ok guys help me make up my mind.have a stock 454 mag carb in my 25 active thunder.want to supercharge it,which blower should i use,roots or centrifical? i like the procharger for the intercooler and the power comes in at upper rpm so less stress on drivetrain but i also like the blower shop 250.should i make changes to motor?what upgrades should be done to the fuel system?any suggestions from guys that have done this would help.had bad luck with a 350 with 144 b&m so i need a setup that will work and last.this motor has 250 hrs on it.should i freshen it 1st?

not to be a turd but,,,,,,keep it stock and build a motor to handle a blower.......then when your stock one needs freshining you have a nice set up already waiting.......

Why not just clone the old Merc 525 SC's ? They were based on the 454 4 bolt block that you have, used the same crank and rods, low compression pistons, a mild Crane hyd flat tappet cam w/ the Gold rockers. Same GM heads upgraded with the better 225/188 valves and springs to match the cam. Nothing real exotic, just good quality basic materials. Used a Weiand 177 blower with a Holley 1050 Dominator at 5 lbs of boost for 525 hp, add a chiller and change the pulley and you are at 600 hp (+ - ). You can find all the specs in the Merc HP service manual at any Merc service dealer. They were marketed by Merc with the standard Bravo drive.

I ran a pair of these with the chillers and 7+ lbs boost for over 6 years with no problems at all, oil and filters every 25 hrs and plugs at the begining of each season, they were great motors. There was an article in Hot Rod mag years ago that stated these were one of the most reliable/sucessfull blower motors ever marketed.

I have a 454 bored .030 over with forged JE Pistons, Forged Crank, Eagle Rods, Dart Heads (freshened), and Crane Gold Roller Rockers for sale.

The engine is having new bearings installed, being honed and new rings installed.

Your choice of cam.

short block is fine...run a B&M 250 or 420 or 6-71 at low boost (4-5#) and it will live a very long time....with the larger blowers they are turning slow enough that you won't even need to worry about a chiller....

There are lots of used 525SC blower setup including carb and associated parts out there.
You could bolt those goodies on a gain 100HP easy.
Of course, if you rebuild the engine with a bigger cam and head mods, she'll make more power...

A 6:71 blower works great on that motor.

Quad Rotor Whipple

Whats wrong AT you daydreaming at work again????

need some more hp to get past you daga