ozzie-crawl

you mite be on to something there looks cool to. have been thinking about what u want to do and i reckon your best bet might be to set it up so it comes on at full throttle by the servo that way you could be on say 1/3 throttle floor it and you get 2-3 seconds of nos [sm=idea.gif]

ttoks

on a full sized engine the nitrous is injected directly into the intake manifold, BTW NOS is a company that make nitrous systems for automotive uses, Nitrous Oxide Systems.

to get it to work you will need to do a few things, first you will need to have a way of getting the nitrous directly into the carbie, next (we've already talked about this on msn though) you will need to figure out how to add more fuel while your using the nitrous, and i mean exactly the right amount, to little will run you lean and it will break somthing to much and you won't get any performance increase because you will just be running rich, a boat carbie with a servo adjustable high speed needle (like the one i showed you from the RB c5 boat engine) useing a servo with an adjustable end point so you can have the non nitrous and the nitrous needle settings pre-set , then you need to figure out how to retard the ignition timing to prevent detonation because of the increased amount of pressure in there cylinder due to having more fuel and the nitrous.

in short as i'v told you, it proberly isn't going to work, and if it does it wont be a practical solution, there is a lot involved in adding nitrous to an engine and unless you can make it all fall in place it doesn't work, the reason it works so well in cars is because the engine management system adds the exact amount of fuel needed and retards the ignition timing to the exact setting needed at exactly the right time to use the nitrous effectively.

Codeblack

I hope that with some dead on measurements and calculations, some really really really accurate tuning, I will be able to get something going. This is a very tough project since it involves way more thinking than RB innovations had to do .

Codeblack

I think that for the 2 relays what ill do is take a pair of servo logic chips and get it soldered onto two of these little guys:

Then the part list is finished

Codeblack

Does anyone know what the average temperaure of a cold glow plug and the hot plug is?

ross_jsy

when its in the combustion chamber? if you want i can go read the temp of a hot one right now but not internaly

Codeblack

If only I had a cold plug. But If you could measure the temperature of hot plug coil that would be super, because if its lower than 300C then this idea will definitely work. but if higher there is a chase of a big boom, i will have to experiment. Who knows.
I only got .only small plugs
It would be useful to know the hot plug too, for the sake of comparison

Codeblack

Here is a nice diagram for all you good people who contribute to this project. Tried to make it look super simple, its straight forward but dont make it fool you because its probably hella hard to tune>>>

Ohh and the 2 fat arrows lead to exhaust pipe.

Codeblack

Let me know if you see anything wrong with it

ttoks

how are you going to do the ignition timing? remember you will need to run a colder glow plug for the nitrous and 25% mix then the 45% mix, that is crucial.

Codeblack

why cant i run cold plug for 25%nitro mix? That was kind of what i had in mind, run cold plug for both processes. but before i do, i was going to see at what temperature cold plugs are, so oxygen separation does not happen beforehand. Even with if separation happens partly, i dont think there is going to be a detonation if 2% of molecules separate. I dont see how N2O has enough particle energy to cause a chain reaction like nitro fuel.

Codeblack

Before even thinking of putting the cold plug on we gotta check at what temperatures either one burns. Maybe the hot plug glows 230<300C. ya know?

downunder

It's amazing what I'll do in the interest's of science . OK...I just put my thermocouple probe down onto the coil of a plug glowing bright red. The best I could come up with was 670C but this isn't accurate because if the probe touches the coil then it cools the coil way down and if it's not touching the coil then it's not picking up all the heat. Kind of a Catch 22 situation.

However it isn't the temperature of the coil itself that indicates a hot or cold plug, it's the ability (or the ease) with which it can ignite the methanol vapours that come in contact with the coil. The actual temperature of the coil does play some part in it but not the whole thing. If the coil is down inside a small cavity in the body of the plug then it's harder for the vapours to get inside to start burning and this would make it a cold plug. If the same coil is inside a larger cavity then vapours come in contact more easily and then it's a hot plug. A "hot" plug fires the mixture more easily and this advances the ignition point. A "cold" plug retards the ignition.

