Tunnelstuff in Norway

[Joern Markset]

It`s been quiet for a while... Just wanted to share some stuff I`m working on
This is a new gearbox for the 45 tunnel. It is supposed to carry 2 x .21 engines (Or whatever will fit in a .21 mount)
I really believe I will get more power from 2 times OS R2104 than from a single NR .46. Of course there some challenges, but if there wasn`t it would be very very boring ;-)

 

[Carl Van Houten]

Me and Talley worked on a twin 3.5cc tunnel (Shaman) a few years back that was very successful. I machined a dual engine mount that allowed us to mount two complete engines together. I made a couple of 442's for it to start with and that worked good but then I made a pair of 1440's that really got it rolling.

It was very fast but where it would get you in trouble is during mill time. You had to keep the heat up in the engines (water cooled short muffler versions at the time) and those engines were lacking torque and letting them cool down any during mill time would make that problem worse. The new long muffler air cooled version engines should be a lot more spunky off the kick. That was a fun boat. We still have it and have recently talked about getting it back out. I am looking forward to seeing what you come up with.

-Carl

 

[Kris Flynn]

I assume this is 2 X motors to 1 shaft? Sweet idea if that's the case!

 

[Kris Flynn]

BTW, I was running my pretty much bone stock Nova 46 recently (head volumes reduced a fair bit, mainly due to cleaning up squish after some piston failures lol) and I was VERY happy with its performance.

What did you not like about the 46 Nova or what was it not doing that you need it to? I understand you run tight corners and short straights...did you try a smaller (10mm) carby??

 

[Joern Markset]

Me and Talley worked on a twin 3.5cc tunnel (Shaman) a few years back that was very successful. I machined a dual engine mount that allowed us to mount two complete engines together. I made a couple of 442's for it to start with and that worked good but then I made a pair of 1440's that really got it rolling.

It was very fast but where it would get you in trouble is during mill time. You had to keep the heat up in the engines (water cooled short muffler versions at the time) and those engines were lacking torque and letting them cool down any during mill time would make that problem worse. The new long muffler air cooled version engines should be a lot more spunky off the kick. That was a fun boat. We still have it and have recently talked about getting it back out. I am looking forward to seeing what you come up with.

-Carl

That is very interesting, Carl. It is really exciting to read about what all of you have been into.
You mention lack of torque, that is a big issue and a challenge. In Norway we don`t have any milltime for the tunnels as the race starts from the pontoon. We have been working with our setup to maintain the working temperature, that means small coolingheads/jackets and very restricted watercooling even no watercooling at all if it is cold weather.
It was very noticeable when I started using the car engines (they have large cooling heads) engine was fine until I had like 50 meters on the water, then it became veeery rich due to overcooling.
In my head there is a voice telling me that I will gain torque using two engines over one, even if the combined enginevolume is less than the .46 the .21 on-road engines are very powerfull. Of course they are dead lazy on low rpm, but that is taken care of by the gearbox. I had great succes on the .21 with a gearbox. One engine is at TDC when the other one is at BDC.
And I have to say the sound of two engines screaming at 40K rpm is just sweet music to my ears, that`s just a bonus.

I`m also thinking of 2 x Novarossi 46 mounted on a gearbox.... I`ve allready ordered engines for this purpose...
This has nothing to do with racing, it is just me who find it very interesting to make stuff and see if it works the way I want it to work. I guess you understand 100% what I mean

 

[Joern Markset]

BTW, I was running my pretty much bone stock Nova 46 recently (head volumes reduced a fair bit, mainly due to cleaning up squish after some piston failures lol) and I was VERY happy with its performance.

What did you not like about the 46 Nova or what was it not doing that you need it to? I understand you run tight corners and short straights...did you try a smaller (10mm) carby??

Yes, Kris, that was the idea, two engines to one prop.
You might have misunderstood me, cause I`m veeeery satisfied with the Nova .46, in fact I would pick that engine over any 7,5 on the market.
The only thing I don`t like is the Nova carbs. The Nova carb was replaced rather quickly with a 10 mm OS carb, and that made the trick. Later on I replaced that carb with another OS carb with 3 needles and mounted floatchamber. That was an amazing experience.
So as an answer to your question, the Nova .46 does everything I need it to do. And it is very reliable, I`ve been trying to kill these engines for quit a long time, but I have not succeeded on that task so far...

 

[Carl Van Houten]

Joern,

The water cooled O/S had a short muffler and you had to have a prop with enough pitch to get you to the upper 50's but one that would also allow the engine to make to rpm needed. The old saying "heat makes power" is always true but too much heat is bad. Its a game of heat and pitch. We always thought that the original engine was a slacker in the corners and apparently O/S did too and is why they went to the longer muffler and air cooled head.

