PatriYacht

That engine is a good candidate for supercharging. It has a lot of good parts and 8.8 to 1 compression. 600 is possible with a 250 blower and a single 1050 carb. I would freshen the engine and add good head gaskets and roller rockers.

cdscarab

I run a Merc 420 with a B&M 174 blower, single 800 Holley, Gill exhaust, 4.5# boost, and routinely make ~535hp. So getting 600hp from your mags shouldn't be that difficult, provided your long blocks don't have too much time on them. Over 300hrs, probably should have a valve job at the very least. I agree with KAAMA, a B&M 250, a good Nickerson blower carb, 6# of boost, and you should be close. If you do a valve job, then have someone like JimV do the heads and have him install bigger, 2.25" severe duty intakes, and inconel exhaust. It will make it easier to make power and live longer.
Do it right the first time, or don't go. Otherwise you'll get to do it twice for half the fun and four times the money.

SeaRay Jim

Someone else may pipe in with the details, but there is a Crownline 225 bowrider with a Whippled 454 MAG that dyno'd at just under 800HP. However, I don't think the inside's are stock, neither are the heads.

cooltoys61

I have 2 sets of Procharger M3s(12 rib) with 504 intercooler,polished 50hrs . Its for 454
MPI but I bought the carb boxes if you want to go that route. Some brackets for alt and steering pump will need to be bought or made but they are simple, I made mine but used them on my NA motor. $5300 for MPI setup,$6300 with carb boxes included. Go to procharger.com to see typical results on diff boats. I thought I had these sold last time there was a post like this. I'm tempted to keep for a future boat but got mine to 80 without and don't really need more on my current boat.

tomcat

If you only want 600 HP then a B&M 250 is enough blower. I would use an superchiller underneath it just for safety reasons (less chance of detonation). There is used equpiment out there but you can also buy new from the Blower Shop.

If you think there is a chance that 600 HP will not satisfy then go to a centrifugal blower system. A used procharger M-1 system will deliver 650 HP @ 7 psi on your engines. cooltoys M-3 will do better than that. Our system will deliver 740 HP @ 9 psi. We can get away with the extra boost because the supercooler works so well.

These numbers are all for stock 454 Mag. Reliability comes from upgrades to fuel system, cooling system, oil system, exhaust valve material etc. Listen to these guys about doing it right the first time. Nickerson carbs work well. Good luck!

Biggus: wicked looking oil system, what issue is that article in? Say hi to Paul for me. New system dyno test at Tyler Crockett's before Christmas.

SkiDoc

iTrader: (4)

Thanks everyone for the replies, the motors are mags they run strong, tested compression on just one of the motors and was happy with the results. The only thing that I am concerned about the centrifuagals is the space available to mount the compressor on the port motor, they may not fit. But if I go with a roots then need new engine hatch. With the roots, how should I expect idle to be? I know it would be good with the centrifugal. Tomcat, can you tell me more about your system, are you selling a complete kit ...or just a better intercooler system. Cooltoys, is the setup the SC or not you are close as I am in Bowling Green. CDScarab I'll heed the advice of doing it right. Sounds like I really need headwork to do it right with 328 hours. If I need to pull the heads, how much would it cost for aluminum heads, would it be worth it? If I did the heads, it would make sense to go the extra for cam and hydraulic roller lifters? Lastly, about how much should I expect to pay for Nickerson's carbs?
Thanks for the replies fellow adrenaline junkies

cdscarab

Eric, my 420 has more cam than your mags and it idles better than my 330 did, probably the best running motor I've ever owned. Unless you are thinking more HP, then your stock cams would be the way to go, good idle, already broken in, and paid for. Roller cams are great except for the cost to buy, the cost to replace lifters every 2-400 hrs.*, and the cost to repair/replace a motor when a lifter dies. *If you run them HARD, they will die, just depends on how much you like doing engine work verses driving your boat.
The centrifugal blower set ups are cool, they fit under the hatch. But myself, I like the clean appearence the roots blowers have, and yes, they'll probably interfere with the hatch. But for me theres nothing quite like the looks you get when you raise the hatch to see that shiny blower sitting on top of the motor.
For 600hp you don't need aluminum heads, they'd be nice, and they'd make 600hp real easy on cheaper gas, but their what,~ $2200 a set. Intercoolers would be a better choice. Also, your bravos will only stand so much grief, so be sure to get some drive showers on them.
I haven't priced Nickerson carbs lately, but you can call him for prices. Also, I've read that their having great success with the new Sea Demon carbs. One of their tech guys is usually on this site. Chuck

cooltoys61

Yes,M3 superchargers included. So you are about 90 min away. Small world.Do you ever go to KY lake?

mcollinstn

a low boost blower motor will idle better than the same motor minus the blower, as long as the timing advance is changed to something the blower motor likes.

vette131

with 320 hrs you should freshen the motors before supercharging. be sure to change the exhaust valves to inconel.