up the Horse power on a 30hp Johnson?

[m casey stock]

Hey guys,

My father-in law just bought a nice 89 20ft tracker pontoon. The boat has a 87 model 30hp Johnson tracker outboard on it and it lacks the giddy up he was hoping for. Now he wasn't expecting it to be a rocket, being a pontoon boat, and I think the motor is operating to it's full potential as a 30hp, but it would be fun to pull a tube around if we wanted. Is there anything that can be done to increase the Hp? I understand that it's the same base motor from 20hp to 35hp (so I was once told) and that putting a 30hp carb. on a 25hp Jonson will pull the hp rating up 5 hp (again, so I was once told), but will that work from 30hp to 35hp? Is there any truth to any of that and are there any other tricks that can be done to increase the Hp on his motor other than prop swapping. He really doesn't want to trade motors, but would like to get 50Hp out of the one he has, is that possible? Anyway, thanks for any advice or ideas you are willing to share.
Casey

 

[muskiemike12]

Pulling tubes with that engine just ain't gonna happen! Sell it and get something 70 - 90hp to pull a tube.

 

[m casey stock]

The boat is not rated for anything over a 60HP, so I'm guessing he doesn't need to put a 70HP on it. Sounds like tubing is out for this pontoon, but a little more basic zip would be good. How much would 5 more horses help? And is there something else in the tuning to squeeze out even another 5? giving a total gain of 10HP. I think in the end he will swap out the 30 for a 50 or 60, but for this season he is tapped out on big cash to spend for a different motor, just trying to get by until this winter.

 

[muskiemike12]

I would think that the time and money spent trying to make 5 more HP from that motor should be saved to get a 60 next year. There are quite a few 60 hp omc motors for sale in my region for under $1000. Try to find a private dealer who buys motors fixes and sells them. He would probably take yours on a trade.

Good luck.

 

[m casey stock]

Found a 35hp carb. on ebay for $100.00 (cleaned with new kit, ready to go) and a new set of reeds for $38.00 should get about 10hp out of the upgrades for $138.00 bucks (we'll do the work ourselves, so labor is free) also it's a lot less hassle than swapping the motors, and we get to enjoy a little more pep this year, heck, if it works out well enough, he might not even need to get a different motor at all.

 

[jasper60103]

Found a 35hp carb. on ebay for $100.00 (cleaned with new kit, ready to go) and a new set of reeds for $38.00 should get about 10hp out of the upgrades for $138.00 bucks (we'll do the work ourselves, so labor is free) also it's a lot less hassle than swapping the motors, and we get to enjoy a little more pep this year, heck, if it works out well enough, he might not even need to get a different motor at all.

Please keep us posted.
FYI. Johny25 has a thread similar to the upgrade you're doing...
https://www.tinboats.net/forum/viewtopic.php?f=4&t=23898

 

[m casey stock]

Will do, but after reading the entire thread that you gave me the link to (great read BTW!) it sounds like it only confirms what my research had already told me, so I'm sure I will get similar results especially with the reed swap that I'm doing.

 

[m casey stock]

Okay, update...the carbs and intakes on the 30HP and 35HP are the same, so no need in me spending that money unless I want to put them on my 1988 Johnson 25 (which I may do for the better idle qualities that has been previously mentioned) But the aftermarket reed/leaf valves should add 5HP. This leaves me wondering what the actual difference is between the late 80's early 90's 30HP and 35HP motors. I see that the factory reeds/leaf valve are also the same on them. So where did Johnson get the 5HP gain? Is is something even more simple than the carb. swap? I'd love to hear from someone that has the answer to that. Of course, if I find the answer, all of you guys will have it too.

 

[Lil' Blue Rude]

In the 80's they rated motors at the powerhead. In the late 80's to early 90's they started rating them at the prop. That's where they 5hp is lost.

 

[m casey stock]

Still confused, because in 1988 you could buy a 30HP or a 35HP the two models of 35HP listed are J35RCCE and J35RLCCE is the 35 not really a 35? and the only difference the decals on the cover? I want to find that other 5HP!! Waaawaaa LOL

 

[blunt]

the late 80's and 90's 35hp model numbers you see are identical to 30hp we have here in the states. those models were sold in other countries like Argentina and were still rated at the crank instead of the prop.

 

[m casey stock]

the late 80's and 90's 35hp model numbers you see are identical to 30hp we have here in the states. those models were sold in other countries like Argentina and were still rated at the crank instead of the prop.

A marketing gimmick.....I see.....can't fool the good Ol' Boys in the US, so lets give it a try in another country....Gotcha! I was beginning to wonder if that was the case, but thought "surely not, that would be mighty wrong of them" but didn't think about that they had sold them somewhere that still rated their motors at the crank. Makes sense I guess, don't like it, but it is what it is 8) thanks for all the input. Maybe a one shot NOS system? Just joking of course. I'll let you guys know how the reeds/leaf valves works out.