HPBCANADA.COM
https://hpbc.ca/

Not Expensive Why not try a Small Tunnel in Stock Outboard?
https://hpbc.ca/viewtopic.php?f=20&t=4843
Page 1 of 1

Author:  Hounddog [ June 24th, 2025, 3:34 pm ]
Post subject:  Not Expensive Why not try a Small Tunnel in Stock Outboard?

I believe it’s a catch ten.....
https://www.facebook.com/share/14zZse7T ... tid=wwXIfr

Author:  Hounddog [ June 25th, 2025, 7:33 am ]
Post subject:  Re: Not Expensive Why not try a Small Tunnel in Stock Outboa

“What makes and models of outboards would run on that tunnel”?

Because of its size you would run a C or a D class motor.
If you wanted to run a Stock Outboard motor you could run the Yamato C class or the mercury D class motors.

It becomes far more interesting in motor options when you look at the production model two strokes. The transom mounted water pickup eliminates the gearcase from running thru the water. Only the skeg of the motor is in the water. There is less drag resistance with this setup compared to the race motors..

Both the Yamaha 30 triple and the tohatsu 40C twin are C motors.
The Yamaha 50 triple and the tohatsu 50 triple are D motors

In Europe they have been successful with the F4 class. That’s the 60 hp mercury four stroke race motor on a tunnel with transom mounted water pickups. It’s a 65-70 mph class. The drawback is the motor doesn’t turn race rpm....6200 to 6500 rpm is the maximum . The class has been unsuccessful in North America.

To date we haven’t seen development of a small “Race” tunnel in North America. Once a few tunnels get on the race course it shouldn’t take long to have the design refined to make them better.

Is the potential there? YES, the Mod C which ran the Yamaha 30 and in Formula 50 which ran the tohatsu 50D , those tunnels ran 75 to 80 mph and didn’t have transom mounted water pickups.

Page 1 of 1 All times are UTC - 5 hours [ DST ]
© 2000, 2002, 2005, 2007 phpBB Group • http://www.phpbb.com