2stroke to 4stroke

[Patrick A McGuire]

If you do go from 2 to 4stroke, is there a guide for figuring out hp difference?
My 115 hp 2stroke merc isn't going to be the same as a 115 4stroke is it?

 

[jevery]

Re: 2stroke to 4stroke

Holeshot will be a little slower, but WOT throttle power will be the same, so top speed's about the same.

 

[gcboat]

Re: 2stroke to 4stroke

Generally speaking they will pretty much be the same. The two main differences will be lower end torque and a slight weight difference. The 4 stroke tends to be a little heavier and a little slower on the initial run-up.
If you haven't purchased a motor yet you might want to take a look at the new E-TEC's. Haven't bought one but I certainly am keeping my options open.

 

[kenmyfam]

Re: 2stroke to 4stroke

4 strokes are heavier than the equivalent 2 strokes. More weight , less speed. 4 strokes are quieter though and are said to troll better for long periods. Higher service costs. No personal experience of 4 strokes so this is merely what I have heard from people with them.

 

[Patrick A McGuire]

Re: 2stroke to 4stroke

So, probably the weight difference is going to be a bigger factor on a smaller boat than a larger one, right? Or is it the fact that the older boats were designed for the lighter 2stroke? With the added weight of the 4, the stern is going to sit lower in the water, so you'll need better trim for it to sit right under power. Otherwise, the bow will be to high.
So-if needed- how do you fix that problem on a classic 16' Glasspar, which is fairly light to begin with? Add even MORE weight and stuff the bow with it to even out the ride?

 

[snowman48047]

Re: 2stroke to 4stroke

I did some digging on this as I want to repower with a 115hp. The Merc Opti is listed as 375 pounds and the 4 stroke at 399 pounds. There isn't a boat out there rated for a 115hp that you would notice a 24 lb difference. Now if you were comparing those to say a Honda 115hp 4 stroke at 496 lbs, ya there'd be a little more to notice, but still its only 100 lbs.

I asked Mercury this question. The response was, there is no difference as long as the hp rating of the boat is not exceeded. There simply isn't enough weight diff to make a big deal of.

 

[swordfish25]

Re: 2stroke to 4stroke

If it is a short shaft boat then 24 lbs will make a difference, a motor well will help.

 

[Patrick A McGuire]

Re: 2stroke to 4stroke

What's a motor well. I haven't heard that term before. And I believe mine is a long shaft.