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Supercharging mercruiser 57 v8

R

rodneyb

New member
i am interested to talk with a

i am interested to talk with anyone who has installed a procharger series type supercharger
on their boat and would appreciate any input good or bad about this issue.
 
"Ayuh,.......
Gotta know Mor

"Ayuh,.......
Gotta know More about your boat 1st,.......

Alpha or Bravo drive,..??..
Carbed or EFI induction,..??
Which EFI if applicable,..??...
How many Hours on the Motor,..??...
And,... Lastly,......
What Exactly are Your Expectations,..??...."
 
"my boat is a 27 foot chaparel

"my boat is a 27 foot chaparell alpha 1 drive, 5.7
with roller cam, rochester carb. crate motor installed with about 100 hours on it. my expectations are to get cruise speed of boat into
mid 30 mph range, boat currently cruises at 26 mph 3400 rpm with a 15 x 17 inch prop, have tried
larger prope but engine doesnt have torque to get above 3000 rpm with them, i am hoping that supercharging engine would build enough torque to get to desired speed while not working the engine into the ground. i often cruise the boat on trips over 80 miles and would like to cut down my travel time and was hoping this would be the answer rather than dropping a big block into it. thank you for your imput: rodney"
 
"rodney;
You can get various

"rodney;
You can get various blowers that will get you 40-60 % power increases depending on what claims you want to believe.
Trouble is you will be overpowering your Alpha drive and it wont last. Merc rates the Alpha at 300 hp, so you would need to switch to a Bravo, which is good for 550 hp.
This is a big change including the transom assembly, gimbal ring, drive leg, etc. The inner transom plate is the same, so the mounting location of the motor will be the same.
You can check on Merc prices for the Bravo setup, but new you are looking at several thou. And that does not get you the blower yet.

Rod"
 
"thanks rod, i guess shy of sp

"thanks rod, i guess shy of spending 10 grand to get to my destinations quicker i should just leave earlier. thank you for the valuable info it appears i may just repower to a big block with the bravo drive system but that will have to wait til next year, thank you:rodney"
 
"Ayuh,......

It's going

"Ayuh,......

It's going to take a BBC,+ a Bravo for what you Want......."
 
well ive have built alot of ch

well ive have built alot of chevy 350's and you can get the horse power up alot but i see the problem with the outdrive not handling the power. The other problem you will run into is you can increase the heck out of the horse power but your gas milage will disappear.
 
"Adding a supercharger will ov

"Adding a supercharger will over power the alpha drive. Your engine parts are not designed for a 50% power increase. Your alpa will tear out its guts. The engine will blow, how soon depends on how you use it and it can blow a hole in the bottom. Best investment is PFD's and location beacon."
 
"thanks guys for all your inpu

"thanks guys for all your input, i understand increasing horsepowe wil increase fuel consumption but in the long run saving time will save overall fuelcost. plus arriving earlier has its rewards. ejbreeze has an informative link and i think you should take a look at it. i may just be getting a manifold, ignition, carb and exhaust manifolds to get an additional 40 or 50 hp and i will put the alpha 1 to the test, fortunatly i do have a backup drive and seatow."
 
put a drive shower on it if yo

put a drive shower on it if you are going to run it hard and use synthetic OD oil.
 
"if you are staying with stock

"if you are staying with stock cam and heads use a dual plane intake and dont over carb it let the engine breath. One of the most common mistakes ive seen on car enignes is over carbing them. Here is the site i use to buy engine parts from and they have marine use parts. http://www.summitracing.com/"
 
"Rodney
If it was me I think

"Rodney
If it was me I think I would be concentrating on the items you have already mentioned, the carb the cam and the prop and maybe some work on the heads and manifold before I started bolting on blowers and reducing the overall reliability of the package for just a few MPH gain.
However if money is no object then build an engine from scratch, consulting a recognised proffesional engine builder (not a backyarder)who can build you an engine that is designed to work well with a blower to give you the results you want.
Just bolting things on to an engine to boost performance is not what I would call best practise, particularly if you are intending to run your engine for prolonged periods of time at, or close to, WOT.
Engine building is a bit of a science, find a good scientist and they will give you the answers you want, it may cost you, but in the long run it has the potential to save you heaps of bucks and possibly a long tow back to shore.

Just my Opinion.

Cheers
Peter C"
 
I agree with peter ill do my o

I agree with peter ill do my own engines and stuff but wouldnt do someone elses. If i mess up i have myself to blame. You can also buy create motors built to your wants.
 
"Hey, a 26 mph cruise speed at

"Hey, a 26 mph cruise speed at that rpm is pretty nice! I know lots of guys who'd love their boats to be that "slow".

Jeff"
 
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