Need more HP. Anyone ever Super Charge a straight 6?

[John3]

I'm considering adding a Supercharger to my 160 HP, 250 Cubic Inch, straight 6, Mercruiser Engine.
Have had my 23 ft Cabin Cruiser for 30+ years. It never did have a lot of power and over the years I guess I've added stuff which increased the weight it has to carry.
Pretty soon I'll probably need to rebuild the engine and I'd like to get more HP without having it rattle & shake like a hot rod.
Anyone have any experience with a supercharger or??? to get an extra 20 or so HP?

 

[CheapboatKev]

Re: Need more HP. Anyone ever Super Charge a straight 6?

I honestly dont think that a supercharger is worth the $$$..Prochargers are being used on big block racing marine motors, which that straight 6 is not.
Rebuild her, get another 30 years of enjoyment..

 

[Lyle29464]

Re: Need more HP. Anyone ever Super Charge a straight 6?

Lets see. you would need custom made pistons That six would not handle stock ones.
A custom made cam
A steel mesh net to avoid flying parts.
Increase tow boat coverage.

That six does great at 4200 thats about it.

 

[Bondo]

Re: Need more HP. Anyone ever Super Charge a straight 6?

I'm considering adding a Supercharger to my 160 HP, 250 Cubic Inch, straight 6, Mercruiser Engine.
Have had my 23 ft Cabin Cruiser for 30+ years. It never did have a lot of power and over the years I guess I've added stuff which increased the weight it has to carry.
Pretty soon I'll probably need to rebuild the engine and I'd like to get more HP without having it rattle & shake like a hot rod.
Anyone have any experience with a supercharger or??? to get an extra 20 or so HP?

Ayuh,... Upgrade to a V6 for another 40hp or so...
Upgrade to a V8 for about Double the Hp...

 

[mkast]

Re: Need more HP. Anyone ever Super Charge a straight 6?

to get an extra 20 or so HP?

That might get 2 MPH more, for how much money?

 

[John3]

Re: Need more HP. Anyone ever Super Charge a straight 6?

Was just asking if anone had actually tried it.
Re, over reving the engine. I think changing to a higher pitch prop might prevent that. I don't think it would be so much running at higher engine/boat speed, rather getting up on plane faster and cruising at about the same boat speed & lower RPM (Seems like more HP & a higher pitch prop should do that).
Anyway, if someone has tried it I would like to know how it worked. Perhaps that's what Mercruisers reply is about?

 

[Tail_Gunner]

Re: Need more HP. Anyone ever Super Charge a straight 6?

Tons have supercharged marine motors, No big deal at all.....But you better have pretty deep lose change laying around..say about 6-10000. In many ways marine motors and car motors are very much the same frankly they are... with tiny little exceptions. Think of it this way....would you take that inline 6 supercharge it just the way it sets...put it in your car....hook up 3500lbs and run down the highway at 4000 rpm in first gear for hours at end? I think you know the answer....But it sounds like fun...

Ok not to many mechs will do marine motors they dont have the backround and those that do there is a price...and they say horses are the sport of kings.....supercharging a motor was not around back then...

 

[achris]

Re: Need more HP. Anyone ever Super Charge a straight 6?

Even if you were to get 40 hp more, that would only pan out to a speed increase of around 4 mph. Is it worth it? If you really do need all that much more power, replace engine with big block. Has supercharging been tried? Probably, but you don't hear about it from the people who've done it because it was an exercise in futility, otherwise they'd be screaming from the rooftops about it.....

 

[kilowatts]

Re: Need more HP. Anyone ever Super Charge a straight 6?

Hi Guys:

My guess is that someone must have tried it somewhere but they probably don't talk about it much! I guess it would be a giant flop as the inline 6 will only do a limited amount of things no matter what you do to it. If you look at the inline six auto sites on the web you'll see that in all the world there seem to be very few companies that "soup up" the venerable motor compared to thousands for the V8 Chevy. I think that says something quite loudly,eh? Add to that the challenges with a marine application and there are even less advocates. I tend to agree with the previous post that about $10,000 would be about right and then the upgrade of the outdrive to handle the increased HP. Good luck with the project.

kilowatts

 

[gilby246]

Re: Need more HP. Anyone ever Super Charge a straight 6?

Havent done it in a (gas powered) boat yet but a buddy and I are turbo charging a straight six in a chevy omega. Im fabing everything myself and do it everyday at work... but for diesel applications (Im a welder/fabricator in the marine industry.. commercial side) It can be done, just not easy