The air cooled O/S is noticeably faster than the water cooled version right out of the box but be careful...that extra heat can also kill that P/S fit and if you hang too much wheel on it one time or over lean it, then it's time to pay for your mistake by replacing that P/S.

On our twin we struggled with the inside engine going lean in the corners and actually ended up tipping the inside prop by about .015" and set it about two clicks rich to help. It was fine once we did that. Yes, It was a compromise but nobody ever knew the difference but us. Your single prop setup will cure that issue.

I like the water cooled head and long muffler combo.

 

[jsmidt]

This picture is not of a twi, but intended to illustrate some of the issues reflekted in recent posts.
An OS (car) engine with an outboard crank, mounted on a K&B leg(adapter plate designed by Jørn), a water cooled head(initailly dry or with limited flow), a three-needle carb, a float chambet and a tunedpipe/sikencer combo to fight noise. We are struggeling a little bit over here due to a 20%nitro limitation.

 

[anders-e]

Jörn
Somewhere I´ve been reading you are with success using three needle OS carb for the Nova 46
which one are you using.
Thanks

//Anders

 

[Joern Markset]

Jörn
Somewhere I´ve been reading you are with success using three needle OS carb for the Nova 46
which one are you using.
Thanks

//Anders

I am using several carbs, so far mostly 60M and 40L

 

[Kris Flynn]

Yes, Kris, that was the idea, two engines to one prop.
You might have misunderstood me, cause I`m veeeery satisfied with the Nova .46, in fact I would pick that engine over any 7,5 on the market.
The only thing I don`t like is the Nova carbs. The Nova carb was replaced rather quickly with a 10 mm OS carb, and that made the trick. Later on I replaced that carb with another OS carb with 3 needles and mounted floatchamber. That was an amazing experience.
So as an answer to your question, the Nova .46 does everything I need it to do. And it is very reliable, I`ve been trying to kill these engines for quit a long time, but I have not succeeded on that task so far...

Excellent, was just curious.

So in other words, you are a tinkerer and just never quite satisfied ;-)

 

[Julio Almazan]

Hi there:
... just a couple of things...

Me and Talley worked on a twin 3.5cc tunnel (Shaman) a few years back that was very successful.I machined a dual engine mount that allowed us to mount two complete engines together. I made a co uple of 442's for it to start with and that worked good but then I made a pair of 1440's that really got it rolling.
It was very fast but where it would get you in trouble is during mill time. You had to keep the heat up in the engines (water cooled short muffler versions at the time) and those engines were lacking torque and letting them cool down any during mill time would make that problem worse. The new long muffler air cooled version engines should be a lot more spunky off the kick. That was a fun boat. We still have it and have recently talked about getting it back out. I am looking forward to seeing what you come up with.
-Carl

Where can I get this information?... Is there a post about that work?... Any link?, PLEASE!!!

So in other words, you are a tinkerer and just never quite satisfied

As is generally known, Spain is going through a very, very committed health crisis ... the only thing we can do is stay at home ...
So I am taking advantage of these quarantine days to read the wonderful posts that you write ... Thank you ... really, thank you

Thanks to all of you for contributing in this forum

 

[Joern Markset]

So, it was time to release the new moulds for the two new Noddcat design. First out is the .21 size.
This time I did not mould them myself due to lack of time, so I hired a friend of mine to take care of the ****** work. Came out nicely.

 

[Joern Markset]

Cowl for the .21 boat popped out not too bad. Actually I had a moment of satisfaction *lol*

 

[Carl Van Houten]

I posted pictures of that boat on here a while back. I'll look around and see if I can find them. Jerry Dunlap had a buch of pictures of it years back... What Joern is doing should work too. I like driving one prop better. That is the way to go for sure.

 

[Joern Markset]

I have made a testprint of the gearbox, some adjustment is needed.

 

[Carl Van Houten]

That's COOL! You inspired me to make one too. I had to space the centers out on mine to get them indexed to 90 degrees (45 degrees off center for each). Your project is so cool. Thanks for sharing.

 

[Brian Sorgente]

Very cool stuff. What kind of gearing and ratios are you guys planning to use?

Brian

 

[Joern Markset]

Very cool stuff. What kind of gearing and ratios are you guys planning to use?

Brian

I am planning around 1,5:1
Steel pinion and brass spurgear

 

[Carl Van Houten]

Very cool stuff. What kind of gearing and ratios are you guys planning to use?

Brian

I have been bouncing info off of Joao Xavier and I am hoping to fall into the 1.25:1 range but I am finding out that this may not be the case. I had originally thought I would use a timing belt to drive the prop shaft but that may change. A belt drive would mean 2 outboards and gears would mean 2 car engines so I will see what works best.