Set Up Help 11' Tunnel

[Infoless Racer]

It should be able to turn 6500 to 7000 with no problem. It is basically the same as a SST 45 powerhead.
Mark N

Mark with my Tohatsu M50D2 3 banger, what rev would it do stock without exploding

Guess Sport C runs the Tohatsu 40C which is a small simpler block....

[MN1]

The Tohatsu powerhead used in the D class in Stock Outboard produces 57.8 HP at 6500 RPM. So, I would think 6500 to 7000 should be OK for your motor since it is the same powerhead. I believe this D class motor has it's crank welded by the builder (Bass). But in Sport C I have never heard of any problems with the cranks when turning high RPM's. Crank welding is not permitted in Sport C class.
Mark N

[JohnsonM50]

The Tohatsu powerhead used in the D class in Stock Outboard produces 57.8 HP at 6500 RPM. So, I would think 6500 to 7000 should be OK for your motor since it is the same powerhead. I believe this D class motor has it's crank welded by the builder (Bass). But in Sport C I have never heard of any problems with the cranks when turning high RPM's. Crank welding is not permitted in Sport C class.
Mark N

The stock Tohatsu will be fuel injected While the Bass is carburated? Is there much difference?

[MN1]

The Tohatsu M50D2 is carburated. The new ones produced for consumers are fuel injected and have the model number MD50BE.
So far the only ones I know of being used for racing with fuel injection in the USA will be the Merc 60 four stroke and the motors used in Champ class and drag racing. I'm sure it will work fine. Lots of engineering goes into them.
Mark N

[Infoless Racer]

Guys thanks. That is assuring.

I have a dumb question. I am trying to run the aeromarine research tunnel hull program. I do not have my engine with me yet, it on order. Can anyone tell me the dimensions of the lower unit and skeg. Mark I think you know what I mean as you have the prog.

Torpedo diameter
Skeg width
Skeg height
Skeg thickness

Thanks

[MN1]

I looked at my program and it looks like it is listed in the Nissan category.
If you don't have it I'm sure Jim will find it for you. Shoot an email to him and he will respond with an answer right away.
Mark N

[Infoless Racer]

I just might do that. My program is the 7.0 verson which has very little data on Nissan/Tohatsu, thanks

[marinetech51@earthlink.net]

I can give you some Sport C info. Our 40 hp Tohatsu's have a 13:25 gear ratio and we use Merc Hub Cleaver11.25" to 12" dia x 18" pitch props. No low water pickup and no nose cones. My motor is set at 5/8" above the bottom at 3 degrees trim. Our race weight is 675 lbs.
Hope this helps,
Mark N

Mark, what part of the motor is 5/8" above the bottom?

[MN1]

It's the middle of the prop shaft. But this takes into account the transom setback. So, actually the prop shaft is 5/8" above the water when the boat is trimmed at 3 degrees. (On paper that is).
Mark N

[Infoless Racer]

Mark you have a unique one-off design of your tunnel. You have any pictures posted here in the forum?