nick205
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| posted on 31/8/10 at 08:25 AM |
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Running an LPG car...?
I'm looking at switching from a company lease car to taking a car allowance.
Basic criteria...
1. 20-25k miles/year
2. Estate
3. Diesel
4. Keep for 3 years
5. I like VAG cars
6. Reliable/Economical
Looked at cars around £7-8k including...
1. A4
2. Octavia
3. Passat
Then I came across a BMW 330i Tourer with an LPG conversion which got me thinking....
1. What's involved in running an LPG converted car - servicing difficulties, costs, long term reliability etc?
2. With the reduced MPG vs. cheaper fuel actually save you any money?
3. HMRC - I'd be claing HMRC advisory fuel rates for work miles - would an LPG converted car be considered petrol or LPG (the rates are quite
different!)?
4. Anything else.....?
Advice and experiences please ladies and gents.
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fha772
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| posted on 31/8/10 at 08:31 AM |
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I've had 4 cars on LPG, (v8 mgbgt, 1992 twin turbo 535i BMW, 4.0 Jeep Cherokee, 4.0 v8 RangeRover), and never noticed any real difference
compared to running on petrol.
The MPG is roughly the same, so is performance.
The only time you have any extra expense is when something on the conversion needs repair.
http://www.ppcmag.co.uk/forum/viewtopic.php?f=47&t=6743&start=105
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coyoteboy
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| posted on 31/8/10 at 08:42 AM |
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They're fractionally down on power and economy compared to petrol, but it's only ~5%ish on a good injection conversion. Fuel is 55p/litre.
What's to lose?! New injectors are generally cheap as chips if you need them for some reason (rail of 4 usually comes in around 70-100 quid).
The rest of it is pretty bomb-proof.
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nick205
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| posted on 31/8/10 at 08:56 AM |
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quote:
Originally posted by fha772
I've had 4 cars on LPG, (v8 mgbgt, 1992 twin turbo 535i BMW, 4.0 Jeep Cherokee, 4.0 v8 RangeRover), and never noticed any real difference
compared to running on petrol.
The MPG is roughly the same, so is performance.
The only time you have any extra expense is when something on the conversion needs repair.
What makes/models of LPG system should I be looking for?
Is there a trade body for reputable installers?
Cheers
Nick
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Ninehigh
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| posted on 31/8/10 at 10:01 AM |
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If I were you I'd rate the vehicle as whichever rate means you pay less..
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coyoteboy
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| posted on 31/8/10 at 10:11 AM |
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Anyone capable of building a kit/locost/doing some minor mechanics is more than capable of fitting one. You should be able to find someone to certify
it fairly cheaply. There's plenty of installers about but I can't recommend any as we've always done it ourselves. Trade body - not
sure, sorry.
The process involves a bit of tin snipping, drilling and tapping your manifold near the ports, fitting some nozzles, then connecting up hoses, bolting
down the tank, checking for leaks at joints and then cutting your injector wiring as per their instructions. They all should come with instructions on
how to fit them and how to tune them. Tuning is a bit more fiddly, but again the instructions that come with them usually tell you how to tune them to
a reasonable degree, if you want it perfect you can tinker or take it to someone. Ultimately they use your original petrol maps to calclulate exactly
how much LPG to put in (its a direct multiplier) but in reality it varies a little at different RPM due to things like gas dynamics, but you'll
be able to run the car pretty much out of the box IME
Just make sure you get a kit suited to your car. If you have sequential petrol injection you may need a sequential gas kit - the supplier should tell
you that at the start.
[Edited on 31/8/10 by coyoteboy]
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nick205
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| posted on 31/8/10 at 10:35 AM |
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quote:
Originally posted by Ninehigh
If I were you I'd rate the vehicle as whichever rate means you pay less..
That's exactly what I'd do - HMRC often have their own views though and past experience has shown it's better to check first 
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nick205
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| posted on 31/8/10 at 10:36 AM |
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quote:
Originally posted by coyoteboy
Anyone capable of building a kit/locost/doing some minor mechanics is more than capable of fitting one. You should be able to find someone to certify
it fairly cheaply. There's plenty of installers about but I can't recommend any as we've always done it ourselves. Trade body - not
sure, sorry.
