Classic SeaCraft Community - rebuilding/repowering a 20' center console

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- - rebuilding/repowering a 20' center console (http://www.classicseacraft.com/community/showthread.php?t=22374)

Re: rebuilding/repowering a 20' center console

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I'd appreciate if anyone has performance stat's on a bracketed 150hp thru 200. The smaller I can go and still get great performance the better. . . I had a 200hpdi on a wellcraft v-20 steplift before this boat and that would hit just 50mph with only myself in the boat.

John, if you'll PM me with an E-mail address, I can send you some Excel spreadsheets/plots from a bunch of prop testing with data from I-Command system on fuel flow/gps speed/rpm and prop slip calculated. Also have a spreadsheet comparing specs/materials, etc. on all the 140-175 hp motors that I put together when I was trying to decide on a motor. My motor is a 25" shaft. Don't know if the 30" shaft is available on the small V-6 but you should be able to find out from this link.

A bracket is typically worth about 3 mph in top speed. I've seen 49.5 mph on gps on my boat with a full tank of fuel and just me on board with a 4B 14x21" pitch prop. Could probably get more with the right 3 blade prop, but they don't have enough stern lift for my stern heavy rig. Also think the motor could go a little higher but I'm already in the top hole and cavitation plate is about 3.5" above the keel. I'm not that interested in top end anyway, and normally run a 15x15 4B PowerTech that jumps on plane very quickly at less than half throttle with a total weight of about 4000 lbs!

That V-20 is a very hard riding hull, one of the worst built I've ever seen (I personally know of 5 that have busted up running offshore here), and I don't think it's nearly as efficient as a SeaCraft. From my experience, I think a properly rigged SC20 can easily break 50 mph with about 175 hp on a bracket.

Re: rebuilding/repowering a 20' center console

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Go to Bay Manufacturing

I know of nothing available for any Suzuki.

I emailed Bay Mfg. and while they don't have anything now, they advised that they were working on it. They couldn't say how long it would be, though. [img]/forum/images/graemlins/tongue.gif[/img]

Re: rebuilding/repowering a 20' center console

Quote:

...From my experience, I think a properly rigged SC20 can easily break 50 mph with about 175 hp on a bracket.

Quite right Denny. I used to run a 2.0L Mercury XR4 150 that was balanced to .1 gram of reciprocating weight during re-manufacture, and got aftermarket reeds and re-jetted carbs, along with a nose-cone and low-water pickup. This motor dyno'd 193 hp on a hydro-dyno.

With my Seafari, (which is heavier than a MA or SF), this motor, and no bracket, once I got it propped right, even with my ablative bottom paint I could just touch 54 mph in the right conditions. I believe with a Hermco bracket I could have achieved 57, possibly 58 mph. (The motor did suck fuel at a prodigious rate, though, at anything over 5600 rpms)

The current Etec 175 reportedly actually produces between 188 and 195 hp at the prop. (The Etec 150 about 165 hp). So with the right prop, a nose cone and a bracket, it should easily reach 55 mph on a 20' SF with a slick bottom. And cruise at over 3.5 mpg, too.

Of course, with my 90 Optimax, I still cruise at 24 mph, but get over 5 mpg :cool: :cool:

Re: rebuilding/repowering a 20' center console

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...I used to run a 2.0L Mercury XR4 150...

Frank,
I thought the 150XR4s were all 2.4L. My '91 XR4 is. I just assumed the XR2s were 2.0L, the XR4s were 2.4L and the XR6s were 2.5L. Not so?
Dave

Re: rebuilding/repowering a 20' center console

Quote:

...I used to run a 2.0L Mercury XR4 150...

Frank,
I thought the 150XR4s were all 2.4L. My '91 XR4 is. I just assumed the XR2s were 2.0L, the XR4s were 2.4L and the XR6s were 2.5L. Not so?
Dave

Nope. My XR4150 was a '90, with large gearcase lower unit off a '96 225. The XR4 150 up to and including '91 were definitely 2.0L, (as was the regular 150 and 135 V6, but the '88-'91 XR4 200 motors were 2.5L, as were the 150-175-200 XR6 motors which came out in '92.

Of course, there exists the possibility that I'm completely wrong. Tim (BigShrimpin') would be the authority on this. I know a lot more about the pre-'88 Merc inlines.

Re: rebuilding/repowering a 20' center console

I just took some photo's, how do I post them now?
Thanks,
John

Re: rebuilding/repowering a 20' center console

John, you first need to open up a free internet account on some site (Photobucket is a good one many of us use) that allows you to upload the pictures from your computer to that site. It's actually a good way of backing up important pictures to prevent loss due to a hard drive crash, etc., and you can then get to them from any computer with internet access. Checkout this post from Capt. Chuck in the Photos section that provides step by step instructions. It's real easy once you learn the process. Denny

Re: rebuilding/repowering a 20' center console

Thanks for the input on photo's, I just set up a photobucket account,here's a couple of pictures

[image]http://i1190.photobucket.com/albums/z454/jfc6866/th_100_0296.jpg?t=1297280175[/image] [image]http://s1190.photobucket.com/albums/z454/jfc6866/?previewTheme=84&track=interstitial&previewCancelU rl=http%3A%2F%2Fs1190.photobucket.com%2Falbums%2Fz 454%2Fjfc6866%2F#!cpZZ2QQtppZZ20[/image]

Re: rebuilding/repowering a 20' center console