LPG Mixer

[hattymender]

Out of curiosity I took one of the alloy elbows off a carb of my V8 'garage ornament' (waiting for good weather to fit it) to have a look at the mixer. Can't get in to measure it but it looks to be taking up about 1/3 of the bore, which must be about 1/2 of the cross section area.

This must be restricting power?

I guess they must be designed to be convergent/divergent to cause a pressure drop and 'draw' the gas but restricting the standard airflow doesn't seem to be a good idea, surely it's be better to fit a bigger than standard pipe and reduce the cross section area at the mixer to something more akin to the standard intake?

I've not looked into mixer design, are some better than others?

Rich

[TomG]

On top of my old Weber/Edelbrock 500 setup I had a Sprint Gas active mixer, this took a vacuum feed from the carb, switched through a 12v solenoid which deflated a balloon inside the mixer and raised up the (restrictive) mixer plate when on petrol and lowered it for LPG.

I don't think LPG injection systems (for EFI) restrict the airflow

[MickMac]

I used to run LPG a few years ago and mucked about with venturi mixers with a couple of us making/modifying our own. Settled on a 50mm ID with 6mm holes (from 36mm and 3mm holes) for a 3.9 EFI using the standard air cleaner to keep the pressure drop across the mixer up to a decent level.

The set-up for SU's or Strombergs wasn’t quite so restrictive if I remember correctly although it was Landi gas components I was using though so there might be differences between manufacturers.