MicroSquirt.com read only forum (Jan.15,2018)

I`ve been interested in liquid lpg injection for a couple of years, and I`ve been looking everywhere for info on it.
There isn`t much to find, as you already have found out. So I`ve been thinking alot on how it could be done, without spending a fortune.
What do you think about this idea?
If you use the old K-Jetronic fuel injectors, that has a opening pressure of 50psi. You use one K-Jet. injector, and one fast acting solenoid valve for each cylinder, with 10-15cm betveen the soleniod valve and the injector.
Then you put a pressure sensor on the "fuel rail" (just before the solenoid valves), to measure the lpg preasure from the bottle to the injectors.
The lpg is stored at around 10bar, and the K-Jet. injectors will hold back 3.4-3.5 bar of that pressure, so the solenoid valves must only hold max 7bar, and when they open, the K-Jet. injectors will be feed with a 10bars, and at that pressure the lpg would be in liquid..
Any thoughts about inject liquid lpg this way?
A`m I mway of or could it be done..?
Ronny

Since the LPG is being stored in a state of equilibrium, as soon as you lower the pressure only slightly, it will being to vaporize.
It's critical that the LPG is in a complete liquid state as it is injected.
And for it to be a liquid at 10 Bar at Standard Temperature Pressure, the fuel would have to be pure propane. A typical mix of gasses for LPG (propane, butane and isobutane) would be closer to 15 BAR at STP.

Brian is absolutely right .
Using tank pressure at ambient temperature isn't possible .
You'll be injecting liquid and vapour at thesame time , and there's
no telling wich amount of each .

You have to either raise the pressure to abt 15 bar , wich is what vialle does . They have a pump inside the tank .
I'm attempting a rebuild of one of those pumps .
I can post pictures if anyone's interested .

Theoreticly you could also lower the temperature of the lpg enough to eliminate the vapour fase .
Tried this once , I had to empty a tank , the one with the broken pump .
So I had no alternative then to vent it to the air .
After a while the gas flow stopped , and the outside became all icy .
To my surprise tha tank was still filled abt halfway with liquid
but the pressure was gone . I could pour the liquid out , wich started vaporising as soon as it hit the much warmer ground .

Pat

The main concern seems to be getting injectors for lpg.
So if the pressure needs to be pumped up to 15bars. How would a water injection pump that deliver 110psi of pressure, work for this purpouse?
It could be controled with "pwm" to obtain the wanted pressure. Just another thought..

All you need is to make sure the fuel doesn't start to vaporize. Only a slight increase in pressure is needed over that in the tank, as long as you regulate the heat input into the fuel system. The system ends up being very similar to a gasoline system, i.e., pump, bypass regulator (of sorts), return line.
I encourage you to read the patents I left the link for above. It describes all the components in great detail, and there are some innovative ways to keep the fuel in liquid form.
I'm learning more about the BDE, Ltd. deal. The whole thing was sold to Schwan's (crazy huh?) in 2001 for use on their delivery trucks. I was told it was a closely guarded secret. But it seems now, they are going to market the technology.
http://www.bi-phase.com/publish/default.htm
I'll post more as I get additional information.

mitsuko wrote:Knowing the physical caracteristics of lpg , I cannot believe that
story of petrol injector emulation .
Nor the story of increased power with gaseous lpg injection .....

Pat

Heres a link to Kiehin lpg gaseous injectors and the italians are past masters at anythiong LPG,especially Romano,who advertise that their system will give increased power over gasoline. Published in a issue of "Practical Classics" (UK) a couple of years back was an article about a mercedes W108 280SE converted to LPG,where it was shown that the injection set up did indeed produce more Horsepower.http://www.prins-lpg.com/en/products/vs ... rrail.html

Oh yes , the keihin injectors are among the best money can buy .

Very good equipement , also very expensive and hard to obtain .

The theoratical loss of power can be calculated
For a 30/70% mixture its 2.4% .

The usual 10% to 20 % loss is due to the tradiitional mixer setup that restricts the air flow . The engine will also loose power on petrol if the mixer is installed .
And secondly because the charge cooling of the vapourizing petrol is no longer there .

Now with an injection setup , the mixer is gone , so the airflow remains untouched .
The lpg is already gaseous so the atomisation will be better , resulting in a cleaner burn with a little more hp output .

But the intrinsic power loss due to less energy / weight of fuel , and the
charge cooling effect that is gone will remain .

So in my opinion more power on gaseous lpg without engine modifications
isn't possible . Perhaps if you can adapt the ignition timing , but still , I'm not convinced .
With Liquid injection , yes its possible because of the massive charge cooling .

Pat

I've added a power curve of a mixer steup
Notice the interesting crossing of the two petrol curves at low revs .

1 : on petrol without the lpg conversion
2 : on petrol with the lpg conversion inactive
3 : on gaseous lpg , mixer steup .

I have been searching the web for months on info about this.Being in Australia,i have yet to telephone the companuy mentioned previously who claim to be able to inject the gas and effect a power increase.
There is also MOGAS in the uk but there product is totally beyond me ,price wise.
There is also an American firm who make gaseous LP injectors,which are similar to the japanese items in that they able to be fitted in the same ports as petrol injectors.Unfortuantely i gave up on them and lost the link,as the price per injector was US $150.when i'm looking to buy 16 it's a bit much.
http://www.gas-injection.com/contact-ga ... ron B. :)

keihin LPG / CNG injector

abit of info around on them, did not see any mention of keihin in this thread so far so I hope its not redundant

according to a post here:

Feel free to contact me.
My name is Yost Fulton, & I work for Keihin Fuel Systems in Detroit.
Keihin manufactures an excellent gaseous fuel injector used with CNG, LPG, & hydrogen.
fulton@keihin-us .com

ah, crud - its right above, sorry