carb upgrade

[ldixon]

Hello there,

I own a 1989 Johnson 28hp SPL on an Alumacraft MV with side console full deck and live well it is about 16ft. It is rated at 40hp.

I have been told that i can put larger on it around a 60hp but would like to be more like 50hp. I was also told by the same person that the 28 hp was not enough for this hunting boat with 2-3 men in it.

And that the johnson motors of 25hp, 28hp, and 30hp were the same they only had different carbs. Would it be possible to install a car from a 30 hp motor onto my 28 and it actually be stronger. Also if i wanted more power out of this motor what could i do. i do not have much experience in outboards but have rebuilt motors in atvs and such.

Any help or ideas are much appreciated.

 

[steelespike]

Re: carb upgrade

If the boat is rated for 40 you shouldn't go over,both for safety and legal reasons.
I don't think you would notice a difference with a carb change.And I don't think you could get 35 with just a carb change.
Carefully setup you should get about 25 mph if the motor is solid and well tuned
With careful prop selection you should be able to plane with a couple of guys aboard.Assuming they are not offensive linemen. Weight distribution and no excess weight.If you get us the prop size,and your present max rpm and speed
We can suggest a prop for best load performance.

 

[JB]

Re: carb upgrade

Howdy IDixon.

The 28SPL and the 30 are the same engine. The 28SPL is a "stripped" entry level version, just like the 48SPL is a cheap 50.

28HP is 70% of the rated max HP, which is usually quite enough for decent performance. I think the engine is actually 30HP.

Do not even think about overpowering your boat. Winter boating is far more dangerous than summer boating. Chances of dying in a minor accident are more than double.

Good luck.

 

[ldixon]

Re: carb upgrade

thanks for all the input. I to agree that over powering the boat is not a good idea.

JB... to clarify on what you said. Is my current setup actually making around 30hp? What types of things could i add to get closer to that hp. or would it not even be worth it.

 

[noelm]

Re: carb upgrade

as a general rule, once you start swapping parts to make what you have the next model up, all you end up with is a poor performing motor that no one will be able to get running properly, with almost all engines that share a common "family" there is a lot more difference that a carby or main jet!

 

[JB]

Re: carb upgrade

JB... to clarify on what you said. Is my current setup actually making around 30hp? What types of things could i add to get closer to that hp. or would it not even be worth it.

Definitely not worth it. I believe that your "28" is exactly the same as a 30 except for options. It was created as a marketing ploy.

 

[Faztbullet]

Re: carb upgrade

Even if you swapped it, 2hp wont do much and doubt you could tell the difference. Get a 40 tiller

 

[tashasdaddy]

Re: carb upgrade

the motor have identical parts. keep what you have and be happy. spend money on shells and beer.

 

[Rudi2]

Re: carb upgrade

the motor have identical parts. keep what you have and be happy. spend money on shells and beer.

Now THAT'S what I'd call good advice! ;-)

Seriously, everyone here is giving you good advice, if you honestly feel you are underpowered it would be better to trade up to another engine, just don't go over your rating. On the other hand if YOU are happy with what you got, stay with it. The fellow that told you to put a 60 hp on your boat must have some "inadequacy" problems.

 

[chipper31]

Re: carb upgrade

I heard the same thing from a reputable marine mechanic,,except he said it was the 25hp and the 35 hp johnson. I have been going there quite awhile for parts for my old motors. I believe that by the time you buy a carb and gaskets and new jets and everything else you WILL run into will cost you more money and time than trading up for something you want. Got anybody you could borrow a different motor from to try it out and see for yourself? By the way I'm new here. Cool sight. good luck to ya