There’s been a lot of talk lately about bi-fuel cars running on LPG and propane, most notably from Chrysler and Lancia in Europe, but in the US as well, with several companies offering propane conversion kits. Propane has a few advantages of gasoline, of course. It tends to burn more cleanly, it’s cheaper, etc.
Still, nothing is perfect. Like any fuel, LPG/propane has some draw-backs that you’ll definitely want to be aware of before you “pull the trigger” and finally convert your car to propane. Here’s a brief rundown:
Tuning for Propane - As many of you who’ve looked under a car’s hood lately can tell you, cars in 2013 are rolling computers. There are sensors, processors, wires, connectors – a bunch of electronics, in other words, and they’re all driven, controlled, and calibrated by software. That software, by the way, is often encrypted by the manufacturers to make it difficult (if not impossible) to change stuff. On top of that, all those sensors, processors, etc. were built for gasoline, not LPG/propane.What that means to you, would-be-propane converter, is that getting it wrong is far, Far, FAR easier than getting it right. When you get it right, the rewards can be huge, which is why companies like Switzer Performance and Syvecs spend tons of hours and dollars developing engine management solutions for flex-fuel cars – and why they charge upwards of $10,000 for a bulletproof conversion – which brings me to the next problem.
Good Conversions are Expensive - The Switzer/Syvecs flex-fuel conversions I’m talking about should be considered “neutral ground” here, because they focus on ethanol, rather than propane, but did you notice that their conversions are almost exclusively featured on $100,000 sportscars? That’s because, as I touched on above, getting conversions right is expensive, and it could be years before a conversion pays for itself.I can already hear the peanut gallery chanting, “That’s why I’m going to convert an older car: fewer computers to mess with!”Ill grant you that older, simpler vehicles will be easier to convert, yes, but they’re also older. As such, they may be (read: will be) less reliable, parts may be harder to source, and it’s an objective fact that pretty much every aspect of vehicle performance from acceleration and braking to safety and fuel efficiency has improved significantly since the carburetor became a niche product for guys building Pro-stock Darts in their driveways. So, even though you found that cheap propane conversion kit on eBay and read about how awesome it was on that forum and you’re pretty sure you’ve got what it takes to convert that old pickup to propane, it might still be years before it pays for itself.
Limited Range on Propane Alone - In the introduction of this article, I talked about some large-scale manufacturers developing bi-fuel vehicles that could be run on either propane or gasoline. There’s a solid reason for doing so: cars running on propane have less range, compared to the volume of the fuel stored, than cars running on conventional gasoline. The main difference in range comes from a difference in heat energy per liter of fuel (gasoline’s is better).Of course, BTUs are only one small part of the overall equation. It doesn’t take into account the thermal efficiency of a fuel, it’s detonation-resistance, etc. – all of which, if optimized, can tip the scales towards an alt-fuel’s favor … but we’re not talking about building an engine that’s optimized for a given fuel. We’re talking about converting an existing engine that’s been optimized for gasoline. See disadvantages no. 1 and 2, then start adding up the cost of the turbos, intercoolers, injectors, etc. that you’ll need to buy and tune for to optimize the engine you’re trying to convert.
No Universal Connectors - Let’s say you decided to convert your car to propane. You’ve done the conversion “right”. You’ve skipped the bi-fuel step, since it’s impossible to optimize a given hardware set for two fuels, and decided that your “LPG is the fuel for me!” t-shirt is ripe for the wearing. Good for you! Now, it’s time to re-fuel. You head to the nearest KOA campground that sells propane and suddenly, horrifically realize that it was all for nothing.Their nozzle won’t fill your tank.This isn’t strictly an LPG/propane problem. In truth, none of what you’re reading about here is a problem that’s specific to propane – even electric cars are having this problem. Tesla’s Supercharger system isn’t compatible with Nissan’s Leaf, and maybe neither of those are compatible with the SAE’s Combo Connector. The lack of universal connectors, nozzles, etc. is an alt-fuel problem of the first order, and one of the biggest obstacles any future fuels will need to overcome.
The Tax Credit for Propane is a Joke - In theory, the government will cover 50% of the cost of converting your car or truck to propane. In practice, however, they’ll cover $500, which isn’t enough (see disadvantages 1-3, again). If it was enough, you’d see a bunch of propane conversions. It’s not. Ergo, you don’t.SO, if you absolutely, positively, must convert your car to propane, my advice is as follows: Spend big money. If you don’t have big money, buy a Morgan.