Propane/water/alcohol injection and O2 sensors

[bill.shurvinton at nokia.com]

Now I am confused.

In a brief literature search, which left be a little bewildered the following patterns emerged.

1. Vapour phase mixing uses reduces HP by 5% beacause of loss of air volume
2. Liquid injection offers higher HP than vapour phase (figures of 20% more than petrol have been quoted, 60% in one case!)BUT little/no data on how the injection is carried out.
3. Propane has a RON of 112 so needs advanced timing not retarded

But it would appear that propane systems are still a bit basic in 97% of cases.

What you are saying about expansion makes sense. I need to do much more research.

Bill

-----Original Message-----
From: ext Phil Lamovie [mailto:phil at injec.com]
Sent: Wednesday, April 10, 2002 9:06 AM
To: diy_efi at diy-efi.org
Subject: Re: Propane/water/alcohol injection and O2 sensors



Brian wrote:-

> This has two advantages over the standard water/alcohol injection:
> the propane is quite a bit colder, and it is in gas phase and so
> there's no danger of pooling or uneven distribution.

There is very little danger of making a puddle of propane but some
of your other assumptions are a little shy of the mark.

When the liquid to gas phase change takes place a large amount
of manifold space that was to be filled with air is now filled with
propane vapor. The expansion rates are extremely high. This very
sudden and uncontrolled expansion can cause very severe air
distribution problem. and thus A/F ratio chaos will result.

You will also need to retard the timing as a mixture of air, petrol
and propane has much lower advance requirements.

The need to distribute the propane at an appropriate place in the
manifold is one of the most difficult aspects to nut out when making
this type of modification.

A reasonable compromise is to cool the intake air with an intercooler
cooled by phase change propane this way the expansion takes place
in a controlled environment and the air is cooled with out any drag
being created. Then you can distribute the almost atmospheric
pressure propane to a suitable mixing device.

The solenoid will also experience a surplus of cooling so there may
be ice formation in its immediate vicinity. Some degree of stuffing
around with placement and piping is to be expected.

HTH

Phil

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