SB

iTrader: (1)

I too played with some 525SC's. Intercoolers, pulley's and etc. Gains where decent. One of the biggest gains was setting the timing correctly. Shop that tuned it before set total timing at 3000rpm. Unfortunately they messed up since the module that comes with these engines actually advances to near 4200rpm. I set total timing to factory specs of 35 degrees but checked at 4500rpm to make sure wasn't advancing further.

Factory hyd flat tappet cam is relatively mild but lives a long time. I def think there could be 30-50hp here if you are willing to run rpm up another handful of rpm - with the new hyd roller cam of course.

Also, according to Merc the stock 525SC has a very low 7.5:1 compression ratio. If looking into heads, I'd get them with smaller comb chambers to up the compression. With the intercooler and aluminum heads I wouldn't have much of an issue with up to 9:1 compression. You can get most aftmkt heads set up with somewhere between 110-112cc com chambers. Stock has 119cc or so. Every half a point compression should really help.

Lastly, if you are taking things apart, you may want to get the blower checked out to make sure it is still sealing well.

SB

iTrader: (1)

He's a very good friend to have !!! He knows his schit. Between him and RMBuilder, they will help you get the job done if you let them help you.

Back4More

Been there done that,
6psi is all that thing can handle...it will rattle itself to death in no time after that.
I also agree with SB on the proper ignition timing setting.
An Isky hyd roller cam #396275/284 ground on 114 and a good 8-71@8psi with 750's would be better than innercooling the 177 at 8psi

awsomethunder

i heard a guy over on speedwake picked up 200-300 rpm by sending his 177 blower to darren mayer performance.i guess he does some mods to the case.

Rambunctious

have you looked into efficiency of the boat?

remember, those 3 or 4 small blades are the only connection of that horsepower to the water.

I would look into labb finishing the most appropriate props for your boat to gain efficiency as well as dialling the engine into it's exact rpm
also drive height raised can have a a big effect

this will not decrese relaibility and will also gain more MPH per $$. at least optimize that first, then look into additional HP mods
you may find 3-4 mph for $500

Ramb

Griff

BTW, if you are going to run the smaller pulley's, change the SC lube every 25hrs. Mine is still going strong with 500+hrs by now and was never rebuilt.

scottsumrall

Griff, how many hours can you get out of the 525sc if 98% of the time it was run at 3k rpm? THANKS Scott

Griff

A whole bunch

Mine was a 1996 and had 475 hrs on it when I sold the boat to Dude Sweet in April. I'm sure it has well over 500 now. Most of my time was spent at 4000rpms or below.
I rebuilt the top end around 350hrs and added the roller cam, new ex valves and springs. The only reason the top needed to come apart was because of a hairline crack in the Gil exhaust that caused some pitting on an exhaust valve stem.

scottsumrall

Griff, 1000 hours if ran in freshwater? thanks scott

scottsumrall

Griff, also what is the weak link on the 525sc?