Trick Out A Force 150hp, Yes Or No?

[scufumup]

OK im back and after getting some great advice on restoring my boat i have decided a new engine would not give me the results i desire in the end. I love my 1989 cobra fish and ski! I will be restoring it this coming winter. what i dont like is when i'm not with the family and i'm doing a little fishing for myself the boat only goes about 38MPH. its a 19' by 8' and is about 2000 pounds. I found out that it was sold as a 1990 because it was new in 1990 and they just put a 1990 force on it and took the 1989 force off it. The specs call for a 150hp engine so i cant really upgrade to a higher HP engine with out some backlash. SO i would like to trick out my 150 a tad to get a little extra uhmfff out of her. has anyone done this or does anyone know how it would turn out if i did do it. could i get a significant out come by tricking it out and if i did what are the costs i'm looking at. By the way i'm not a reckless person i am just looking for some gains!
THANKS FOR ANY ADVICE!
Scott Brown

 

[WillyBWright]

Re: Trick Out A Force 150hp, Yes Or No?

If you want some significant gains, get a Mercury Black Max 150. Heck, even a 135 Black Max would blow that Force out of the water no matter what you did to it. I would expect at least a 10mph gain.

150 was the biggest Force ever made. I wouldn't be at all confident that the gearcase would handle any more. Which is probably a non-starter in the first place. I'm not aware of any performance products made for any Force. There were a few for the older Chryslers, but there was never a 150 Chrysler.

One of the biggest upgrades you can make to any outboard is the prop. There are unlimited possibilities for Mercs. Virtually none for that Force.

 

[Frank Acampora]

Re: Trick Out A Force 150hp, Yes Or No?

It is a winter project: You can port the bypass side and gain a few horsepower, but this requires a full tear-down to do. I did it on a 4 cyl Chrysler 140 and gained about 4-6 mph. I also noticed a slight increase in mileage at cruise. On an 18 footer, I averaged about 5 miles per gallon at about 20 MPH. Top speed went from about 32 to about 36-37

But don't touch the exhaust side. You will actually lose the gains made from the bypass porting. This is because of the overlap of the port timing and the fact that all cylinders dump into a common exhaust cavity. By porting the exhaust, you increase exhaust scavenging efficiency but you also increase the efficiency and amount of exhaust blowback into the cylinder.

Cost is just your time and a Dremel with a flex shaft and some carbide bits. The only other thing you can do, is if you have the small WB carbs. If you can find the manifold plates and TC carbs, that will give a very little more HP.
TC carbs are much larger in bolt pattern, inlet diam, venturi diam, and jet size.

If you truly want to spend the time--hand porting takes 1-2 hours per cylinder-- Search the net. There are several articles there about theory and practice of porting small 2 cycle dirt bikes. They tell what to do for desired results ie. Top end speed or low end torque or mid range power. The basic theory carries over to outboards, but you need to be careful: Most of the bikes are smaller displacement and are tuned piped.

If you want to see what porting looks like, I have several photos of three cyl. blocks on Chrysler Crew photo albums --Frank's boats.

Other than that, like the man said, there's not much you can do.

 

[steelespike]

Re: Trick Out A Force 150hp, Yes Or No?

You could fine tune your set up.specifically raising the motor.If you can gain an inch you could get 2 to 3 mph.Then you could go over to the prop forum they may be able to help you with a better prop.They will need your present rpm and speed, boat type and weight.With the better prop you may be able to get a little more height.Be sure it keeps pumping water after you raise it.

 

[Frank Acampora]

Re: Trick Out A Force 150hp, Yes Or No?

Couple of other hints: Stainless steel prop will give 2-400 more RPM and a few MPH more than the aluminum. My experience with the 3 and 4 cylinder engines is that they do not like cupped props. You will get more speed out of a plain 19 than either a cupped 17 or cupped 19.

