Cars - petrol / LPG

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- Alfa Romeo (http://www.autobanter.com/forumdisplay.php?f=19)

- - petrol / LPG (http://www.autobanter.com/showthread.php?t=358997)

This post is the same question that I just asked in uk.rec.driving.

After converting a petrol engine to LPG, can the car still use petrol as a
backup, or is it LPG only?

Anyone converted an Alfa? 2.0JTS specifically.

GT

"GT" > wrote in message
...
> This post is the same question that I just asked in uk.rec.driving.
>
> After converting a petrol engine to LPG, can the car still use petrol as a
> backup, or is it LPG only?
>
> Anyone converted an Alfa? 2.0JTS specifically.
>
> GT

Sorry to bother everyone - I have a reply - you can run on either fuel.
Aparently, it is advisable to run on petrol occassionally to keep the
injectors/pumps from drying up.

However, doesn't seem to be an option for the Alfa anyway - aparently not
compatible with direct injection. Aren't most petrols direct injection these
days (last 10 years or so). Carbs are a thing of the past, aren't they?

GT wrote:
> "GT" > wrote in message
> ...
>> This post is the same question that I just asked in uk.rec.driving.
>>
>> After converting a petrol engine to LPG, can the car still use petrol as a
>> backup, or is it LPG only?
>>
>> Anyone converted an Alfa? 2.0JTS specifically.
>>
>> GT
>
> Sorry to bother everyone - I have a reply - you can run on either fuel.
> Aparently, it is advisable to run on petrol occassionally to keep the
> injectors/pumps from drying up.

Dunno about that. My V6 conversion wouldn't start on LPG, which is,
AIUI, the norm. It switched over automagically as the engine temp rises.
>
> However, doesn't seem to be an option for the Alfa anyway - aparently not
> compatible with direct injection. Aren't most petrols direct injection these
> days (last 10 years or so). Carbs are a thing of the past, aren't they?

Typical BS on the 'net then.

http://www.alfaowner.com/Forum/wales...onversion.html

Someone had one done two years back, and had some software problems.
IWHT that they were pretty much ironed out by now ;)

and
http://lpgwales.com/lpg-conversion-d...ar-models.html
and
http://www.brc.it/comunicatistampa.aspx?ID=669&lang=en

Shall I go on?

BTW don't confuse injection with direct injection.

Injection (or fuel injection) took over from carbs a while back. The
fuel is injected into the intake tract or (perhaps) port direct[1]. This
means a lower fuel pressure is required since the inlet valve is open
and mixture is being drawn into the cylinder by the inlet stroke.

Direct injection is where (as the name implies) the fuel is injected
directly into the combustion chamber. This allows greater control and
stratification of the charge (lean burn) *if* you can generate high
enough pressure to inject the fuel during the compression stroke. This
is particularly used when cruising on a light load.

The rest of the time, injection takes place during the induction stroke
again.

Mostly ;)

HTH

[1] Or if you're running a 12v Alfa V6, the cold enrichment is
accomplished by injecting *more* fuel directly into the plenum. My that
can be amusing if you don't start soon enough and then your plenum full
of fuel / air mix ignites. Apparently...
--
Catman MIB#14 SKoGA#6 TEAR#4 BOTAFOF#38 Apostle#21 COSOC#3
Tyger, Tyger Burning Bright (Remove rust to reply)
116 Giulietta 3.0l Sprint 1.7 GTV TS GT 3.2 V6
Triumph Sprint ST 1050: It's blue, see.
www.cuore-sportivo.co.uk

"Catman" > wrote in message
...
> GT wrote:
>> "GT" > wrote in message
>> ...
>>> This post is the same question that I just asked in uk.rec.driving.
>>>
>>> After converting a petrol engine to LPG, can the car still use petrol as
>>> a backup, or is it LPG only?
>>>
>>> Anyone converted an Alfa? 2.0JTS specifically.
>>>
>>> GT
>>
>> Sorry to bother everyone - I have a reply - you can run on either fuel.
>> Aparently, it is advisable to run on petrol occassionally to keep the
>> injectors/pumps from drying up.
>
> Dunno about that. My V6 conversion wouldn't start on LPG, which is, AIUI,
> the norm. It switched over automagically as the engine temp rises.
>>
>> However, doesn't seem to be an option for the Alfa anyway - aparently not
>> compatible with direct injection. Aren't most petrols direct injection
>> these days (last 10 years or so). Carbs are a thing of the past, aren't
>> they?
>
>
> Typical BS on the 'net then.
>
> http://www.alfaowner.com/Forum/wales...onversion.html
>
> Someone had one done two years back, and had some software problems. IWHT
> that they were pretty much ironed out by now ;)
>
> and
> http://lpgwales.com/lpg-conversion-d...ar-models.html
> and
> http://www.brc.it/comunicatistampa.aspx?ID=669&lang=en
>
> Shall I go on?
>
> BTW don't confuse injection with direct injection.

I was!

