Same engine w/different horsepower?

[Swagonmaster]

I've been wanting to ask how did mercury go about getting hp ratings from 90 to 150 from the same basic engine? My 79 140 horse is at the upper end of that range but since I have it torn down right now anyways another 10 hp might be nice to have if it wasn't something big.

 

[Texasmark]

99 cu in as I recall, used at least on the 90-150 hp. I understand porting, carbs, timing were the main attractions. Ping Faztbullet. He used to race them.

 

[Swagonmaster]

Ok, I just answered my own question while looking at the engine specs for another poster's question. They increased the displacement to almost 122 cubes in the 150hp. Still curious about the details of the smaller engines though.

 

[racerone]

Perhaps the 140 ( prop rated ) is EXACTLY the same as the 150 rated at the crankshaft !!!-------It also has to do with factory operation.----Using a basic 6 cylinder block / machines / people to assemble different horsepower ranges from the same platform is a money maker.-------Also done 40 years ago when factories were not as automated as they are today.

 

[fastjeff]

The 150 hp in-line was derated (numbers only) to 140 when Merc brought out their new 150 hp V-6.

Jeff

 

[Swagonmaster]

What I need to do then is get a 90hp engine cover and make it a sleeper!

 

[Texasmark]

I apologize for the disinformation.....only been 50+ years ago....mind going fast I guess. Reason I said 99 cu inch, I was amazed at the time that they were getting 1.5 Hp per cu. in. and that is why I thought what I said. On the 140, had to make room for the V6. Probably just reduced the jet size....yes no???