Difference between 135 hp and 150 hp Black Max Outboard

[Chip S]

From 1992 to 1999 Mercury used the same powerhead, gear ratio, and propeller for the 135 hp Black Max and 150 hp Black Max. I can't figure out what the difference was between the 135 hp and the 150 hp. I have the 150 hp Black Max and my performance is comparable to someone who has the same boat with a 135 hp Black Max. Does anyone know what the difference was?

 

[scoflaw]

Yamaha and Johnnyrude did the same back in the day. 3 different power levels with the same displacement.
Different compression, timing and fueling. Usually the one with the lowest hp output would last the longest.

 

[northern]

With the 9.9 and 15 the 15 turns at higher RPM.

 

[blaster]

Same torque to get out of the hole and a little more speed with significantly more fuel burn for larger motor.

 

[Chip S]

I studied the service manual for the 135 hp and 150 hp Black Max outboards. The only difference between the two is the carburetor jet size. Everything else is the same.

 

[Riptide III]

I studied the service manual for the 135 hp and 150 hp Black Max outboards. The only difference between the two is the carburetor jet size. Everything else is the same.

Wow! I had twin 135hp on my boat. I didn’t think it was possible to get those pigs to burn even more fuel.

 

[scoflaw]

I studied the service manual for the 135 hp and 150 hp Black Max outboards. The only difference between the two is the carburetor jet size. Everything else is the same.

Doubt it, just adding more fuel won't work unless you add more air, probably has a bigger carb on the 150.

 

[Chip S]

Doubt it, just adding more fuel won't work unless you add more air, probably has a bigger carb on the 150.

Agreed. Not that I'm recommending it, but someone looking to change their 135 hp into a 150 hp should change the entire carburetor assembly, not just the jets.

 

[blaster]

I don’t think a few more MPH is worth the added expense for carbs and more gas. Low end will be the same. Been there done that with the 75 vs 90 elpto.