*UPDATE* It Lives!!Need Help! Noob built focus wave motor

[ntoracn]

First, let me say "Thanks" for letting this Noob into the house of PJ fun.

Been wanting to build and run my first motor for a while and finally did it. I down loaded the focus wave motor plans and set to work. I fabbed the motor with mild steel just to see if I could make it work.....and I can't If I light the fuel line in the intake and blow air, I can get it to kinda run. If I light the exhaust with the fuel (propane) and regulate air into the intake, I can get the flame to travel to the combustion chamber with a "throop"/bang kinda sound, but it will not run or self sustain. As soon as I remove the air flow, the motor quits it half a%@ running. I have LPG connector from my BBQ grill minus the regulator portion. I will try to post picture's of my motor so you can tell me if I did something wrong during the build. I've got a boys trip to the desert coming up and I would REALLY like to get it figured out so I can take it with me.

Questions:
1. I'm getting decent flow from my BBQ's propane bottle, but is does NOT come out forcefully.... Should it? At the rate it flows, It would take an hour or two to empty the bottle.
2.

ANY help/suggestion would be very much appreciated, Thank You.

[ntoracn]

A second photo

[ntoracn]

last photo of intake

[Ghrey]

Just off hand, it does sound like you do not have enough fuel flow.

It could be as simple as too small a hole on your tank to hose fitting ( POL {?} ) I have one right here on my desk that would under deliver like that. Pin Hole.


I would wait for others to chime in. I am still learning the habits of FWE type engines my self.


All the best.

[ntoracn]

Thank You Ghrey for the input. I know the tank adapter I have has a one way check valve, not sure if its equiped with an orfice restrictor. I have tried to run the thing at low and wide open and everything in between without success. Since people have gotten electrical conduit boxes to run, I can't imagine that mine is so flawed that it can't run. Are the dimentions so critical that they have to be exact for it to self sustain? My intake flair is not exact and my intake tube is 1/4" shorter than the plans call for. Could these two thing cause it not to run at all? The only other thing that comes to mind is that my spark plug/top of CC is flat and not coned shaped.

I also live here in So. Calif (Riverside) area, I hope all is OK with all the fires in your area.

Thanks again for your help.

Randy

[Mike Everman]

No, small errors/differences are not major problems.
Are you using the sparkplug yet? sounds like not. It's really handy. Tail lighting technique is difficult at best, especially when you haven't gotten the "touch" yet. See my "how to start a pjet" post. It's a lot of variables, and perseverance to develop the touch. Once you do, you'll start anything that can in fact run. I've had good motors take 25 tries to find the sweet spot for fuel and starting air. I won't give up on a motor or make a change until I have tried to start it that many times.

[GRIM]

Having recently built one of these, (although somewhat altered) I agree with Mike, spark ignition is almost essential, I tried the tail lighting routine and the light the inlet deal, no joy, sparks and compressed air got her running though no problem,

Beware of the ¼” , it is actually quite a big amount on such a small inlet , but probably not enough to stop it from running ,

I was also surprised how much gas these little engines need to start up, compared to other engines i have built, Loose any restrictions, check valves, etc in the gas line, and maybe open up the rosscoe a bit,

Good luck

[metiz]

do you use a rossco? ouch! that is not needed with a engine this size. It might actually be a big part of your problem. Ditch the rossco and just use a open tube about 40% in.

[ntoracn]

OK guys, thanks alot, keep the info coming! I will try and bypass any valves in the tank adapter. I will also try the spark plug again. I have also tried lighting through intake and blowing air at the same time. This method produced the half A%# run from the motor but would not run without injecting air.

How far into the intake should the fuel nozzel be. The plans said right at the intake flair.

Its just gotta run.

