Longtime stalker, now hoping to have some time!

[octinum]

Greetings all!

I've been a long time follower of ecomodder, admiring you people's work mostly. Well done!

Where I live, we don't commute too long distances. My daily trip will be around 20 miles (17kms one way), when we return to the office (which is closed because of COVID). Same goes for my wife, who drives an abomination in terms of fuel economy. So I'm not after big gains in economy. This is more like a sport to me.

Petrol is very expensive in Turkey, at around $1/liter, or $3.7/US gallon. For a scale, minimum wage is around $400 in Turkey and almost half of the people are paid at that rate. So many people, including me, drive LPG/Autogas powered cars, or diesels. Autogas is half the price of petrol. You consume around %20 more per distance than you would on petrol.

We have 3 cars at home. One of them, a 1997 Citroen Xantia 2.0 8v auto is my daily drive and future experiment platform.

My first idea is an "injection-deactivation" system. Will start a topic for that, but I can tap into the autogas injectors and the initial plan is to control them using a microcontroller -a Texas Instruments MSP430 kit most likely as I have a little experience on it. Like:

- Shut off 2 injectors when idling at a traffic light (speed=0, brake pedal depressed). Cylinders 1-4 and 2-3 are paired for this (all?) 4 cylinder engines.
- Autogas controller (or the car) does not seem to have injector shutoff when coasting off accelerator pedal, so integrate that (revs > 1200rpm, acc. pos = 0)
- Single injector deactivation, at random, while coasting with low load

These *will* throw AF ratio errors I think, but I can deal with it later, feeding modified info to the car ECU.

Thanks all, for your years of sharing experience!

[Stubby79]

Welcome aboard/out of the closet!

Pics please when you've got enough posts...we don't see many makes/models ya'll get, always curious what things look like, particularly the vehicle(s) in question.

[jakobnev]

Have you considered just not idling?

[octinum]

Thanks @Stubby79! Until I can share my particular car, you can check the citroenorigins website. Mine is dark blue.

I think it has a Cd of 0.32. In fact, it has a lot of potential for aero mods; a very dirty underside in terms of aerodynamics, plus the Citroen hydropneumatic suspension. You can adjust ride height; it is not meant to be driven very low but can be set a little lower. Maybe one day...

@jakobnew trying my best not to. Did you mean stopping the engine and restarting when light turns to green? I'm not sure how long it would take a starter from the last millennium to die on me. Plus, would like to build something. Though I'm open to suggestions.

[cRiPpLe_rOoStEr]

Originally Posted by octinum

Same goes for my wife, who drives an abomination in terms of fuel economy.

What does she drive?

One of them, a 1997 Citroen Xantia 2.0 8v auto is my daily drive and future experiment platform.

I didn't even remember the Xantia being available with the 8-valve engine.

My first idea is an "injection-deactivation" system. Will start a topic for that, but I can tap into the autogas injectors and the initial plan is to control them using a microcontroller -a Texas Instruments MSP430 kit most likely as I have a little experience on it.

I assume your car has what is often called a "positive pressure" LPG conversion. Is it sequential?

[octinum]

Originally Posted by cRiPpLe_rOoStEr

What does she drive?

Another Citroen, 2005 C5 3.0 v6. Again, converted to LPG. That was the only post-facelift C5 with the Hydractive 3+ suspension I could find in Turkey at the time. Not many cars compare to its suspension comfort in soft mode, and it goes to "hard" suspension when required, for example, a moose test.

It's not a bad car for its size and engine in extra urban trips. The car lowers itself around 0.8in at the front and around 0.5in at the rear, when you accelerate past 68mph and if the road surface is suitable. Before LPG conversion, I remember it would do 29mpg (8 l/100km), with an average speed close to 80mph and aircon on all the time.

It's pointless for city driving of course, but we already have 3 cars and I want to keep the car for long distance trips with family.

Originally Posted by cRiPpLe_rOoStEr

I didn't even remember the Xantia being available with the 8-valve engine.

