Big Engines with LPG
Discussion
I just wondered if anyone owned or had a big engined car with an LPG conversion and how you find it?
I currently drive an E320 CDI, so it's a 3.2 straight six and gives me 45-50mpg on a steady run but round town 25mpg. Fortunately only 20% of the mileage I do is round town so that's not much of a factor for me.
But, like any PH'er I take into account the next car I'd like to own. Now obviously with diesels in the doghouse at the moment (especially ones like mine) I have kept in mind the idea of moving away from diesel and that's where the idea of LPG came into it. It sounds like it's a lot cheaper to fuel a car for roughly the same kind of MPG but obviously there is a cost involved in installing it.
So I was thinking, apart from the installation costs, are there any downsides to having an LPG kit installed in something like an E500 or E55 or anything with say a big V8? I'd look into something that could be a keeper but essentially a performance car (with family carrying credentials) but a 100, 200, 300 mile run would cost much the same as my diesel does now?
I currently drive an E320 CDI, so it's a 3.2 straight six and gives me 45-50mpg on a steady run but round town 25mpg. Fortunately only 20% of the mileage I do is round town so that's not much of a factor for me.
But, like any PH'er I take into account the next car I'd like to own. Now obviously with diesels in the doghouse at the moment (especially ones like mine) I have kept in mind the idea of moving away from diesel and that's where the idea of LPG came into it. It sounds like it's a lot cheaper to fuel a car for roughly the same kind of MPG but obviously there is a cost involved in installing it.
So I was thinking, apart from the installation costs, are there any downsides to having an LPG kit installed in something like an E500 or E55 or anything with say a big V8? I'd look into something that could be a keeper but essentially a performance car (with family carrying credentials) but a 100, 200, 300 mile run would cost much the same as my diesel does now?
Because LPG is (roughly) half the price of petrol/diesel, you can take the MPG of the target car, and double it.
Take a bit off because engines running on LPG give slightly poorer economy figures, and you have a number you may or may not want to work with.
Most big old V8 barges that will do 20mpg at best will probably end up costing you the equivalent to fuel as a car doing 35mpg, if running on LPG.
Take a bit off because engines running on LPG give slightly poorer economy figures, and you have a number you may or may not want to work with.
Most big old V8 barges that will do 20mpg at best will probably end up costing you the equivalent to fuel as a car doing 35mpg, if running on LPG.
Alex_225 said:
Thanks for the replies, that is some good food for thought.
Essentially if you can get a car running 25mpg then the cost equivalent of 40mpg doesn't sound too bad. Given that you could run a 400-500bhp car with sensible running costs.
Any down sides in terms of performance?
i had a 4.4 v8 range rover. there was a slight degradation in performance, but only with the right foot planted. was a particularly poor lpg installation though, so the newer ones probably have this nailed.Essentially if you can get a car running 25mpg then the cost equivalent of 40mpg doesn't sound too bad. Given that you could run a 400-500bhp car with sensible running costs.
Any down sides in terms of performance?
Thanks again guys, some useful info.
In an ideal world, I'd love to get my hands on a later E55 AMG, so obviously all the practicality of my current E class but with a 5.5 supercharged V8. Have a good LPG kit installed enabling the boring driving I have to do 600 miles a month) to be more cost effective but ultimately still have a 450bhp+ car to drive day to day. Cleaner burning than the diesel but obviously half the MPG. I'd factor in the conversion into the buying price.
Doesn't sound like it's an entirely daft idea then.
In an ideal world, I'd love to get my hands on a later E55 AMG, so obviously all the practicality of my current E class but with a 5.5 supercharged V8. Have a good LPG kit installed enabling the boring driving I have to do 600 miles a month) to be more cost effective but ultimately still have a 450bhp+ car to drive day to day. Cleaner burning than the diesel but obviously half the MPG. I'd factor in the conversion into the buying price.
Doesn't sound like it's an entirely daft idea then.
I had a P38 Range Rover V8 4.6.
Bought it after it had already been converted. Took it to a well regarded local specialist and he declared it a good LPG kit but poor install. It had only been done 5000 miles previous. He charged me £350 to replace most of the hoses, retap the hot coolant circuit in a more appropriate place and changing the map then tuning it.
After it was sorted it was great. You'd not really notice any difference between running on unleaded or LPG.
The only thing to watch out for is engines with soft valve seats. LPG causes hotter valve temperatures and can lead to valve seat recession. There's loads of information online about which engines/models to avoid. You can add flashlube systems to inject stuff to protect the valve seats, but personally I wouldn't bother. If the engine has soft valve seats just don't run it on LPG.
Bought it after it had already been converted. Took it to a well regarded local specialist and he declared it a good LPG kit but poor install. It had only been done 5000 miles previous. He charged me £350 to replace most of the hoses, retap the hot coolant circuit in a more appropriate place and changing the map then tuning it.
After it was sorted it was great. You'd not really notice any difference between running on unleaded or LPG.
The only thing to watch out for is engines with soft valve seats. LPG causes hotter valve temperatures and can lead to valve seat recession. There's loads of information online about which engines/models to avoid. You can add flashlube systems to inject stuff to protect the valve seats, but personally I wouldn't bother. If the engine has soft valve seats just don't run it on LPG.
4.4 V8 Range Rover with a BRC LPG system here. 18 MPG in mixed use, about 15 MPG on LPG. Locally there's a Sainsbury's with LPG well under half of the petrol price, so 35 MPG cost equivalent. Only problem is the 75l tank only lasts a week for me, which is a bit of a pain.
No impact on performance, but I'm not heavy footed in it.
No impact on performance, but I'm not heavy footed in it.
mr_spock said:
4.4 V8 Range Rover with a BRC LPG system here. 18 MPG in mixed use, about 15 MPG on LPG. Locally there's a Sainsbury's with LPG well under half of the petrol price, so 35 MPG cost equivalent. Only problem is the 75l tank only lasts a week for me, which is a bit of a pain.
No impact on performance, but I'm not heavy footed in it.
Wow, goes to show the cost difference right there! No impact on performance, but I'm not heavy footed in it.
For me the main interest for the tank would be if I can get 260 steady motorway miles out of it. Reason being is that my daughter lives in Bristol so I pick her up regularly. I'd gladly use LPG for that run and then switch to petrol for the minimal driving I do throughout the week.
bigee said:
Biggest problem is finding a supplier for lpg, many are dropping out of the market.My nearest station is a 14 mile round trip which is a pain (might explain why i am about to install my own bulk tank mind ! )
I was chatting to a friend of mine last night who always buys LPG cars. He always tends to buy old cheap cars which are already converted and he said much the same. The nearest place that sells LPG to me is probably 8-9 miles away. Although for my usage that wouldn't be so much of an issue as I'd only use the LPG for specific journeys that I take every couple of weeks.
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