make a 150hp in to a 175hp

[dpd2483]

i have a 1986 johnson 150hp how do make it a 175hp

 

[eavega]

Re: make a 150hp in to a 175hp

Sell the 150. Buy the 175.

Rgds

 

[boobie]

Re: make a 150hp in to a 175hp

Not worth the effort or the $$$$$$$$.

 

[goboatnow]

Re: make a 150hp in to a 175hp

All the internal parts and bore are the same as the '85 and older 175's. If I'm not mistaken the only difference would be jetting in the carbs.

 

[boobie]

Re: make a 150hp in to a 175hp

The 150 was known as a "flat back" and the 175 as a "bubble back". Many differences as blocks, exhaust parts and adapter housing. As I said, not worth trying. Best to just buy a bigger mtr. BUT, the 150 flat back in those days was a real sweetheart.

 

[emdsapmgr]

Re: make a 150hp in to a 175hp

Boobie's correct. The 150 block is 149 cubic inches, the 175 is 160 cubic inches. The 175 is actually a detuned 235. Not much in common between them, except the midsection. The 175 carbs are 1 3/8" throats and will easily overfuel a low port 150 block. Heads cannot be swapped. If you are looking for more hp, look at the 150S model parts list for 1986. That XP/GT engine puts out close to 165 hp. All those parts will bolt right on your block. Heads, carbs.

 

[jtcarter]

Re: make a 150hp in to a 175hp

Wise man once told me..... if it runs good leave it alone. Not worth messing up a good motor for minimal HP gain.

 

[boobie]

Re: make a 150hp in to a 175hp

For the extra 25 hp you might gain an extra 2 to maybe 3 mph.

 

[Dhadley]

Re: make a 150hp in to a 175hp

In 1986 the 150 was a 149 cid motor and the 175 was a 160 cid motor. There were some 149 ci 175s in other years. In the years that the 150 and the 175 were both 149 ci, the powerheads were exactly the same. They were rated by the NMMA (as submitted by OMC) differently. In those years if you wanted to make your 150 a 175 all you needed was a decal. Both had the same powerhead, exhaust, gearcase and gear ratio. The carbs were different but the motors produced almost identical torque. Even the 160 ci 175 didn't make much more torque.

The XP/GT models used a different head which did make some difference but only slightly. You'd have to have a pretty good hull to tell the difference.

 

[samo_ott]

Re: make a 150hp in to a 175hp

They say you need 4x the HP to get 2x the speed. Adding 1/6th more hp would probably do squat for top speed.

 

[ChrisAG]

Re: make a 150hp in to a 175hp

All the internal parts and bore are the same as the '85 and older 175's. If I'm not mistaken the only difference would be jetting in the carbs.

Jetting only changes the air/fuel ratio, it does not change the overall power.

 

[dpd2483]

Re: make a 150hp in to a 175hp

i did not know it runs 70 mph now thinks

 

[jtcarter]

Re: make a 150hp in to a 175hp

70 is plenty fast.

 

[Fisherball]

Re: make a 150hp in to a 175hp

The 175 would drink more gas.