Necam Factory fit BiFuel Systems CNG or LPG
 

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.

The low pressure regulator was made in two versions. The recon kit must be bought accordingly. But a CNG kit will fit an LPG car and vice versa.

Again, a regulator form a LPG Transit or a Vauxhall, both fitted with Necam back in the day will fit a CNG car. As the previous post, it's the high pressure stage that is differs, not even present on LPG cars.

P1 cars don't have a temperature gauge. Not sure if thsi applies to P2 cars. P1 cars get a fuel gauge in their place. I've installed a Scnguage permanetly wired into my OBD2 port. Sits under the trip odometer. Menas I have permanet scannign abillity too and it looks neater thatn fitting any aftermarket gauge.

I ripped the idea form thsi guy. Mines the smaller, cheaper version of the Scangauge, and I've rerun my OBD2 port under my dash using the wiring from a breaker.

https://www.youtube.com/watch?v=Nj34dakoayM

I read that back and I realsie I may confuse soem of you. The parts are almost the same:

1. High pressure regulator is only present on CNG
2. Low pressure regulator/Vapouriser uses same repair kit, but body I believe is in variation
3. Dist. Stepper motor is intercahngeable.
4. Dist: Inner throttle (section with 6 x slots, i x unused ) is CNG or LPG specific. Uses same repair kit.