Supercharged 3.0 Litre Mercruiser

[chargerboy]

Being a hot rod enthusiast, I wonder how easy is it to soup up my boat. The 3.0 Litre engine sounds like it's a good strong block, has anybody had any experience bolting a supercharger on? I know there's easier ways to get power out of a boat (i.e. replacing with a bigger engine) but I like to be a bit different and having a supercharged boat just sounds like a great idea.

I've thought about machining a manifold adapter plate to accept a 4 barrel carb, installing a Roots type supercharger, an Edelbrock 4 barrel marine carb on top, and replacing the double belt pulley on the crankshaft with a GM 3 belt pulley off my old parts truck to drive the supercharger.

What are everybody's thoughts on this? I've never heard of it being done before to a 3.0 Litre. Can this engine handle any amounts of boost? Is there any used chargers I should be looking for in particular off any production vehicles? Or am I just completely retarded for even thinking this is a good idea.

 

[TyeeMan]

Re: Supercharged 3.0 Litre Mercruiser

I hope your ready for a beat down, , , , ,

My first comment is would meet Coast Guard "approval".
I would imagine you would probably need to put a bigger cam in it too.
It would probably hold together, , , for a few minutes.

Aside from that might be fun to make a sleeper hot rod boat!

 

[chargerboy]

Re: Supercharged 3.0 Litre Mercruiser

Well my friend is ex coast guard officer from Yellowknife, says there shouldn't be any problems as long as I don't go over the boats horsepower limit. I have already rebuilt engine new rings, pistons, bored out .015, new valves, lifters, etc. I only want to run around 7 pounds boost.

 

[bomar76]

Re: Supercharged 3.0 Litre Mercruiser

Great idea, but the hardest part of supercharging a 3.0 is finding a Marine Knudeson Valve..

I suggest you search ebay several times a day untill you find one.

 

[chargerboy]

Re: Supercharged 3.0 Litre Mercruiser

Great idea, but the hardest part of supercharging a 3.0 is finding a Marine Knudeson Valve...

A what? If you mean a bypass valve for the pressure I wasn't planning on using one, they're not necessary. I didn't have one on my old cutlass, just an old supercharger bolted to the manifold and carb on top.

 

[45Auto]

Re: Supercharged 3.0 Litre Mercruiser

No reason it won't work if that's what you want to spend your money on. Expect it to be about as powerful as a typical V6 and no where near as reliable.

A Knudeson valve is not a bypass valve, it's generally used on supercharged boats that use raw water cooling to take the place of an intercooler and a proportioner/adiabatic valve. They usually at least triple the horsepower output, unfortunately they're extremely rare and expensive.

 

[bomar76]

Re: Supercharged 3.0 Litre Mercruiser

A Knudeson valve is not a bypass valve, it's generally used on supercharged boats that use raw water cooling to take the place of an intercooler and a proportioner/adiabatic valve. They usually at least triple the horsepower output, unfortunately they're extremely rare and expensive.

A friend said he bought one really cheap last week off Craigslist, it was Marine, but metric and the seller didn't know about the trick of drilling 17 concentric holes around the inverse flange.

Might want to seach all the Craigslist's in North America.

 

[daydreamer1252]

Re: Supercharged 3.0 Litre Mercruiser

I think Bomar's cleverness has been lost.......a Knudeson valve is one of the very under used parts on a mechanical device, it is usually connected to the Johnson rod. They both came into being as inside jokes in the auto industry as the parts you "sell" an unsuspecting motorist when trying to pump up the bill. :redface: There were probably some sold but not sourced or installed as they don't exist. Bomar, I got it, but sometimes Jay Leno doesn't get the laugh that was expected either...

 

[bomar76]

Re: Supercharged 3.0 Litre Mercruiser

The OP spending time looking for a Marine Knudsen Valve would be more productive than any attempt to produce a blown 3.0.

 

[frank246]

Re: Supercharged 3.0 Litre Mercruiser

Ok it aint no supercharger....
In the `80s there was a turbo kit from M&W for the 3.0L Engine.
There is one on ebay $775 including engine and boat.

 

[Howard Sterndrive]

Re: Supercharged 3.0 Litre Mercruiser

I got a heavy kicker bracket here rated for 40HP.
One of these on each side of the transom with a pair of the lightweight 25HP johnnyrudes from the 70's

probably half the price of any blower.

could you imagine the launch!

 

[bomar76]

Re: Supercharged 3.0 Litre Mercruiser

Now I am waiting for the Nitrous Oxide guys to come out of the woodwork....

 

[Bt Doctur]

Re: Supercharged 3.0 Litre Mercruiser

Why not use Dyelythium

 

[bomar76]

Re: Supercharged 3.0 Litre Mercruiser

Or just cover the boat with JEGS stickers.
Each one is worth up to 10-15 HP

 

[Bt Doctur]

Re: Supercharged 3.0 Litre Mercruiser

Your wrong, there at least 25hp, STP and Rislone are 15 each.
And i get the feeling Don`s going to close this soon.

 

[bomar76]

Re: Supercharged 3.0 Litre Mercruiser

Which it what it deserves.

 

[ezmobee]

Re: Supercharged 3.0 Litre Mercruiser

There is no need for the animosity in this thread. Anyone is free to explain why this idea is impractical or impossible without the attitudes.

 

[45Auto]

Re: Supercharged 3.0 Litre Mercruiser

It's not impractical or impossible, just like building square wheels for your car isn't impractical or impossible. It's easily doable, the question is: "Why?". Everyone just has to make the cost/benefit decision for themself.

I think most people that have been on this board for a while have pretty much come to the conclusion that if you have to explain it, you're wasting your time. Plenty of threads about it if you do a simple search.

 

[Bondo]

Re: Supercharged 3.0 Litre Mercruiser

I think most people that have been on this board for a while have pretty much come to the conclusion that if you have to explain it, you're wasting your time. Plenty of threads about it if you do a simple search.

Ayuh,.... Especially Us digitally impaired....
Now,... Marine Knudsen Valves,... I can peck away All night talkin' about those danm things,....

I have already rebuilt engine

Are your Pistons up to the task of being Blown,..??

 

[wca_tim]

Re: Supercharged 3.0 Litre Mercruiser

Some things are worth doing simply to be different... this probably isnt one of them. imho