|Aug 11, 2008, 03:23 PM|
Joined Aug 2008
Benefits with a Spark Ignition on a Glow engine.
Hi every one. I'm a silence watcher of the forum for some time now, but after search and read many, many post I can't really understand the whole benefit of using a spark ignition on a glow engine. It looks very interesting
Can any one explain some things?
Thanks in advance.
1º) Can any glow engine use a spark ignition?
-I think any glow engine can use a spark ignition, but I read that small engines (below 120) receive no benefit because the components of the ignition are too heavy. Did I understand right?
2º) Does a glow engine running with a spark ignition spend better the fuel?
-As I read the spark ignition systems make the engine able to use every fuel put into the engine, not like glow plugs that make the engine unable to burn all the fuel and many of it goes out of the engine by the exhaust. Did I understand right?
3º) Is a glow engine with spark ignition easier to tune than normal glow plugs engines?
All the information you can provide about this will be welcome.
|Aug 11, 2008, 07:05 PM|
1. Yes. In reality the weight penalty allows ignition systems to be used on models of about .40 size at the smallest. There are a few systems that could be used on .20 size models.
2. The carb can be tuned leaner and still run well. This is because the glow plug and fuel mixture interaction is eliminated. Ignition occurs when spark occurs so timing is set by the ignition and not by glow plug, air-fuel mixture, and compressions ratio. I believe that many glow engines are set up such that they must be run relatively rich.
3. Yes. High end is non-critical and low end is easy. The low end can be extremely rich and it will still fire and run. In general mixture is non critical.
|Aug 12, 2008, 03:46 AM|
Joined Aug 2008
4º) Will the ignition give more torque and more rpm?
5º) What the right mixture 18% oil - 5% nitro... 20% oil - 10% nitro? Or simple can I change the mixture for each diferent kind of flight?
|Aug 12, 2008, 07:31 AM|
Ignition does not have a significant impact on the power output. It might if the engine was not optimized with glow.
You can run the same oil ratio as recommended in the engine manual. I was running only 5% castor oil and balance methanol in my Enya 46-4C. Peter Chinn's old four stroke book suggests that many four stroke engines could be run on much less oil than manufacturer recommended at the time. The engine was doing fine, but only had about a liter of 5% oil fuel through it when I broke the airplane. It's waiting for repairs.
I'm going to convert an OS FS-52 to ignition and increase the compression ratio to 13.5:1 to see how this influences power.
|Aug 12, 2008, 07:55 AM|
Joined Feb 2007
See red inserts.
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