Merc's 525 and 575's
 

I haven't read much on the specifics on these motors, so, if you guys could answer a couple of my questions:

I assume they're 502's?

how much boost do they run?

what year did they change from the 525 to the 575?

Is the only difference between these motors the cam profile and the boost pressure to get the extra 50 hp.?

How much are the 525's worth to sell out- right? Assuming of course they are in top shape.

Any additional info is also appreciated.

Thanks
DAVE

525 is a 454 with a weiand 177 blower, about 5 lbs boost.
575 is a 502 with a B&M 250 blower if I remember right.
Gary

Oh yeah, for the old timers. Merc used to make a NA 540 cid, tall deck motor that was rated at 575 too.
Gary

From what I know, the 525 has the same longblock as the 454 mag motors (Posted many times by engine shops in the know). Neither the 525 or today's 575 are intercooled so there is easily more to be had by intercooling and using a smaller pulley to get more boost. The 525's were offered by Merc with Bravo drives. For reference sake on the reliability of this combo, my buddy has a 93 35' fountain with twin 525s, about 650 hrs. Motors were freshened once, drives still running strong with fluid changes and shower. Nice but pricey factory offerings. I'm a Whipple advocate myself. :D

The 525 was a carbed version the 575 is a TBI fuel injection setup. This was a major improvement. The 525 is a 454 block the 575 is a 502.

The 525SC is built around a 454 cubic inch engine, rectangular port iron heads, most had hydraulic flat tappet cams, static compression ratio was 7.5:1, it used a 177 Wieand blower with a Dominator carburetor. The 575 is built around a 502 cubic inch engine, rectangular port iron heads, hydraulic roller camshaft, static compression ratio is 7.5:1, it uses a Holley/Wieand 256 with throttle body fuel injection. Neither are intercooled. :)

Thanks to all.

DAVE

I'll give you $2,000 for your 525's !


Hey ,you can't blame me for tryin' :p
I need one for my ski boat and one for my girlfriends 12' fishing boat ! :D

boot,
:rolleyes: :D

I just had my 575scis intercooled with whipples manifold, bigger fuel pump, dialed in the timing and we added 3lbs of boost for a total of 7.5lbs. Best run without the intercoolers was 91mph. Last week Offshore Performance hit 95mph on the first run. Ill personally be on the boat in Miami next week so Ill let everyone know how it runs. Dustin and Jim Herring are going to help with hopefully another 1-2mph. The setup is on a 2001 38 top Gun. If anyone has done a similar setup let me know. :) ST