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In Belgium cars running on LPG cannot park in underground garages even though they go through very stringent MOT-like checks. One of the problems is that conve

In Belgium cars running on LPG cannot park in underground garages even though they go through very stringent MOT-like checks. One of the problems is that conversions need more than just a switch of just gas to LPG. You need a tune and you need an adjustment / expansion of the cooling setup. LPG runs a lot hotter than gasoline and this needs to be managed. Funnily enough modern gasoline engines are tuned to manage temperature by ... dumping in more fuel. Which is why your turbocharged 3 cylinder .9L has amazing mpg while driving calmly, but once you push it it proportionally consumes way more. https://youtu.be/9aO2vC_iMTI?t=252 https://youtu.be/9aO2vC_iMTI?t=252

Gordonjcp 4y ago
You don't really need to do much. Most "modern" conversions bypass the petrol injector electrics to pick up injector pulse timing for the gas injectors, and have a separate ECU that manages the fuel mapping. Once you've got it installed and given it an initial rough setup (not much more than programming in how many cylinders and how large an engine) it'll just trim itself. The LPG ECU maintains a map that makes the vehicle's own ECU think it's running at a perfect mixture on petrol, and is otherwise totally unaware that anything is different. Older systems are a bit cruder, but still don't need much more than an extra lambda sensor fitted for the gas ECU.
- WirelessGigabit 4y ago
  You're still dealing with a system that expects that under certain conditions injecting MORE fuel will induce a cooling effect. Not the case when you have an LPG system installed. Whether the piggy-back understands this procedure and and obeys it or fakes it is irrelevant. If your cooling system cannot handle this increased heat output you'll run into issues. Better fan will help, but again, this is more heat coming from the inside of the cylinder, so certain blocks will handle upgrades better than others.
  - Gordonjcp 4y ago
    This turns out not to be a problem, because the engine runs cooler on LPG. The gas leaves the tank in liquid form and has to be boiled into a gas. Its boiling point is -40°C, and so the vapouriser is plumbed into the cooling system. This pulls a lot of heat out of the coolant. I regularly tow at the maximum permitted weight and speed with my LPG-converted Range Rover, and the coolant never gets above its normal 95°C even on the hottest day.

Gordonjcp 4y ago

You don't really need to do much. Most "modern" conversions bypass the petrol injector electrics to pick up injector pulse timing for the gas injectors, and have a separate ECU that manages the fuel mapping. Once you've got it installed and given it an initial rough setup (not much more than programming in how many cylinders and how large an engine) it'll just trim itself. The LPG ECU maintains a map that makes the vehicle's own ECU think it's running at a perfect mixture on petrol, and is otherwise totally unaware that anything is different. Older systems are a bit cruder, but still don't need much more than an extra lambda sensor fitted for the gas ECU.

WirelessGigabit 4y ago
You're still dealing with a system that expects that under certain conditions injecting MORE fuel will induce a cooling effect. Not the case when you have an LPG system installed. Whether the piggy-back understands this procedure and and obeys it or fakes it is irrelevant. If your cooling system cannot handle this increased heat output you'll run into issues. Better fan will help, but again, this is more heat coming from the inside of the cylinder, so certain blocks will handle upgrades better than others.
- Gordonjcp 4y ago
  This turns out not to be a problem, because the engine runs cooler on LPG. The gas leaves the tank in liquid form and has to be boiled into a gas. Its boiling point is -40°C, and so the vapouriser is plumbed into the cooling system. This pulls a lot of heat out of the coolant. I regularly tow at the maximum permitted weight and speed with my LPG-converted Range Rover, and the coolant never gets above its normal 95°C even on the hottest day.