Excalibur502mag

Arcticfriends,
This has really sparked my interest, as I am going to take out my 502 mag and rebuild it. When I look at the picture on your profile I am assuming it is a 502 mag efi with a turbo of some kind. Do you have any advice for me? Sorry to interupt guys. I am somewhat on the same page as I am ready to take the engine all the way down and build it right, due to 20% low compression. Is the 502 mag efi engine a good one to build with a supercharger and maybe expect 600 hp?

articfriends

Excaliber,thats a procharger m-3. Procharger claims 685 hp w/stock exhaust at 7-8 psi boost. Your 502 is a excellent candidate for supercharging,just read a few of the threads on here,Inconel valves with a wide contact margin on heads are important for longevity and ditch the low tension metric ring pistons while rebuilding your motor,they cause more problems with oil control on 502's than anything else. The whipple charger looks like a cleaner install (less screwin around),i'm not partial to procharger but it doe's work good (once you get the bugs worked out). If your block has no real ridge in it when you rebuild it,j/e makes a .004 over piston with std rings that drops in after honing with a torque plate. Keep in mind your supporting equipment (steering,outdrive etc) will have to be upgraded once you get the thing making good power ,a fast boats no fun if it's sitting around with a blown up outdrive or is out of control with stock steering!!

articfriends

Here is a better pic.

cooltoys61

I have a slightly used(50hr) pair of polished M3's, polished intercoolers(504?the big one) with or without the carb box or EFI attachment and a pair of semi prepped 750 DP Holleys. I am thinking about selling because I have 2 much on my plate as is and may be moving soon. It has polished mounts and some of the spacers /brackets I have fabbed.Also the crank pulleys. They are the 5 psi but can be raised later with a change to the pulley on the blower. Supposed to add 50% with no mods. Go to procharger.com,,these reatil for 6K each when polished.I have $6,800 in all of this and just want to break even.My email is [email protected]. Thanks,Allen

tomas_wallin

Thanks for all the answers! I've got a 454 330hp. I would like to spend as little as possible (boring I know...), but it would be fun to see what you can do without getting too expensive.

If I go with the 174-blower, what else do I need to rebuild/change with then engine? And what costs are we talking about in that case?


Thanks,

Tomas

bpine

Tomas, here is a great reference guide that hits it right on the money! From B&M before Holley bought them! I also have the Teague prepared Holley out in the shop on a shelf dialed for that motor, I believe a quick going through and you would be on your way! I would let it go cheep! I believe you can get away with this combination in a light boat and if the driver always kept in the back of his mind "" I DON'T HAVE INCONEL VALVES!"" The key is to keep the boost down around 4 pounds! If you can’t read the chart let me know and I can e-mail it to you! Its great info! It specifically addresses yours and all Merc motors! And you are right that the 174 is not a great SC to put on the 502! This at the time did what I wanted! I wanted the looks of a root! The additional power, I figured I received the best bang for my buck! I am sure there are more choices out there, so what fits your needs the best, is the right answer for you!

Bryan

bpine

Can you read me now!

tomas_wallin

Thanks alot bpine! But the pic was a bit hard to read... I would be very thankful if you could email it to me at: [email protected]


Thanks

tomas_wallin

What kind of amounts ($) are we talking about for the stuff I need? I assume that I have to change the carb and perhaps the fuel-pump?! Please correct me if I'm wrong! Is there anything else?

Thanks again!

Gary Anderson

Lets see, minimally:
177 supercharger $2000
Carb $600
V6 ignition module $300
Bigger oil cooler $250

You could add a cam, valves, valve springs too.
Exhaust probably wont make much difference at 450hp.
Gary