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Fuel injectors that can tolerate 120psi
2

Fuel injectors that can tolerate 120psi

Fuel injectors that can tolerate 120psi

(OP)
Anyone know if there are any fuel injectors I can purchase or obtain that can go to 120psi without exploding? I'd like liquid propane delivery, but normal gasoline injectors will just explode at the nessasary pressures. Diesel injectors may be my last resort if I can't find anything else.

I have seen the tech reports for the Multec Bottom Feed Methanol injectors, claiming pressures up to 1000KPA (130psi gauge pressure). They would be perfect, except.....you can't buy them. I have been told they only come packaged with race engines, Delphi doesn't sell them.

http://www.delphi.com/pdf/racing/multecbottomfeed_meth.pdf

RE: Fuel injectors that can tolerate 120psi

I believe liquid propane injectors are commercially available. Try a google search.

Also gas phase injectors are available

Regards
pat

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RE: Fuel injectors that can tolerate 120psi

(OP)
Believe me, I have google searched for hours. Can't find anyone selling liquid propane injectors, can't even find a reference or tech sheet to such a thing existing.

If I did, I'd bet the flow rate would be insufficient.

Found vapor injectors, they can only do like 40HP/injector, no go there.

RE: Fuel injectors that can tolerate 120psi

I have anecdotal evidence that there is a sysyem being made in Holland for liquid phase injection of propane, but I have no recorded details

Regards
pat

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RE: Fuel injectors that can tolerate 120psi

(OP)
Any theory as to if side-feed injectors may tolerate the pressures better than top-feed? The potential for the injector to blow open is far less, as the fuel rail actually surrounds most of the injector.

RE: Fuel injectors that can tolerate 120psi

Clean air Partners in San Diego makes a variety of large flow CNG injectors.
Quantum in Irvine, Ca. makes very large flow injectors for hydrogen.
Bosch makes CNG injectors for lots of OEMs.

Regular pintle injectors such as Bosch 403 have been used in the past with methanol in Indy Car engines at pressures up to 10 bar without
damage or leakage.

RE: Fuel injectors that can tolerate 120psi

2
First a clarification: for liquid LP injection, you will need injectors with the capability of at least 50 psig above vapor saturation, or around 350 to 450 psig.  As you already noticed, this is no small feat.  There are some companies making systems which includes a custom tank, electronic interfacing, injectors, injector lines, etc, but they are vehicle specific.  I believe Prinz of the Netherlands, several Italian, Australian, New Zealand and Canadian companies are also playing around with LPPFI.

This is not to be taken lightly, as contemporary injectors will pop apart around 120 psig.  The one American company, formerly known as Bi-Phase, custom made their injectors and had great difficulty here also.  I dont know of their source of cores and most of my contacts there have left.  (Bi-Phase has been acquired by Schwans, the food prople.)

The BKM, Clean Air Partners, and Bosch do indeed make CNG injectors, but they are typically low pressure, seldom above 2 bar, and are designed for vapor only.  I have no experience with the Indy type 10 bar methanol injectors, but I suspect they are hand built to exacting tolerances, certainly not off the shelf.  I have seen the side and bottom feed injectors, but all of the LPPFI injectors I have seen in the field are contemporary appearing.
Franz

RE: Fuel injectors that can tolerate 120psi

(OP)
Why would I need 350-450psi? I was planning on using tank pressure and cooling the liquid propane on it's way to the engine. I'd also have some sort of vapor purge for hot starting. Because I'll also have a well ventilated engine bay, it's a inline with one side being cold, one being hot, and the intake manifold itself will be kept pretty cold (built in liquid/air intercooler and phenolic spacer to head), I'd think it would stay liquid.

This also isn't a daily car. It doesn't need to handle 100F days, as I'd never drive it on days like that, and we have so few of those anyway in Oregon.

I'm still thinking side-feed injectors may be able to live at these pressures as they won't be able to bust open at the center. At least they would have a better time than top-feeds.

I'd love it if a injector existed that could flow 76lb/hr of liquid propane at 120psi, but so far, none are for sale.

I'm gonna call Bi-Phase, but I'm betting I get the same response I usually get "not for sale to the public."

