more power!!! ???

[boaterntexas]

Man I have a desire for more speed and power. Any one know of any performace parts for a 1990 3.0 merc with alpha one outdrive? I was thinking cam upgrade, maybe a 4bbl carb.. any ideas?<br />I would really like to improve, topend speed, but adding poneys would be a nice touch as well. The boat runs and performs great as is,, I just wnat to add, or do something to it. Know what I mean I just have that itchin to start fixin'

 

[a.d.mobile]

Re: more power!!! ???

More speed?? speed = rpm=$$$$$$$ we did a old 120 one time, tore engine down had assembly ballanced got custom ground cam$$$$$ new stainless valves$$$ 3 angle valve job, light port work, new intake w adaptor for holly 490 cfm carb. did ok for a old duke didnt get as much speed as torque he wanted to pull his wife up on 2 skis should have seen that!!!!!

 

[Doug Durako]

Re: more power!!! ???

All that will get you 1 or 2 more mph.<br /><br />Before messing with the motor, I'd start from the bottom up----try before you buy, then invest in a good stainless prop ($500) and then clean/wax/buff the bottom of the boat.<br /><br />To gain speed, transfer all the ponies to the water via the prop and reduce the amount of boat (drag) that is in contact with the water.

 

[boaterntexas]

Re: more power!!! ???

have a 19'p merc marine vengance ss prop, on a 17' runabout. the hull is cln and waxed, Is there a better prop for the application. I still want to pull skiers so I'm afriad to jump up another prop pitch

 

[Doug Durako]

Re: more power!!! ???

What is your best speed (GPS) and current max RPM at wide open?<br /><br />Search the board for a propeller calculator someone posted here a couple months ago. It will give you theoretical pitch to reach max speed with minimum slippage for your boat hull design.<br /><br />Can you trim up all the way to your limit switch without sucking air (venitlating) in the prop?<br /><br />You may be doing all the boat can do.

 

[boaterntexas]

Re: more power!!! ???

according to my spedo, my speed is 45 mph at 5000 rpms, I can reach 6k if I wanted to, my motor is rated for max 4200 :: 4600 so I run it at 4200 and 35 mphs, the only problem is that when I trim up that high to get that speed, rpm combo the boat will jump the wakes really violently. so I normally will run the boat trimmed all the way down and turn 4200 rpms at 30 mphs I have never trimmed it all the way to the limiter while running in the water, what would be reason to test this? Speed is a bonus, I'm would really like to find a way to pull my bro 300lbs around on some water toys with out stressing the motor, last weekend we went out, had him on skies, plus another 450lbs onboard, and the boat pulled him up well, just sounded like it was tuff on the engine, I was worried about it, but should I be,, is this normall and no need for concern, or shoudl I not work this motor like that? Granit it didn't sound that bad, just took a long time to get going, kind of liek a small 5 speed truck pulling somthing heavy in to high a gear.<br /><br /> thanks,<br /> Guys

 

[Doug Durako]

Re: more power!!! ???

I don't know your motor that well, but 6k rpm sounds way too high. Are you sure the tach is set for your 4 cyl---should be a switch on the back.<br /><br />The original question was about speed. Yes, it is scary when I trim out and hit 63 mph in a 19 foot boat---it will come out of the water on a big wake and you can only go straight.<br /><br />Pulling skis and tubes, which we have been doing as a family for nearly 3 decades, is a whole different ball game. Then you need the first post about low end torque and possibly a 4 blade prop. Can you borrow one and try it? If you are bogging down the motor, lighten the load or you will do some damage.<br /><br />I am experimenting with a Torque Shift prop which starts at 13 pitch and shifts to a max of 32 pitch. It gets my rig on plane and running about 35 in under 4 seconds---pretty much slams you back in the seat. But I am not satisfied yet with the top end speed and rpm. These cost about $700 new, or you can look out on ebay for a used one. Search this post for lots of Torque Shift prop discussion.

 

[boaterntexas]

Re: more power!!! ???

Sounds cool, wish I new some way to borrow a couple of props for testing, but resources are limited around here. I want speed, but folks around me want to play on the water, tube and ski, so you see there is a problem. what kind of risk is there to the motor as weel and the human lifes on the boat when we jump the wake. Any suggestions on how to lighten the load with out hurting any ones feelings, I don't want to tell my bro that he can't get back there and play becuase he is to big and cuasign damage to the motor .. It doesn't bog down too bad, is it really cuase for alarm.<br /><br /> Thanks,<br /> Thomas

 

[Doug Durako]

Re: more power!!! ???

Yes, you have to do the speed thing responsibly. The top end and wide open throttle stuff is just between me and my rig----no passengers allowed.<br />My 20-year-old son also understands this rule. And, the driver does not drink in my rig. I am more responsible than most boaters I know.<br /><br />My wife and I have taught about 40 kids how to ski over the years. No offense, but your brother is a big boy---have you got the new wider skis and/or bigger tubes for him? Get more planing surface between him and the water and leave some passengers on shore when you tow him.

 

[boaterntexas]

Re: more power!!! ???

Thanks, so bigger tube and ski will make it easier on the boat?

 

[Juancho]

Re: more power!!! ???

there is no replacement for displacement. you want more speed and performance , you have to go with a bigger engine. Simple as that.

 

[boaterntexas]

Re: more power!!! ???

Right on.. any one have a 4.3 to donate?<br /><br /> if I bought a new motor would I also need to upgrade the outdrive? (alpha one)

 

[Ralph 123]

Re: more power!!! ???

If you really want to understand what you can do invest a few dollars and buy "Small-Block Chevy Marine Performance" by Dennis Moore. The book lays out in great detail what can be done and what kind of performance improvements can be expected using the 350 as a model.

 

[boaterntexas]

Re: more power!!! ???

can I get that book at any bookstore, or should I chk out a website?

 

[Ralph 123]

Re: more power!!! ???

You can find it on Amazon.com It is published by HPBooks

 

[boaterntexas]

Re: more power!!! ???

I did go home and check my tach last night, on the back of it it has 6 setting 1, 2, 3, 4, 5, 6<br /><br /> it's a faria 6k guage, what would be the setting for my 4 cyl? I put it on setting 4 and it and that was obvoisly wrong when the rpm jumped to 6k<br /><br /> THanks, <br /> Thomas