Merc. 800 SC
 

Ok, so I went boat shopping recently. I came across a boat with rebuilt Merc 800 SC's (30 hrs).

Does anyone know what the reliability of these motors are. I understand they have a great bottom end (572's) low boost etc.

What is the time between rebuilds? What are some of your experiences?

I have heard the dyno tests on these were around 700 hp. The valve train is the same as the 600sc, (hydraulic lifters) which will last without help unlike the 900sc. You don't have an intercooler to leak. So if you keep good gas in it you could get 500 hrs+, if it was rebuilt properly.

The motors were rebuilt with SuperChillers installed, so I am figuring it would be making 750 - 800 hp at the prop?

500 hrs. that seems pretty good? What does everyone else think?

If 500 hrs. is an honest number, I may be able to live with that. I usually put about 50 - 75 hrs. my boat per season. This is 50-75 hrs of cruising, with short WOT runs once a month or so.

Maybe it is just me but 500 hours does seem real long.

I have very little experience with superchargers, but I can't see a roots style blower lasting very long without being rebuilt.

Best I have seen so far in my years of doing this is 350 hours, and they were not mine.:D :rolleyes:

The blowers would probably need work before 500 hours, my B&M 250's lasted about 400 hrs at 8 psi on a 510 cid. I think the rebuild was under $500 each.

I am surprised, I didn't think that blowers would go that long without needing a rebuild. Good to know..

Anyone know the cam specs on a Merc 800SC? I know of a 41 Apache with 800 SC's in it and it has the sweetest super smooth idle I have heard----it idles like the family van in gear! :)

I have a pair in my 95 32 skater. They have about 140 hours currently and have never been apart, they still have the seals on the intake bolts and do not use oil. The blowers are oil/gearlube in the front and packed bearings in the rear. This can contribute to longevity, if it uses lube, and the bearings need to be repacked, recommended at about 150 hours. The cam is very conservative, hyd flat tappet with total lift of 559 both intake and exhaust. As stated they are 4.5" bore x 4.5" stroke. Due to the long stroke the rpm must remain about 5000 for them to stay together. I am very happy with mine. The boat will run 100mph at 4000rpm and 120,s at 5200. I do not need to run mine hard, not to many on the Cheasapeake that can keep up. A nice set up, just a little windy.

I believe they are hydraulic lifter; 240 degree intake and exhaust, with .560 lift. They were the same as the 600sc's? Crane produced them. They have asymmetrical lobes, easy on the valve train and should last 500 hrs. I had them in a Top Gun and they do sound good.:D

Ok, sounds like a good package, now all I need to do is get approved for the loan. That seems to be a challenge, even though I can afford it.