A Few Hybrid Questions

[Hubb]

move the scrader to the fuel input...this way the air injection will force the propane into the chamber

Yeah. In my first designed (sketched on notebook paper), that's where it is. I don't know why I put it like that in the above diagram. I guess I was just trying to get it on the diagram.

[Hubb]

Bumping because I have another question and don't want to start another thread:

I began construction on the hybrid. I thought about using the spark plug but, once I realized I could not secure it without drilling a hole into the chamber, I scratched the idea. Instead, I built another "spark plug." It is made from a 1/2" pipe cap, pipe nipple, and coat hangers. The hangers are sharpened and secured through the cap with epoxy, where it is screwed onto the nipple, allowing 1/2" threads, which means no drilling through the chamber.

I hooked this up to a piezo and, although it made a good spark (the electrodes have a gap of about 1 mm), I am concerned with it igniting in 6x or more mix. I have recently disassembled a camera to use. BTW: It hurts like a b!tch when it discharges through the thumb.

My question is, has anyone ever used a piezo in a hybrid with 6x or more? If it doesn't work, can the camera sparker be used without running it through an ignition coil or equivalent?

[Fnord]

I think nova uses a piezo at 8x. A gap of 1 mm will be fine for a typical grill igniter.

I don't think there's any way of using a camera flash in a hybrid without a coil of some type. The voltage is just too low.

[Novacastrian]

I think nova uses a piezo at 8x. A gap of 1 mm will be fine for a typical grill igniter.

Yes I do use a piezo at 8x mixes. I run about a 1.5mm gap so it would probably still work at 16x mixes at a .75mm gap. After i buy a shock pump i plan to build a 16x Hybrid

[Hubb]

Yesterday, I tested my hybrid. It fired at 4x so far, however, I had to hit the piezo several times for it to do so. There is still a small leak somewhere on the chamber that needs to be fixed so as soon as I fix it, I'll mount it on a stand (it's a pita to hold and fire because of its weight).

I was going to put JB Weld around all the threads and stuff to get a good seal. I let you guys look at it (although it's nothing special) when it's finished. Thanks guys.

Edited for a question: As mentioned above, I had to click the piezo several times before it fired. Do you guys think that if I extended the spark moreso into the chamber, that it would ignite faster? The attachment is how my current setup is:

[Novacastrian]

Are you sure that the wiring isn't shorting out on occasion?

[SpudBlaster15]

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[Hubb]

Spark gap is about 1mm. The leak was coming from the nipple that connects the union to the reducer. This probably had a lot to do with me not being able to find my pipe wrench.

As far as the gap shorting out, the wires running into the cap are insulated and testing revealed it sparking every time.

I plan on rebuilding it and making the wires longer to reach more into the chamber. I also plan on removing all the teflon tape and just putting JB Weld on the threads to permanently seal it.

@Spudblaster: A picture would be nice. If you're referring to my spark idea, I thought it was original. Apologies.

[SpudBlaster15]

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[Hubb]

I was referring to the whole launcher design.

That's just how a pictured a hybrid to look. I guess yours would be considered the standard in hybrid design


Anyway, I fixed the leak except one, that FREAKIN' burst disc

I used so many pieces of aluminum foil trying to get it to seal (as in trying 2 layers, 3 layers, 4 layers, etc about 15 or 20 times each, wasting about 6 hours of my day) but it would not. I then used pieces of a ziploc bag but it wouldn't hold pressure past 2x.

I took the union and put a bead of that liquid gasket material stuff around it and it is curing now (to create an o-ring type seal). Maybe that will work. Any other help is appreciated.

[DYI]

So it wouldn't seal with a simple butyl rubber gasket on the union? That seems kind of strange, because the union on the SCTBDC seals at up to 500 psi fairly well with alu. foil disks.

[Hubb]

Then I guess I got a bad union. You see, the one I bought didn't have any kind of seal in it.

[DYI]

Oh, mines didn't have a gasket either, I had to make one. So you're saying that you expected to seal without any sealing material?

[Hubb]

I guess so. I've never used one before with this. Besides, I managed to seal it earlier and achieve a 4x.

But don't eat me. That seems to be the only thing (and hopefully is) I've messed up with the hybrid so far. Do you think the liquid gasket material will work okay?

[DYI]

I have no idea, I've only ever used butyl rubber gaskets. If it's a gasket material though, I see no reason that it shouldn't work if applied properly. Alu. foil disks are a lot easier to seal than sheet alu. disks.