I don't think Citroen themselves remember all the engine options they sold with Xantia. It can be a country-specific thing, but X1 (Series 1) Xantias had this engine, and also a turbocharged version called "Turbo Constant Torque".

Originally Posted by cRiPpLe_rOoStEr

I assume your car has what is often called a "positive pressure" LPG conversion. Is it sequential?

Yes, I believe that's what it's called. It's a sequential system, with a separate ECU, regulator/evaporator and 4 separate port injectors. They are mounted I can access easily, in fact, one of the injectors have some wiring issues right now and I'll use this as an excuse to add four connectors and short wires for the future.

[cRiPpLe_rOoStEr]

Originally Posted by octinum

That was the only post-facelift C5 with the Hydractive 3+ suspension I could find in Turkey at the time. Not many cars compare to its suspension comfort in soft mode, and it goes to "hard" suspension when required, for example, a moose test.

AFAIK the adjustable suspension was a standard feature for the ones sold in my country, yet it's a PITA to find mechanics who know what they're doing while servicing vehicles fitted with this type of suspension.

It's pointless for city driving of course, but we already have 3 cars and I want to keep the car for long distance trips with family.

Sure it might be a nice car for long distance trips, but I must confess I would be quite tempted to get a Peugeot Partner/Citroën Berlingo instead. I have even seen some with underbody CNG tanks, as it's more usual than LPG in Brazil and some neighboring countries. I hardly see a Diesel-powered one by now actually.

I don't think Citroen themselves remember all the engine options they sold with Xantia. It can be a country-specific thing, but X1 (Series 1) Xantias had this engine, and also a turbocharged version called "Turbo Constant Torque".

I remember the turbocharged engine being fitted to the Peugeot 806. Haven't seen one for more than 10 years.

Yes, I believe that's what it's called. It's a sequential system, with a separate ECU, regulator/evaporator and 4 separate port injectors.

I used to see some illegal LPG conversions in my country that didn't have an evaporator, yet once in a while the intake manifold could freeze.

[octinum]

Originally Posted by cRiPpLe_rOoStEr

AFAIK the adjustable suspension was a standard feature for the ones sold in my country, yet it's a PITA to find mechanics who know what they're doing while servicing vehicles fitted with this type of suspension.

Sure it might be a nice car for long distance trips, but I must confess I would be quite tempted to get a Peugeot Partner/Citroën Berlingo instead. I have even seen some with underbody CNG tanks, as it's more usual than LPG in Brazil and some neighboring countries. I hardly see a Diesel-powered one by now actually.

Correct, hydropneumatic suspension, called Hydractive 3, was standard for all pre-2008 C5s, which is height adjustable. There are two variants of the system though, regular Hydractive 3 and Hydractive 3+. You can recognize the "plus" variant from the Sport button between the height adjustment buttons.

Dynamic qualities of these Citroens are precisely the reason I bought these cars. And with limited funds and a taste for rare cars, I think the commercial vehicle based MPVs are not my cup of tea. I'm not saying they are bad vehicles; I don't find the Mercedes A and C class, or BMW 1 or 3 series attractive as well. Personal preference.

Current Berlingo is great by the way. I would choose it over any "regular" compact family car any day.

Originally Posted by cRiPpLe_rOoStEr

I remember the turbocharged engine being fitted to the Peugeot 806. Haven't seen one for more than 10 years.

I used to see some illegal LPG conversions in my country that didn't have an evaporator, yet once in a while the intake manifold could freeze.

Oh, I remember people fitting kitchen type LPG tanks in the boot here.

About that... I'm also thinking of a LPG liquid injection adventure. Not yet -I moved here from another city during Covid, new job, new home, so I'll have to take it slow. A controlled charge in the intake manifold wouldn't freeze anything I guess. How this would help with fuel consumption is its suitability with turbocharged small engines. Of course I can't do an engine swap on my current cars but if LPG liquid injection works, it would be applicable to smaller, lighter engines with adequate power when needed, which would also be easier on the start-stop systems.

