More HP for 420Hp
 

Looking for upgrades that can be done to a 420Hp motor?

Re: More HP for 420Hp
 

Supercharge. That engine has all of the hard parts in it already. Add a small blower like the one on the 525 sc Merc and it'll run great.

Re: More HP for 420Hp
 

If you add a small blower without an intercooler you will spend about $3500 to gain 100 HP. If you add a centrifugal blower and a supercooler you will spend almost twice as much, but you will add almost 300 HP. I'm not kidding; I have the dyno sheets to prove it. 454 Magnum upgraded to about 450 HP with mild hydraulic roller cam, minor porting, good exhaust valves and exhaust manifolds. We made 740 HP @ 5400 RPM with 92 octane; 9 psi boost and 30 degrees total timing.

You see, that's the trouble with this forum. You ask for a water pistol and there's always somebody trying to hand you a rocket launcher. :D

Seriously though, those engines are one of the best combinations that Mercury ever put together. If you upgrade one thing you will need to upgrade a lot of other things to keep the package all at the same "level". For example, new intake, aluminum heads, roller cam, better headers, probably a new carb to go with it too. You just spent $7000, you might gain 100 HP and you would have to rev the engine hgiher to get it. That's why the small blower is the best way to go for an extra 100 HP. it's cheaper and doesn't require higher RPM.

Re: More HP for 420Hp
 

I got 2 sets of used M3 Prochargers and intercoolers for $5800. Polished!!

Re: More HP for 420Hp
 

but unfortunitly I need to find the deal too!
Not for sale are they???

Everyone screams Procharger's! I am definately interested in keeping the engine hatch stock so it would seem a sidewinder would be the way to go. Are there other sidemount marine superchargers reccommendable?

Re: More HP for 420Hp
 

Here's your deal! I need to sell to make up for the 2 blown motors I'm rebuilding(I never got a chance to boost:( ). A few spacers/bolts are missing. I also have carb boxes and carbs for sale if you are not FI. , email your # and I'll call. [email protected]
Thanks, Allen

Re: More HP for 420Hp
 

We use Vortech centrifugal superchargers in our kits, but the Supercooler works fine with Prochargers too. If that's the price for two kits, cooltoys is giving you a deal. How many hours on those blowers?

Re: More HP for 420Hp
 

formula377
You must have the 357sr1 blues. Ride is great on these resin buckets. Speed is tough to achieve without big hp. I have the same problem. 86' 357 425hp I see a screaming speed of 65gps. I still love the boat, and I'm jealous of your sweet, whited-out dash. Keep me posted on your quest for bigger power. Good Luck!!

Josh

Re: More HP for 420Hp
 

PS thanks for all the info everyone.
Thanks perfectmix.. it was a good spring project. IT was well worth the work...when I was done.

Re: More HP for 420Hp
 

50 hrs on the blowers. Yes for 2 kits. They came off a Sunseeker with triples. I blew both motors and rebuilt for Nat. asp.
Sacrilege I know, but 80 is enough in my 29'(for now)