CenturyUltra

I have a the factory mercruiser supercharger and manifold off a 525SC engine. Is there any difference between this and an automotive Weiand 177? I want to run it on my 88 242LS Formula. The boat has the 454 MAG bone stock with 200 hours. Can I just bolt it on with a 1050 dominator and a set of stainless marine headers? It looks like the 525 is basically a 454 MAG with a supercharger any other differences? I see the compression is lower I'm assuming thats pistons? Is the head gasket and studs the same? Also anyone have a 10 rib crank pulley for sale? Thanks.

dykstra

iTrader: (1)

PM GRIFF, he is the resident 525SC guru.

Donzi Dude

I'm sure Griff knows alot more about this than me but I'm pretty sure that the only thing a 454 and 525 have in common is that they are both BBC

X-Rated30

Don't confuse the 525sc with the new 525. 525sc was a 454 with a blower on it. I think it was a 6-71, but I have been out of the I/O scene for a while.

Audiofn

525sc uses a 177 blower.

f311fr1

The upper pulley shaft on the Merc 177 has a different spline than the automotive 177 so Merc customers could not put smaller pullys on to raise the boost and increase warrenty claims.

blue thunder

Yes you can bolt that directly to a 454 with rect port heads. There are things that would be nice like inconnel exhaust valves and cometic head gaskets but not entirely necessary. You will need to find some tbolt 4 V-6 ignition modules to get your timing curve right. Set the all in for 30*, 98s all around on jets and have fun. You shoud run high octane due to your compression as well.

flat rate

iTrader: (3)

You can put smaller pulleys on those. Mercury called them high altitude pulleys and they were also
available aftermarket. We had them on a trip 42 Fountain

Griff

As was said, the auto and marine SC's are the same except for the shaft for the pulley. Merc used a splined shaft and they are NLA.
There are also 2 different types of pulleys with different depths that were used for the upper pulley on the Merc SC.

I would try to find a slightly smaller pulley for the lower crank pulley to reduce boost. You might be able to order a new lower pulley. I think the stock Merc upper was 3.5" and the lower was 7"....or it was 3.25 and 6.5. Either way it was 2:1 overdriven and was 5.5# of boost. With your higher compression, it would be smart to reduce boost a little and use a 1/2 inch smaller lower bring boost down 1/2-1# and make it about 1.85:1 overdriven. You should be fine with a V8-24 ignition module and should be able to run the stock 32* of timing.

The 525SC was hand assembled and balanced at Merc Racing. Different pistons, cam, roller rockers and a lot of other little stuff that are different from a 454mag.

Griff

Teague used to carry smaller upper pulleys that could increase boost to 8#. Not sure if they still do. I was running just under 8# of boost on my 525SC with no problem at all.