The process involves a bit of tin snipping, drilling and tapping your manifold near the ports, fitting some nozzles, then connecting up hoses, bolting
down the tank, checking for leaks at joints and then cutting your injector wiring as per their instructions. They all should come with instructions on
how to fit them and how to tune them. Tuning is a bit more fiddly, but again the instructions that come with them usually tell you how to tune them to
a reasonable degree, if you want it perfect you can tinker or take it to someone. Ultimately they use your original petrol maps to calclulate exactly
how much LPG to put in (its a direct multiplier) but in reality it varies a little at different RPM due to things like gas dynamics, but you'll
be able to run the car pretty much out of the box IME
Just make sure you get a kit suited to your car. If you have sequential petrol injection you may need a sequential gas kit - the supplier should tell
you that at the start.
[Edited on 31/8/10 by coyoteboy]
Thanks for the detail - much as I'd be happy having a go, this will have to be a proven ready converted vehicle that I can just buy and drive.
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britishtrident
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| posted on 31/8/10 at 10:47 AM |
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With current LPG systems which use sequential gas injection you do get a loss in power and increase in fuel consumption. Power loss is between 8 and
15% and Fuel consumption increase is between 10 and 20%.
A properly fitted LPG provided it is of decent quality will be reliable and only needs servicing every 15,000miles --- change filters, clean out
accumulated residue, check for leaks and check system is in tune.
With 330i on LPG you will return an real world MPG of 23 to 27. Running cost entirely depend on how far you are from a cheap LPG seller.
Currently my Rover is doing 270 miles to 48 litres of LPG at 60p per litre + £3.00 for petrol ---- say £32
Equvalent mileage cost on petrol £48
I could save a lot more if I was prepared to travel if I travel annother 4 miles for cheaper LPG
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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nick205
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| posted on 31/8/10 at 11:01 AM |
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SO23
Nearest to home (Shell) = £0.68/litre
Nearest to work (Shell) = £0.68/litre
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coyoteboy
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| posted on 31/8/10 at 11:25 AM |
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Don't just look at petrol stations, find local industrial gas suppliers - they often will fill you up, and notably cheaper.
FYI we have a 3.5litre BWM (original economy was 21mpg average) getting 19mpg and with (seat of the pants) virtually no reduction in power. OK, a tad,
but it's barely noticable, you'd have to check it on rollers. A 0-60 timing is imperceptibly different.
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nick205
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| posted on 31/8/10 at 11:31 AM |
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quote:
Originally posted by coyoteboy
Don't just look at petrol stations, find local industrial gas suppliers - they often will fill you up, and notably cheaper.
Good tip!
Any suppliers I might look up (did a quick google, but not overly useful!)
Cheers
Nick
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coyoteboy
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| posted on 31/8/10 at 11:35 AM |
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My local is a calor gas supplier, charges 49p/l.
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britishtrident
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| posted on 31/8/10 at 11:57 AM |
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The 8% minimum power loss is mainly down to LPG being supplied to the inlet manifold as a gas, because it is a gas it displaces more air than liquid
petrol droplets.
The Fuel consumption increase is mainly due to the lower calorific value of propane compared to petrol.
Order of calorific values per litre from low to high is
LPG (Propane)
Petrol
Diesel.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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britishtrident
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| posted on 31/8/10 at 12:00 PM |
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quote:
Originally posted by coyoteboy
My local is a calor gas supplier, charges 49p/l.
Are you buying from Calor or the outfit in Bridgeton behind London Road Cop Shop ?
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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britishtrident
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| posted on 31/8/10 at 12:09 PM |
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quote:
Originally posted by nick205
quote:
Originally posted by coyoteboy
Don't just look at petrol stations, find local industrial gas suppliers - they often will fill you up, and notably cheaper.
Good tip!
Any suppliers I might look up (did a quick google, but not overly useful!)
Cheers
Nick
http://www.flogas.co.uk/gas-finder/south-east/hampshire/west-meon-service-station-petersfield/
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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nick205
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| posted on 31/8/10 at 12:15 PM |
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Found a couple of local suppliers via yell.com and waiting on a call back with prices. One of them is actually closer than the nearest filling
station with LPG too!
