9.8 hp vs 9.9 hp outboard engines

[OnLakeLawrence]

I'm familiar with why there are 9.9 engines, but can't find much info on why manufactures make a 9.8 hp motor. Anyone know? State restrictions as well? Thanks.

 

[matt167]

Tohatsu I think started that and other manufactures followed. The 9.8hp are tuned up 8hp variants, and the 9.9hp are de tuned 15hp variants. They are sold at different price points, and weigh differently

 

[racerone]

Marketing 101 and just a decal.----I think you will find that an 11 hp motor cab be marketed as a 9.9 and a 14.1 can be marketed as a 15 HP.

 

[OnLakeLawrence]

Tohatsu I think started that and other manufactures followed. The 9.8hp are tuned up 8hp variants, and the 9.9hp are de tuned 15hp variants. They are sold at different price points, and weigh differently

Yep, that is where I saw it, a Tohatsu motor. Thought I might learn something, but as racerone says, marketing might explain it.

 

[matt167]

Yep, that is where I saw it, a Tohatsu motor. Thought I might learn something, but as racerone says, marketing might explain it.

It's not marketing in this case. In the case of Tohatsu, The 9.9 is 333cc and the 9.8 is 209cc. They are different motors. 9.9 and 9.8 both exist because of 10hp limited lakes, but between those motors, they are built for different purposes

 

[Sea Rider]

Yep, boaters thinks that one decimal point won't make that much difference but in this particular case it's 124 CC more, extra added weight and more money involved...

Happy Boating​

 

[OnLakeLawrence]

It's not marketing in this case. In the case of Tohatsu, The 9.9 is 333cc and the 9.8 is 209cc. They are different motors. 9.9 and 9.8 both exist because of 10hp limited lakes, but between those motors, they are built for different purposes

And those purposes are? I’m a little dense. Why would a company make two different motors for 10 mile lakes? Thanks.

 

[JimS123]

Tohatsu is a relative newcomer in the outboard biz. Back in the Day Merc always had a 9.8 while the 'Rudes were 9.9. Probably a marketing thing back then, one just trying to distinguish themselves from the other. Its not just a lake requirement thing, but also an under 10 HP racing class.

 

[racerone]

Your lake might be 10 miles.----But when a motor leaves the factory they have no idea where it ends up.----The type of boat that it is going on !-----Or if the operator is 20 years or a 70 year old careful fisherman , operator

 

[matt167]

And those purposes are? I’m a little dense. Why would a company make two different motors for 10 mile lakes? Thanks.

Bigger boats vs smaller portables

 

[Scott Danforth]

merc started the 9.8's in the 60's the 7.5hp and 9.8hp motors were 11 cubic inch twins. same motor, different carb.

later the merc 9.9's and the 15's were same as the motors got fatter, er bigger in displacement like the OMC product. the 9.9's getting a smaller carb

the whole thing started as a need to be under the 10hp rule for HP restricted lakes.

in fact many of the 15hp motors were re-decal'd as 9.9's as people like to cheat

@OnLakeLawrence Matt covered the needs for two different motors, and I will expand on it. the smaller displacment motor is much lighter so when you have portage, you dont throw your back out. the larger kickers work best lugging as they have more low end torque. difference in weight between a 11 cubic inch 9.8hp 2-stroke and a 20 cubic inch 9.9 2-stroke compared to a 9.9 4-stroke is 67# vs 75# vs 112#

when needing to carry the motor, light weight is everything.

reference https://forums.iboats.com/threads/w...993-20hp-and-1986-9-9hp-all-2-strokes.537607/

 

[racerone]

The 7.5 model had a ----COMET ---decal on it.-----Intake ports on the side of the cylinder were smaller on the 7.5 comet than the lightning 9.8 engine block!