And of course, in a country like Turkey, it would be a huge gain in terms of fuel costs.

I think my next post will enable me to attach images and links. So continue teasing please.

[cRiPpLe_rOoStEr]

Originally Posted by octinum

Dynamic qualities of these Citroens are precisely the reason I bought these cars.

Citroën is often praised for its handling, even though it's not the same as it used to be.

And with limited funds and a taste for rare cars, I think the commercial vehicle based MPVs are not my cup of tea.

I also have a taste for some rare cars, but I consider practicality a priority.

Current Berlingo is great by the way. I would choose it over any "regular" compact family car any day.

AFAIK the 1st generation is still made in Argentina, where it seems to have effectively fulfilled the role as a replacement for the 2CV

Oh, I remember people fitting kitchen type LPG tanks in the boot here.

It used to be more common here in Brazil too, even though nowadays it's mostly done in small towns without a CNG supply.

I'm also thinking of a LPG liquid injection adventure. Not yet -I moved here from another city during Covid, new job, new home, so I'll have to take it slow. A controlled charge in the intake manifold wouldn't freeze anything I guess.

Sure a controlled charge is less likely to lead into trouble, and so is the sequential injection. Most of the times I see frozen intake manifolds, it's on vehicles fitted with a non-electronic fumigation setup, and those are so bad they lead to manifold freezing even with CNG (which is more common as a motor fuel in my country).

How this would help with fuel consumption is its suitability with turbocharged small engines. Of course I can't do an engine swap on my current cars but if LPG liquid injection works, it would be applicable to smaller, lighter engines with adequate power when needed, which would also be easier on the start-stop systems.

You mean the ones with direct injection? Some conversion kit manufacturers claim a liquid-phase LPG injection can be done through the stock fuel rails on engines fitted with direct injection.

[octinum]

Originally Posted by cRiPpLe_rOoStEr

Citroën is often praised for its handling, even though it's not the same as it used to be.

I also have a taste for some rare cars, but I consider practicality a priority.

If wifey accepted the Xantia, C5 would be extraurban-only. Sometimes I consider replacing the Xantia with a small city car, but I don't find them safe enough for Turkey. Nightmares of an idiot rear ending the car; I'd prefer some boot between the rear bumper and the child seat at the back.

Originally Posted by cRiPpLe_rOoStEr

AFAIK the 1st generation is still made in Argentina, where it seems to have effectively fulfilled the role as a replacement for the 2CV

Makes sense! Never driven a deux chevaux myself. Would give much love to a red one I guess.

Originally Posted by cRiPpLe_rOoStEr

Sure a controlled charge is less likely to lead into trouble, and so is the sequential injection. Most of the times I see frozen intake manifolds, it's on vehicles fitted with a non-electronic fumigation setup, and those are so bad they lead to manifold freezing even with CNG (which is more common as a motor fuel in my country).

You mean the ones with direct injection? Some conversion kit manufacturers claim a liquid-phase LPG injection can be done through the stock fuel rails on engines fitted with direct injection.

I understand now, you're right, I'm talking about converting a proper sequential injection system.

Not necessarily the direct injection ones, but the main thing with liquid LPG injection was those as you say; gasoline normally cools down the combustion chamber, gaseous LPG does not.

Small turbo engines rely on very rich mixtures under high load conditions to prevent preignition. When you switch to LPG in gaseous form, you remove cooling effect of gasoline vaporizing, whether direct or port injected. Hot spots and high exhaust temperatures follow, even if you somehow avoid preignition (with high octane of LPG mix).

LPG as vapor also replaces some of the air in the intake charge. So less oxygen to burn an already low energy content fuel.

What I'm thinking is to use the cooling effect of LPG as it vaporizes in the intake manifold. This should also be a simpler system without the need for the evaporator. As you said, some manufacturers just use the original gasoline injectors for two purposes, so a common, cheap injector from a gasoline car should work.

I wouldn't want to use the cars own injectors though; this is not a mass production project. Should be easily reversible, or at least I should be able to drive the car home with own petrol form in case I screw up.