Increased outboard motor horsepower by more then 20%!

This week on the channel, we walk through how we increased the horsepower of out Tohatsu 8hp dinghy outboard motor to 9.8Hp, a 22.5% increase. In doing so, our 9' 8" aluminum rib now planes with 3 people aboard where it would don't do the with 8hp.

We love the ocean and boating! We cruise in our 2001 Sea Ray 400 Sedan Bridge, Calypso II, on the South Coast of Massachusetts and Cape Cod and the Islands. Join us on our adventures - we share favorite ports and places to visit, favorite boating products, and how-tos.

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+ Our current boat - Calypso II, a 2001 Sea Ray 400 Sedan Bridge:

In 2019, we wanted a new boat that was bigger and had a longer range, so we targeted 40-footers with diesel power to achieve both of these goals. With our criteria and budget, we searched for a diesel-powered Sea Ray 400 Sedanbridge 2001 or newer. After scouring the Internet we found a boat on the Chesapeake Bay which would become Calypso II.

+ Specs - 2001 Sea Ray 400 Sedan Bridge:

• Length: 40 feet
• Beam: 14 feet
• Draft: 4 feet
• Fuel: diesel 350 gal
• Power: 2 Caterpillar 3126 inboard straight-shaft turbocharged diesel engines 350hp each

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+ Dinghy

2021 North Atlantic Inflatables, 9" 8" Aluminum RIB
Tohatsu 8Hp outboard motor

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+ Where we cruise:

Calypso II is moored in Sippican Harbor in Marion, MA - in Buzzards Bay. We use our boat to explore the islands, ports, coves, and harbors of this amazing place.

For overnight boating, we often head to Cuttyhunk Island, Martha’s Vineyard Island or Nantucket Island, off the coast of Massachusetts. In 2021, we plan to head to Maine to explore some of the beautiful harbors and ports of Southern and Mid-Coast Maine.

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+ Our commitment to the sea:

Because we enjoy boating and the fun it brings our family, we are committed to protecting the bays, harbors, and oceans we cruise on, as well as the ones we dream about. Starting with following no-discharge rules, not using disposable plastic bottles, and only using biodegradable products on Calypso II, we try to do our part to preserve this invaluable resource.

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Join us on our adventures - we share favorite ports and places to visit, favorite boating products, and how-to's.

[christboyce]

If you look down the front opening of the carb, the orifice for air intake should be larger. look behind the choke plate. This combined with a larger jet will make the engine generate more power.

[Pleipoy]

I also have an 5 and 6 hp. They also run exactly the same speed provided you change the prop om the 5.

[Auddictive]

I guess you also need the exhaust port round part.

[jamesfairhurst]

I have just bought a display 8hp Parsun motor. I understand it is a Mercury/Tohatsu clone. I plan on doing this exact same conversion, using an inexpensive generic 9.8hp carb. Can you please elaborate on what was misaligned so that the choke was jammed?

[vihreelinja]

this does not boost hp. Adding more fuel will just make the mixture rich so it might have a bit more torque but it will loose peak hp. To get more hp you need to add more fuel and air.

[jonathansantillan]

I am interested in your old carburetor if you still have it laying around?

[coochieman]

Dude did you voice Chris from family guy Lol

[thomasmartenson]

I made the same mod but changed back because the 8 carb runs exactly the same ie. NO power increase what so ever.

[stephanekerouack]

If you do some porting you will get even more

[omieyouknowme]

9.9 is completely different bigger block more weight. 8-9.8 are proven motors for tohatsu dont break if it isnt broke.