can I make my 40 hp a 50?

[reitsma]

Hi

Bought a 1995 Force 40 hp 2-cyl, good condition, new cpu.

To my common knowledge most outboards can be tuned up (f ex 9,9hp->15hp), is this the same for my 40hp? Can it (easily) be tuned to 50?

Thanx.

L.

 

[steelespike]

Re: can I make my 40 hp a 50?

The Force experts should be along.I can tell you the 40 and the 50 are the same weight and the 89 35 was about 40 lbs lighter.

 

[Frank Acampora]

Re: can I make my 40 hp a 50?

This question comes up time after time!

The short answer is NO! You can not get something for nothing.

This is like asking if you can easily change your Chevy 305 to make horsepower like a 350 since they are both the same block.

I can not speak specifically for the Force 40 and 50 ---BUT-- The old Chryslers from which they were derived have a different stroke and of course different compression. The exhaust chambers were larger on the higher HP engine. Thus, simply changing a carb or other minor changes had almost no effect.

NOW: IF---your 40 has the same bore and stroke as the 50 then a carb change and timing MIGHT yeild extra horsepower BUT--- it is likely that the bypass ports and exhaust ports were cut differently in the two engines and you would be disappointed.

HOWEVER: If you wanted to disassemble the engine and enlarge the bypass and exhaust ports (porting) you would find some extra usable horsepower. IF Boyeson makes reeds for that size engine, you may also gain a bit of power there too.

 

[sweezy722]

Re: can I make my 40 hp a 50?

It looks very simple and tempting from the available information. I have a 1999 40hp Force. The top of the block has a sticker stating timing and RPM specs for both the 40 and 50hp. Parts diagrams state every engine part on both motors is identical except for the main jet in the carb. I bought the jet for the 50hp and put in my 40hp.

It does not work.

At least it does not work the easy way of replacing the main jet. You could probably gain more power by changing the porting, you could have it rebuilt and blue printed like a race engine. However, it would be cheaper to just buy a 50hp engine. Unfortunately my 40 hp will stay a 40 and your 40hp will probably stay a 40. Look at the bright side - that 40 will sip gas if it is like mine.

 

[Frank Acampora]

Re: can I make my 40 hp a 50?

Yep! In the old Chryslers, the 125 and 140 had a stroker crank. The casting and part numbers were the same the only differentiation was a groove cut in the bottom crank cheek. Additionally the 140 block had the same part number as the 115 block and the 105/120 block had the same numbers. The only difference was a splotch of red or green paint inside the bottom of the 140 casting. Port timing was different in all the blocks. Goofy way of separating things. Perhaps this antiquated system carried over into the Force engine line. Even with the larger Force engines, a 120 can not be made into a 125 since the 125 is small bore long stroke and the 120 is short stroke big bore.

 

[roscoe]

Re: can I make my 40 hp a 50?

Actually according the the hp rating rules of the NMMA, ( +/- 10% of the stated hp), your 40 hp could be 44 hp, and a 50 hp could actually be 45 hp. So the two motors off the showroom floor could actually be within 1 hp of each other.

Your best and least expensive option is to make sure the motor is running at its best, and propping it to hit the top of the rpm range. I would aim for 5300-5500 rpm.

 

[reitsma]

Re: can I make my 40 hp a 50?

Thanx!

Haven't had it out on the water yet, but hopefully it will do a 25-27 knots with my 15" Skibsplast, properly tuned. Should be good enough.

L.

 

[sweezy722]

Re: can I make my 40 hp a 50?

I have a Bass Tracker 17.5 feet long. When I first got it the 40 Force had a 13 pitch prop. It would go about 21-22 mph. I later put a 14 pitch prop on and it now goes 25-26 mph. I put a 15 pitch prop on it for 1 day and went around 30 mph. I do mostly fishing and trolling and did not like the take off and trolling with the 15 pitch. All speeds are with fishing gear - 16 gallons of gas - and myself and my son in the boat.