Fuel econonomy on lpg v8

[evil_mx6]

Just wondering what typre of fuel econonomy you guys are getting on your cars been either straight gas or dual fuel.....
my vs 5LT statesman has averaged about 17L/100km
i have worked this out by litres filled divided by km's travelled.
Highway driving she mite drop to about 15L/100km.

I have changed the o2 sensor and coolant temp sender. This has probably only helped by a litre if that.

I know lpg burns more than fuel but i think that the figures i have are way too much.

Gas system is a Gas research with Gas research throttle body.

Mods to the car are a cat back exhaust.
Nothing else.

What are you guys getting either as is or pre tune and after tune.

Looking at getting a foam tune and then finalised on the dyno to fine tune some points via a gas research specialst.

Let me know....i am wrecking my brain about this.....

The cars trip computer reading will say about 8-10L/100km on highway driving.

City driving will read about 13L/100km

[MasterOfReality]

What is the average speed indicated by your trip computer?

I don't have gas but my 5 litre will easily get average 21 L/100km in the city over a tank, and the average speed for that tank would be around 30-33 km/hr.

On the freeway, the instantaneous consumption drops to 10 L/100km, but mix in a bit of city traffic and I always get around 15 L/100km, and the corresponding average speed is around 40-50km/hr.

Just fill her up, reset the trip computer and go on a couple of hours drive down the freeway. If you end up with an average of around 10 L/100km after a couple of hours running at 100km/hr then all is fine.

[levymetal]

those figures are actually better than average, no reason to complain . remember lpg uses 30% more than petrol so 17L/100 gas equates to 13L/100 petrol. which is extremely good for a v8. my 5ltr on gas uses between 18-20L/100 with lots of highway driving

[evil_mx6]

hmmmm.....i thought that she would of been a bit better.....well the other day a done a 160km round trip on the freeway....all hway driving....the cars readout was 9.8L/100km....avg speed readout 91km/h.....and when i filled the gas up my average consumption based on kms and litres filled was 15L/100km......
Are the gas research systems generally better? and will they benefit much from a proper memcal tune and then a dyno tune to adjust the gas to the new tune?

Did you guys notice any improvement when you got a dyno/ memcal tune done to the car (performance and econonomy) ?

Cheers

[levymetal]

you have to calibrate the computer to show the correct reading - 88greenvn did it and he said it works good but i could never get it to be accurate with gas myself.

15L/100 on gas equates to 11.5L/100 on petrol so i don't really know what kind of economy you're expecting from an old v8 in a heavy stato...

gas research is the best you can get for carby-type setups (aka non injection). you might want to pm nicefrog on ebay and get a tune from him, should get you more power and slightly better economy but your car seems to be pretty damn good at the moment.

oh by the way is your car dual fuel or dedicated gas? if it's dual fuel the tune is always a compromise, lpg has quite a different spark curve than petrol.

[evil_mx6]

well the petrol side of things is not working maybe a dead fuel pump.....so the car is pretty much on straight gas and thats how i think i will be running it anyway.....if i do fix up the fuel pump itll only be on petrol for emergency back up anyway.....

[Gaz_3110]

You do need to run your Petrol system for about an hour a week. My Vp Calais pulles 8.1L/100Km Average.
7.1L/100km on open road, 9 - 10L/100km in the city. Add 30~% for gas. I did 1000 Km on the weekend and used "82.xxL". Put in about 110L of gas and have more than I left with.

[BT1-355]

hmmmm.....i thought that she would of been a bit better.....well the other day a done a 160km round trip on the freeway....all hway driving....the cars readout was 9.8L/100km....avg speed readout 91km/h.....and when i filled the gas up my average consumption based on kms and litres filled was 15L/100km......
Are the gas research systems generally better? and will they benefit much from a proper memcal tune and then a dyno tune to adjust the gas to the new tune?

Did you guys notice any improvement when you got a dyno/ memcal tune done to the car (performance and econonomy) ?

Cheers

Well since your car is running straight gas, there is no piont of getting a tune from greenfoam as the gas system has its own computor (to control the amount of gas etc etc). The money would be better spent on getting the gas research system tune and service. 17ltrs to 100km sounds about right (they are big and heavy cars) , i use to own a super6 with injection gas system and i was getting around 12ltrs to 100km. BTW have you got gas spark plugs and a clean airfilter??? Just remember every servo will give you diffenert amount of km's as there mixes are different from pump to pump. I recommend using supergas as there gas is pure bbq gas, unlike other servo which uses a mixes of propane and butane

[levymetal]

the ecu still controls the ignition timing though, and the stock one's not optimal for lpg, so i'm sure greenfoam could whip something up that has a more lpg-suitable curve. but yeah getting the gas tuned is very important, same with keeping the ignition system in good condition. btw does anyone know the correct spark plug gap for a 5ltr on gas?

