new member introduction, also can i get opinion on ignition

[kevin lee]

On Friday I ran my pj for the first time. I ran it for about 2minutes.

On Saturday I ran it again but after about 2mins it started too die on me, I figured that the engine was warming and also the gas bottle was chilling and loosing pressure. I flipped the bottle upside-down to try out liquid.

This killed it out right and the bottle valve got clogged by some black sutty stuff. I couldnt get any decent flow from the bottle. Also it wouldn't shut off either.

Managed to fix it after some time. However, the pj won't start now, it grumbles, growls, groans, pops and farts. My guess is lack of fuel so won't fire up and sustain.

I have a regulator on the bottle. This can only supply a maximum of 2bar!

Today I bought a pol fitting to replace the regulator. So now ill have bottle pressure but only the bottle valve for fuel/throttle control.

I'll report back with any news tonight

[kevin lee]

Tonight remade the fuel line and had another go.

https://www.youtube.com/watch?v=o5jTK0C ... ata_player

I ran it for quite some time but I don't think its running the same as before!?! Not as loud and I can still run it flat out without it flaming itself out. Only an 11kg bottle though

I have altered the injector since the first run. it wont run on a freshly cut roscojector but will if I file it back a bit so there is more of an opening! I tried different depths which made some difference but I need to adjust and take note what happens.

It doesn't really throttle up or down!

Anyone feel free too offer some advice or ideas of things to change. Iam tempted to just get on and build the m40 instead now like I originally planned.

[PyroJoe]

Might try backflowing the injector. If the bottle had crud in it, some may have passed the valve and ended up clogging the injector.

[kevin lee]

Good call, I will try that! Iam using 1/8 ID copper brake pipe for my fuel line + injector.

I just took delivery of some parts so I will build a new one with the correct size combustion chamber. Iam still waiting for stainless sheet before I start the m40

[kevin lee]

Made another one tonight needs some tuning before it'll sustain without compressed air. I was limited to how much noise I could make tonight

Hopefully some decent runs tomorrow night

https://www.youtube.com/watch?v=g3TG-4m ... ata_player

[kevin lee]

This is also made from random ugly scrap out of the skip at work















The jet was just a quick hash up to get some kind of combustion.

Tomorrow we will try harder

[kevin lee]

The specs of it are as follows

Cc 91mm id x 175mm with random cone
Exhaust 48mm x 960mm
Inlet 38mm x 128mm with flare

[kevin lee]

Built another.




I bought a ball valve for fuel control. It needed some adapting to work with my setup










I mounted the new engine with bolts at the front and wired the front down.










The 2nd engine is dead now, full of cracks from diferent rates of expansion. And also I ran out of gas just before Christmas but sorted out some more today. I think all my running probs were due to empty gas tank.

Vids tomorrow

[PyroJoe]

Looking good, have some earplugs handy. Ball valves can be a little touchy, can't wait for the video.

[PyroJoe]

Looks like its running rich for some reason. Intake to tail diameter ratio is at 0.791, probably be better closer to 0.88. How is the injector crimped?

The CC is slightly long, maybe 20mm. That CC cone looks a little steep near 30 degrees range. 20 degree cones tend to give my engine starts the least amount of grief. Still looks like it should have at least started though.

hope that helps.

[kevin lee]

Looking good, have some earplugs handy. Ball valves can be a little touchy, can't wait for the video.

Thanks Joe, i do have lots of ear plugs haha. by touchy do you mean, not very precise! all or nothing!

Looks like its running rich for some reason. Intake to tail diameter ratio is at 0.791, probably be better closer to 0.88. How is the injector crimped?

The CC is slightly long, maybe 20mm. That CC cone looks a little steep near 30 degrees range. 20 degree cones tend to give my engine starts the least amount of grief. Still looks like it should have at least started though.

hope that helps.

Hi Joe are you referring to the video i just uploaded on youtube the other night? i noticed that you subcribed to my channel

this one
http://www.youtube.com/watch?v=e0JWlCzz ... AAAAAAAAAA





I agree that it looks rich and that the cc is too long. the cc stacks up to 7 calibers so ill shorten it back by 2 calibers.

ill also alter the cone and see what difference it makes.

i was reading some ttiopics about rear loaders last night and one of the guys posting (maybe mike or mark) was saying how they needed a much longer intake to exhaust ration to get the engine running. ill have a play about today

[kevin lee]

The injector is just a rosscojector that has been opened up a little too flow abit better, ill crimp it tighter again and have another try.

the first engine i built needs to have a fully open ended pipe with no crimping or squashing of any kind. it wont really start up without maximum flow. i have come to the conclusion that the reason for this is that the cc is huge. its some thing like 8inch long by 7inch diameter lol. would need alot of fuel to really get it going well.

here are the recent short runs that you have probably seen
http://www.youtube.com/watch?v=pz1_zSny ... AAAAAAAAAA

http://www.youtube.com/watch?v=84zOV0G2 ... AAAAAAAAAA

[PyroJoe]

Yes thats the one. Might try just slicing 20mm of the CC length, and crimping the injector a little more.
Propane is a thick gas and it takes a "shredding" effect to have it mix with air.

The large CCs dont need as much because they cycle slower and there is more time/volume for mixing. The smaller CCs cycle very fast and have less time to mix the fuel/air. Another reason I typically pull the injector out near the flare to give a little more distance and turbulance before entering the CC.

The intake length is just slightly short, but I've run them that short before, even much shorter. ha

Those fat CC really like the fuel and produce a hellish amount of heat!

[Tonskulus]

For finetuning, how about telescopic intake tube? Would be very easy to find out which is the best length for intake to get maximum thrust.

[kevin lee]

Yes thats the one. Might try just slicing 20mm of the CC length, and crimping the injector a little more.
Propane is a thick gas and it takes a "shredding" effect to have it mix with air.

The large CCs dont need as much because they cycle slower and there is more time/volume for mixing. The smaller CCs cycle very fast and have less time to mix the fuel/air. Another reason I typically pull the injector out near the flare to give a little more distance and turbulance before entering the CC.

The intake length is just slightly short, but I've run them that short before, even much shorter. ha

Those fat CC really like the fuel and produce a hellish amount of heat!

Ah Joe thanks that's some great info, its hard too find some answers because most info on here is over my head Haha but Iam getting there.

I have made some changes and I have had it locked in very nice with some compressed air. Iam convinced that I need to get a decent injector + decent posituon + finer fuel control.

It's close too sustaining but unfortunately I didn't film the good attempt

For finetuning, how about telescopic intake tube? Would be very easy to find out which is the best length for intake to get maximum thrust.

Yeah its a good idea, I saw an adjustable intake within the forum. i think mike everman may have built one. To be honest Iam not too worried about this engine. I have some materials for a 12lb Chinese so ill make one of them next