> Injection (or fuel injection) took over from carbs a while back. The fuel
> is injected into the intake tract or (perhaps) port direct[1]. This means
> a lower fuel pressure is required since the inlet valve is open and
> mixture is being drawn into the cylinder by the inlet stroke.
>
> Direct injection is where (as the name implies) the fuel is injected
> directly into the combustion chamber. This allows greater control and
> stratification of the charge (lean burn) *if* you can generate high enough
> pressure to inject the fuel during the compression stroke. This is
> particularly used when cruising on a light load.
>
> The rest of the time, injection takes place during the induction stroke
> again.
>
> Mostly ;)
>
> HTH

Definitely!

> [1] Or if you're running a 12v Alfa V6, the cold enrichment is
> accomplished by injecting *more* fuel directly into the plenum. My that
> can be amusing if you don't start soon enough and then your plenum full of
> fuel / air mix ignites. Apparently...

[1] er... not that lucky! Just 4 cylinders here.

GT wrote:
<snip>
>
> Definitely!
>
>> [1] Or if you're running a 12v Alfa V6, the cold enrichment is
>> accomplished by injecting *more* fuel directly into the plenum. My that
>> can be amusing if you don't start soon enough and then your plenum full of
>> fuel / air mix ignites. Apparently...
>
> [1] er... not that lucky! Just 4 cylinders here.
>
>

*BANG* ;)

It was a *very* primitive CSED[1]. Not entirely surprising since (IIRC)
the injection was a bolt on for the US market.

[1]Cold Start Enrichment Device. Choke as it used to be ;)

--
Catman MIB#14 SKoGA#6 TEAR#4 BOTAFOF#38 Apostle#21 COSOC#3
Tyger, Tyger Burning Bright (Remove rust to reply)
116 Giulietta 3.0l Sprint 1.7 GTV TS GT 3.2 V6
Triumph Sprint ST 1050: It's blue, see.
www.cuore-sportivo.co.uk

Gt spoke:
> After converting a petrol engine to LPG, can the car still use petrol as a
> backup, or is it LPG only?
>
> Anyone converted an Alfa? 2.0JTS specifically.

IFAIUI from when I looked into it for a 4l Jeep, they won't start on LPG, so
you *have* to have petrol to get the motor running, then switch over to LPG.

Do your sums carefully though. You do get lower power and lower mpg from
LPG, and at least in my case, the payback would have been around 3 years,
which is as long as I normally keep cars for.

--
Rob Pearson
156 1.9jtd sportwagon (now)
164 V6 Lusso (gone)

R C Nesbit wrote:
> Gt spoke:
>> After converting a petrol engine to LPG, can the car still use petrol as a
>> backup, or is it LPG only?
>>
>> Anyone converted an Alfa? 2.0JTS specifically.
>
> IFAIUI from when I looked into it for a 4l Jeep, they won't start on LPG, so
> you *have* to have petrol to get the motor running, then switch over to LPG.
>
> Do your sums carefully though. You do get lower power

I had to check *really* carefully on the V6 to notice it was on LPG, and
it was impossible to tell on motorways.

>and lower mpg from
> LPG, and at least in my case, the payback would have been around 3 years,
> which is as long as I normally keep cars for.

That was about right, although I had a different cost price ;)

--
Catman MIB#14 SKoGA#6 TEAR#4 BOTAFOF#38 Apostle#21 COSOC#3
Tyger, Tyger Burning Bright (Remove rust to reply)
116 Giulietta 3.0l Sprint 1.7 GTV TS GT 3.2 V6
Triumph Sprint ST 1050: It's blue, see.
www.cuore-sportivo.co.uk

On Thu, 05 Aug 2010 20:30:46 +0100, Catman
> wrote:

>R C Nesbit wrote:
>> Gt spoke:
>>> After converting a petrol engine to LPG, can the car still use petrol as a
>>> backup, or is it LPG only?
>>>
>>> Anyone converted an Alfa? 2.0JTS specifically.
>>
>> IFAIUI from when I looked into it for a 4l Jeep, they won't start on LPG, so
>> you *have* to have petrol to get the motor running, then switch over to LPG.
>>
>> Do your sums carefully though. You do get lower power
>
>I had to check *really* carefully on the V6 to notice it was on LPG, and
>it was impossible to tell on motorways.
>
>>and lower mpg from
>> LPG, and at least in my case, the payback would have been around 3 years,
>> which is as long as I normally keep cars for.
>
>That was about right, although I had a different cost price ;)

Looks like you are all newbies to LPG
My first was a 164 with a brc system which had a vapouriser between
the air filter and air flow meter. Power loss was approximately 25%.
My current car is a 166 V6 24valve. This has a direct injection system
with a piggyback unit that fools the cars engine management into
thinking it is still running on petrol. There is no power loss at all
and switching between petrol and gas is faultless with no hesitation
from the engine whatsoever.
Oher benefits from lpg are lower imissions and a vastly cleaner
engine. Oil stays amber coloured between changes and engine life is
greatly increased. Diesels? Forget them! LPG I can get for 53p per
litre