[Graham C. Williams]

Please see this Topic.

viewtopic.php?f=3&t=2021&start=0&st=0&sk=t&sd=a

Here you see the FWE as made by James D. He is using spark ignition !
To quote James D
"The FWE is built to the dimensions given by Larry in his jetzilla article, 1.25" tailpipe and 26" total length etc.
The "Rosscojector" is made from 5/16" copper brake pipe, cut through with pliers as per photo."

The "Rosscojector" works fine. If the Motor is correctly made and the fuel flow is correct and you have made the injector correctly it should run like this. Mike has it correct.
I hope this helps.

Graham.

[metiz]

The "Rosscojector" works fine. If the Motor is correctly made and the fuel flow is correct and you have made the injector correctly it should run like this. Mike has it correct.
I hope this helps.

Graham.

I have found that with a engine this size coupled with a less then perfect build, a Rossco is not ideal. non the less, just try both and see what she does, you'll get there eventually

[tufty]

Assuming you built more or less to spec, particularly with respect to inlet and exhaust lengths, you should be okay. Sounds to me like not enough fuel as well, the "fwoop" into the chamber is a good sign. Not sure if the FWEs are rosscojector-friendly, but that's often a good way of finding the best place to put your fuel inlet.

God, I hate the "save" button on these forms. I hit it *every* time.

I also hate the fact I hadn't read through the rest of the thread. D'oh!

[ntoracn]

ITS ALIVE!!! So here's what I did.
First I rigged up a spare distributor hooked up to a drill motor (since I don't have a model T tickler) with an auto coil. this allowed me to control the gas valve and compressed air nozzle. After all of this, still it wouldn't run. CRAP I said. Dejected, I grabbed a piece of spare 2"D X 24"L ehaust tubing and hung it onto the exhaust outlet just to see if it would make any difference. OK now ignition on, gas on low, now add a bit of air and "hey its starting to sound like it might run" I say to my self. A bit more fuel and air and sure enough its self sustaining!! I think the hoot I let out rivaled the Db of the motor. After it test throttle up and down a few times, I set it at about 1/4 throttle and then slid the crude exhaust augmentor off and the motor immediatly stopped running.

The exhaust augmentor(?) was the key component for sure.

Now the question is, why? Is the lenght of the intake/exhaust out of sync? Wht won't it run without the augmentor? I don't have anyproblem running it, I would just like to understand what I did wrong. Also, there has to be a simpler ignition source like a model T tickler, any links to a simpler ignition source?

Thank You for all of your help and encouragement.

[Mike Everman]

Cool. Welcome to the world of fire and noise!
OK, so that pipe on the tail lowers the frequency, which makes things easier for starting. Try again, but keep it at high throttle when you go to remove your starting tube. It may all mean that you need a tail extension, or a little off the length of the intake, or maybe a smaller diameter intake. Just some random thoughts. What is the inside diameters of the CC and the two holes in it?
As to sparking, I mostly use an AC sparker from a household stove. You can use one from a gas clothes dryer, too. In the field, I'll either use that and a car inverter, or these neat AAA battery sparker replacements for BBQ's.

[Graham C. Williams]

Good work!
Glad to hear you got it going.
Intake and Exhaust internal diameter is as important as the length of these pipes. Perhaps it's better to say that the internal diameter and length of the pipes are related. If your happy that the lengths of the pipes are correct look to the diameter of the pipes.
As you tune these motors for increasingly better performance and the Advanced FWE (due to Eric) is a tuned version of the original FWE straight pipe motor, the accurate rendition of: length, diameter and location of the Pipes and Pinches becomes increasingly more important. For example, in the most advanced (to date) FWE designs at least one of the diameters must be +or- 0.5mm (or better) of the correct internal dia. at the working temperature! Luckily the motor you have chosen is a good place to start appreciating these concepts.

See what effect you get by reducing, a little, the induction dia. at the open end? You can do this with a short sleeve (10mm Long) pushed into the induction pipe.
The question you should consider is: By reducing the induction diameter a little do I have to increase or decrease the length of the tail extension or can I remove it altogether?

Graham.