I"am on my second pair of 525sc. I have freshened all four of them at one time or another . If tuned right they run great for a mild blower engine. once you own a blower boat it is hard to change . Take a ride in a large non blower boat and it takes forever to get on plane. Yea,yea,yea. HAPPY NEW YEAR.

How many hours inbetween freshining them up? What were the oil change intervals? I use red line in my other hp motors.

I did a top end rebuild on my 525SC at 335 hrs. Only did it because the Gil exhaust had a leak and pitted 2 exhaust valves. Everything inside looked good except the water ports on the intake. They were eaten away pretty bad and would not have made it much longer without filling the engine with water. The boat had some salt usage before I bought it.
I run Mobil 1 synthetic as did the prior owner and chnage it about 30 hrs. It uses about a quart every 20hrs.

Good to hear Griff, thanks, seems the general word is they last if ya take care of them. that makes iy easier to make a decision. Both boats have right around 200 hrs on them. one in fresh other in the keys, and well taken care of.

Whats the supercharger for? 525hp out of a 454 is easy unblown and MILD....I've just never understood why Merc built this motor. But I agree it should be absolutly bulletproof.

The 525sc is a 454.

I second that!

I'd lean toward the fresh water boat. My boat was well taken care of and flushed after each use. The problem on the intakes is the small gap around the water ports that the gasket doesn't quite cover. If the gasket went right up to the edge of the ports they would be fine. It looked like salt collected in the gap and ate away the aluminum. Aluminum and salt don't go wel together.

Here's a pic of my intake http://www.offshoreonly.com/forums/s...t=525sc+intake

I see what you mean. aside from that, youve had good reliablitly with them? I like the fact that they are low compressiona nd seemingly bullet proof. I know the bilge gremlins always have a way of showing up. and I expect that and can deal with it. I know that most blower motors can be finicky too, i have one in my pickup truck, and a 383 stoker sitting on a stand. the salt water one was only run to the bahamas and never sat in water, was always lift kept and cleaned.

I love the reliability of my 525SC. Turn Key!