The SVIS (Sequential Vapour Injection System) is Technocarb's main alternative fuel system product for gasoline vehicles. The SVIS is a complete digitally-controlled, sequential vapor injection underhood conversion kit with versions available for both port and direct-injected engines. The closed loop LPG or CNG digital controller is an advanced computerized device factory pre-programmed for each specific application.
The main problem with converting fuel-injected vehicles is the high internal volume tuned intake manifold. While this intake manifold is great for improving torque, it also causes a fuel signal transport delay with mixer-style propane conversions. This delay can lead to costly repairs from lean fuel-mixture backfires. The solution of course is to keep the fuel out of the intake manifold with vapour injectors at the intake ports. Besides eliminating lean mixture backfires, port vapour injection also makes the engine more responsive. While the old Impco fumigation systems generally have propane fuel economy around 75% to 80% of the car's gasoline economy, Technocarb's SVIS (Sequential Vapour Injection System) result in a propane fuel economy of about 90% of the car's gasoline economy. Power only drops by about 10% too.
While not a DIY project for a novice mechanic, Sequential Vapour Injection is quite straightforward and relatively easy to do. Technocarb has very kindly supplied us with the following documents for their Sequential Vapour Injection System: