speed

I

insanity

Petty Officer 1st Class
Joined
Sep 7, 2009
Messages
227
What is the fastest I can get a mercruiser 140h, with an alpha 1 outer? This is in an 86 4 winns horizon 195. I have read that changing prop and cleaning everything boosts speed considerably. I am curious as to how fast I can go with this combo, so I know where to start looking for possible problems.
 
ziggy

ziggy

Admiral
Joined
Jun 30, 2004
Messages
7,473
Re: speed

so I know where to start looking for possible problems.
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what ya need is not to know how fast it'll go but can you achieve the wot spec. for your engine. you can find this info in the service manual which most likely you'll be able to obtain from the adults only sticky at the top of the i/o forum here.

fwiw. the boat in my sig., which is 19', reaches 42 mph @ the high end of my wot spec. for my engine.... i'd venture to say my boats lighter + i got a larger engine. so i'd guess your speed may be less than that.
 
W

wca_tim

Lieutenant Commander
Joined
May 28, 2007
Messages
1,708
Re: speed

insanity said:
What is the fastest I can get a mercruiser 140h, with an alpha 1 outer? This is in an 86 4 winns horizon 195. I have read that changing prop and cleaning everything boosts speed considerably. I am curious as to how fast I can go with this combo, so I know where to start looking for possible problems.
Click to expand...

depends on how good the tires and bearings are on your trailer. :D
 
I

insanity

Petty Officer 1st Class
Joined
Sep 7, 2009
Messages
227
Re: speed

I believe it is 4600 rpm I have yet to see that with a 14.5x17 and 14x19 props. Top speed I have seen is 27 mph on the 14x19 at 4000 rpm, I didn't have a working speedo with the 14.5x17 but the rpm was between 3500 and 3800 rpm.
 
H

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: speed

wca_tim said:
depends on how good the tires and bearings are on your trailer. :D
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toothlessgiggler.gif
 
N

n2ostroker

Petty Officer 2nd Class
Joined
Aug 9, 2008
Messages
177
Re: speed

Really though...
Clean it all, tune it up and prop it right. Get those rpms up and it'll be better all around. I'd guess 30-32 gps mph.
 
B

Blujay96

Petty Officer 1st Class
Joined
Jul 8, 2009
Messages
310
Re: speed

I have a 18 foot Rinker with that same motor and drive. I get about 36 MPH at 4500 RPM with a 14X19 Prop. With that prop I have some throttle left. So with a 21 in prop I would guess it would do about 40. On you numbers for the props, it seems like they are backwards. The more pitch you have the lower the rpms should be and the faster you go. If you go to the Prop Section talk to Hwsii. He is very good at sizing the correct prop.
 
CheapboatKev

CheapboatKev

Vice Admiral
Joined
Oct 4, 2008
Messages
5,813
Re: speed

insanity said:
I believe it is 4600 rpm I have yet to see that with a 14.5x17 and 14x19 props. Top speed I have seen is 27 mph on the 14x19 at 4000 rpm, I didn't have a working speedo with the 14.5x17 but the rpm was between 3500 and 3800 rpm.
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Take a GPS outtta the car..more accurate anyway
 
I

insanity

Petty Officer 1st Class
Joined
Sep 7, 2009
Messages
227
Re: speed

I bought a manual for the mercuser, and learned a lot from it. I think one of the reasons I am not getting the speed I think I should be getting. Is the poitns are not aligned properly. From what I read that they have to be aligned perfectly other wise they retard the motor. Unfortunately I wont get to see the difference for a year.
 
fat fanny

fat fanny

Lieutenant Commander
Joined
Feb 9, 2006
Messages
1,935
Re: speed

45auto that bubba test was great that was funnier than some of the stuff you see newbies do @ the launch.insanity don't expect to much more than 35 to maybe 45 tops in best possible conditions the best I ever got out of my 3.0LX 17.5' WAS 45MPH water was like glass and hull waxed just me and the Hen and I still think the mph was high by @ least 5 to 10 mph.
 
I

insanity

Petty Officer 1st Class
Joined
Sep 7, 2009
Messages
227
Re: speed

fat fanny said:
45auto that bubba test was great that was funnier than some of the stuff you see newbies do @ the launch.insanity don't expect to much more than 35 to maybe 45 tops in best possible conditions the best I ever got out of my 3.0LX 17.5' WAS 45MPH water was like glass and hull waxed just me and the Hen and I still think the mph was high by @ least 5 to 10 mph.
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My expectations was more in the range of 30 to 35. Which after adjusting the points and advancing it from 0 to 6 degrees I should see that. That would make me happy. If that still doesn't fix my want for speed I guess I will have to upgrade to a 260. Though 27 that I was getting off the speedo was probably more like 30 seemed fast enough. I just want to be able to have a full load and still be able to pull a tube or skier.
 
45Auto

45Auto

Commander
Joined
May 31, 2002
Messages
2,842
Re: speed

A 4 Winns 195 Horizon is a lot of boat for that 4 cylinder. Best I ever saw on my 16' with a 120 Mercruiser was 33 or 34 MPH. I think your expectations of low 30's are realistic. Not sure how successful you'll be pulling skiers up with a full load in the boat, though.
 
I

insanity

Petty Officer 1st Class
Joined
Sep 7, 2009
Messages
227
Re: speed

It may be high hopes but I will be surprised to see it work the way I want it to.
 
W

wca_tim

Lieutenant Commander
Joined
May 28, 2007
Messages
1,708
Re: speed

never hurts to try! you're doing the right things. make sure the engine is in good tune (plugs carb, cap and rotor, filters, etc...), that your bottom is clean and smooth, that you're not carrying any extra weight (especially in the back), that your prop's in good shape, drive oil is fresh and clean, etc... all the little things tend to add up. weight is a big one.

(ps. my boats generally go a lot faster on the trailer than in the water too...)
 
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