LPG mixer size?

[ytt105]

I've got LPG on my 87 RR, 3.9 V8
The mixer is bolted to the air intake side of the air flow meter and the resulting air intake hole is sunstantially less than the original air intake.
Am I correct in thinking that this is too small for proper operation. The car seems to feel as though it is strangled when you try to make it rev and it goes crap on petrol, though that could be because I have heaps of advance for running on gas.
What size mixer should I have and where should it be placed.
I'll be getting rid of the air flow meter soon when I re-install my 'MegaSquirt' so I will probably need a new one that can be fitted to the air intake hose somewhere.
Any idea where I could get one, who much, etc?

[RaginRover]

What do you mean by significantly smaller do you mean 50% smaller or just 10mm smaller all around. Mine is more like 10mm smaller all around
and works fine - after some tuning.

Just to be sure you have put it after the air flow meter and between the plenium right ???

Tom

[ytt105]

It's probably a little bit more than 10mm smaller, and its placed between the air flow meter and the air cleaner.

[RaginRover]

It's probably a little bit more than 10mm smaller, and its placed between the air flow meter and the air cleaner.

I was pretty sure it was really difficult to tune them up like that.

Is your setup flapper or hotwire - if it is hotwire then run it behind the AFM and it will be easier to tune and shouldn't change the petrol properties too much (the restriction will change the top end a bit but not that much)

Tom

[ytt105]

It's flapper at the moment, but soon there won't be any air flow meter when I go to MegaSquirt so I need another mixer that I can fit in the air flow hose. Any ideas where and what to get?

[RaginRover]

Well,

I had a kit off a discovery that I put on my 3.9 rangie and it had a mixer that fit on the end of the plenium where it stepped down to put the hose on the to the AFM. It fit over that lip - IMO this is the best way to go, here is a photo.

Go to a gas shop I suppose, a mixer is worth about $90 last time I bought one, although I found it hard to get one just like mine last time, I had to settle for an inline on that just fit in the hose.

You should also fit a backfire protection flap too to help protect you AFM, the problem is that these are worth about $90 too and now you are up to $180. If you are going megasquirt then I would wait till you were ready to go before putting LPG on, i

You will have to re-tune once the mega is on and if you are changing over soon the savings just won't add up.

If it is going to be a "while" before you get it up and running then it may be worth it

Tom

[RaginRover]

Here is the photo