Scarab Billy

Hi guys, most of you are going to giggle at these questions,...but I have to ask them anyway. I am new to high performance boats. I recently purchased a 1988 28ft Scarab Excel that was in need of repairs. I got it VERY cheap, so I can afford to put some time and money in it. Of course the last owner lied alot to sell the boat, but I caught most of them anyway. The question is...This boat is dry and is solid. It has a new 450Hp 502 CID crate engine in it. Merc outdrive. A Quicksilver 3 blade 26 pitch (I believe anyway) prop. I have had it on the lake several times. Everything works very well and the engine sounds great. But I thought the boat would be faster. The best on GPS is 51mph @ 4,300 rpm. Any suggestions on what I can do to get at least 60mph?

1BIGJIM

iTrader: (1)

Why to big of a prop. You need to get the RPMs at around 4,800, try a 23p prop.

wfo1

Are you trimming it correctly? If so, you don"t have 450hp and you found another lie. The prop is porbably a little on the big side too, not allowing you to get into te proper rpm range.

jeffswav

I agree with these guys, your prop is to big or you do not have a 450HP engine. Try a 23 mirage and see what that does. What is the RPM range of your cam? I have a 21 Mirage that might work for you.

Scarab Billy

Thanks for the thought on that...never considered the prop being too much...it was already on the boat when I got it. as far as the engine is concerned. It seems to be a stock 450hp 502 from chevy . I am sure it is a roller cammed moter..(I had the intake off) but I don't know what the factory specs are. The engine doesnt seem to have ever been apart for anyone to mess with. The block is stamped with 8.1 on the side, how else can I tell the horsepower of the engine?

Scarab Billy

Well everybody seems to agree it's too much prop. How much is your 23 Mirage?

crapr6

RPM's are way under just like the rest of the crew has posted. Reprop it and you should see a big diffrence in performance. I have a 23P mirage on my boat right now and the rpm's are way to high but I dont want to sell the 23P until I have another prop to replace this one.

fireboatpilot

Hey Crapr6, why dont you trade him your 23 for his 26? Sounds like what you both need. Billy thats a very heavy boat but as they have said you are seriously over proped. Maybe a 21P 4 blade might do the trick. Is it a TRS or has it been switched to a Bravo1? Same prop splines so you know.

jeffswav

Sorry I do not have a 23 but I have a 21. $200 for the 21 Mirage. http://stlouis.craigslist.org/boa/1191442838.html I just looked in the Jegs catalog, looks like you should prop for 5250 RPM. The 21 may be a better fit for your boat. No way to be sure without trying it.

Scarab Billy

It's a Bravo 1. It does seem a little nose heavy...but has absolutly no trouble getting on plane. It does get to 50 very quickly, then just stops increasing speed. I have never been aboard a fast single engine boat, so I have no idea what to expect from this one. Nothing to compare it to. Thanks very much for your insights.