RE: Fuel injectors that can tolerate 120psi

Keeping the LP cool would certainly help.  Saturation pressure at 70°F is about 120 psig, so you will need to keep it at least 50°F.  The reason you need it boosted is to keep it in liquid phase to avoid heat saturation at the engine.  Your idea to vent the vapor into the bay is a little risky though.  Have you thought to purge the vapor into the intake during start up to assist there?  You could use a single point PWM injector.

Bi-Phase will not sell to the public, I've tried, and I know (knew) the principals, designers, and tech staff well.  76 lb per hour is a lot, you may need to pair injectors for that flow rate.  Its been done before.

You will also need to create your fuel flow tables with pressure and temp as inputs.

This could be interesting project, how large is the engine?

Franz

RE: Fuel injectors that can tolerate 120psi

Onya Franz

I knew you would be the one to come through with the details.

I sometimes wonder , if in order to maintain constant fuel pressure, the propane tank could be heated with a thermostatically controlled electric blanket, with the thermostat set high enough to give enough pressure to avoid vapourisation of the propane in the lines.

This would restrict the need for purging after hot soak to the injectors only, and would remove one variable for calculating fuel metering.

Regards
pat

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RE: Fuel injectors that can tolerate 120psi

(OP)
Heating the tank (increasing system pressure), then cooling the fluid as it goes to the engine bay is one idea. I'd rather increase the distance between target LP temp and vaporizatio LP temp (at whatever pressure I'm at), by using some type of pressure boost, with very cold LP temps.

I pondered perhaps just cooling the whole container of propane, then using a inline pump to get pressure up. If I could cool the propane down to say 40F, the tank pressure would only be 65psi. Then I could use a inline pump to get pressure up to about 100psi at the injectors. The LP would stay liquid so long as it didn't get above 65F at that pressure.

One of the plans for the engine was to put the AC evaporator inside my antifreeze reservior for the liquid/air IC. I could also use this fluid to cool the propane in any number of ways, be it the tank, or just the fluid on the way to the motor.

I could start and idle the motor on a fixed vapor amount through a orifice, then run the AC to cool down my reservoir, then switch to LP once the coolant is cold enough.

I was NEVER going to purge vapor under the hood. I was planning to purge vapor into the engine.

RE: Fuel injectors that can tolerate 120psi

One method I experimented with was self refrigeration.  Take enough vapor from the LP tank during starting and low speed running and the tank temperature and pressure will drop low enough.  Note that this is highly variable due to ambient weather conditions, tank size, tank fuel level, etc.  Toss in about 8 more input parameters into the fuel injection logic.
If a pressure sensor detected increasing tank pressures, the LPPFI system would decrease while increasing the vapor system.

Using a pump to boost pressure is fine, but remember that if the engine is ever shut off, the rail pressure and temp may hit 350°F during soak and ruin everything!  Thats why the tank pressures are so high, plus the need for a purge return line.
Franz

RE: Fuel injectors that can tolerate 120psi

Mitsubishi GDI injectors run at pressures over 250 psi in order to inject Gasoline directly into the combustion chamber. They are slightly larger than standard fuel injectors.  One part number I have is DMX078132C.  How well/long they will work on liquid propane...Anyway you may need to order them from a UK supplier, as GDI vehicles are not big in the USA. They also are not cheap.

RE: Fuel injectors that can tolerate 120psi

The mechanical injection 911 engines (early '70s) used high pressure injectors (I believe around 240 PSI) but they are essentially diesel type, spring loaded valves with a high pressure supply pump. I take it you are looking for electromechanical types?

RE: Fuel injectors that can tolerate 120psi

When I worked at Siemens, I work on an LPG program for the Chrysler 5.2L V8 engine. This was a multi-point system utilizing the Siemens Deka II bottom feed injector. There is an example in this Orbital literature. http://www.orbeng.com.au/orbital/aboutOrbital/pdf/OEC_SYN.PDF They were able to take the required 400psi. I don't have a part number for you and doubt they were ever sold direct to the public. They did produce some LPG vans in Canada with these injectors.

