Any way to increase power?

[Streffpilot]

Ok, so iv got a Mercury thunderbolt 1150. As I was welding away at work, my mind started wandering. Need more power. Gotta has more power.

Any way to get more power out of this engine, or will I have to suffer with only 115 hp :/ ?

 

[gm280]

Re: Any way to increase power?

Ok, so iv got a Mercury thunderbolt 1150. As I was welding away at work, my mind started wandering. Need more power. Gotta has more power.

Any way to get more power out of this engine, or will I have to suffer with only 115 hp :/ ?

The answer to your question is YES. But that cost is the real issue. Anything can be made more powerful but in realistic terms, at what cost? If you know how to port and change timing, not ignition timing but internal timing as to when the intake ports open and close and the exhaust ports open and close. You could even push some nitrous as well. But cost, know-how and many other things cost lots of money and trial and error. Simply changing carbs and such don't yield much with these OBs. If you seriously want more power, buy a 150 HP and apply...

 

[wired247]

Re: Any way to increase power?

Yes. The earlier 140 is basically the same motor with raised ports and the later 150 reeds and different jetting and high domes. You could do it yourself or have someone who knows inlines well port the motor. Raising the ports to 150 specs wouldnt be terribly difficult to do as the ports are accessible from the back side. You wouldnt have the boost ports of the 150 block but neither did the 140's. You'll need high dome pistons. A few hours with a die grinder then a hone job to clean the port edges up. You would have to disassemble the motor and change reed blocks to 150 blocks. . Chris Carson makes a good set of fiberglass reeds for those. The bottom end power will suffer .

That only applies if you have an early 115. If you have the late 115 it is the same motor as the 150 with slightly lower compression and better ignition. Just the rating method changed.

Buying a 1500 powerhead and swapping it is always an option but its a total crapshoot if you dont build it yourself or have a reputable builder go through it. Lots of worn out or just plain shot 1500's out there for sale.

 

[Scott Danforth]

Re: Any way to increase power?

the easiest way is as follows:

unbolt 115 from transom
list 115 for sale
sell 115
take money from 115 and put towards bigger motor
buy bigger motor
put bigger motor on transom

 

[Bob_VT]

Re: Any way to increase power?

Well....... what kind of more power? Are you struggling with a skier? Need more speed?

The block you have might be boosted to a 140 but you will not notice too much .......you will have spent allot of money and the return will be small not to mention you will be risking your current motor.

It was mentioned above......sell it and look for a 150....a newer 150 where the power is measured at the prop and not the powerhead. A newer Optimax 115 is a true 115 at the prop and the even the 125 will blow your shorts off compared to what you have.

The 1982 and later mercs were prop rated HP. The older 115 motors were re-badged as 90 hp and the 140 hp motors were re-designated as 115 hp. So if your motor is pre 1982 you are out of luck and if it is post 1982 the tricks have been done.

 

[jimmbo]

Re: Any way to increase power?

The Late 115 is not the old 150/late140 inline. Reeds are different, as is the porting, and sometimes the pistons are too. Carbs will be different as well

If you decide to tear it down, so not use fiberglass reeds on these engines. They have limited lifetime and being buried so deep in the engine are a real PITA to change when they break.