another Snow engine

[fumopuc]

Before I go ahead with the report about R&D work here  I have to own up to an another boo-boo, discovered in the centrifugal pump.
At the beginning of this session, I have mentioned, that the pump was blocked after long time at the shelf.
I have found the flow diagram at my collected Snow date file and looking at it, there should be some reasonable flow at 800 to 900 rev/min available.
This pump was build end/beginning of 2014/2015.
After that I have build another batch of 3.
One is working together with my Opposed Piston Twin without any issues.
Also the Bruce Macbeth engine cooling is done with this pump.
During all my R&D work there in the last two month, there was nothing conspicuous.
   
So the decision was done to take the pump of and have a look at it.


When I looked into it, from the surge pipe, I have been irritated by seen the shape of the shaft in full format already.
So after taking the cover of, I could see the entire mess.
There was a part oft the shaft, covering the intake by nearly 80%.
It seems, that I have forgotten to short it down, close to the brass center disc of the impeller.
At the very beginning of the life of this pump in 2015, I have made some experiment with water in it, to get an feeling about the flow.
So it was turned in a test set up and I wanted to know if there is a reasonable flow at 1000 rev/min visible.
It looks like, that from this experiment there have been some rest of water in the pump for a longer time.
I do not have any other explanation for the visible corrosion.
I am still having no explanation for the corrosion at the gasket surface, because there should have never been any water contact.
A new gasket was available and the pump could get its way back to the engine again.


The next long run was archived easily. Over all I do have 180 minutes of run time in the records now.
The coolant flow is much better now. I can measure the coolant,  water jacket of cylinder #1 and #2 (outside in the middle with IR/Laser thermometer) nearly the same temperature at all running conditions.
If the coolant and cylinder are heated up to 75°C than the outer heads are heated up to 98° C and coolant starts cooking.
This does happen after 30 Minutes ongoing run time.


Conclusion: For me this is more success I have ever thought to archive with this engine build.
It is not an easy model engine to build and I have heard of several people, who never get it running so far.
So I am very happy with the status as it is now.
The last prepared fuel mixture is burned and after some cleaning I have put it back under the acrylic cover at the shelf.


Thanks for watching and following along.

[slproject]

Hello.
 I am very interested in this engine. There was an idea to increase it twice.

 1. Will it work slower?
2. Cylinders will be stainless steel. Since I read that many who did this engine face that the rust and cylinders rust.
3. With an increase in the engine 2 times, what gears should be used? If I correctly considered, then you need to increase the number of teeth twice, to keep the ratio of the crankshaft and shaft of eccentric.
4. Which ignition sparc are the best rearing?

[fumopuc]

Hi and sorry for my late answer.


For Question
#1 I would say, that depends on your development work and accuracy the model will be build. Maybe experiments with others cam lobes are necessary.
#2 My cylinders in all my model engines are made by free cutting steel, so no experience with stainless so far. Some more oil in the last fuel mix, before going back to the shelf may be useful here.
#3 If you like to increase the scale of the model, than of course you can select some bigger gears. The number of teeth are not so relevant, that depends on the pitch/Modul you will select. Only requirement, the ratio must be 2:1.
#4 A CDI ignition system is my choice for all engines so far, other options are possible. Advantage of the the CDI system, a small Hall sensor is easy to hide.

[slproject]

what kind of carburetor is needed if the engine is 1.5 times larger?

  Now almost all drawings are made in the metric system.

[Admiral_dk]

I don't think that you need to increase it - unless you think it is too slow ....

On the other hand - the square root of 1.5 cubed will be 1.83 - so making it 1.5 times bigger as the rest will be somewhere in the ballpark 

Per             

[slproject]

Which carburetor can be put?  If the engine is increased 1.5 times?  And what is his size?

This question remained incomprehensible.

[Admiral_dk]

You can try to send Achim a PB and see if he answers - not much around here anymore (his last detour happened because he was commisioned to build a Race Truck for the Paris Dakar Rally ~ 11 months) .... or do a thorough read thhrough the posts in this thread - to see what size and model Carb he used ....

Per