Increasing HP in a 454 big block.

J

jan9898

Cadet
Joined
Apr 3, 2010
Messages
23
Hey everyone,

I'm sure these questions can be answered in many different directions.

Assuming the existing engine was rebuilt or like new condition, can someone tell me the least expensive simplified overview of what is involved with taking a standard 330 HP 454 7.4 ? Carbureted big block and increasing it to 450 HP

I know that at the very least the prop needs to be changed, I'm not so intrested in knowing the external modificaitons rather just chnages to the engine. i would like ot know whats involved without the use of chargers/blowers etc.

THANKS!
 
Bondo

Bondo

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Staff member
Joined
Apr 17, 2002
Messages
71,128
Re: Increasing HP in a 454 big block.

Assuming the existing engine was rebuilt or like new condition, can someone tell me the least expensive simplified overview of what is involved with taking a standard 330 HP 454 7.4 ? Carbureted big block and increasing it to 450 HP
Click to expand...

Ayuh,... This question is asked BEFORE the motor is rebuilt...
Because the recipe used would be Totally Different...
Short answer is,... It Ain't gonna happen.....
 
H

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: Increasing HP in a 454 big block.

Howdy,


I'd like to the same thing. Your best bet would probably be to speak to these guys... http://usengine.us/mercruiser.html They do it for a living.

NOT using a blower always requires more cu-inches, stroker kits (which gives you more CU-IN), raising compression ratio and performance camshafts... (the cam is limited though due to reversion unless you're using it in a jetboat with dry stacks etc)

Raising the comp ratio may limit you to only using premium fuel though, which is not always available at every marina or lake.............

Most of the automotive rules apply to marine engines except most automotive "hot-rod" engines make all their HP at 6000 RPM and above.....

If you're using the engine in a jet, that may be ok but in an I/O you need to make most of your HP and torque at RPM's well below the above RPM unless your outdrive costs more than your boat!;)


Regards,


Rick
 
J

jan9898

Cadet
Joined
Apr 3, 2010
Messages
23
Re: Increasing HP in a 454 big block.

let me re-phrase,

i have a good condiitoned standard 330 HP 454 7.4 ? Carbureted big block and increasing it to 450 HP that is a perfect candidate for a re-build.

How could I bincrease this 330 HP 454 - to a 450 Hp 454???

Thanks!
 
H

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: Increasing HP in a 454 big block.

How could I bincrease this 330 HP 454 - to a 450 Hp 454???
Click to expand...

Talk to the guys at US Engines and ask them about what they do to their 450hp Mercruiser 454...... (or just about any good machine shop) It will take a comp ratio increase, different (marine) cam and maybe a stoker crank and it may have to run over 5000 RPM to make that HP.

They may even be able to send you a dyno chart on that engine build. I would be leery of anyone however, that claims any HP without backing it up with a dyno.
 
D

dakine

Seaman
Joined
Sep 2, 2009
Messages
71
Re: Increasing HP in a 454 big block.

5 psi boost and premium fuel will get you there.
You won't like what happens to your fuel consumption.
 
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