86 johnson 150 vs 150gt

[ceejkay]

Hey guys i was just curious what the difference between an 86 150 and an 86 150 gt are.. i currently have a 150 and will be acquiring a 150gt that is in much better condition than my 150.

 

[SparkieBoat]

Re: 86 johnson 150 vs 150gt

the GT motors usually had the 175 HP heads and larger bore carbs and almost the same size jets as the 175, the porting in the block is also larger. they are supposed to produce about 15 more HP than rated. so if it is in good running condition you could expect to see a noticeable increase in HP, maybe 2 or 3 MPH more on top end and a little more jump out of the hole. overall great motors. OMC started producing these to try to keep up with the mercury XR2 motors, the mercs would still out run them though.

 

[ceejkay]

Re: 86 johnson 150 vs 150gt

ok so its basically a 175hp instead of 150hp.. i take it i will expect fuel economy to drop as well, not that its very good to begin with.. so the carbs are bigger, heads are bigger and the block is ported largeer.. other than that is the rest of it the same? and its still a crossflow engine correct? so the lower units should interchange?

 

[Dhadley]

Re: 86 johnson 150 vs 150gt

The 150 and 175 crossflow blocks are the same - they have the same porting and they use the same heads. The XP/GT models have different heads that have a much better swirl pattern. Some of the early 150 XP/GTs used the 200 porting. The lower units are the same, the XP/GT powerhead will bolt up to your midsection, no problem.