LPG Discussion Forum

Hi,

I have an 09 Subaru Forester Manual X 2.5 ltr that has had an Icom JTG LPG liquid injection kit fitted. Prior to fitting the kit I was told that the following about economy--

1. Liquid Injection offers around 10% better economy than the best vapor systems.
2. Old vapour is 30% to 50% worse than petrol mileage.
3. New vapour (or the better systems) are 16% to 20% worse.
4. Liquid is 8% to 10% worse but some vehicles do better ECU dependent.

On petrol driving country cycle I can get in the high 7ltr/100klm to mid 8ltr/100klm (say low 30's MPG), the car is good on fuel when driven lightly. On gas I am seeing 11.5ltr/100klm (country cycle) (around the 24.5 MPG mark). Given the claims I was expecting 9 to 10 ltr/100klm (28-31 MPG) on gas. Currently the consumption is around 30% worse than my normal consumption on petrol, which has me wondering why I paid the premium for the liquid system?

The fitter has been very professional and some time has been spent getting the systems calibration correct, its the first Forester they have done so that is to be expected. However, so far none of the calibration efforts seem to have made a difference to the consumption. I also note that the car seems to consume all most the same on gas across all driving "intensities" where as on petrol it ranges quite significantly... a light foot is rewarded far more on petrol than gas.

Has anyone got any experience with liquid injection systems that might help me understand if I am seeing the best of this or if there is something astray here. So far the sales talk and reality have yet to line up!

Cheers
Z

my forester (1998 2.0 N/A) runs around the 26 mpg mark on LPG and about 29 if im lucky on petrol. Thats under normal driving, not booting it very often. If its driven hard then i have had it down to around 21mpg! They are fuel friendly machines! Im running a multipoint vapour injection system on mine, so is a little different to yours, but thought the MPG figures would be of more intrest...

Hi Ttalps,

Thanks... hmmmmmmm... not sure what I make of that, I know that the 2009 2.5 N/A Forester is much better on fuel than the previous 2.5 N/A models despite being essentially the same engine. They did something but I don't know what. My stepfather has a 1999 2.0 N/A Forester and says that the 2009 is slightly better on fuel despite being .5ltr bigger and a bigger car (survey of one???!) Your numbers confirm that, I better the quoted 30.3 MPG and normally get around 32.5 MPG on petrol but not much city in that!

The liquid system is supposed to be better than the vapor so given the petrol consumption I was hoping to do better... considering what I was told before I bought the system, 29.25 MPG seemed like a reasonable target for my normal cycle.

I think that there is still some calibrating to be done, the little flare in revs that the ECU seems to provide between gear shifts is still much more noticeable on gas than petrol. This has been the give away in the past and so far we have come down several sizes in "jets" but I suspect that there is more to come. In the middle of a 4000K road trip right now so I should have a good feel for consumption by my return.

Thanks again

yeah the newer engines are slightly more efficient, not by much though!
They are thirsty old things and eat fuel for the fun of it im sure!

My normal drive is to work which is 18 miles and urban driving around 40mph most of the time, so get a decent mpg figure out.

On the motorway it stays around the same, load dependant though and of course speed dependant! Start giving it beans on the motorway and my mpg just drops hugely!

I have been getting around 25 in the hot weather with the climate control on with A/C which im happy with anyway!

Zedlum wrote:Hi,

I have an 09 Subaru Forester Manual X 2.5 ltr that has had an Icom JTG LPG liquid injection kit fitted. Prior to fitting the kit I was told that the following about economy--

1. Liquid Injection offers around 10% better economy than the best vapor systems.
2. Old vapour is 30% to 50% worse than petrol mileage.
3. New vapour (or the better systems) are 16% to 20% worse.
4. Liquid is 8% to 10% worse but some vehicles do better ECU dependent.

On petrol driving country cycle I can get in the high 7ltr/100klm to mid 8ltr/100klm (say low 30's MPG), the car is good on fuel when driven lightly. On gas I am seeing 11.5ltr/100klm (country cycle) (around the 24.5 MPG mark). Given the claims I was expecting 9 to 10 ltr/100klm (28-31 MPG) on gas. Currently the consumption is around 30% worse than my normal consumption on petrol, which has me wondering why I paid the premium for the liquid system?


Cheers
Z

bet you've been reading Steve's go-lpg site ..

vapour systems / open loop, on a long run are more economical than than sequential.

reason ..

sequential systems try to equal the petrol performance.........so they are tuned to ram more gas in ..if they are fitted to a car with with a O2 probe and complex ECU they have too to avoid upsetting the ecu...the 20 percent difference in calorific value is made up for by putting more in

open loop systems on an older carbed car are more economical ...the car will be slower both in acceleration and top end ..but will use less LPG

the 20 percent difference is seen as slow acceleration and low top speed..

my old car had open loop and gave equal miles per gallon on petrol as on LPG.

wish i had known that before i converted to sequential......i also read so and so's site


all the best.markj

Hi Mark,

No I dunno about Stevos site?! URL pls All I have been told comes from users and the importer of the JTG Liquid System.

So far on this trip I have varied from +10% to +30% on petrol with no rhyme or reason to it. I suspect that the calibration is still not correct and the ECU is getting off track after running on Gas for a while. When I flick back to petrol it appears to settle the gas down for a bit... not real sure what is happening yet but I am watching closely!

Z