V8 LPG Questions

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Idris - 27 Oct 2006 12:36 GMT

Have a Defender 110 with a V8 that has twin SU carbs with a Landi Renzo LPG
conversion that was on it when I bought it. The LPG is fed in to a device
between the carb and the manifold. This presents a restriction to the air
flow and whilst I can see that it might be necessary to get a venturi effect
to make the system work, I am keen to do away with any restrictions to the
air flow and potential consequential power implications.

Is there a way to stay with carbs but avoid this "restriction"?

If the restriction has to stay is it possible to fit efi in a relatively
straight forward way?

If I fit efi would it be preferable to go for the flapper or hot wire
system?

How much of the present LPG equipment would have to be replaced?

Would there be power or economy benefits from doing this work?

Gerald

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Badger - 27 Oct 2006 13:31 GMT

> Have a Defender 110 with a V8 that has twin SU carbs with a Landi Renzo LPG
> conversion that was on it when I bought it. The LPG is fed in to a device
[quoted text clipped - 4 lines]
>
> Is there a way to stay with carbs but avoid this "restriction"?

Not really, the gas system needs a venturi to operate.

> If the restriction has to stay is it possible to fit efi in a relatively
> straight forward way?
>
> If I fit efi would it be preferable to go for the flapper or hot wire
> system?

Flapper would be cheaper, but more prone to backfire damage. Hotwire will
fit, with the correct 3.5 discovery fuel map and tune resistor, but will be
more expensive. Still have a restriction though, due to gas system's need
for a venturi to operate.

> How much of the present LPG equipment would have to be replaced?

Just the mixer, really.

> Would there be power or economy benefits from doing this work?

A small power increase due to the efi system having a far superior inlet
manifold design in the first place, but then there's that venturi
restricting the airflow still.
If you are intent on going efi, then a better solution is to go the "whole 9
yards" and fit a hotwire system complete with lambda probes and run it
closed-loop, then convert to an SGI type of lpg system. This is the only way
you will eliminate the inlet restriction, boosting power and giving better
economy in the process.
Badger.

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Austin Shackles - 27 Oct 2006 14:10 GMT

>Have a Defender 110 with a V8 that has twin SU carbs with a Landi Renzo LPG
>conversion that was on it when I bought it. The LPG is fed in to a device
[quoted text clipped - 4 lines]
>
>Is there a way to stay with carbs but avoid this "restriction"?

You have, of course, got a similar restriction in the carbs themselves, for
exactly the same reason...

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Austin Shackles. www.ddol-las.net my opinions are just that
Satisfying: Satisfy your inner child by eating ten tubes of Smarties
from the Little Book of Complete B***ocks by Alistair Beaton.

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