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Post by sauerkraut on Aug 10, 2020 1:31:56 GMT -5
Spark plug is mounted near the propane orifice, which sprays out radially, in the end of the combustion chamber. The chamber is mounted at a 45 degree angle with the turbo up high.
I've got a working theory on what went wrong -
I was babying the gas too much, there just wasn't enough there. As I kept trying to light the thing, I ended up frying my ignition coil (I assume by overheating it). I can hear it arcing internally which means nothing going to the spark plug.
Anyway, earlier today I attempted to light it up by having a friend hold a torch to the exhaust, lighting the fuel/air mixture after the turbine, and trying to get the flame to jump the turbine into the combustion chamber. I wasn't able to get it started this way.
I've got 2 new coils on the way, should be here Friday. I'll update as things go along.
Thanks again for all the help everybody!
Edit: I notice that I'm really not able to spool the turbo up very high, using either a leaf blower or compressed air. When using my leaf blower, I notice that I'm getting a lot of blowback from the anti-surge, which makes me concerned about the smaller pipe connecting the turbo to the combuster. Is this normal, or have I created too much resistance? Also, the turbo spins very freely with the oil pump off; as I increase the oil pressure, the bearing resistance increases noticably. Is this normal for journal bearing turbos?
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Post by sauerkraut on Aug 16, 2020 12:40:10 GMT -5
Update: Got the new coil, still having ignition issues. I was able to get it to light once while I had it spun up, unfortunately it either flamed out, or I tripped the OPD. I also got a quick light by letting some gas flow into the flame tube, then turning off the gas and letting it settle. I didn't actually have the gas running when this happened, though. Out of numerous attempts to start it, these are the only two times I got any gas to light. This is very intriguing to me - I can't think of a reason that the gas would be lighting so sporadically; I'm completely stumped here. I've even got two different spark plugs that I've been switching between to try and get it lit. One is very short, and one is an "average" length. A quick side note that I found interesting is that at times, when letting the gas flow without using my blower, I could see propane coming out of the cold side, but not the hot side. Perhaps it was just the wind or something like that, I just thought it peculiar. Here are some pics (I know, wood is bad, this is a temporary test bed that I'm using until I get the thing running).
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Post by racket on Aug 16, 2020 16:25:09 GMT -5
Why do you have the black wire ( earth??) going to the plug and the red wire (active) going to the plate ??
You might need to have the red wire under the plug as a washer
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Post by sauerkraut on Aug 16, 2020 16:41:20 GMT -5
Why do you have the black wire ( earth??) going to the plug and the red wire (active) going to the plate ?? You might need to have the red wire under the plug as a w0asher The wire is black because I didnt have a red alligator clip lying around. Also, I dont actually know which wire is high and which is low, not that it should really matter. The wires coming off of the coil are both red, I just attached a ring to one and the alligator to the other.
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Post by racket on Aug 16, 2020 16:55:50 GMT -5
OK , but try fitting the red wire at the plug washer so that theres a closer distance for the current to go .
If that doesn't improve things we'll look at other options
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Post by sauerkraut on Aug 16, 2020 19:14:30 GMT -5
I just tried that, unfortunately no dice. I fit the red wire at the plug washer, and modified my fuel delivery a tad (it sprays out in 6 directions instead of just 2). I also removed the pipe connecting the compressor and the combustor and just blew air straight into the combuster. Again, I got it to light just two times, seemingly at random. I've been doing some more thinking, and this is all I can come up with...
-The battery I'm using is a small wet cell 12V that a friend used to use on his fishing boat to power accessories. It discharges faster than I expected when powering my pump and gauges. During both tests today, I got it to light twice very near the beginning of my tests, then I couldn't get it to light again. Perhaps the battery only has enough "umph" to light a flame when it is very near fully charged.
-The second replacement coil that I ordered hasn't arrived yet, but maybe I'll have better luck with that one. So far the coils I've used output 500kV, but the one that I haven't gotten yet outputs 80kV at a much higher current.
If anyone has other ideas, I'm all ears. I really can't think of anything else.
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Post by racket on Aug 16, 2020 19:41:43 GMT -5
More info on your "coil" please , voltage etc etc , maybe a pic or two of the setup
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Post by sauerkraut on Aug 16, 2020 20:04:21 GMT -5
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Post by racket on Aug 16, 2020 22:55:45 GMT -5
Hi
Have you tried just a very gentle application of the leafblower , hold it a few inches away from the comp, but close enough that you can feel some air exiting the turbine , this will produce a bit of turbulence with the injected propane and hopefully a combustable mix.
Also after a successful ignition we need to purge the combustor of spent gasesbefore attempting another ignition .
Also "pure" propane won't ignite , so your injector should squirt all over the spark plug , but a bit to the side of it .
Your concerns about the battery are valid , try doing ignition tests without the oil pump running , if you can get several positive ignition in succession, look to increasing battery power
Cheers John
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Post by sauerkraut on Aug 18, 2020 0:51:01 GMT -5
Thanks for the advice!
I'll have some time for more tests in a couple of days. I'll update as things unfold. What would you recommend for a battery, should I determine that to be the issue? I'm a bit shy about going the LiPo route because I don't have a LiPo balance charger. Without that I'd be limited to 1S batteries as far as I know.
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Post by racket on Aug 18, 2020 4:12:14 GMT -5
Just use a standard car battery , it needn't be huge , just something for a 4 cylinder auto.
Today I did some testing of a similar coil with a propane/air mix and found it rather difficult to ignite which I found "worrysome" , plenty of spark yet when the F/A mix was blown across it, nothing :-(
Propane has a wide combustable mixture strength and I had no problems igniting it with the oxy sets flint sparker ..............very strange .
I've never used these spark generators to get any of my engines to light off , prefering to use automotive coils either with a flasher unit or points to make the spark .
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Post by sauerkraut on Aug 18, 2020 6:48:56 GMT -5
If I were to use an automotive ignition coil, I would need to have a capacitor in parallel with my pulse generating device, correct?
What capacitance is appropriate?
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Post by racket on Aug 18, 2020 16:47:06 GMT -5
Yep , you need the standard bits used with the coil , so 12V through toggle switch to positive on coil, with condensor and "other bits " on the negative
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Post by sauerkraut on Aug 19, 2020 0:17:48 GMT -5
I'm not the most knowledgeable on vehicle ignition systems...
Would it be feasible to use a coil designed for "Direct Ignition" aka "Coil on Plug", or is it better to use a more traditional coil minus the distributor? How would you make the points work without the distributor? It was my understanding that it is driven by the distributor cam.
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Post by racket on Aug 19, 2020 1:12:01 GMT -5
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