Help!! More HP needed

[blairjbyrd]

I have a 454 mercruiser carb and it is rated at 300hp. Im looking to add more HP.

Any ideas?
I would like to be able to do it myself so nothing to major.

thanks in advance

 

[Philster]

Re: Help!! More HP needed

You have a carbed 454 Merc and want to produce more horsepower?

Get a bigger carb. But... what year is the engine? What is the current exhaust setup?

What CFM carb are you running now?

I've seen carbs that looked like five gallon containers sitting on 454's... and I swear, I could hear the fuel sloshing around in them... and smell it, too. There be some BIG carbs out there.

What was that about not wanting to spend a lot of money? How does 1.5 MPG sound to your wallet?!

 

[HT32BSX115]

Re: Help!! More HP needed

I have a 454 mercruiser carb and it is rated at 300hp. Im looking to add more HP.

Any ideas?
I would like to be able to do it myself so nothing to major.

thanks in advance

Let's see.....


You have a 241 Lib, it's got a 454 + ALPHA (or Bravo I) drive and it's a veritable "DOG" outta the hole!!!! RIGHT?


So was my 87 211 Lib when I had the 340 (crankshaft)hp OMC King Cobra installed. My brother bought my boat new(in 1987) and it was a DOG out of the hole then too! (not too bad at WOT though......about 60mph once it finally got going......) It was just AWFUL to ski behind because it would drag you for so long while it was getting up on a "plane"..........



I removed the Wonderful High Technology OMC 460 King Cobra (

) a few years ago and installed a 1997 carbed 454 + Bravo III drive that came out of a wind-damaged 1998 Bilgeliner 24' cuddy.

The difference was nothing short of SPECTACULAR! (top speed was not much different...... 460 King Kobra 5000RPM=60 radar mph, 454 Bravo III 4600 RPM=57 GPS MPH......rev-lmited to 4700 RPM)

The difference was in the hole-shot..... With the Bravo III it just ROCKETS out of the hole with slightly LESS HP. (Merc 454 : 330 crankshaft HP)


Changing your carb, intake manifold, etc will not do a thing for your top speed and will absolutely NOT do anything for your dismal hole-shot.


There's only one way to increase your top speed. rebuild the engine and increase CU-IN, via boring & stroking and increase compression. (then running premium gas etc)

Fixing your hole-shot will require a Bravo III or Volvo Penta Duo-Prop drive.($$$)


I am now looking for a 502 to replace the 454. I want to build the 502 with aluminum heads, manifolds and risers to take a few hundred pounds off the back of the boat....

Then remove my current 26p props and install 30p props. I think I'll be able to safely run the 502 at a about 5000 RPM.

5000 RPM, 1.81:1 drive and 30p props should give me a conservative WOT @ 70mph according to the Prop-slip calculator and I'll still have my "Rocket Hole-Shot".......



Cheers,


Rick

 

[wca_tim]

Re: Help!! More HP needed

If you're running through hub exhaust, you can make a huge difference in hole shot by running a vented prop...

 

[26aftcab454]

Re: Help!! More HP needed

everyone would like to run faster but I have no complaint on hole shot- and my boat is heavy W/ hot water heater -genset- and alot of other junk.