RE: Fuel injectors that can tolerate 120psi

Hi Obanion,
How did you go in your search for an injection system for LPG? I have come across half a dozen companies around the world that have told me they can sell me the gear to sequentially inject LPG into my turbocharged engine up to 500HP.
When I get time to digest it all I will.
If you want me to email all the replies (3 pages worth) let me know your email and I will send them through.
I just found this forum and have written to franzh about what the best timing curve would be for my 265CI Valaint Ute. Did you get the 360 running (RE: LPG for performance)?
Cheers.

RE: Fuel injectors that can tolerate 120psi

Turkeyokato-
I am working on a similar project, of LPLI system. It is a lower power generator application, but I would be interested in seeing the replies of the injector companies that you do have. I have looked at many injectors but only able to come up with one or two that might be feasible for me, and I'd like to cross reference against your list.

ETeene@Dal.Ca
Thanks,

RE: Fuel injectors that can tolerate 120psi

Willeng:
These injectors are designed for gasesous natural gas or propane and are not suitable for liquid propane.  The last time we investigated them (they are excellent vapor phase injectors) the orifices are too large and the moving compenents are too heavy to work against the liquid propane, and at the action cycle time needed.  With large orifices these CNG injectors have, the open duration is measured in well under .01ms.
Franz

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RE: Fuel injectors that can tolerate 120psi

franzh

No worries, i was unsure not being into this side of things, i just stumbled onto them when looking for something else. The info you supplied on them is interesting though!

RE: Fuel injectors that can tolerate 120psi

I am considering a project with hydrogen injected ICE. One of the problems is injectors. I think the best way is hydrogen direct injection, it yields best efficiency. Now I'm looking for hi pressure injectors that could inject hydrogen. The diesel injectors seem like the only option, although the problem is the hydrogen is a dry fuel, and there is no sufficient lubrication. Another idea is to inject liquid hydrogen to reduce combustion chamber temperature and prevent detonation.

RE: Fuel injectors that can tolerate 120psi

Uh, before you jump in and get over your head, several years ago I was part of an investigational team working with Natural Gas/Diesel on a locomotive engine.  What we found the biggest problem to be was providing lubrication to the NG injector and it suffered the highest failure.  This was a DI engine.  Direct injection in a SI engine will encounter the same problems, only diesel fuel will not be the pilot ignition source.
Also, you really should look at the physical properties of L-H2, storage, temperature, thermal shock, etc.  Almost all metals react violently to the thermal shocks of being exposed to the incredibly low temperatures of L-H2 on one side and combustion temperatures on the other.
Go with port injection H2, many Natural Gas products work.  Also, investigate Hydrogen imbrittlement, it will open some eyes on material selection.
Lastly, H2 is not especially efficient in comparison to other fuels.  It is currentlty the sweetheart fuel of many politicians which gets it more than its share of "air-time".  There is a thread somewhere in this forum that deals with H2 issues.
Franz

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RE: Fuel injectors that can tolerate 120psi

There was a show on The Speed Channel (US) recently where they installed an injector for Propane (liquid) into the manifold of a V8 diesel engine.  The system came as a bolt on kit.  I wasn't paying much attention until they claimed (?125?) dynamometer increase in horsepower.
If I recall correctly they mentioned they were spraying liquid Propane.

RE: Fuel injectors that can tolerate 120psi

Yes, I understand the implications, it will take a lot of experimenting to find a best working solution.
The efficiency depends on several factors like CR, mixture and injection metod. If all factors are considered it can result in efficiency beyond that of gasolne. Also,  fact that you can regulate output by changing mixture is rather attractive. In this case I'm more interested in output, not emissions.
As for storage, really efficient one is still to be developed. 10000 psi tanks were introduced recently, but I see it as temporary solution. Best storage would probably be based on carbon nanotubes, it is very promising technology.
Thermal shock is one of the big problems, and I'm aware that special materials will be required. There are few things that might help, MMC alloys, ceramic coatings, etc.
This is a long-term project, and I'm still in a phase of puting the theory together ang gathering information, so, every insight into the matter is appreciated.

