Griff

Then that is a 365hp engine. Its a decent candiate for supercharging, but that depends on the hours on it. I would not SC it without at least a top end refresh and better head gaskets.

A good cam, intake, carb and exhaust combo will get you about 450-475hp.

Either scenario, you are looking at 5k to get the power to get to 70.

Your best banfg for the buck is to get your prop labbed by BBlades. For $400 or so you can gain 2mph or more.

Budman II

iTrader: (1)

Upgrade the exhaust valves to inconel or Ferrea super alloy while the heads are off if you are planning to run the supercharger. Good insurance. I am 99.7% sure that the black engines just have standard stainless exhaust valves, and that Merc only put the inconel ones in the blue engines.

kneeslider74

I have a gen 4 HO for 4k efi making 500Hp. Add a Once over by Bblades and you are there.
http://www.youtube.com/watch?v=L__3xcJfbjs

REDS32

I would put blower pistons and high temp rings to the list just keep growing until you spend more than the cost of switching motors.

FogduckerIII

iTrader: (-1)

The "cost" of building or "switching" motors to somebody elses "used" motor is subjective........some people want to build their own instead of buying a complete used motor that someone else has built, history unknown, nothing wrong with that......but who knows what they are buying with a "used" motor.......yes a new motor can cost a lot although as long as it is done correctly and maintained, a new motor should last a while..........IMHO....

FIXX

iTrader: (2)

exactly!! thats why im banging your x old ladymany times,she was well used and abused

kneeslider74

You know as well as I do that it does not matter a bit new or used. They all can have issues, yes even a new rebuilt one. I think what you are trying to convey is warranty is worth the $. I have been down both roads and have had decent luck with the used if you can sort out the junk. Check the video does that sound like a pile? These motors push a 10k lb boat to 90 mph no problem. If the person wanted to spend or could spend 10k I would advise him to avisit a reputable builder.
IMHO!

Bodi

I would build a 525SC clone. Pull the heads and make sure everything up top looks OK. Replace your intake and exhaust valves and full roller rockers. Put on a 177 Weiand with an 850 Holley. Run 4 lbs of boost and run 2 temp range cooler spark plugs. Install a 120' thermastat. Add a higher flow fuel pump and monitor fuel pressure and boost as a minimum. Then lab finish whatever prop you end up running. I think this will get you close???

In my opinion this is a good place to start. Your 454 Mag has good components. The 8.8 compression is a bit high. The weak link are the intake and exhaust valves and the stock exhaust is only good for 450 PSHP at best.

I know it takes a lot of HP to gain a so