underpowered 454?

[Frankiea87]

hey guys i got a 88 sea ray sundancer 268.. 454 merc 7.4l with alpha drive with 4blade prop.... i feel like its not getting top speed it should be getting as people say. at 3500 rpm in not even at 20mph and cant get on plane... about 4500-5000 rpm ill be on plane at 25mph and then full throttle 25-30mph. i feel like i should be able to hit 30mph at 3500rpm.and almost 40 at 4500rpm or am i wrong?

 

[Bt Doctur]

Re: underpowered 454?

" 88 sea ray sundancer 268.. 454 merc 7.4l with alpha drive with 4blade prop"
That combination just dosent sound right.

 

[Challenger84]

Re: underpowered 454?

Check to see if all the cylinders are firing.
Check compression!
Good luck.

 

[Frankiea87]

Re: underpowered 454?

what should a "good combination:" sound like? haha

 

[JustJason]

Re: underpowered 454?

How's the bottom look? Much growth?

 

[Frankiea87]

Re: underpowered 454?

still has bottom paint... will be getting redone this winter but not too bad

 

[Bt Doctur]

Re: underpowered 454?

The big block / Alpha was used on much lighter boats because the 330 hp would destroy a alpha even with the 1.32 gearing, reason why Bravo`s were invented.

 

[a70eliminator]

Re: underpowered 454?

what should a "good combination:" sound like? haha

454 Brava or is it Bravo

 

[Frankiea87]

Re: underpowered 454?

think its an alpha.. just baught the boat few months ago and its been in water since.. assumed it was alpha looks like one... maybe bravo? how could you tell difference? would 3blade prop be better?

 

[jtmarten]

Re: underpowered 454?

That 268 weighs, what, 7500-8000lbs?
I don't think you'll see 45mph with a single BB. 30mph is pretty good for a stock, single BB.
I thought '87 was the only Alpha/BB year?

 

[Bt Doctur]

Re: underpowered 454?

http://mercstuff.com/fiche.htm

 

[26aftcab454]

Re: underpowered 454?

1996 7.4 Bravo3 in my1984 Wellcraft 26 aft cabin- see avatar .
35-3800 RPM = 30mph // 4600rpm= 43mph GPS
I have a gen set-hot water tank-lots of heavy stuff--plus it is a heavy hull.6000lbs +total loaded.
I have had distributor cap issues/ fuel pump replaced last year.
check fuel/water filter and make sure all cylinders are firing.
Make sure you don't have crud growing on bottom.

I use my trim tabs down to plane faster ,trim in then raise them both.

I would think you have something not working right.
good luck!

 

[TilliamWe]

Re: underpowered 454?

" 88 sea ray sundancer 268.. 454 merc 7.4l with alpha drive with 4blade prop"
That combination just dosent sound right.

Well it is right. That is indeed the combination that lead to the developement of the Bravo series drive. It was used in 87 and 88 only, as far as I know.

The Sea Ray 268 Sundancer is a HEAVY boat. You are NEVER going to hit 40mph with it, ever. So give that up.
My dad's used a 15 pitch 4 blade prop in order to get up on plane, and it might have hit 35mph at top end. I'll ask him.

Make sure the bottom is clean and the motor is running right. But that said, your boat is never going to amaze you with holeshot or top speed. Sorry.

 

[TilliamWe]

Re: underpowered 454?

1996 7.4 Bravo3 in my1984 Wellcraft 26 aft cabin...

Your boat/engine/drive combo is so different from what he's got that it's like apples to oranges. His boat is 29' long when you count the bolted on swim platform and the bow pulpit. So it's TRULY a 26' long boat. Yours is more like a 24.5 footer, with a molded in swim platform. And Sea Ray's of that era were built WAY heavier than any Wellcraft was/is today. Then you have a 300hp, at the propshaft, engine mounted to a twin prop drive (6 total blades) with props that have 16.5" and 15.5" diameters. He's got a 330hp crankshaft rated engine (although that engine is a better/heavier built engine than your 7.4) attached to a single prop drive with a 15" (most likely) diameter 4 blade prop. Almost nothing besides their fiberglass construction is the same about the boats.

 

[jtmarten]

Re: underpowered 454?

And Sea Ray's of that era were built WAY heavier than any Wellcraft was/is today.

I don't see how this is relevant, the Sea Ray is an '88, the Welly is an '84.

 

[OldNBold51]

Re: underpowered 454?

at 3500 rpm in not even at 20mph and cant get on plane... about 4500-5000 rpm ill be on plane at 25mph and then full throttle 25-30mph.

You're not on plane at 20 mph? is your trim all the way down?

 

[sethjon]

Re: underpowered 454?

4 blade prop is ok but whats the pitch? wrong pitch could be a big difference. As far as top speed goes that sounds about right.

 

[shrew]

Re: underpowered 454?

Deleted Response

 

[TilliamWe]

Re: underpowered 454?

I don't see how this is relevant, the Sea Ray is an '88, the Welly is an '84.

I missed the part about that other boat being an 84. And it could truly be a 26' boat with a bolt on swim platform. But my statement is still correct, the Sea Ray will be heavier. (especially since the Sea Ray is actually 26' 8" long) And there is no way that it will perform like his boat.

 

[26aftcab454]

Re: underpowered 454?

Your boat/engine/drive combo is so different from what he's got that it's like apples to oranges. His boat is 29' long when you count the bolted on swim platform and the bow pulpit. So it's TRULY a 26' long boat. Yours is more like a 24.5 footer, with a molded in swim platform. And Sea Ray's of that era were built WAY heavier than any Wellcraft was/is today. Then you have a 300hp, at the propshaft, engine mounted to a twin prop drive (6 total blades) with props that have 16.5" and 15.5" diameters. He's got a 330hp crankshaft rated engine (although that engine is a better/heavier built engine than your 7.4) attached to a single prop drive with a 15" (most likely) diameter 4 blade prop. Almost nothing besides their fiberglass construction is the same about the boats.

Mr. We---never the less , my boat hull is 26ft4inch+ 18" factory bolted on teak swim platform + 2ft anchor pulpit = 30 feet!
Just trying to give a similar size & powered boat's performance-take your meds!