H.P. Ratings???

[Boilermaker]

I have a 1978 115 Johnson. I have read that the way they rated Horse Power back then is differant then how it is rated now. I was just wondering what the equivalent hp rating on a modern engine would be??? If I repowered to keep the same performance, what size engine would I choose???<br />Thanks

 

[rwise]

Re: H.P. Ratings???

Boilermaker<br />I have read on here that it is about 15% diferance, so about 100 hp today = 115 hp yesteryear.<br />Richard

 

[rickdb1boat]

Re: H.P. Ratings???

If you were to re-power, I would stick with a 115 HP or close, as it will only give you more power than the old one and more satisfaction. I would not drop down to say, a 90HP, as I believe you would be dissapointed with the performance. I understand it's only about 6-8% difference, but I could be off on that one.

 

[Dhadley]

Re: H.P. Ratings???

Your motor was flywheel rated and the new ones are propshaft rated. You also have to remember that the NMMA allows the motors to be within 10% of their advertised horsepower. <br /><br />Some "familys" of motors have their "members" rated at different rpms to get different advertised horsepower. <br /><br />Torque is what you want to look at and nobody publishes that. Lets look at your motor and compare it to todays two stroke V4's. The 60 degree V4's are light and rev up quick. They make more torque than your crossflow. The 90 degree looper is heavier than yours but is a torque monster. And loves rpm. And the DI motors get way better fuel milage.<br /><br />Good luck!

 

[Walker]

Re: H.P. Ratings???

Dhadley pegged it. My 120 looper has a ton of guts. Cubic inches do matter.

 

[Boilermaker]

Re: H.P. Ratings???

Did they Increase the engine displacement on the loopers??? I would have imagined the same bore & stroke between the x-flow 115 & the looper 120. But what do I know??? Is there ANYTHING I can do to increase the power(low end torque, or high end HP) of my 115 without giving up reliability??? Just curious>>> <br />Thanks

 

[spike440]

Re: H.P. Ratings???

I know my 71 Johnson 50 looper is a beast. My gps says I can wring a blistering 15.4 mph out of the mighty pontoon at full throttle...if I'm alone. lol<br /><br />-Spiker

 

[Dhadley]

Re: H.P. Ratings???

The 3 motors are all a completely different design. Yes you can fiddle with the crossflow and improve it somewhat but it will never produce the torque either of the other two do stock.<br /><br />You asked about repowering and maintaining the same performance level. The newer crossflows will maintain that same level, perhaps slightly more due to better gearcase shapes. Same bore, stroke and gear ratio. Repowering with any V4 looper (60 or 90 degree) will only maintain present performance levels if the set up is off a mile. Otherwise you will gain performance. <br /><br />Good luck!