75 horse Mariner vs 90 horse Mariner Specs

[starkyb]

While looking at the spec sheet in the owners manual for my 1988 75 horse Mariner, I noticed that the specs for the 75 horse were the same as the 90 horse except for the WOT rpm range. The 75 horse is 4750-5200 rpm while the 90 horse was 5000-5500 rpm. What is the different about the motors that the rpm range is different and is there something I can do to get 90 horse from the 75 horse that I own?

 

[Yesterday]

Re: 75 horse Mariner vs 90 horse Mariner Specs

While looking at the spec sheet in the owners manual for my 1988 75 horse Mariner, I noticed that the specs for the 75 horse were the same as the 90 horse except for the WOT rpm range. The 75 horse is 4750-5200 rpm while the 90 horse was 5000-5500 rpm. What is the different about the motors that the rpm range is different and is there something I can do to get 90 horse from the 75 horse that I own?

Perhaps someone who knows these engines specific will chime in, but usually the difference is in the carburetion, as well as timing/placement of the ports. quite a few manufacturers have engines spanning a significant horse power range (20+HP), which on the surface appear identical.