# 8hp vs 9.9 hp



## Brett (Jul 16, 2008)

If we're talking about new 4 strokes, they're basically the same engine.
Difference in speed is 2 or 3 mph under load. The important part is that the 9.9
doesn't have to work as hard as the 8 to maintain the 8's top speed under load.


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## Frank_Sebastian (Oct 15, 2007)

I have an 8 HP 2 stroke Tohatsu and a 9.8 HP Nissan with a Sting Ray foil on it They have the same prop and are essentially the same engine. My hisider will run faster with the 8 HP without the foil even though it has less HP. I have never tried the 9.8 without the foil.

Best regards,
Frank_S


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## noeettica (Sep 23, 2007)

Kinda weird how some of this works the Tohatsu 9.8 is the same as the Merc 9.9 (4 stroke) you would be very happy with one of these ...Run a 10 pitch prop 

Lots of differences through the years Older 9.8 Yamaha 4 strokes are a bit heavy 

The 8 and 9.8 tohatsu 2 stroke are the same motor only difference is carb 

also some motors just run strong same model just production variations 

If you put a 15 hp carb and tuner on a 8 hp merc it will scoot ... horrible idle though ... uses lots of gas ...


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## hennavin (Jan 24, 2010)

NoeEttica,

the merc I am looking at is a 2000 8 hp and the other is a 2003 yamaha 9.9 hp. $650 for the merc and $800 for the yammie. what do you guys suggest?


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## noeettica (Sep 23, 2007)

If 2 stroke get the yamaha


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## firecat1981 (Nov 27, 2007)

I'd go with the 9.9hp yammi, it literally has 20% more power then an 8hp and it's 3 years newer for the same weight class. Thats assuming they are both 2-strokes or both 4-strokes.

Frank, why would you be running the same prop on both motors? Wouldn't that be kind of handicapping the 9.8hp since it should be running a higher pitch and thus running faster at speed given equal rpm's?


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## noeettica (Sep 23, 2007)

If Its the 4 stroke yamaha it is Too heavy ...

can you PM me photos of both motors cowl off showing carb


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## jlee150 (Oct 29, 2009)

Buy the merc, if its a two stroke all u need is a carb to go from an 8, 9.9, or a 15 identical power head diff carbs


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## hennavin (Jan 24, 2010)

is the 2006 yami 9.9 4 stoke still to heavy??


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## noeettica (Sep 23, 2007)

91 pounds I have run an 87 pound motor on a Highsider ... You may need to run a tiller extension but If you Don't overload the boat it could be doable ...


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