I have a 98 scarab with twin 350 sb
the engines are not stock but i bought the boat and it had been repoed and I got no information on anything. It have exhaust, intake and quick fuel carbs. the engines have been out and something has been done to them.. What I dont know they sound to have a larger cam but not rediculous, I can see through the hole you add oil in it has nice anodized roller rockers. Besides the obvious of what i can see from the outside I really dont know. The boat is not really any faster than they claim the boat should be stock. Best I have seen is 72 on the gauge. My question in I want to get in the mid 80s or better. Can I achieve that with a blower? Or by the time I apply enough boost to do that I will more than likely gernade the engines?? Chances are there isnt anything to fancy inside..... SO if that doesnt work what do I do? Strokers? Strokers with blowers??? 85+ 98 scarab 29.

As you might imagine, without having a build sheet and knowing exactly what's in them, and how it's set up, there is no way to state how much boost they might tolerate. If they currently run on 87 octane, and never knock, then you probably can assume they could take a few psi running 92, although without inconel exhaust valves, it might not last long. To get a worthwhile setup, you are going to have to invest in quite a few areas besides just the blower, fuel delivery and dyno time. In my eyes, doing all of that and not tearing them down first doesn't make sense. Get the blocks set up with blower pistons, cam, heads, and of course carb.

Or, instead of struggling with all this, just put in some relatively mild BBC's. You could have 550-600 hp without trying and get you mid-high 80's. This is coming from someone who owns a pair of blower motors that run great. For your application, that's what I would do.

is engine spacing wide enough for big blocks? what do you need, 33 1/2 min and better yet around 35? wellcraft is famous for using a 31 and change center with small blocks.

Yea I'm pretty positive bbc will not fit

Probably a more important question - what drives are on it?

Bravo 1

Adam, I had the same situation with my 85 Chris Craft Stinger 260. I wound up improving my top speed by 4-5 m.p.h. (from 58 to 62-63). Since you are already seeing 72 m.p.h. (I'm guessing that is not GPS speed) you will need about 160 additional horsepower to reach 80. A blower would add about 5% per pound of boost.You would need about 5-6 pounds of boost to reach your goal. The need for 92+ fuel is the deal breaker for me on blowers as that would mean I would never be able to go any distance that required refueling on Puget Sound. This may or may not be the case with you. I would be REALLY tempted to just leave the boat alone. 72 GPS m.p.h. is faster than my Fountain with twin 6.2s. Without knowing your engine specs you may already be near your limit for a reliable marine build. Going to a stroker/bore 383 cubic inch short block could be worth up to 60 combined horsepower and about 3 m.p.h. You might also get some gains with a prop blueprinting. Good luck with your adventure!