More speed

rgsterling

Cadet
Joined
Sep 19, 2012
Messages
9
I have a 93 stingray 606zpx with a 4.3LX mercruiser with a 4 brr alpha 1 genII with a 5 bladed prop with a 23 pitch. Right now Im cruising around 30 mph at around 3000rpm and wide open about 50mph at 4500rpm trimmed out. I was wondering if anyone could tell me an easy way to get a little more speed out of it. I would love to be able to run about 60mph but I don't think its going to happen without a lot of motor work. Im open for anything. Thanks
 

haulnazz15

Captain
Joined
Mar 9, 2009
Messages
3,720
Re: More speed

You aren't likely to get much more than you are currently getting without major dollars. Perhaps a prop change would help, but I doubt you'd see much more than 1-2mph change at most. Your options are, lighter boat (probably not a lot that can be done) or more HP. You could upgrade to an SBC V8, but that isn't cheap, and won't likely net you for than 3-4mph top end at the most. The drive is your next limitation, as the Alpha is limited to 300HP (although some run more through it). A BBC and a Bravo I/III are really the only viable option for considering going to the 60+mph range. You might not like how that Stingray handles at that speed, either.

Cheapest option to go 60mph or more: buy a different boat.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Re: More speed

Is that boat an 18 footer or longer? If so, that is an excellent speed.
 

rgsterling

Cadet
Joined
Sep 19, 2012
Messages
9
Re: More speed

Yea this was pretty much the answer I was expecting. 50mph will just have to do it for now.
 

tpenfield

Moderator
Staff member
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Jul 18, 2011
Messages
17,621
Re: More speed

I know how to get more speed . . . :)

More horsepower. :D

Which of course, probably means new engine :facepalm:
 

Roger Wilco

Cadet
Joined
Jul 18, 2010
Messages
13
Re: More speed

that extra 10mph is going to cost you, you could swap a 350 (5.7L) or a 305 (5.0L) relatively easy since you have a 4.3, that should get you up to 70ish
 

greenbush future

Lieutenant Commander
Joined
Aug 28, 2009
Messages
1,814
Re: More speed

Sounds like she's dialed in nice now, as others have said, you wont get much more w/o more power. 50 mph is darn fast on the water, 60 would seem scarey to me, but I'm past my speeding days too. Have fun!!
 

spoilsofwar

Lieutenant Junior Grade
Joined
Jun 29, 2011
Messages
1,124
Re: More speed

I would think you could get a bit more out of it by switching to a 3 blade prop. You'll probably hate the drop in holeshot though.
 

haulnazz15

Captain
Joined
Mar 9, 2009
Messages
3,720
Re: More speed

that extra 10mph is going to cost you, you could swap a 350 (5.7L) or a 305 (5.0L) relatively easy since you have a 4.3, that should get you up to 70ish

You are out of your mind. The 5.0L chevy isn't much of an upgrade over the 4.3L, and the 5.7L isn't hitting 70mph, even if you strap a blower on the thing.
 

Bondo

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Staff member
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Apr 17, 2002
Messages
70,468
Re: More speed

Originally Posted by Roger Wilco
that extra 10mph is going to cost you, you could swap a 350 (5.7L) or a 305 (5.0L) relatively easy since you have a 4.3, that should get you up to 70ish

You are out of your mind. The 5.0L chevy isn't much of an upgrade over the 4.3L, and the 5.7L isn't hitting 70mph, even if you strap a blower on the thing.


Ayuh,.... Agreed,.... 70 mph ain't gonna happen.., a 350 may or may not get it to 60 mph,... 'n that's doubtful,...
 

H20Rat

Vice Admiral
Joined
Mar 8, 2009
Messages
5,199
Re: More speed

I have a 93 stingray 606zpx with a 4.3LX mercruiser with a 4 brr alpha 1 genII with a 5 bladed prop with a 23 pitch. Right now Im cruising around 30 mph at around 3000rpm and wide open about 50mph at 4500rpm trimmed out. I was wondering if anyone could tell me an easy way to get a little more speed out of it. I would love to be able to run about 60mph but I don't think its going to happen without a lot of motor work. Im open for anything. Thanks

Is that on a GPS or the speedo? If that is GPS speed, you are already well dialed in and be thankful you are hitting that! If its speedo, you might want to pull out a GPS...
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: More speed

I agree with the others that you are dialed in, and 60 MPH is a serious barrier.

I would think you could get a bit more out of it by switching to a 3 blade prop. You'll probably hate the drop in holeshot though.
I agree with this too. And by a bit we mean maybe 3 MPH. Oh, and BTW 50 MPH is fast in stock bowrider world ;)
 

jclem

Cadet
Joined
Aug 19, 2012
Messages
21
Re: More speed

50 mph is no slouch, very respectable for your 4.3. How much time do you plan spending at 60? I doubt it would be worth the cost it would take to get you there. I agree with spoilsofwar, you might get a bit more from a 3 blade prob. Enjoy what you have, slow down and enjoy a cold adult beverage!
 

jestor68

Commander
Joined
Jun 12, 2012
Messages
2,308
Re: More speed

According to a test of that boat when new, it did 55 mph with a SS 3 blade. With the High Five, it did 52.

Both were 23 pitch.

If you want to go faster, get rid of the "5" for a "3".

As expected, acceleration was quicker with the five.
 

rgsterling

Cadet
Joined
Sep 19, 2012
Messages
9
Re: More speed

If I get a 3 bladed should I go with the same pitch as the 5 blade or should I go with a 19 or a 20? The 5 blade is a 23.
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: More speed

Any boat that only loses 4 MPH from new test data is perfect. They never run as fast as the test data. They gain weight, and the test unit is always setup by factory techs, engine and boat. I am surprised that you have only lost 4 with the 5 blade. But looks like things are very good to me.
 

shrew

Lieutenant
Joined
Dec 29, 2006
Messages
1,309
Re: More speed

Also keep in mind that the Max RPM range for that engine is 4400-4800. You are wringing her out and getting 4500. You're within spec, but actually at the low end. Going for a larger pitch, is going to further drop max RPM to below the threshold. This is essentially overloading the engine. Decreasing pitch will raise max RPM and give yo ua better hoel shot, but lower top end speed. 5 blade, 4 blade, 3 blade is going to further complicate the equation, but the same general principals apply.

As stated, you've got it about as dialed in as she's going to get.
 

scott8058

Petty Officer 2nd Class
Joined
Jul 15, 2012
Messages
192
Re: More speed

I have a 20ft bayliner (light boat) with a 5.7 and a 21p 3 blade aluminum and w just me i've hit 56 on gps and on glass. I need to try a bigger prop bc i can't run wide open with that prop (even w a normal load, 2 adults 3 kids 50mph @ 4500) as i run to high rpm's but still don't think ill get near 60. 50 is pretty darn fast on water and will smoke a lot of boats so i'd just start bragging about that v6 or buy a different boat!
 
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