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nick205
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| posted on 31/8/10 at 12:23 PM |
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quote:
Originally posted by britishtrident
http://www.flogas.co.uk/gas-finder/south-east/hampshire/west-meon-service-station-petersfield/
Just checked here...£0.64/l
A bit out of the way (~10miles), but @ 4p/l cheaper than the Shell garages, would be worth filling up there.
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sebastiaan
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| posted on 31/8/10 at 12:35 PM |
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Fuel consumption increase will be roughly 20% (due to the lower energy content of the fuel per litre); power loss will be somewhere around 5%. Try to
get a quality conversion done. Yes, it costs more but it will save you a considerable amount of aggrevation later. One of the best in the market today
is Prins.
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coyoteboy
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| posted on 31/8/10 at 12:39 PM |
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Kilbirnie street - I've not actually bought from them yet (still working on finding suitable parts for a 75hp/cyl conversion) but I checked out
their prices a month or so ago.
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se7en
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| posted on 31/8/10 at 05:21 PM |
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quote:
Originally posted by coyoteboy
They're fractionally down on power and economy compared to petrol, but it's only ~5%ish on a good injection conversion. Fuel is 55p/litre.
What's to lose?! New injectors are generally cheap as chips if you need them for some reason (rail of 4 usually comes in around 70-100 quid).
The rest of it is pretty bomb-proof.
I have had several LPG cars and every one that I had was faster on acceleration using gas compared to petrol.
In the BTCC the Ford Focus are using LPG and they are 3-4 MPH quicker than the others.
The gas consumption gives about 90% of MPG compared to petrol. But considering that LPG is about half the cost of petrol it is economic. The down side
is that LPG systems need servicing and the components are quite expensive.
HTH
Tom
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bj928
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| posted on 31/8/10 at 05:50 PM |
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with the london C charge you only get dicount if its a factory fitted system i believe, so you might have to get a factory fitted vehicle as well,
loads about though, you might want to ask if it has to be factory system.
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britishtrident
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| posted on 31/8/10 at 06:49 PM |
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quote:
Originally posted by se7en
I have had several LPG cars and every one that I had was faster on acceleration using gas compared to petrol.
In the BTCC the Ford Focus are using LPG and they are 3-4 MPH quicker than the others.
The gas consumption gives about 90% of MPG compared to petrol. But considering that LPG is about half the cost of petrol it is economic. The down side
is that LPG systems need servicing and the components are quite expensive.
HTH
Tom
Quick reality check the LPG system currently available to the mass market are vapor ( ie gaseous) injection because of this the engine gets 8% less
air to burn --- in other words 8% + power loss is fact of life.
The BTC Fords run on the latest state of the art liquid phase lpg injection which doesn't displace any noticeable amount air and
can actually gain power from the liquid gas evaporation cooling the inlet charge.
The engines in the BTC cars because they run only on LPG can be built with compression ratios and ignition timing take advantage of the higher
octane rating of LPG. (approx 112) .
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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coyoteboy
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| posted on 31/8/10 at 06:50 PM |
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People keep saying components are expensive. What components? You can buy a full new fuel system for under 400 quid with perfectly adequate
injectors/vap for the majority of cars? That's injectors, vap, electronics, the works. Most 4 cyl injector rails are ~£100. There's no
petrol injectors that come close to that?
quote:
The BTC Fords run on the latest state of the art liquid phase lpg injection which doesn't displace any noticeable amount air and can
actually gain power from the liquid gas evaporation cooling the inlet charge.
I've been waiting for liquid injection to come of age, last time I checked (6 months or so ago) the general consensus was that it was still a
long way away as injector freezing is a problem, it requires a dedicated high pressure pump etc etc. I wonder if these ford bits can be had elsewhere
or from scrapped cars. Their older gas-phase injection systems were shocking though, so I'm not sure I'd want to go there!
[Edited on 31/8/10 by coyoteboy]
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britishtrident
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| posted on 31/8/10 at 06:53 PM |
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quote:
Originally posted by bj928
with the london C charge you only get dicount if its a factory fitted system i believe, so you might have to get a factory fitted vehicle as well,
loads about though, you might want to ask if it has to be factory system.
Some professional aftermarket conversions are accepted but each model the company doing the conversions has to submit an example for emission
testing to get it on the approved list.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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