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frank_ster 01-10-2013 12:53 PM

propane conversion thread
so some people have been starting to ask questions on propane so might as well start a thread.

first question :

excuse my dumb?, but how does that work exactly? i am very interested in that if its an option for my 05 gt

a propane tank is installed in your car. Different tanks can be installed they have simple rectangular tanks, round tanks and spare tire location tanks.

there are two types of propane systems. vapor injection and liquid injection.

the tank sends propane to vaporizer that lowers the pressure to about 15 psi above manifold pressure. the vaporizer is heated with coolant from the heater core to prevent it from freezing and yes it can freeze in the middle of summer if your driving fast!

the propane is then sent to an array of injectors. the injectors are simply mounted near the stock injectors, then hoses run down to nozels that are tapped into the intake manifold.

the systems comes with a ecm to control the fuel and when it begins working after warmup. the engine needs to be warmed up on gas when below certain outside temperatures. inside the car there is a small switch that also has 4 led lights indicating the level of propane in your tank. so pressing this switch will switch from gas to propane while you drive. you may feel a light jerk.

Lpi liquid propane injections is pretty much like regular fuel injection
you have a tank pump injectors and pressure regulator.

lpi you can cold start on propane and even in -20 deg temperatures.
lpi the fuel is injected as a liquid that will vaporize in miliseconds that will freeze to about -40 deg. this will cool the intake charge. so expect more hp on propane than gas when using lpi.

lpi there are no kits as far as i have seen on ebay yet. and would be for dedicated change to propane or have two injector fuel rails.
the lpi system uses stock like injectors on the stock like fuel rail. i say stock like because i'm testing the compatibility, i have seen photos of lpi systems ( new your city garbage truck and other city trucks using lpi that the injectors appear stock.
so i tried it. so in the 1 hour i ran it its fine. the orings and seals on a gasoline engine are perfectly compatible to propane also.
the key that i didn't have in the video is a circulation pump. the circulation pump is for when the fuel rail gets warm or hot the propane has a tendancy to "vaporize" this pushes the liquid back into the tank. and when your try to restart its injecting propane in a gaseous form which is much less dense, so a fuel pump is used to circulate the fuel in the rail to push new liquid propane into the rail. the vapor will return to the tank to cool some of witch will turn into a liquid again.
the pump i plan to use is a gerotor type and have a 5 psi regulator back into the tank.

costs: the ebay kits are about 1700$ with the tank. 1000$ for the injection components and 700$ tank give or take.
cost of propane is typically half the cost of gas. but it can vary. to estimate your fuel consumption you can figure 1 gallon of propane will get you 90% as far as gas. so if your getting 22 mpg figure about 20 mpg after.
depending on how much you drive the kit will pay for its self in 3 months to a year.

the liquid propane will likely be cheaper. if the stock injectors and fuel rail can actually be reused, circulation pump is about 100-150$ and the return regulator is 8$. i would run new steel lines or stainless braided hoses to the fuel rail.
the tune may be altered by 10% , cranking pulse widths change is still unknown, the wot full rich can be made even richer 9.5-10.5 to 1 afr you can run much richer using propane with out the black smoke, which is the key to the increased power levels.

on the kit ( vapor system ) you may have less power on the propane, and in the case of you wanting more power you can hit the switch and in half a second your back to gas ( may feel the engine stumble depending on the tuning) and your exactly where you were before the conversion.

mwiener2 01-10-2013 01:21 PM

How big and where are you putting the propane tank? How crash safe are you expecting this to be?