Also: If your engine has a 1.78 to 1 lower unit gear ratio switching to a 2 to 1 gear ratio and increasing prop pitch by 2 will also give a few more MPH. This is on the 3 and 4 cylinder engines. Should be the same for the 5--I don't know why it works, it just does. The math is this for example: 1.78 to 1 with a 17 pitch prop is just about equal in theoretical forward distance traveled by the prop to a 2 to 1 with a 19 pitch. To check gear ratio, mark 1 prop blade and set it to vertical. Mark flywheel. turn flywheel until blade again becomes vertical. It will either be about 1 3/4 turns for 1.78 or 2 turns for the 2 to 1.

 

[Matthew A.]

Re: Trick Out A Force 150hp, Yes Or No?

Frank...recommending a Mercury over a Force...have you no shame! too!

 

[scufumup]

Re: Trick Out A Force 150hp, Yes Or No?

ok sorry for my ignorance but i think im about to get ragged on for this question. You tell me to buy an new merc 150 and i will see incredible gains.. what woul dthe differnce be they are bot 150 hp engines? because if there is a major differnce in lower end gearing or fuel injection and it would top me out at a faster speed and keep alot of the power i have then i will be shopping for a new engine tomorrow!
dont come down to hard on this cherry!
thanks for all advice
Scott

 

[Frank Acampora]

Re: Trick Out A Force 150hp, Yes Or No?

It is a well known urban myth that Mercury since its inception as an outboard manufacturer has always under rated the horsepower of its engines. 150 is not necessarily 150. But before you go shopping, remember how much cubic money you will drop for one. The Force has the advantage of being cheap and already on your boat. BTW after this answer, I am going to post a few thumbnails of a HOT 90 Force in Outboard Discussions.

 

[WillyBWright]

Re: Trick Out A Force 150hp, Yes Or No?

In the mid 80s, most outboard manufacturers took advantage of a new method of rating horsepower. Prior to that, horsepower was rated at the crank. After that, horsepower was rated at the prop. About 15% of horsepower is lost in the gearcase, so a 1986 150 has 15% more power than a 1984 150Hp. Force never took advantage. At best, your 150 is a 130 compared to the competition.

There is also a question of displacement. Merc offered a 2.5L 200Hp and a 3L 200Hp. The 3L would blow the 2.5L out of the water by a good 10mph (depending on the boat).

 

[steelespike]

Re: Trick Out A Force 150hp, Yes Or No?

As I understand it The change in about 85 was from crankshaft horsepower
to prop rated hp. Thus in the new rating at the prop was actual useable hp.
Before 85 hp. was at the crank thus hp at the prop was somewhat less than rating I've heard anything from 3% to 15% my guess is 6 to 10%.
Any thing after 85 what you see is what you get.

 

[gregmsr]

Re: Trick Out A Force 150hp, Yes Or No?

38 mph not fast enough? Buy a bass boat.

 

[Bry21317]

Re: Trick Out A Force 150hp, Yes Or No?

I had an 88 Bayliner Capri 19 foot with a Force 125 on it. I had a 17 pitch Hustler Prop on it and it would pull about 40-45 on the lake. I also put Boyeson reeds in it, and they made a world of difference.

I just got rid of the boat 2 weeks ago aftear 11 years of very very few problems with the Force, and went to alot faster boat. I got a 94 Crownline wtih a Mercruiser 305 and thru hull exhaust, so at some point you will want to upgrade. Right now that boat may be good for you.

I know I love my new one, but I will tell you that Force was a work horse.

 

[CharlieB]

Re: Trick Out A Force 150hp, Yes Or No?

Long before tearing that Force down OR spending a pile of money for a newer Merc, you should spend some quality time and make sure that Force is dialed in and running up to 'snuff.

What's the compression?
What plugs are you running and how do they look?
Are the carbs sync'd correctly?
Is the throttle cable adj'd correctly, do you really get WOT?
What is WOT RPM?
What prop are you running?

There are a LOT of factors that need to be double checked before you condemn any engine, you may be surprised how well that Force runs in the right hands.