RE: Fuel injectors that can tolerate 120psi

turkeyokato, thanks for the link. I had pretty much the same information as you,

Franzh, you seem to have a good background in this area, would you know of any liquid phase LPG injectors or automotive injectors that would work at the necessary high pressures to maintain the lpg as a liquid? I have read some reports of experimental systems running with Deka II injectors, but not really much else. I am excluding injectors such as the Bi-phase or Liquiphase type systems, where the entire fueling system is unique and has completely different function from a normal fuel injector.

I also came across a website somewhere that says the mitsubishi GDI injectors mentioned above would die pretty quickly when used with LPG.

RE: Fuel injectors that can tolerate 120psi

Have you looked at the injectors from Evinrude and/or Yamaha direct injection 2-stroke outboard motors?

RE: Fuel injectors that can tolerate 120psi

You might get some info from these people. You might have to goto Austin and front a couple of beers.

http://www.me.utexas.edu/~sae/37chevy.html

I have to take back my previous post as the system that was installed was a vapor system.

RE: Fuel injectors that can tolerate 120psi

Gaseous injection is quite easy .
Liquid injection isnt .

There's one manufacturer in Holland .
Don't email them , they don't bother to answer .
But they have a liquid phase multipoint setup .

It uses an pump inside the tank that deliveres the lpg
at a pressure of about 16 Bar .
Never try to use tank pressure , it won't work .
You'll be injecting a two stage fluid , and there's no relationship between pulsewith and injected amount of fuel . The pumps are fragile , and often require rebuild .
This is because the lpg isn't lubricating , and the bearings wear quickly .

The lpg injectors are extremely low impedance , and require
a special peak and hold driver to control them . Lm1949 based . They are also huge compared to std bosch injectors . Manifold clearance is often a problem .

I'm gonna use this setup someday on a turbocharged audi I5 . Abt 260 Hp . I'll use megasquirt as an ecu .

The biggest advantage of liquid injection is that it cooles the air charge , and if you also have an adapted ignition timing , it produces more HP than gasoline .


Pat





RE: Fuel injectors that can tolerate 120psi

I have looked at both of those injectors previously.

Evinrude's injectors are Ficht type injectors that produce the high pressure at the injector from a rapid solenoid hammering the fuel to high pressures. I don't see this working for LPG, because the high pressure needs to be maintained through out the system, to prevent vapor lock. It would be interesting to see if the Ficht type injector could compress a vapour LPG to liquid, but that is something I wouldn't have the resources to investigate.

The Yamaha HPDI injection system seems adequate at pressure, but my research has indicated that they do seem to have some durability issues with lubrication. This could be amplified when using LPG.

I remember a few years ago I was investigating a HPDI system, and that gasoline fuel pumps to operate at such a high pressure were impossible to find/get hands on. Diesel pumps would run at high pressure, but the fuel would lubricate the pumps. So this would create a lubricity scale something like this, is this correct?:
Diesel fuel > Gasoline > LPG

Mitsuko, by two stage fuel, do you mean two phase (ie. mixture of liquid and gaseous fuel? At 16 bar throughout the system, the LPG should stay in the liquid phase. I could see the dual phase LPG occuring at lower pressures such as 1.5-2.0 bar, but not at such a high pressure.

RE: Fuel injectors that can tolerate 120psi

I have looked at both those injectors.
The evinrude injectors use Ficht injection, which uses a solenoid to rapidly hammer the fuel, which generates the high pressure at the injector. This would not work when trying to maintain a high pressure throughout the system to maintain LPG as a liquid. It would be interesting to see if the ficht injector could compress vapour LPG into liquid form, but that would just add complexity to the system.

The yamaha HPDI injector system seems alright, although I did read a report or two about injectors failing due to lubrication issues. I came upon this system a few years ago looking for a high pressure gasoline fuel pump. However, obtaining any high pressure fuel pump for experimenting was impossible. Using diesel pumps was not a valid solution either. For lubricity of fuels it would then go something like this:
Diesel > Gasoline > LPG liquid > LPG vapour
I could see these injetors/fuel system struggling under LPG, if this is correct.

Mitsuko,
by two stage fuel, do you mean two phase fuel (i.e. both liquid and gaseous states). I would expect seeing this at lower pressures such as 2bar, but not at something as excessive as 16bar. What temperatures are you running at to cause that?