700watts 01-10-2013 01:39 PM


frank_ster 01-10-2013 03:05 PM

1 Attachment(s)
attached is a photo of a 55 L tank,
the tank is used in europe on thousands of cars.
the tank fit perfectly with no modifications to the spare tire hole. and is held down with the spare tire screw.

the tank is sealed around the bottom and there is a upper cover. the connections go directly out of the car cabin so if there is a leak in the valve , hose , fittings the pressure can easily go out side.

frank_ster 01-10-2013 03:08 PM


Originally Posted by mwiener2 (Post 4240427)
How big and where are you putting the propane tank? How crash safe are you expecting this to be?

there are many videos of propane safety, and is known to be as safe or even safer than gasoline.

propane tank in a accident is just as safe as a gasoline tank. it has a 3/4" tube with dump valve in case of crushing.

also propane does not soak some one and cause their skin to catch fire and burn as gas does !

Whatisit 01-10-2013 11:40 PM

When i was growing up, my gramps had a propane powered lincon towncar (I think it was a 1980 or 1981). His tanks where massive and took up 1/2 of his massive trunk. His car ran strictly on propane, and as i recall his oil change intervals where very very long as the oil never carboned up. I think i remember him having an issue with some seals drying out because the propane flame was hotter then gas, i could be totally wrong. Its really cool knowing that propane is making a comeback. please keep us updated

05wagongt 01-11-2013 05:16 AM

thank you for the sticky

Serb Legacy GT 01-11-2013 09:20 AM


Originally Posted by mwiener2 (Post 4240427)
How big and where are you putting the propane tank? How crash safe are you expecting this to be?

Propane tank conversions are very popular in europe. Over in Serbia it seems like 50% of the cars are on propane there. It's about 50% cheaper which is the driver over there, especially when you're looking at $1.50/L (almost $6/gal on much lower monthly income than the US), so it's hugely popular. I've driven propane cars that have the propane tank, and in the event you run out of propane, you can switch to gasoline. The only difference is that under gasoline power the car is a bit quicker and peppier, and is slightly more fuel efficient. I would believe that if the car was designed to run on propane from the start you could get it to be just as fuel efficient, and just as quick as a regularly fueled car. The slight drop in mpg's still makes the propane conversion worth it over there because the propane is so much cheaper that they still come out ahead.

As for safety, they have their accidents over there just like anywhere else and I've never heard of a vehicle exploding or the propane making an accident into something worse. Most likely in an accident, either the tank is not damaged or if it is, you just have propane vent out.

Durkin 01-11-2013 11:16 AM

I don't know a lot of the specifics, as my department does not use the systems, but my county's sheriffs office has some crown vics with the gas/propane system. They're told the tanks will take a serious crash to be punctured, and their location (right behind the back seat in the trunk would be difficult to hit during a wreck, so it makes sense). I'm told the fuel efficiency is down but it seems as though the propane cars are quicker. If I can locate any data on it I'll bring it here, obviously not the same engine, but some might carry over.

frank_ster 01-11-2013 11:41 AM

propane has 10% less btu's per vollume than gas.
so they will always be slightly worse economy.

propane engine and gasoline engine are the same.

propane engines can be built with slightly higher compression due to the higher octane.

SCHM1AN 01-17-2013 07:32 AM

Any progress reports?

frank_ster 01-17-2013 06:38 PM

the tank i purchased , came with a filler attachment but the european type,
there seems to be 3 types world wide.

1-1/4" acme north america and suthern europe

cup type northern europe

and england has another type. i think its just like a regular propane left hand thread thing.

so i had to order this part seperately. i was not able to find anything untill i found sherwood valves. i found one on a liquidator on ebay for 25$.
so i need this to fill the tank!

the next item i will drill and install a larger bung on the rear bottom of the tank. from there i will install a gerotor pump capable of 140 gph that will circlulate the propane though the rail. the pump i'm going to use is a mallory 140 capable of 10 psi.

thats where i am at this point.

ehsnils 01-21-2013 04:41 AM

Just don't mix up LNG (Methane) and LPG (Propane) fittings.

No harm when putting LPG into LNG, but the other way around can make a decent explosion since the pressure of LNG is higher.

frank_ster 01-21-2013 05:50 AM

we cant even get lng here as far as i know . at least to the public

derp 01-21-2013 06:35 AM

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