what PSI is CNG injected to engine?

[sr_ryan1]

what PSI and does it change with TP opening or WOT?

[CNG MOTORS]

Re: what PSI is CNG injected to engine?

most high pressure regs bring it down to 150 psi then coming out of the low pressure reg not sure but super low maybe 1-5 psi

[afvman]

Re: what PSI is CNG injected to engine?

Ryan,

That one's easy. NG fuel injection rails or manifolds are all in the 100-200 psi range. CNG MOTORS is correct.

Fumigated systems, i.e., older fixed ring venturies or air valve systems are below 1 psi. They're measured in inches of water (WC) and run around 3-5 in. or almost nothing.

Hope this helps.

afvman

[afvman]

Re: what PSI is CNG injected to engine?

Ryan,

I didn't answer your question about pressures at WOT and the effect of throttle position...

As with liquid fuels, the pressure (tries) to remain constant across the whole range, but the pulse width varies with all those different conditions.

A lot of the CNG programs i.e., Baytech, ECO, simply take the gasoline pulse width and convert it to an equivalent amount of CNG. Sounds simple, but it's more complicated. Others, i.e., Zenith, GFI, develop a completely new fuel map of their own.

Probably more than you really wanted to know.

B/R,

afvman

[freedml]

Re: what PSI is CNG injected to engine?

Fuel Injection requires more pressure than 'fumigation.' On my GX, the label on the low pressure regulator says it is set at 36.3 PSI. The 'fuel rail pressure' shouldn't ever change unless you run out of gas.

[larrycng]

Re: what PSI is CNG injected to engine?

The '95 prototypes and the '98 production GX's did vary the pressure according to load; between around 29 and 39 psi. (I'm not sure when or if they changed) There was a vacuum line between the intake manifold and regulator that caused the injector rail pressure to vary with load.

Most system do not vary regulator pressure with load change. The old fumigation systems (Impco, OHG) also varied final stage regulator pressure on the feedback systems using air valve vacuum and a signal from the O2 sensor.

Larrycng