Flame out on fuel increase. Failure at self sustain

[mrlindeman]

Hi all. Im new here. I have been reading for quite some time. I have built a turbocharger jet recently and had some issues in regards to throttle flame out.
The turbo is 60mm inducer
Flame tube made based off of jet specs, I cannot get the jet specs to work lately now for some reason.
Oil pressure is 40.
Injection is radial. 4 1/16 inch holes spraying into the primary zone.

So fuel and ignition is good. I open the tank a bit and spark ignite to rumbling combustion.
Then I start adding air to compressor via leaf blower as I here the turbo start to spool I softly increase propane fuel.
At about 1.8 boost pressure the engine is controllable via propane throttle while leaf blower is still going.
It's not until I increase fuel to about 3 psi boost that the engine just flames out. Poof! As the bottle gets colder I can only achieve lower pressures until the same results. My propane bottle has no regulator. But I think my propane hose has a tiny check valve that may be cutting fuel when I try to increase throttle to get over the hump and get the thing self sustaining.
Sometimes it will run all on its own at 2.5 to 3 psi for a few moments without the leaf blower until I try to give it more fuel.
Sorry for the long winded post. I am so close I can feel it. Any help is greatly appreciated.
Bud

[racket]

Hi Bud

60 mm inducer is getting to the larger size that can be run on propane using the standard 9kg-20 lb BBQ cylinder .............more info please on your cylinder and delivery lines etc .

4 injection holes isn't enough , theres too large a gap between the fuel sprays , drill another 4 holes as a minimum so that the fuel sprays cover the full primary zone.

LOL, don't worry about being "long winded" , the longer the better :-)

Cheers
John

[mrlindeman]

I will drill more holes. Should the injector holes be 1/8 or 1/16 inch?
The propane is a standard 20 lb. No regulator. Hose is braided and screws onto the tank, then attaches to a 12 inch long metal tube that mounts the injector to the combustion chamber. The hose has some cind of shut off valve inside where it screws onto the tank. I cannot remove it. Is it safe to run a straight uninterrupted hose from tank to my combustion chamber? I'm worried that the fuel will ignite and travel to the tank causing a very dangerous situation.
Thanks for your help so far

[racket]

Hi Bud

1/16" holes to keep the fuel pressure high.

It sounds like you have a "safety" device in your tank , they're unsuitable for our use :-(

Don't worry about the fuel igniting back into the tank , there ain't no oxygen in there , so no chance of a "flashback" , the cylinder pressure will aways be higher than your engines airpressure .

Unless you can source a non safety valve equiped cylinder , your only option is going to kero/diesel, which for your sized engine is probably a better option anyway , use the propane as a pilot light to ignite the liquid fuel

Cheers
John

[mrlindeman]

I know I can buy the old non safety valves for tanks and do a conversion swap, but I don't think anyone would fill the tank lol. I have no knowledge on running on liquid fuel, and from what I understand; my entire flame tube and combustion chamber would have to be completely redone. I really don't want to rebuild something I just spent months on. The hose for the propane has a spring loaded ball bearing that keeps slamming shut when I increase fuel supply once the engine starts responding to fuel input. I will redrill the injector nozzle, and get a supply line that has no restrictions going from propane tank to engine. That should help to at least get to idle I hope right?

[racket]

If the "safety??" device is in the hose , and the hose can be "replaced" , then without it you'll certainly get up to idle and beyond until the drawoff starts to chill the tank contents and its vapour pressure drops

[mrlindeman]

Yea, in the threaded attachment end of the hose there is an excess flow shut off built in. It's strange because my weed burner wand and hose for keeping my property tidy does not have one. I can run tank full open and cook some dandelions all afternoon lol. The weed burning wand has a 25 psi diaphram regulator so that probably keeps the tank from chilling.
Why does the propane tank get cold and wet like that? I notice once it starts that process the fuel is not even ignightable until I give it a break for a while

[racket]

Hi Bud

The liquid propane in the cylinder needs to turn into gaseous propane , so the liquid needs to "boil" , that requires heat , that heat is extracted from the remaining liquid and lowering its temperature in the process ...........to prevent/delay this you can add heat to the cylinder by placing it in a warm water bath , the require heat for evaporation then comes from both the liquid propane and the water .

Propanes vapour pressure is related to cylinder temperature over a certain temperature range , in very cold weather the vapour pressure is low even with no drawoff of fuel, but in hot weather if the cylinder cools it'll attract condensation and become wet , same as a can of cold drink gets wet on the outside on hot humid days .

It is possible to run our engines on liquid propane by inverting the cylinder , the system needs to be fool proof though as its a dangerous practice , very easy to have a fire ball :-(

Cheers
John

[mrlindeman]

She runs! Got the fuel delivery situated, as well as spark to match the new fuel rail.
I did a test run tonight and it throttled up to 5 psi on the boost gauge and ran on its own without the starter until I shut it down. I observed the turbine and did see it was glowing a deep red color at 5 psi.
I wanted to throttle up but was afraid of causing damage. I have no rpm or temp gauge yet.
If my turbine is glowing at 5 psi at a red color that should be ok but I don't want a glowing turbine at all lol. It makes me nervous. It was completely self sustaining and I was able the throttle up and down. But I don't want to wreck my turbo.
I know I was over the hump. But is there something I can do for cooler turbine temps?
Thanks for all your help so far John.
Bud.

[racket]

Hi Bud

Congratulations :-)

Without know your turbo specs its difficult to advise about your temperatures , high temperatures are generally an indication of too much backpressure from an undersized jetnozzle .

5 psi is still kinda low , temps generally improve at 7-10 psi as compressor efficiency improves, before increasing again as pressures rise further

The coolest running is at ~10-15 psi P2 without a jetnozzle

Cheers
John

[mrlindeman]

Oh ok. I don't have a nozzle but I will throttle it gently to 7 psi and see if it gets cooler.

And Holy moly this thing gets loud lol.

[racket]

Hi Bud

It should get cooler .

Do you have a Link to the turbo you are using ??

LOL ...............loud at 5 psi , wait until you get her up to 30 psi with a jetnozzle :-)

Cheers
John

[mrlindeman]

Hi John. Here's the turbo specs.

Turbine Trim: 84.2
Turbine A/R: 0.63
Turbine Inducer Diameter: 68mm
Turbine Exducer Diameter: 62.4mm
Compressor Side:
Compressor Trim: 56.9
Compressor A/R: 0.7
Compressor Inducer Diameter: 61.5mm
Compressor Exducer Diameter: 81.5mm
Compress Inlet Size(Air intake): 4 inch (103.5mm)
Compressor Outlet Size: 2.5 inch (63.6mm

[racket]

Hi Bud

Sounds like a GT3582 www.garrettmotion.com/racing-and-performance/performance-catalog/turbo/gt3582r/

Your 0.63 A/R turbine scroll is the problem, its kinda "tight" which is reducing your flow through the comp and making it run in a less efficient region of its map , this will increase your temperatures , the 1.06 A/R is a better option

Cheers
John

[mrlindeman]

I'm going to set up a temperature monitering gauge with the probe at the turbine scroll. That way I can really keep an eye on it for sure. I will report back on my findings this weekend.
Thank you again John 😁