 

[flyingscott]

merc started the 9.8's in the 60's the 7.5hp and 9.8hp motors were 11 cubic inch twins. same motor, different carb.

later the merc 9.9's and the 15's were same as the motors got fatter, er bigger in displacement like the OMC product. the 9.9's getting a smaller carb

the whole thing started as a need to be under the 10hp rule for HP restricted lakes.

in fact many of the 15hp motors were re-decal'd as 9.9's as people like to cheat

@OnLakeLawrence Matt covered the needs for two different motors, and I will expand on it. the smaller displacment motor is much lighter so when you have portage, you dont throw your back out. the larger kickers work best lugging as they have more low end torque. difference in weight between a 11 cubic inch 9.8hp 2-stroke and a 20 cubic inch 9.9 2-stroke compared to a 9.9 4-stroke is 67# vs 75# vs 112#

when needing to carry the motor, light weight is everything.

reference https://forums.iboats.com/threads/w...993-20hp-and-1986-9-9hp-all-2-strokes.537607/

The only thing I will disagree with there is the Merc 9.9 started out on the smaller block. It shared the 6/8 hp block it did not go to the 15 hp block until early to mid 90s.

 

[OnLakeLawrence]

Thanks everyone, now I can see why a 9.8 would be desirable. Great input.

 

[Sea Rider]

Thanks everyone, now I can see why a 9.8 would be desirable. Great input.

Which brand 9.8 motor do you plan going for ?

Happy Boating​

 

[OnLakeLawrence]

I'm actually going for a Suzuki 9.9. It's for my RIB. I need something with power tilt, as the island I want to travel to and from has a shallow rocky beach. Siince I live on the lake and have a dock, the weight doesn't matter much.

This one ->> 2021 Suzuki 9.9 HP DF9.9BTHS3 Outboard Motor​

 

[reelfishin]

merc started the 9.8's in the 60's the 7.5hp and 9.8hp motors were 11 cubic inch twins. same motor, different carb.

later the merc 9.9's and the 15's were same as the motors got fatter, er bigger in displacement like the OMC product. the 9.9's getting a smaller carb

the whole thing started as a need to be under the 10hp rule for HP restricted lakes.

in fact many of the 15hp motors were re-decal'd as 9.9's as people like to cheat

@OnLakeLawrence Matt covered the needs for two different motors, and I will expand on it. the smaller displacment motor is much lighter so when you have portage, you dont throw your back out. the larger kickers work best lugging as they have more low end torque. difference in weight between a 11 cubic inch 9.8hp 2-stroke and a 20 cubic inch 9.9 2-stroke compared to a 9.9 4-stroke is 67# vs 75# vs 112#

when needing to carry the motor, light weight is everything.

reference https://forums.iboats.com/threads/w...993-20hp-and-1986-9-9hp-all-2-strokes.537607/

The little 9.8 Mercury motors and even the 7.5 11ci motors punched well above their weight but I always felt the lack of prop choices limited their application. They were great on small light boats where the two prop options would work. For the most part, in the earlier motors, the 9.8 came with a two blade prop, the 7.5 came with a lower pith three blade.
Sticking the 7.5hp 3 blade prop on a 9.8hp would make the thing tolerable on a heavier boat in restricted lakes.
I had several of them over the years, they run forever and are easy to work on. On my 14ft boat, the 9.8 would struggle with the stock 2 blade prop, never getting on plane, with the three blade prop, it would get on plane but just barely and if you added any weight, it just plowed water.
On my 12ft Duranautic, with nothing in the boat by me, the 9.8 hp would feel like it was going to take flight with the two blade prop..

For the most part though, the 9.8 vs 9.9, or even 10hp moniker was just for advertising or to differentiate between various models and or series. Actuall hp was likely different than the decal on the side. some higher, some lower than what they advertised. I've seen the same thing with small engines and garden equipment. The only difference between some motors were the decals or max throttle setting, or type of muffler. I've seen a few motors where all the extra cost of two more hp was spent on just a decal and a fancy ad. The actual motor was part for part identical to the lesser, cheaper model. Truth in advertising is just a dream, and more so 40 years ago I guess.