Fiat Uno Lacks Punch After LPG Conversion

You lose HP because LPG needs more air per pound of fuel and 1 cubic foot of LPG has 2500 BTU where as 1 cubic foot of gasoline has 4500 BTU. Gasoline engines are fixed volumetric machines, so you can but as many BTU's into the engine with LPG. You get a slight increase of volume because of some cooling, but not enough to compensate for the loss of total mass.

As Guest replied, it's all about volumetric efficiency and BTU's but you might be able to help yourself out a bit if you can adjust the spark timing up a bit. Petrol and LP/CNG have quite a difference in octane equivalence and with CNG and LP you can run the engine at higher spark advance and compression ratios to give yourself back some of the power. Raising the compression may be a bit more of a task because it would involve changes in the pistons but if you have a movable distributor, the spark timing should be an easy adjustment to give you a few additional horses.

When I was looking into doing this on my truck the company I was asking questions to said they would include a little computer box that would automatically change the air ratio settings depending on weather I was using Gasoline or LPG. Didn't your conversion include this computer. Or did you completely switch to LPG. If so why wasn't the fuel air ration changed to compensate.

I do believe that most systems in cars are automated to start in Petrol and only switch over to gas when the engine is warm. If yours is not an automatic system, then you probably need to read the handbook on this point a bit more carefully.....

Other posters have pointed out the fact that the fuel is not as high a calorific value as petrol, but of course its really cheap!!!

The conversion is slightly "greener" and economically more viable......

You could have a Turbo added, this will recoup at least some of the lost power, but your savings may dissappear completely + the cost of the Turbo and installation!

then there is the fact that you are driving a Fiat Uno. These are not known for their power, acceleration or mechanical reliability.

lack of oxygen or air might be a probable cause for loss of power.

i would suggest u to try foe NOX cylinders