The VSI (vapour sequential injection) system is from Prins Autogassystemen B.V. from the Netherlands.

The system is designed to integrate fully with the host vehicles OBD (on-board diagnostics) system and to run as a 'slaved' system in that it operates directly via signals from the original vehicle's ECU (engine control unit). This makes the system as close to OE (original equipment) as is possible, resulting in minimal (if any) loss of performance and optimum emissions. In addition, Prins use Keihin injectors (Keihin make injectors and automotive components for some of the worlds largest petrol car manufacturers).

Prins' Keihin injectors are rated by colour, as follows:

Injector 32cc green
Injector 42cc white
Injector 52cc blue
Injector 63cc orange
Injector 73cc yellow
Injector 100cc brown

Yellow injectors were chosen for my 286 BHP (stock flywheel power) car, however, Prins have even larger capacity injectors for extremely powerful cars.

The quality of the Prins VSI system can be seen by examining the sub-components such as the reducer/vapouriser, injectors and gas-filter when compared to alternatives (such as Romano). In addition, the Prins software is actually quite professional and does not crash every 5 minutes like some 'home-brewed' software knocked-up in a few days.

Prins VSI vapouriser
Prins VSI Vapouriser 1

Prins VSI vapouriser
Prins VSI Vapouriser 2
Prins VSI injectors
Prins VSI injector rail mounted with 4 'yellow' injectors
Prins VSI gas filter
Prins VSI gas filter
Prins VSI software
Prins VSI configuration software

There were many systems available to choose from, however, personal extensive research had shown that the Prins VSI and BRC Sequent 56 were the two systems proven to be used on high performance vehicles around Europe.

A variery of other systems are available which are based upon the same AEB technology - some of these are: OMVL, Romano, Zavoli, Tartarini and BiGas etc. These are quite cost-effective systems, however, the quality of 'system makers' hardware that comes part of these systems (vapouriser and injectors) can vary. The long-term reliability of these systems does not also appear to be up there with Prins and BRC; however, this does not mean that these systems will not work - a lot of this depends on the actual installation and it's always best to find out if your potential installer has converted your make of vehicle before - ask to speak to those satisified customers he has converted!

Split Fueling

In recent times the term 'Split Fueling' is being banded about by some LPG system advocates as a 'feature'. Put simply, this isn't really a 'feature' but a limitation of the system as it it allows the system to inject petrol to compensate for the LPG it cannot deliver. Therefore, it is being wrapped as a 'feature' for powerful cars.