(dont shoot me) LPG coversion ups and downs
Discussion
I have a 400 se an although I love this fire breathing monster ther are a few fundamental problems I have with it.
1, It costs a bomb on fuel :furios:
2, I is seriously polluting
I know that maybe I should get a 2CV if I want to be green but it aint going to happen!
The performance of this car is already amazing so is there anything that can be done to increase fuel economy. LPG conversion has crossed my mind but what affects would that have, would it damage the engine. Any advice would be much appreciated.
1, It costs a bomb on fuel :furios:
2, I is seriously polluting
I know that maybe I should get a 2CV if I want to be green but it aint going to happen!
The performance of this car is already amazing so is there anything that can be done to increase fuel economy. LPG conversion has crossed my mind but what affects would that have, would it damage the engine. Any advice would be much appreciated.
I'm running a 4.0 Cherokee on gas, there is a slight decrease in power and the engine doesn't run as smoothly. I've halved my fuel costs but wouldn't think of converting my Wedge because of the loss in power. If you don't want pure performance it might be a good option for you. Shop around for your tank you can get all kinds of shapes and sizes, maybe ditch your spare tyre and use mousse instead?
Hi,
There is a lot of information (and mis-information...) about LPG.
Basically it is a good fuel for automotive use, as it is in gaseous form when it enters the engine, so there are fewer fuel distribution issues (this would only apply when compared to a carb of course...).
It is clean buring - engine oil is typically still golden in colour after 5000 miles.
LPG has an octane rating of about 115, so compression can be increased. Ignition timing also needs to be modified.
Problems with conversions can stem when both petrol and LPG are required. The two fuels have different characteristics and what works for one won't work for another (compression ratios for example can be in the order of 12:1 for LPG, probably a bit high for road petrol).
Other downsides are the weight of the fuel tank and availability of LPG, although this seems to be getting better.
I own a car that I drive on the road and race in sprints and hillclimbs. The engine is a 5 litre V8 based on the Rover engine. This runs dedicated LPG and has the compression, cam and ignition timing alered to suit. On a dyno this engine made 220 HP and 300ft-lbs at 5000 RPM. A friend has a Chevrolet 406 cu V8 running on dedicated LPG that makes about 380HP at the wheels.
Finally, turbocharged engines respond well to LPG due to its high octane rating. In Australia it's becoming popular for turbo RX-7 etc that couldn't meet emissions requirements otherwise......
There is a lot of information (and mis-information...) about LPG.
Basically it is a good fuel for automotive use, as it is in gaseous form when it enters the engine, so there are fewer fuel distribution issues (this would only apply when compared to a carb of course...).
It is clean buring - engine oil is typically still golden in colour after 5000 miles.
LPG has an octane rating of about 115, so compression can be increased. Ignition timing also needs to be modified.
Problems with conversions can stem when both petrol and LPG are required. The two fuels have different characteristics and what works for one won't work for another (compression ratios for example can be in the order of 12:1 for LPG, probably a bit high for road petrol).
Other downsides are the weight of the fuel tank and availability of LPG, although this seems to be getting better.
I own a car that I drive on the road and race in sprints and hillclimbs. The engine is a 5 litre V8 based on the Rover engine. This runs dedicated LPG and has the compression, cam and ignition timing alered to suit. On a dyno this engine made 220 HP and 300ft-lbs at 5000 RPM. A friend has a Chevrolet 406 cu V8 running on dedicated LPG that makes about 380HP at the wheels.
Finally, turbocharged engines respond well to LPG due to its high octane rating. In Australia it's becoming popular for turbo RX-7 etc that couldn't meet emissions requirements otherwise......
Spot on Simon!
Both of my V8s glug LPG through a multi-point injection system. It's the SGI (Sequential Gas Injection) system made by AG. Uniquely and craftily, it translates the fuel injector pulses into gas injector pulses.
The special thing about this is that the original ECU is still in control of the fuelling. Even better is that once the car has been mapped on petrol, it is automatically mapped on gas. No power loss either!
However I am influenced by the local gas emporium dispensing the marvellous liquid for 29.9p/Litre
I got both mine done by Andrew Reed at AMR Autos. Well worth the journey, and as perfect a job as you could wish for. Check out their web site on
www.amrautos.co.uk
or RPI Engineering on
www.rpiv8.com
The Discovery (4.6, 280BHP/315lb/ft) is on the dyno in Cheltenham tomorrow morning for some fine fettling.
Both of my V8s glug LPG through a multi-point injection system. It's the SGI (Sequential Gas Injection) system made by AG. Uniquely and craftily, it translates the fuel injector pulses into gas injector pulses.
The special thing about this is that the original ECU is still in control of the fuelling. Even better is that once the car has been mapped on petrol, it is automatically mapped on gas. No power loss either!
However I am influenced by the local gas emporium dispensing the marvellous liquid for 29.9p/Litre
I got both mine done by Andrew Reed at AMR Autos. Well worth the journey, and as perfect a job as you could wish for. Check out their web site on
www.amrautos.co.uk
or RPI Engineering on
www.rpiv8.com
The Discovery (4.6, 280BHP/315lb/ft) is on the dyno in Cheltenham tomorrow morning for some fine fettling.
Kevin - LPG has approximately 85% of the energy (calorific value) of petrol. So you will only get 85% as far on the same volume of the stuff.
When you factor in the price difference you will get about twice as far with your £5 on LPG as you did on Petrol.
The power penalty with the injection system turned out to be 1.8% (loss on Petrol), although that could be eliminated by a little ignition timing therapy.
When you factor in the price difference you will get about twice as far with your £5 on LPG as you did on Petrol.
The power penalty with the injection system turned out to be 1.8% (loss on Petrol), although that could be eliminated by a little ignition timing therapy.
I did contemplate this about a year ago, but I spoke to a couple of people and read a few things that kind of put me off. Then of course the wife kicked me out so I didn't have the cash...;-)
Anyway, a couple of points that I recall include the potential for a backfire on gas to crisp the airflow meter. Also, the initial installation cost would buy quite a lot of petrol, so unless your V8 gets a lot of use, it would take a while to recoup the outlay (since you still have to pay to put the gas in as well!) - though obviously a Rangey or similar is more likely to get daily use than a TVR. The fuel tank can be quite small, but as you can only fill it to about 80% (IIRC) you lose some capacity right away. The car is no more economical in real terms, it's just the fuel being cheaper. So if you opt for a small tank to keep some boot space, you'll find yourself filling up more often than you do already. Could be a problem as gas pumps aren't that common once you get off the main roads, i.e. just the places you want to drive a TVR.
Just my 10p-worth....
Ian
Anyway, a couple of points that I recall include the potential for a backfire on gas to crisp the airflow meter. Also, the initial installation cost would buy quite a lot of petrol, so unless your V8 gets a lot of use, it would take a while to recoup the outlay (since you still have to pay to put the gas in as well!) - though obviously a Rangey or similar is more likely to get daily use than a TVR. The fuel tank can be quite small, but as you can only fill it to about 80% (IIRC) you lose some capacity right away. The car is no more economical in real terms, it's just the fuel being cheaper. So if you opt for a small tank to keep some boot space, you'll find yourself filling up more often than you do already. Could be a problem as gas pumps aren't that common once you get off the main roads, i.e. just the places you want to drive a TVR.
Just my 10p-worth....
Ian
Gassing Station | Wedges | Top of Page | What's New | My Stuff