525 SC hop up's
 

A freind of mine is rebuilding some 525's that he got and is wondering if there is anything he can do to get some more power out of them.
He can't afford intercoolers at this time (unless someone has some used ones) but he plans on running 6 pounds of boost and is considering some mild port work and maybe a custom ground cam.
his goal is to make 575hp.
Any suggestions ?

7 psi pulley will give you 575hp. Advancing the total timing to 30 degrees should give a few more hp. Just be sure to use over 92 octane gas.
Gary

I guess I should have mentioned that he has to run on 91-92 octane. He keeps the boat on a hoist at his house so he has to get gas on the lake.

If you go to the smaller pully, it would be wise to add a intercooler.

Octane booster?
Whether it's a pulley, cam change, head work, advanced timing, or increased CR, you're going to have increased cylinder pressure to generate more hp. That means you'll need higher octane to avoid detonation. An intercooler or aluminum heads might get you around this.
I would try the 7psi pulley with 26 degrees total timing. Use a crossover and run the engine a little cooler. Make a few runs and check the plugs. That's what I did on mine.
Gary

Do you guys think there is any advantages in having a custom cam ground ?
I know in drag cars you cam the motor for how it is going to be used , nitrouis , turbo , supercharged etc.

Swap out the little 177 for a B&M 420 or even an 8-71.
A roller cam too.

Yes a bigger supercharger would work but if he can't afford intercoolers I'm sure superchargers are out of the question

FYI, 525SC's are set up with 35* total timing in stock engines.

Also, running 7lbs of boost without an intercooler will not do much for overall gains. The small blower will create SO MUCH heat spinning that fast that the intake fuel charge will be a lot hotter and less dense. Thus, the actual gains from the increased boost will be greatly diminished due to the increased temp of the fuel charge.
Intercoolers would be the simplest and most efficient solution. If he cant afford them now, do the rebuilds and add them later.

If on a budget...roller cams with 6psi boost...you may have to go with new input shafts due to Mercury Marine.
They don't like warranting pulley swaps.
And leave the timing at 35*...We got 580HP out of ours.

No intercoolers= DO NOT increase boost!!!!

That blower already creates heat and as Griff stated you will net no overall gain in H.P.

I would go the cam route and I would get the carbs souped up a little. Also try to fabricate some type of cool air induction. Cooler intake air is a good thing and is free H.P.

Griff
I thought he had posted these were Hawk 525s previously. Those are the same engines I had. Hawk specs are only 26 total. I was never sure why only 26, since the specs are fairly similar between the two.
Gary

Isn't the static compression on those engines very low? Like 7.5:1. That blower would have to work very hard to fill that much space. Maybe that's why they spec so much timing (35).

Yes, static CR is 7.5 to 1 in a merc 525SC.

26, Are we talkin Merc or Hawk?

They started out as Merc 525's but somewhere down the line the wieand blowers got replaced with B&M 174's and the 1050 's where replaced with Nickerson 830's

umm...are you sure they were 525SC's.

Yes, There were 525's .
My friend bought the boat from the repo lot and has know the boat since it was new.