Quote Originally Posted by userfriendly View Post
Just spoke with the Green Autogas, they said that the traditional type of lpg kit which uses the venturi principle has risk of backfire. They said they do not recommend using this type of system. According to them, there is about 5% chance of getting a backfire and it may damage the airfilter housing. Is this true? LPG users, feedback please.

They were recommending the sequential type which according to them has zero risk of backfire and no power loss. Catch is it will take 3 days to install and they will drill holes in the manifold for the injectors. They further said that if I decide to remove the kit in the future, the holes can be welded or repaired by a machine shop.

If I convert, it will take about a year to recover the cost of the traditional kit. For the sequential type, about 2.5 years. Is it worth to convert? And if so which is the better deal?
In a typical modern engine, the chance of a backfire is pretty remote UNLESS you are playing with the adjustments for the engine's ignition timing or valve cams.

Major advantages of a sequential type LPG kit are:
-no loss of engine power (due to the venturi pipe)
-less sensitive to air filter condition
-more efficient than venturi type

Disadvantage:
-costs at least twice more than venturi type
-drills holes into the engine intake manifold (for the injectors)

IMHO, the decision to get either type depends on your reasons why you are getting a LPG kit in the first place. You want to save money. Next thing to consider is how long do you plan to keep the car. If you plan to keep the car for the next four years or more, you could get the sequential. If the car is rather getting old, then the traditional venturi type LPG kit would be the realistic choice.