Lpg Conversion

[Barry1000]

I have just had my 430 converted to run on LPG by Profess in Wales. They seemed to have done a very good job but I Must confess that I am disappointed at the economy. On the runs that I do on petrol the car would average 25.5 to the gallon. On LPG covering the same type of journeys the car averages about 18. Has anyone had similar experience as I had hoped for at least 20 to 22.

[Lexmanic]

I have just had my 430 converted to run on LPG by Profess in Wales. They seemed to have done a very good job but I Must confess that I am disappointed at the economy. On the runs that I do on petrol the car would average 25.5 to the gallon. On LPG covering the same type of journeys the car averages about 18. Has anyone had similar experience as I had hoped for at least 20 to 22.

The way to compare LPG v Petrol is by cost of LPG against cost of Petrol AND 18mpg to 25mpg your still winning cost wise. You've lost a 1/4 in mpg as against gaining almost 1/2 reduction in cost of fuel

[Bluesman]

I have just had my 430 converted to run on LPG by Profess in Wales. They seemed to have done a very good job but I Must confess that I am disappointed at the economy. On the runs that I do on petrol the car would average 25.5 to the gallon. On LPG covering the same type of journeys the car averages about 18. Has anyone had similar experience as I had hoped for at least 20 to 22.

Hello Barry. I don't know how many miles you have covered since the conversion but wait until after you have taken it back for its 1000 mile checkup. Mike

[ipwn]

In the real world thats basically 25.5 on petrol and 35 mpg on LPG?

As youre paying half the price for your LPG no?

Or am I thinking too simply?

[wow300]

That's correct and yes the 430 is not great on fuel, the LS400 is better, especially on long runs

[ManicMark]

I have just had my 430 converted to run on LPG by Profess in Wales. They seemed to have done a very good job but I Must confess that I am disappointed at the economy. On the runs that I do on petrol the car would average 25.5 to the gallon. On LPG covering the same type of journeys the car averages about 18. Has anyone had similar experience as I had hoped for at least 20 to 22.

Where have they put the injector nozzles in the plenum or directly next to the petrol nozzles, are the pipes to the nozzles of equal length. What Kit went on & how much did they charge out of interest. On my 400 I lost about 5 to 10% efficiency against the trip meter I got it converted within a week of purchase so didn't really have a good amount of time on petrol to compare.

[bookend]

When I had my 430 done the economy improved after they made some adjustments on the 1000 mile check.

[brendangeorge]

At the moment I am getting 15 to 16 MPG on LPG - I use this calculator (http://www.mpg-calculator.co.uk/). This is short runs so not too bad for the winter. On motor way runs I used to get 20 ish on LPG. I don't drive slowly and have notices the lads who run 400s reporting better fuel consumption on LPG than 430s - I thnk Dave pointed this out.

LPG has abpu 80% of the energy of petrol so on short runs I used to get 16 or so round town and overall 22 - with LPG 15 on short runs and 19 on the motorway - that is pretty good. I could always lighten my foot and improve consumption.

I have a BRC system that is supposed to optimise consumption automatically and has done 80K miles + so is it worth upgrading the electronics or putting in a different system to improve ful economy? Has anybody any experience of doing so?

Also if one of you has nicked the Sun please put it back in the sky because I am freezing to death :)

Bren

[SHELLDRAKE]

Yes: I pinched the sun,it's up here in sunny Ellesmere Port :)

[bookend]

Just checked my spreadsheet my LPG figures are on the LS 430

Long run 23.56 mpg

Around town 19.4 mpg

Lowest ever heavy Trafic 16.59 mpg

[brendangeorge]

Just checked my spreadsheet my LPG figures are on the LS 430

Long run 23.56 mpg

Around town 19.4 mpg

Lowest ever heavy Trafic 16.59 mpg

Great numbers Steve better than mine - are you a steady driver or do you boot it along (like me)?

Bren

[wow300]

Must be steady to get them figures

[bookend]

I have my moments but those figures are fairly consistent since having the system tuned.

I keep a record at every fill up its ready for it's 10 k LPG service and the figures are just starting to drop slightly.

When I first had it fitted the figures were poor but the system was calibrating itself and needed balancing but there was a noticeable improvement after its 1k service

[bookend]

Have just checked my figures and my average since conversion in 20.93 mpg over the total mileage

[ManicMark]

That's correct and yes the 430 is not great on fuel, the LS400 is better, especially on long runs

I think the ls400 has a lower drag coefficient ( better than a porsche 911) it is also a fair bit lighter.so that would explain the better economy. The facelift 430 is good on the run due to the 6th gear final drive ratio effectively an overdrive.0.58 against 0.73 on the early 430s, Or around that anyway

[mikesands]

My figures are at the poor end of the ranges being quoted above (about 17 round town and 21mpg on a run. I am pretty gentle on the throttle in fact I drive it in snow mode to make sure.

When I did the research it seemed to me that the energy content of LPG was nearer 70% than 80% of petrol. And that fits exactly with the results from my LS430.

If this is true, I worry that the only way the LPG engineers can get better than '30% worse' is to tune it to run lean - which has got to be a bit worrying surely?

Mike

[Bassman]

Could be interesting to find out which makes of conversion are being used here.

I wonder if a certain make or installation is better with fuel than another?

[cruisermark]

i remember reading (dont know wether it was this forum or other) that make of kit doesnt matter - what matters is how well the system is installed and tuned/mapped or whatever they call it

[bookend]

My kit is a KME Deigo which is one of the cheaper kits but the install is spot on with all the pipework even in length. I'm very pleased with the results.

[ManicMark]

I had a brc plug & drive conversion on my last one, The injector nozzles were installed directly next to the petrol ones the pipes leading to them were of equal length & at least 3 hours was spent on the initial set up + 2 hours on the re calibration after a few hundred miles. I was down max 10% against petrol. In 5 years & 60,000 miles I didn't have a single blip with it.

I have only heard praise for profess in Wales even though the kits are cheaper Polish ones but am a little concerned at the consumption figures. i may get in touch with my last installers battersea autogas & see what they are charging now.

[brendangeorge]

My figures are at the poor end of the ranges being quoted above (about 17 round town and 21mpg on a run. I am pretty gentle on the throttle in fact I drive it in snow mode to make sure.

When I did the research it seemed to me that the energy content of LPG was nearer 70% than 80% of petrol. And that fits exactly with the results from my LS430.

If this is true, I worry that the only way the LPG engineers can get better than '30% worse' is to tune it to run lean - which has got to be a bit worrying surely?

Mike

Hi Mike it is 80% if you are a chemist - it may only be 70% when used in your car because of other efficiency factors.

Bren

[Barry1000]

Having had the car retuned it is doing about 20 to 21 compared to 25 on petrol comparing the same sort of journeys which overall is not too bad. The car runs superbly on gas and it is impossible to tell it is running on gas instead of petrol. Overall I am pleased with the job.

[ManicMark]

Having had the car retuned it is doing about 20 to 21 compared to 25 on petrol comparing the same sort of journeys which overall is not too bad. The car runs superbly on gas and it is impossible to tell it is running on gas instead of petrol. Overall I am pleased with the job.

As you are on gas, Are you a little bit more heavy footed on the acceleration. I know this was the case with me on petrol I was very careful on the go pedal with gas at 70p a litre I drove the car with a bit more enthusiasm.

[Barry1000]

I think that you could be right this may account for a mile or two to the gallon! It is much more fun not having think quite so carefully about the fuel consumption all the time.

Barry

[ManicMark]

Hi Barry how much was your lpg conversion & did they recommend flashlube thanks Mark