150 hp. Johnson vs 175 hp Johnson

[285proxl]

I just purchased a 2005 285 pro xl stratos with a 150 hp Johnny. I am turning a 25 4-blade renegade at about 5200 (I still have a little pedal left.) Also have a 6" jackplate. I was reviewing the specs on the 150 hp and the 175 hp. They seem to be the same engine. Could anyone tell me the difference between the two? And could you get 175 hp performance out of the 150 with minor modifications? <br /><br />If I were turning 5500 rpms on the same boat, same prop, same setup, what would be the difference between the two engines as far as performance.<br /><br />thanks

 

[rabidfish]

Re: 150 hp. Johnson vs 175 hp Johnson

If you were turning the same rpms, with the same prop, you would be going the same speed...<br /><br />Know this about modifications... Every dealer in the US has signed an agreement to not modify that engine. ( it's part of the standard dealership agreement ) Any changes will almost certaily void your warranty, & just cause confusion for a service technician.<br /><br />Having said that, there is a difference in the carbs, but the cylinder block is different also. Beyond that, I am not certain... Good luck !

 

[Dhadley]

Re: 150 hp. Johnson vs 175 hp Johnson

Welcome!<br /><br />There are some things that can be done to the powerhead but with your present set up at 5200 I doubt you will see much increase. You arent taking advantage of what you have now. You will be much further ahead, money and time-wise, to work with the set up to get the true potiental out of what you have.<br /><br />Even with certain mods you will still have the same displacement, bore, stroke and gear ratio of the 175. <br /><br />You have a good hull which should respond to set up improvements very well. You have a jackplate and a decent prop. Once you get to 6000 your rig should really come alive. <br /><br />5200 is lugging the motor. Let her breathe!

 

[285proxl]

Re: 150 hp. Johnson vs 175 hp Johnson

I was told not to run the engine more than 5500. I have had several people tell me I could turn 5800 - 6000. I will say this, when turning 5200 the boat is performing very well as far as speed and lift. If 5200 is lugging the engine, will that cause problems down the road? I have a 24 3-blade I could put on the motor, that should increase the rmps a little.<br /><br />Thanks for your responses!

 

[JB]

Re: 150 hp. Johnson vs 175 hp Johnson

The main differnce between the 150 and the 175 is a few hundred bux.

 

[crazy charlie]

Re: 150 hp. Johnson vs 175 hp Johnson

When I was looking at some engines ,I had a mechanic at a dealer tell me that the motors are the same except for the carbs.I was referring to the weight of the motor and that was the answer I got.Charlie

 

[Dhadley]

Re: 150 hp. Johnson vs 175 hp Johnson

Lugging the motor like that increases the combustion temps. That promotes coking and the related problems coking causes.<br /><br />Dont worry about the rpms. If the motor wasnt meant to be turned then the rev limiter wouldnt be at 6200 or 6700.

 

[Mercathode]

Re: 150 hp. Johnson vs 175 hp Johnson

Lower your pitch to 23 and pick up a few more g's. 150's are not free breathers so power falls off after 5500. A 175 would develope more power and pull the same prop at more rpm giving you more speed. The blocks of the 175 and the 150's are essentially the same. They have to detune the 150 so it will only produce 10% +or - 150. The 175 is built to produce 10% + or - 175 with a similar block. They often do this by carbs size, porting, exhaust defusers, compression, etc. A 175 will have more hole-shot, more mid-range, and more top end speed and cost a few hundred bucks more but worth it. I would not recommned trying to make your 150 a 175. The cheapest way to get Horse power is when you buy the boat.

 

[walleyehed]

Re: 150 hp. Johnson vs 175 hp Johnson

Yea, kinda like making my 150 blow a 200 away.<br />Proper set-up is way more important than 25 HP when in this range on this type of boat.<br />Find the optimum heigth and set back for the maximum RPM possible, and by no means be afraid of 6K. 5500 would be the absolute minumum you would want. <br />If you haven't found the max heigth or tried some shims on the transom, and are not yet to the point of ventilating, we have some set-up work to do.....and if Dhadley says 6200, then he's the man in the know...he helped design these engines, so listen up if you want to maximize your set-up.