I know it isn't easy, but it still might be worth attempting.

RE: Fuel injectors that can tolerate 120psi

Yes i mean two phase fuel .
Sorry , I'm dutch speaking .

You'll only have two stage liquid if you use tank pressure at the injectors . You know that  at a given temperature ,
each liquid has a matching vapour pressure .
There's no way telling what the amont of liquid an vapour will be at the injectors , if you feed them using the
"natural" pressure of the tank .

With the pump at 16 bar , you're absolutely sure to have liquid only . Vapour cannot exist anymore .
Then injector pulsewith will have a correct relationship to the injected mass of fuel .

Thesame happens with gaseous injection .
The liquid is heated above 80° C by engine coolant ,
vaporised and reduced in pressure to ambient.
This makes sure no liquid can exist anymore , and you inject once again a single phase fuel .
Still the pulsewith needs to be corrected for both temparture and pressure .
PV=nrT . Pulsewith = V , nr is a constant .
T an P need to be taken in account to calculate the correct
mass of fuel .


Fascinating stuff

Pat




RE: Fuel injectors that can tolerate 120psi

There's a bi-fuel FIAT Multipla normally sold in the Italian Market, which is equipped with two completely separated injection systems (also two divided ECUs). The LPG liquid-phase injection system is sold by Metatron (formerly a joint venture between FIAT, Tartarini Auto and others, now a separate firm) ... we at the University just both a comlpete Metatrono LPPI injection system to set up an experimental activity on the fuel spray (which tends to form ice particles at the inlet manifold obstructing the injector and prejudging partially mixture control). The injectro rail alone costed 220 € (the 4 injectors and the rail), the complete system (without the ECU: tank, manifolds, injector rail) was 980 € (for educational purposes). The system is not equipped with a pressure regulator, so it still has some problems in controlling air fuel ratio, expecially at high engine speed, when injections at different injectors overlap.

RE: Fuel injectors that can tolerate 120psi

What if you used a nitrous oxide kit and ran propane through it? The solenoids could be triggered off of a crank or dist p/u. It would be crude but might work

RE: Fuel injectors that can tolerate 120psi

These solenoids do not have enough sensitivity or fine action control, and cannot cycle fast enough to serve as an injector.  
Franz

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RE: Fuel injectors that can tolerate 120psi

Checkout the last post by optimum:
 
Thread71-108825

RE: Fuel injectors that can tolerate 120psi

These injectors are designed for gaseous LP, NG and H2. Look at www.qtww.com May be the answer to problem. Have used on liquid with good results. The main issue is thermal, not pressure, as these can handle many bar., FD

RE: Fuel injectors that can tolerate 120psi

Just a very strongly worded warning!
Anyone attempting to use a vapor service fuel injector, or a gasoline/petrol injector for liquid propane applications is in serious jeopardy of inviting an engine fire, a hydrostatically locked engine with uncontrolled fuel expansion into the crankcase, exhaust, or upper valve train areas, a blown apart fuel rail with disastrous consequences, injury, or worse.  Since the liquid is 270 times more dense than vapor phase, and is very thermally reactive,  anyone thinking of pressures should probably double their best guess to start.  I know personally of several systems that have had over 450 psig in the fuel rail and tank, just from heat absorption from the engine.
Liquid propane injectors are hand matched, precisely machined components with precision orifices.  The control strategy is VERY, VERY hard to implement.  The one system used here in the US is purpose built and only suitable for very few applications, none aftermarket for the user-built.  The ones used in Europe and down under are uniquely designed and also precision components.
Lastly, please be very careful when working with modified gasoline or other components in liquid phase propane/LPG, interesting things can happen very quickly, and traditional methods of mitigation may not work.
Just ask how I know, been there, done that.
Franz

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RE: Fuel injectors that can tolerate 120psi

I was involved in some basic R&D work for LPG fuel systems.  One issue that constantly hounded us is the heavy hydrocarbons (propylene, etc) in LPG polymerizing and clogging fuel injectors and other components exposed to heat soaks.  As Franzh stated, most OEM systems are careful balances of component interaction and have limited application outside their initial design.

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