multi port liquid propane injection.

[frank_ster]

2005 subaru legacy with 3.8 buick v6 turbo ms3 x sequential injection. 5 speed auto ( soon to be controled via megashift.)
this is my current daily driver.

current tests being done are propane flex fuel. due to very low propane price about 60 cents a liter. have already exprimented with mpfi liquid propane through the stock fuel rail. below are videos. i have searched and searched and there was very little information on propane injection. and specific propane injection kits are quite pricy.

The below test showed me a few things.
#1 propane in liquid form can be sent through gasoline fuel injectors
#2 the injectors do not overheat nor freeze thus far.
#3 propane was fed into fuel raid that still had gasoline inside. while running with out issue. however the reverse is difficult due to the higher pressure of proapne 60 -150 psi depending on the temperature of the tank 5 c -30 c. so a purge would be needed to return to gasoline. for seamless transition from gas to lpg I would think seperate fuel rails would be best.

https://www.youtube.com/watch?v=oMdDSJbMGHQ
https://www.youtube.com/watch?v=7DnWMVhdGHg

and my readings the hp potential would be the same if not better than of gasoline, propane running on the rich side does not have the black smoke effect.
i have purchased a in spare tire location lpg tank with sending unit.
and will soon do some driving tests and will provide updates.

any questions dont hesitate to ask ! but i hope to be able to drive my awd muscle car with per km cost the same as a prius running on gasoline !

[JaccoF]

The only LPG liquid injection system I know of is, called the LPi http://www.vialle.nl/home.html?L=1
A friend of me has 2 car running this system, both Volvo's, a V40 with 465.000km and a V70 with 400.000km stock ecu no ms.
The system has a pump in the tank to keep the pressure up and I think that you stock injectors won't last long on lpg, no lucubration and I don't think wise from a safety point of view.

I have installed several ms3 lpg vapour injection systems, most V8 one super charged and even on a motorbike, this works just as good as LPi but you don't need a LPG tank with pump in it. The only possible benefit of LPi is the it cools the intake air like petrol because it has to evaporate in the intake manifold.

[frank_ster]

pardon my ignorance but what lack of lubrication ? liquid gas is a solvent, and liquid propane i would think is similar.

[jsmcortina]

There's a lot more in petrol than just plain octane though. Does LPG contain all of those additives? LPG is a much lighter fraction so most likely consists mainly of short-chain hydrocarbons which won't lubricate.

James

[frank_ster]

Next week I will begin commuting using propane through the stock injectors.

The thought has crossed my mind if they would damage my injectors. so i will use smaller stock ones that I would not cry over if they die.

I'm thinking about just plumbing two into the charge pipe before the throttle body to start with. This will at least allow me to test in cruise and light acceleration.

I also have another intake manifold with and added 6 injectors above the stock injectors. This could also be swapped over easily if the first string of tests work well.

And of coarse I will keep you posted. I do about 800 km per week of mixed driving so the endurance of the injectors will add up quickly.

Frank

[Marek]

Dear Frank,
Have you done any long term tests as to what liquid propane will do to all of the rubber components in your fuel system?

You may find that the rubber compounds which are safe with petrol will deteriorate quickly if exposed to liquid propane. Certainly, the rubber O-rings used in LPG (gaseous propane) are not the same spec as those used for petrol and liquid propane will be much more aggressive than gaseous on account of the very high pressure needed to keep it liquid at room temperature.

As James points out, you need to be running a car with hardened valve seats, otherwise some form of lubrication will be in order.

kind regards
Marek

[ashford]

i work on a fleet of trucks that are lpg injected. i have a bit of experience with it and can give you pointers if need be. i will start out with a few point first.

1.the gas injectors will squirt in the lpg but will vary wildy on flow rate and opening times. the injectors i work on use a physical property (area ratio) so no matter fuel pressure(tank to atmosphere) flow is the same al long as boost pressure is the same(supply to tank)
2. the first time you shut the engine off hot it will never restart without a purge system and a pump
3. with underhood temps above @250F it will vaporlock even with stated above. the system i work on has the high pressure hose inside the return hose, which cools the oncoming with the refrigerant effect of the return.

here is a link to the company that makes the system, at the bottom there is a diag pdf. http://www.bi-phase.com/ourSystem.html

on these particular trucks the oil is changed every 25,000 miles. it still makes me cringe but it seems to work. average lifespan of the motors is 140,000 miles of stop and go driving. which is not bad considering the vehicles weigh in about 20,000 lbs.

[frank_ster]

^ nice thanks for the info !
how do these vehicles start in winter ? ie -20 deg c or -5 F ?

the vapor lock is interesting ? what do you mean exactly ? to me the hot temps would cause the propane to expand and any gas would compress into a liquid.


marek
hardened seats have been around for a while my 87 engine has them so shouldn't be to much problems.
buna-n is states compatibility of 4 for propane meaning good for static and dynamic seals. 4 is the best compatibility.

[ashford]

^ nice thanks for the info !
how do these vehicles start in winter ? ie -20 deg c or -5 F ?

the vapor lock is interesting ? what do you mean exactly ? to me the hot temps would cause the propane to expand and any gas would compress into a liquid.

they start as good cold if not better than a gas engine. there is a trick to it though. the early trucks used the factory pcm with a special ect it never reads below @70f the extra fuel a gas pcm injects floods them. i have started them in -20F without being plugged in much to my suprise.

as for the vapor loc this is just basic principals of propane. lets say you hava nice 80f day out tank pressure will be about 125psi(vapor pressure at80f) underhood temps are 180f ans so is line temp in order for the propane to be liquid you need around 400 psi(vapor pressure at 180f). thats the reason for a supply line inside a return line it has a cooling effect. this is even more prominant in colder(weather) temps it takes a longer purge cycle to cool things off.

[frank_ster]

I see what you mean, they run a pump to circulate what is in the rail. Makes sence to me, i could implement that quite easily. any thing else ?

[frank_ster]

in response to the purge cycle, my buell motorcycle runs the fuel pump periodically when temps are hot. i assume its to cool the fuel rail, some thing like this can be set up also with a temperature sensor right on the rail.

but first things first install tank and make it work !