[evil_mx6]

i think the correct plug would be about 1.1mm for gas.....standard gap is 1.0 for petrol....
also if gas is used more BPR7EF would be a better plug since these are more better for hotter environments like gas....standard is BPR6EF....
i have had different opinions regarding getting a tune done, some say memcal tunes will do nothing others say it is still needed to control timing and so on....others just tell me to get a dyno tune done and not worry about the memcal tune.....
just after some advice and what peoples thoughts are.
Will getting a memcal tune still make a big difference like people have witnessed on petrol?

[levymetal]

the memcal tune probably won't make *as* big of a difference on gas as petrol but for the price it's worth it. gas needs more timing at low rpm and less timing at high rpm, and even on the gas the memcal still controls the timing. so the stock tune doesn't have enough timing down low, yet it has too much up top. advancing the timing on the dizzy alone is dangerous practice because you risk detonation at high rpm. i would go for a foam tune over a dyno tune, its 15x cheaper and greenfoam is spot on with the 5ltrs. then all you need to do is get the gas tuned as well and it will be great.

[jimmyd17]

My VP wagon 5 litre on LPG (dual fuel mixer setup) was getting 15L-17L/100km suburban driving, and got around 11-12L/100km on the highway. Its all in bits at the moment cos i'm rebuilding the engine as well as lots of other stuff. The old dizzy and rotor button looked pretty stuffed, but i still got good economy. I'll be interested to see if the good economy i was getting will change for better or worse when its all back together, with a mild cam, new coil, dizzy, leads, plugs, etc.

[PietroChocko]

Mine averaged 15-17L/100km in the city. On the highway that would drop to about 10ishL/100km.

I've blown the odd airbox or two... fun times.

[evil_mx6]

wow guys, some ppl are getting great economy. I have just sent a spare memcal to foam so ill see how that goes once its in.....after a memcal tune is it worth getting the gas system dyno tuned as well?

[levymetal]

get the gas system tuned. not dyno tuned. there is a difference

[evil_mx6]

well ive been told that to get the gas research gas systems tuned properly they are done on the dyno....so they can adjust it throughout the rev range.....but either way im guessing you recomend getting a tune done once the memcal has been done?
cheers

[levymetal]

hmm, well that would be a pretty good tune, but i guess it would be expensive too . my gas installer doesn't have a dyno so i don't know exactly how they tune it but i don't think it's all that complicated, just an idle mixture and full throttle mixture and something else i believe. my gas setup is pretty simple and i don't even think you can adjust it throughout the rev range. maybe the gas research ones are different so before taking my word for it give a few places a ring and see what they say

but either way, after the foam tune is in, gas tune is a 100% must!

[slepar]

i have a vs berlina 5ltr, duel fuel with a gas research set up i get around 16-17 ltrs/100kms around town and after about half hour on an open long hwy i can get into the 9's/100kms depending on wind conditions or if its raining ect ect but never really higher than 11ltrs/100km. but basicly for 17lts around town is bloody good man im very happy as it basicly means $10 per 100ks wich is very good for a v8, i was driving a vq stato 5ltr before this and $10 was getting me no more than 40ks (just cruising) so be thankfull for what ya got lol

[88GreenVN]

hmmmm.....i thought that she would of been a bit better.....well the other day a done a 160km round trip on the freeway....all hway driving....the cars readout was 9.8L/100km....avg speed readout 91km/h.....and when i filled the gas up my average consumption based on kms and litres filled was 15L/100km......
Are the gas research systems generally better? and will they benefit much from a proper memcal tune and then a dyno tune to adjust the gas to the new tune?

Did you guys notice any improvement when you got a dyno/ memcal tune done to the car (performance and econonomy) ?

Cheers

You can adjust the flow rate to get an accurate reading on gas. The flow rate = 625 factory setting for petrol. Bump this up to say 700 to see if the readings are closer to what you get by lts/distance calculate manually. So when you fill the gas tank the lts used = the same.

You set this by having the trip in avg mode (middle window) and press and hold the reset button for 3 seconds. You should see 625 come up, while holding in the reset button press the + button to raise the reading.

[evil_mx6]

cool mate, just done that, but either way.....i just cruise with my car and rarely do i put the foot down. Plus most of my driving is on the open road either 80-100km/h.......so anything under 15's is going to be good.....i just think that 17L/100km with easy driving on open roads/hways is a bit high.....my mix of driving is 70% hway - 30% city......

[88GreenVN]

cool mate, just done that, but either way.....i just cruise with my car and rarely do i put the foot down. Plus most of my driving is on the open road either 80-100km/h.......so anything under 15's is going to be good.....i just think that 17L/100km with easy driving on open roads/hways is a bit high.....my mix of driving is 70% hway - 30% city......

With the greenfoam tune in my VN V8 on the highway I get around 11 L/100 (petrol)

City hoon driving I get around 15-16.

[evil_mx6]

well if i could get that on gas i would be pretty happy....especially on the h'way side of things....