×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Mokai boat

Mokai boat

Mokai boat

(OP)
I have a Honda gc190 in this boat I would like to increase its speed.
Any suggestions?

You can see this boat at mokai.com

RE: Mokai boat

Fit a more powerful motor that develops the same torque but makes more power by making more rpm.

Apply standard hot rodding technique to your engine, ie bigger valves and ports, higher compression, higher lift and longer duration camshaft, tuned low back pressure exhaust, bigger carby and manifold runners.

If you increase the torque to much, you will also need to change the jet unit to gain speed.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.

RE: Mokai boat

What I've seen with squirted boats is the pump is matched to the engine.  Tuning the engine will get you faster accelleration, but not more top speed.  If you increase the RPM of the engine, the pump (fan laws) kick in.  If you double the RPM, the power required to run the pump is increased by rpm^3, so a small increase in rpm requires a big increase in HP.

RE: Mokai boat

It looks pretty slow on those videos, so I assume that you would like it at least twice faster. Probably even more than that. It can’t be done with existing engine and pump. Even if you double the power it will be only 25% faster, but only if you match the pump. To make it twice faster you would need about 50HP with matching pump.

Conclusion is that you need engine and pump from one of those skidoo’s. In order to stay alive in that think you would need to make that boat strong enough for that speed. At least two longitudinal stiffeners all the way. Another problem is: will it float with all that additional weight. Good luck.

RE: Mokai boat

I looked at the web page.  That boat doesn't look like it has a hull that will allow much more speed.

RE: Mokai boat

(OP)
I can add stiffeners to the inside. I believe that the pump is designed to turn 6000rpm and is only using 3600rpm so there is wiggle room.

 The real problem is finding a motor that maintains torque at a higher rpm.

 Find the answer to this problem and I can line people up to purchase your solution.

RE: Mokai boat

A turbocharger or supercharger could give you the desired results.

The power band from a turbo instalation will more accurately match existing pump, so long as the pump will handle the torque.

If it is rated to higher rpm, it should be rated to the torque required to obtain that rpm under load. The water inlet will need to cope with the extra inlet water flow to avoid cavitation.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.

RE: Mokai boat

If pump will work at 6000 rpm, which is quite probably, it can consume 25-30 HP. Original engine can’t be blown to that power. You need bigger engine: air cooled, light, 30 HP @ 6000 rpm. There is a bunch of them for ultralight planes. Rotax 370, Kawasaki 340 … Round $1500 new. Used can do. You are not going to fly it. Hopefully. smile

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources