[CNGBiFuel]

For those of you that don't know, the two systems ex-factory are albeit identical. After teh high pressure regulator, parts are interchangeable for both.

Thus the only difference between CNG and LPG is the pressures. Hence the CNG models have two regulators:

1. A high pressure jobby to drop down ffrom 200har (3000 psi) to LPG type pressures
2. A low pressure regulator to drop to manifold pressures. On thes that's about 0.3 bar (4-5psi) or lower.

Whereas the LPG models only need the one regulator. I understand the Necam system requires lower pressures than most LPG sytems, so other LPG regulators can't be swapped in and used easily.

The Necam distributor and regulator from a Transit or a Vauxhall LPG will fit dandy. it's only the flat top stepper motors that are unique to Volvo. If you're lucky, your car hasn't got one of those either - soem S60 don't have for example. In which case the steppers sold on ebay at £40-50 will do.

LPG is far dirtier and will need more cleaning than CNG or you'll fry and mash your expensive stepper motor with the gunk built-up. Filters are £5.00-6.00 each delivered on ebay. I think I recall teh size was 16mm, wihich is slightly less common but can be had. Mad price from Volvo (£90!). A filter is a filter, is a filter..?. Some CNG cars left the factory without one. Mine did. Splice yours in or cry later. Use CNG / LPG gas rated hose if you need to make it longer.