gmv93

Here is a new thread for LPG systems in engines. Proper way of using commercial alternative fuels to gasoline or diesel. As a note, LPG can be used with special injection systems in Diesel engines simultaneously, increasing efficiency and power. Energy level of unit volume of LPG is %20 less than gasoline roughly. So you consume %20 more to match same performance.

There are two major types of LPG systems.

1- Mixer type analog systems or mixer type digital systems
2- Injector based LPG injection systems.

gmv93

First of all we need to define components of systems.

a) LPG tank with LPG gauge which sends fuel level info for tank to driver
b) Hoses
c) Converter to convert liquid propane to gas. Can be called vaporizer
d1) Emulator (for carburetor systems or mixer used EFI systems)
d2) LPG ECU (For injector equipped modern systems)
e) Pressure regulator
f) LPG filter (For EFI)

gmv93

1)Mixer type systems has two approaches in application. First leaf called mixer attached below carburetor under your round air filter housing. This directly mixes LPG and air. For EFI engines you can still use mixer approach by adding round shape mixer to air filter hose after MAF sensor and this has same mixing affect with leaf type mixer. Those mixers have lots of variations, for bigger volume of engine you need a bigger hole inside mixer to let air pass through freely, if it is not large enough you cant get optimum performance form you engine which is supposed to have when operates on gasoline. There is a manual valve to adjust LPG amount, that valve is there to control amount of LPG under load. Also on converter, which holds a elastic diaphragm inside, adjust LPG requirement according to butterfly, directly related to vacuum created by engine. Idling mixture is adjusted on this converter apparatus.By this approach LPG on demand methodology is possible. You need to install that converter perpendicular to braking direction, and perpendicular to gravity. If not, your car stalls. When engine temp is reached to a pre programmed level, on EFI engines you rev your engine like 3000 rpm and it switches to LPG fuel. On carburetor engines you need to switch LPG manually by pressing a button. This is good when you are living in warm climate and you wont need gasoline to start the engine.

gmv93

2)Injector systems utilize high tech ECU like controller units and injectors for each cylinder. In general injectors are fixed on a fuel rail. Engine block is drilled and LPG injectors are installed with rail. Coil or piezo injectors acts like gasoline injectors but works with gas. Controlled by LPG ECU, those ECU has OBD integrated connection and it is adjusted and tuned with a computer or PDA. When adjusted correctly integration is seamless and you cant evern realize engine is running on LPG. When coolant temp reaches a pre programmed level, it switches to LPG, by sequentially shutting gasoline injectors.

gmv93

a) LPG tank is a tank which holds LPG in pressurized state - liquid. It is made of very thick steel and strongest part of car . Stronger than chassis. There were accidents,no car in the end but there was a tank left on road surface. There is a filling cap installed on tank for commercial pumps at stations. On tank, there is a level mechanism like the one inside flush, to stop refuelling and it keeps pressure stable.

gmv93

b) Hoses are insulated by polyurethane and made of copper alloy. Easy to fit and easy to bend. Strong enough to withstand against pressure. Under hood, usually two valves take place.after converter, on rubber non pressurized hoses. But sometimes it requires only one to adjust LPG rate. It depends on engine design.

c) Converter is an apparatus to convert liquid and cold LPG into warm gas. It operates when coolant temperature rises to a preset value.There is a direct parallel connection to coolant hoses. It is same for both type of applications but on mixer type it is bigger in diameter.

gmv93

d1) Emulator, emulates ECU signals and cheats ECU, by this way ECU thinks injectors on EFI engine is operational, but all gasoline ınjectors are shut. System cant work by mixing gasoline and LPG. It causes stalls during idling and ignition like problems and missfires.

d2) If car is EFI and if system is sequential LPG system, digital circuits are utilize to control every parameter you may think on car engine. Actually it clones car ECU variables and it is adjusted accordingly to tune car engine to operate on LPG flawlessly. Again it shuts gasoline injectors when LPG is ready to used.

gmv93

e) Pressure regulator adjusts the pressure of LPG heated in converter and keeps relatively constant pressure all times. Safety circuit also cuts power to LPG system if it is mixer type or EFI for safety reasons. It also cuts LPG coming from convertor when there is a leak on system.

f) on most of LPG systems,LPG filter keeps unwanted oil residues which may be contained by fuel. It is a closed can.

gmv93

I am using "sequential" system on 4.0 engine. It is BRC branded. Italian products. One of most expensive but advanced system available today. Here in Turkey it cost you around USD 1.800 for 8 cylinders. Little less for 6 cylinder.

I did not install this, somebody did before we bought this car. It has 6 injectors, and a ECU to control everything. It has a special connector to connect to PC. They can see live parameters while driving car, and copiy ECU datas to PC. After switching to LPG, they try to match graphs under different conditions like, full load on alternator, brakes on, full throttle, idling and so on.

On photographs you will see major parts of system. Tank, tank detail, filling hose ECU for LPG system, injectors rail;

gmv93

...and injector details, cut off switch detail with small size EFI type converter/vaporizer, cut of switch and filter, button inside cabin with led LPG meter(4 green leds and 1 fuel type led).

gmv93

you can drive as long as you want. it lasts forever.

mwdouglas

very nice description thank you

Morat

That is a very neat install! Do you really need a sequential system with the 4.0? With an alloy intake, couldn't you use a single point system? (closed loop for preference of course).

Coog

No, I've a single point mixer. Works 100% on the 4.0. Sequential is better but single point is cheaper here. Fuel is half the price (here in the UK/Ireland) and CO2 output (if you're that way inclined drops significantly).



You can see the filler point on the rear quarter on the opposite side of the petrol flap.



Saves me around £30 ($50ish) per fill... our fuel is seriously expensive compared to what you guys pay in the states, hence very usable and quite clean Cherokee's are available from £250 onwards. I picked up my lpg converted one with 106k miles for £700 (about $1200 ish) lol

gmv93

you can keep it simple with less complicated systems on most of engines. 4.0 is easy one to work with but, there are trends in this business i guess. today it is sequential systems, tomorrow it will be CNG. who knows. if i would invest on a system,i would go with analog one with a mixer inside filter hose. that is easier to maintain and cheap setup. regardless of engine displacement, it is around USD 750 in total. Plus you can override almost everything.(even you can inject hydrogen into gas mixture with two other hoses) With two simple screws on converter you can adjust lean or rich mixture during idle by simply observing exhaust color during a cld winter day, you can adjust high revs for performance or economy. if you close valve on hose, it consumes less but hesitates to accelerate, if it is more, it consumes lots of LPG.

for modern cars, like VVTi engines you cant use mixer type ones. you need a computer to maintain everything. for mitsubishi GDI or VW FSI engines, due to intake and fuel system designs, you cant simply use modern sequential systems, even if car is latest technology you need to use analog ones. it depends on your needs, and technology used in engine design.