But the ease with which the coil can ignite the vapours also depends on the pressure of the vapours around it. This pressure comes from compression. The higher the compression the easier it is to ignite so a higher compression advances the ignition point too.

So the ignition point is controlled by matching both the compression of the engine with the correct heat range of the plug to suit whatever fuel mix you're using. Once an engine is running there's not much you can do about either of these things if you switch fuels . If you want to switch fuels while the engine is running then you have to compromise by choosing the compression and plug that best suits the fuel that's more likely to detonate. In this case it's the fuel with the most nitro because nitro won't handle anywhere near as much compression as methanol can.

There's one possible solution but it adds more complications and more tuning. You could use an extremely cold plug and use an on board glow heat controlled through a power panel to vary the electrical heat adding to the plug's own heat (which comes from a catalytic reaction between the platinum in the coil and the methanol in the fuel). When using the lower nitro fuel the plug would need more power supplied to it to advance the ignition and then less power to retard the ignition when switching to the higher nitro fuel. But the compression would have to be fixed to suit that higher nitro fuel or you run into the possibility of detonation.

Another (and better) solution is to convert the engine to spark ignition and use electronically controlled ignition timing.

Codeblack

downunder, you always have some of the most informative posts. Thanks man. That gives me a lot that i dont even want to think about such as building a magneto and converting that glow to spark plug, hahaha, difficult stuff.

The simple way out is running a cold plug with that small cavity, using some electrical power for that 25% nitro mixture as you said, then running cold for 65%. I dont know if glow plugs will be able to handle 7 minutes in a row of constant electrical glowing.[]

Ill read up on how to convert the glow plug and see how that goes because if we were to convert glow to spark plugs... this Nitrous idea would work 100%

Codeblack

If I were to convert to spark ignition then I dont think ill even need higher nitro mixture, engine compression will be way better and will put a lot of stress on the engine block as is. Maybe ill try glow ignition first and see how it runs, if something blows up, ill try spark ignition

ross_jsy

well, the heli guys (not sure about planes though) use dual glowplug heads, normally with a hot and a cold plug. also you can buy glow plug ignitors that come on at a throttle position you decide. large scale planes use them that may help with the whole temp thing.

Codeblack

could you link one of those ignitors/plug combos? I think its possible to change it from progressive to continuous glowing with no problems

ross_jsy

sorry, meant engine head. i dont use them but many people do. as for the glow sytstem, ask in the large scale plane section. they will be more qualified to tell you than me as i dont fly large aircraft

Codeblack

Ok, I posted a question on it, we'll see what they say.

ozzie-crawl

new world order if i was you i would find a old engine rig it up on a test bench and see wat happens when its running if u suddenly drop higher nitro fuel in. if that works then try some nitros as ttoks said on full scale cars they run a plate in the manifold with a jet going straight in not sure but i think it goes in as a vapor you mite be able to drill a small hole in the carb were the filter clips on and run a very small tube threw it and then bend it down so it points straite down the carb.but i have a feeling that nitros has to be added after the air fuel mix cause thats how its done on cars with carbies .dont know about fuel injection. hmm thats a thought fuel injected 2 stroke nitro motor

Codeblack

using a 4 stroke motor is a must, and I dont have any laying around. So I wana try and think of everything that might possibly go wrong, then try it on a new engine. But you are right, I think we are coming to a point where its time to do some experimenting. Right after I finish building my Xray (in a week or so) ill order a fairly nice 4stroke.

Codeblack

thanks to our fellow men down at plane forums I acquired this:
http://h1071118.hobbyshopnow.com/pro...sp?prod=MCD466
here is a more compact version:
http://www.greathobbies.com/products...rod_id=EXRA550

ross_jsy

exactly what i meant

Codeblack

We just gotta make sure that the super cold plug will be able to handle at least 7 minutes of constant electrical glowing...

ross_jsy

should be ablt to...test it. hook up an ignitor to it for 10 mins