rev limiter set at 5800, final tune done by Eddie Young.

Gotcha. Just checking! 5200 no matter what prop had me wondering. :coolcowboy:

snapmorgan...I take it you are running stock exhaust manifolds also? Can't get it in if you can't get it out! :)

Why create more HP robbing back pressure than you need to.

I have a set of IMCO power flow's on it. I am thinking they should be plenty good for this kind of power. What does everyone else think?

The build has went toward a whipple 2.3L unit. Also adding a set of stainless marine exhaust. Any more HP than that a I'll need a new upgraded outdrive. I will need a lower unit soon. How do I know if I need a shorty lower unit?

Thanks

Staying with a short deck BBC will save you from "adjusting" your exhaust requirements. Provided your transom exhaust holes are cut to the Merc spec.