Forum » General Tuning Discussion » Anyone have experiance with LPG Liquid Injection

Anyone have experiance with LPG Liquid Injection

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Hey all, im planning to build a lotus 7 replica from scratch from the ground up but it has to be registered as a ICV (individually constructed vehicle) which means its considered a current model vehicle and therefore must comply with current ADR emissions standards.

BUT if I run it on LPG its totally exempt and does not require any emissions testing.

So as the title says look for experience people have had with Liquid LPG injection. Did it still make good power comparative to petrol/gasoline

One attractive thing is the cooling of the intake charge from the phase change of liquid to gas as its injected into the intake manifold. How much cooling does it actually provide? is it to a point where you could run moderate boost (15-20psi) without an intercooler?

Is it possible to measure it? you would need a temperature sensor just before the valves?

It's been a VERY long time, but as I recall there is a little less energy released, so usually a little less torque/power when directly compared to petrol. The FORD factory 'LPG' engines were supposed to have ~4hp more than then the petrol ones.

However, it also has a very high 'octane number' and works well in very high compression and forced induction engines - it's sometimes used as a fuel alternative for diesel engines, with the associated spark ignition conversion.

I assume you're looking at your local Autogas - this may also have butane, or other gases, in it, so the effective octane may be lower - but there should be a federal mandated minimum.

Back then, we used a gaseous fuelling method that didn't have a cooling affect and, as the fuel burned rather hot and slow (as I recall) when over-rich, there was a problem with inexperienced and/or stupid 'mechanics' overfuelling engines and cracked exhaust manifolds were common. With liquid injection, I would expect some cooling from the latent heat of evaporation, but off-hand, I don't know how significant it would be, even with the addition fuelling mass needed - ah, less than expected.

For different fuels/gases

LPG - 428 kJ/kg

Butane - 386 kJ/kg

Petrol - 425 kJ/kg (average found +/- 2kJ)

Methanol - 1100 kJ/kg for comparison

Tuned a mates car years ago that we dubbed tri-fueled. Ran full flex fuel, 0-100% ethanol and had a seperate map for LPG injection. Still to this day I haven't seen anyone else do it, so I'm claiming it as a world first!

It's a good fuel, good octane rating, very clean emissions and cheap as chips to run a car on. You'll still need to run an intercooler though.

While testing, from memory it was very comparable to 98, but the in tank lpg pump was only good up to about 270rwkw, relatively low output (and low boost) on a big turbo 1JZ. If it had more pump and we could wind the boost up, I'm confident it would have shown decent gains over 98, which we did look into but it wasn't worth the trouble at the time. Being flex fuel we just ran e85 for 400+rwkw. LPG was just a cost saving thing so he could drive it every day.

What engine are you looking at running and what power are you expecting? Have you looked at any lpg kits specifically?