LPG Conversion

LPG, The Money Saver

Wrong. Maybe in the good old days but not so much any more.

Why Not?

2 reasons.

Firstly, the cost of LPG has increased.
2010 = 30p a litre.
2018 = 60p  a litre.
2024 = £1.20 a litre

If you take into account that LPG is 25% less efficient than petrol, it’s equivalent to paying £1.50 a litre for LPG. LPG is 45% less efficient than diesel, an equivalent of paying £1.74 a litre for LPG.

Because the savings have been drastically reduced it takes much longer to recoup the cost of the conversion.

Secondly, people generally want everything cheap which is what blindly leads them to LPG in the 1st place. Companies know this and over the years, cheaper and cheaper kits have been released. They are cheaper because of lower quality construction and missing out on vital features.

What Vital Features?

The main lost feature that was present in 1st generation kits and expensive modern kits is a lubricator. Cheap kit manufacturers realised that engines would last long enough to get the kit out of warranty. These kits were also much easier to fit, took less time and took up less space.

Smart And The Lack Of Space

The main thing about smarts is that they are small. Enough room to be fairly practical but not enough that you want to waste space lugging around extra shit in your boot.

There are 3 main types of LPG tank.
Custom, toroidal and cylinder.

The custom tanks that replace the under-floor fuel tank are ridiculously expensive. Toroidal tanks are designed to go where the spare wheel usually goes. No such thing on a smart. So you have to use a cylindrical tank in the boot which is a massive waste of space.

Woah, Backtrack. Lubricator?

Yes. Petrol and diesel actually contains additives including lubricants. This helps reduce valve and seat recession. LPG is pure vapour with no lubricating properties. This means that valve and valve seats wear much quicker in an LPG converted engine.

So, to counteract this lack of lubrication, an external oil tank is fitted to inject oil into the cylinders. However, only expensive kits have a lubricator but expensive kits are expensive. If you take into account the expense of the kit and the small savings of using LPG, You’ll have to do about 90,000 miles to break even on an expensive kit. Even on a cheap kit, you’ll have to do 60,000 miles to break even.

However, the smart engine probably won’t reach 40,000 miles on a cheap kit. So, if you factor in a replacement engine or head, it’s not worth the conversion.

So, Add A Lubricator And It’ll Be OK?

Nope.

Petrol and diesel actually help cool the engine as well. We already know that expanding gases cool down. LPG has already expanded by the time it reaches the engine so it doesn’t help with engine cooling. So, LPG engines run hotter. This can affect the engine head and possibly even the head gasket.

Excessive heat kills engines, even more so on aluminium engines that already run hot.

Are There Any Benefits?

Yes. If you buy the car with it already fitted, do a lot of miles, have a local fuel station that has LPG, the car has the lubricator injector system already fitted and you don’t need boot space…

…GREAT.

You’ll save money every time you fill the car.

But I Absolutely Have To Have LPG

Go on then, you don’t have to ask my permission but do listen to advice. Don’t go for a cheap kit. Don’t convert a 450 or 451. If you really have to, go for a non turbo 453 (thanks Fernando).

If you want it because your EU overlords have told you that petrol and diesel cars are no longer allowed to drive into certain European cities, you should rise up against them. Consider your own Brexit. Be aware though, if everyone starts converting their cars to LPG, they’ll just ban that too.

I would still recommend not converting a smart. Look at buying a Bi-fuel Dacia or something like that.

Credits

AMR Autos