98 525 S.C. Question
 

I have a pair of merc 525 S.C.'s In our 99 Daytona. I have a unusual set up. Our boat use to have much bigger power in it, so it has #5 speedmaster drives and I know this is not a great combo, but it is not practical to swap drives. The motors I have run great and have not caused any problems at all. My current set up is merc 525 S.C.'s, #5 speedmaster drives with a 1.1 gear ratio ( that is no type-o I have checked over and over again) I am running a 23 pitch 4 blade cleaver prop. All and all I have no complaints about it. The boat planes very easy no matter the load. I am able to cruise 50 m.p.h. at 2700 r.p.m. with 4 adults. The Problem I have is with slip. It is about 20% even with just me in it. I have checked into getting the drives re ratioed but the expense is pretty hard to take for the boat to not go faster, so I am wanting to add a little h.p. to the motors. I have checked into chillers, cam kits, and ingnition systems. Teague told me I can get 50 horse from chillers and 35 from a roller cam. So my question is if I do chillers, cam, and ignition can I get a additional hundred horse? If so will that help my situation. I think if I could run a 25 pitch prop I may be better off. Any advice would be appreciated. I just dont want to get sold parts buy a salesman that wont do me that much good.

The chiller and cam should bump you up to the 600hp range. I did a 731 roller cam and gained about 100-150rpms and my boost was already bumped up. I estimated that I was around 550-560hp. The chiller should be good for another 30-40hp. I didn't have the hatch clearance and didn't want a scoop, so I never did it. The ignition is fine and a change won't give you more HP.

That is about all you're gonna get out of a 525SC with the stock supercharger.

I think you should try to work on your slip issue with some different props if possible. Or add the HP first and then try new props.

what is your max rpm with the cleavers?

I can get about 5200 r.p.m. when I am in the boat alone. I dont really try to run it hard loaded since I dont want to lug the engines.

You can get almost 50hp by just swapping for smaller blower pulleys and running around 7 psi boost. You might have to take some timing out and use higher octane fuel though.
As for the slip, what props are you runninf and have you tried changing the prop rotation?
Gary

griff has the best idea, roller cam and chillers, good for about 200 rpm, that would get you up in the 5400 area, still a little low, but better than where you are at now, but that don't address the prop issue. that will not be enough gain to bump to a 25P. get a hold of b blades or throttle up for prop recomendations.

The chiller upgrade from Teague will include a smaller pulley. You can run 8# of boost with no issues, with or without the chiller. I ran almost 8# w/o a chiller for several hundred hours. without the chiller the added boost will be good for maybe 30hp.

run the smaller pulley use 93 octane and add a water/alcohol injection kit, also try some different props to get the slip numbers down

I am tempted to try the smaller pulley with out the chiller, I always run 93 octane, but dont know what the water injector is that was mentioned. I did find a pair of 575 sci's for sale tonight. I may up the pony's that way. I do kind of miss fuel injection. I am currently running a 23 pitch 4 blade prop, and I can plane at two thousand rpm at less than half throttle. I am going to go out this weekend and get all my numbers on what is is doing at what rpm and then go from there. I think I can run a 25 or 27 pitch prop. I am also going to verify my drive ratio. Thanks to those that have replied...

My 525SC had the smaller pulley with no chiller on it from the day I got it with 200hrs. It made just under 8# of boost. The prior owner didn't realize it and he only had it for about a year and put a 100hrs of the first 200hrs on it. I ran it like that until I did top end refresh at 350hrs. I installed the bigger cam and only then jetted the carb up a little. Before that it had the stock #98 jets all around. You don't need water or alcohol injection for this set up. Just change the blower lube every 50hours since its spinning faster. I ran 92 octane fuel most of the time and 93 when I was on the lake filling up.

Buying all new engine for 50hp is a waste IMO. You can spend 3k per engine and have the same or more reliable hp with a roller cam, chiller and smaller pulley.

With a 1.1 ratio, you're spinning the props faster than you would with a 1.5. Normally, in combination with a lower pitch prop,that woud cause less prop slip. That leads me to think that different props would be better. A larger diameter might do it. Or try lowering the drives with spacers. Your present setup may have been good for very high speed that you are now unable to hit with your 525 hp engines. You have to find a set up that works for the way your boat is now.

Griff is right
 

I have a 525sc and just did the full MSD rig and 7.5 pulley. I got about 30 hp, i would say. That motor does NOT like more than about 5200-5250 rpm. Anything more than that, and you are just wasting gas. And with the 1050 on there, its a LOT of gas. I believe the cam, pulley, ignition, and exhaust will max these motors out. That number is around 575 or 580, i would think. In fact, the factory rev limiter is at 5400, so you CANT get over that.

Also, the chiller is a double edge sword, because it's restrictive it will actually REDUCE boost (teague said so), so that's why it comes with the pulley--to raise it back up to 5.5. So, I don't think the chiller is worth cuttin holes in the deck. Just take out the thermostat (again, teague says so), do the MSD, and run 92 with a tube of octane boost...It will be plenty ballsy with no knocking, mine runs great.

If you do order the pulley, BE SURE to get the 1/2 inch offset- and It's 100 bucks from Teague. It's worth it, even just for the sound..One thing- with the smaller pulley, you have to re-prop up about 1 inch or so, to slow the blower down, cuz it sounds like it's gonna go supersonic.. lol

Personally, I think you need to go to some 5 blades?