3.5cc Tunnel Hull Newbie Tips?

[Mitchel Kauppila]

Hey Guys!

So I am a newbie to Nitro boating. My dad has done it years ago with a Dumas hot shot 3.5cc K&B for leisure purposes, never raced. My background is mainly Nitro Sedan, Nitro Offroad and Electric 1/10 offroad cars. I recently purchased 2 VS1 Tunnel Hulls through Tower Hobbies for my dad and I. We will equip them with OS outboards and run in the IMPBA B Sport Tunnel class. I live 10min from the Badger Boaters in Kenosha, WI, and plan on becoming a IMPBA and local club member next month. So a couple questions:

1:I have read the IMPBA rules and understand that P/S modding, crank filling,crank balancing, and case modding is all legal? As long as I don't modify the carb bore and exhaust outlet?

2: Anybody use setup boards for boats? http://ne-stuff.blogspot.com/2009/05/building-vs1-part-ii.html

3: Also, I come from transponder scoring for surface racing why hasn't the boating community evolved to this type of scoring?

4: Any cool boat box ideas? I really want to make my own!

Those were just a few questions on my mind. I am aware that some have heartburn over the rules and this thread is not meant for bickering, just understanding the realities of the current rules. Thanks!

 

[Kevin Krogness]

I'm no expert but I believe internal mods are allowed just can't touch the outside and openings must stay the same and lower left untouched. Everyone uses some sort of setup board. And I Imagine the transponder setup cost more than most clubs want to spend.

Good luck to you guys this race season!!!

 

[RonShaw]

Mitch,

You are correct. In IMPBA Sport B you can do internal mods, no problem. Carb and Exhaust bore must remain as-is. You are not allowed to mis-match air and water cooled engine/lower parts, so basically, everything you can see on the outside of the engine must remain intact. In NAMBA Stock B, it must remain just that, stock on the inside and outside. Also, Carl Van Houten (Vans Racing) is working on an awesome tunnel setup board he will be offering for sale. You should be seeing news about it very soon. I hope this helps...

 

[Slideblues]

Mitchel Welcome,

The manual with that hull is very well written.

With tips along the build in the "Grimracer Says"

Mike Z. is a member here and will gradly help out if you get stuck or have a question.

Good luck,

Gene

 

[Grimracer]

Mitchel,

VS1 strikes AGAIN..more new RACERS! Welcome to RC boating.



The guys got you straight on the motor rules. There are a few guys in dist 4 that change the inside of the motor and some that dont (like me). I set the head space to .003" (Pull the shims) and leave it at that. Please feel free to ask questions at the races this summer.

I use a setup board. Its a simple board with a slot for the lower. I also have slots on the side that hold a length of music wire. This wire is used under the boat to measure the balance point. (it teeters on the wire).



Believe it or not the system we have for scoring is about as good as it gets. we HAVE to have a spotter anyway.. so he might as well count. So you know we have raced with transponders before and it can be made to work but its just not worth it. Running the bridge is part of the challenge.

Boat box? I have a 5X10 trailer.. and if you lose your mind like most of us... in time... you will too!



Grim

 

[Mark Simmons]

Stock engine w/ tune pipe. Legal for b sport?

 

[Mitchel Kauppila]

Stock engine w/ tune pipe. Legal for b sport?

No, has to come from the factory. So OS and K&B engines w /lowers with stock exhaust only..

 

[Kevin Krogness]

Don't forget the Thunder "kitten" Tiger!!!

 

[HTV Boats]

"Stock" is a word not used as it implies nothing other than out of the factory box and "sport" allows for some internal modification. Exhaust it the leveling field here as without a tuned pipe mods are less effective. Conversely I have taken an unmodded (other than head clearance)OS and with a two bolt change added a tuned pipe which makes a difference. Not super Nova but a powerplant capable of being driven to the podium at any race. An easy switch that can be done between heats and race both .21 classes. For a marginal mod boat like a VS1 an OS with a pipe will be a challenge to drive but doable.(sp).

Mic