Thread: LPG Pipe sizing

Originally Posted by DeeJay

Hope some one can give an answer with this one.
I trolled Google for hours with no luck.
Is 1/4" copper pipe big enough for a 4.2 Litre V8?.
Its been there for years and its only when towing up big hills that the Landie seems to drop off in oomph.
The only thing I could find said that "high performance V8's should have 5/16" size pipe.
It might be something else but the tanks are going back in after a 10 year test and now would be a good time to upsize (if I have to).
Thanks,

What pipe you talking about...runs from where to where....whats it used for....fuel?

Whatever the connections are either end will 'govern' the flow, I don't think the pipe size should make a difference

...........but an interesting thought, I'll try and do some calcs.

Just did some quick calcs, others may want to work out their own to prove me right or wrong, but

The size of the outlet fitting at the tank will govern your flow - so in theory upsizing may not help, however this tends to only be relevant where you have no other restrictions, i.e. straight pipe.

We we know we are not working with straight pipes here, so we have a few bends - maybe even a pipe or two that has been slightly flattened and there would also be a few fittings/joints - these all act as restrictions

So the theory has it that if you measure the outlet size at the tank, then if you have three retrictions move up one size 4 to 7 restrictions go up two sizes.

Gradual soft <45 Deg bends = 1/2 restriction, real bad RH tight corners should be classed as 1.25 restrictions.

It could be that your convertor (vapouriser) isn't up to the task.

I have an OMVL R90/E which I may fit even though my existing converter is rated for high HP engines.

See

Thanks guys,
I will research the vapourisor a bit further, looking at it a bit closer, the 3 tanks are all 5/16" outlets and the pipe fitted is 1/4" with those thicker necked SAE compression nuts.
The fuel lockoffs are somewhere between 1/4" & 5/16" and the vapouriser probably the same. I need a set of metric & english drill bits and a micrometer to work this out better.
Going on what Ladas says, I should really go to 5/16", BUT its possible the tanks are a "one size fits all".
What I would really like to hear is someone saying my 4.6 rangie tows no worries and the inlet pipe to the vapourisor is 1/4"..

I wouldnt be using copper pipe on a 4by, use aeroquip flexible hose especially if there will be flex involved.

Originally Posted by loanrangie

I wouldnt be using copper pipe on a 4by, use aeroquip flexible hose especially if there will be flex involved.

NOW you tell me
Actually I work for a LPG distributor, but we don't do autogas. I will scrounge around for the code at work and if I can use the hose, then I will.
Cursing myself now as I OK'd the depot manager to turf out a whole heap of 5/16 hose as we never needed it.
My personal thoughts were in a fire situation that rubber covered copper might just survive. In any case I would need binoculars to witness it.

Sorry can't totally agree with that.

My D1 which was converted to regs (okay in VIC) had metal pipe - I think it was copper all along the chasis.

It was only from the tank to the chassis, and the chassis to the solenoid near the throttle housing that were flexible 'hoses'.

The metal pipe was supported the full length with 'cushioned' clips.

My chums Ford is copper pipe along the length of the 'ridgid' bit also with flexi hose 'tails'

I personally would prefer to have a metal pipe carrying LPG as long as possible - with just the bit's that flex in hose.