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octinum 02-28-2021 04:13 AM

Longtime stalker, now hoping to have some time!
 
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. :D 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 02-28-2021 11:19 AM

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 02-28-2021 02:16 PM

Have you considered just not idling?

octinum 02-28-2021 06:14 PM

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 02-28-2021 09:08 PM

Quote:

Originally Posted by octinum (Post 643358)
Same goes for my wife, who drives an abomination in terms of fuel economy.

What does she drive?


Quote:

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.


Quote:

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 03-01-2021 04:55 AM

Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 643386)
What does she drive?

Another Citroen, 2005 C5 3.0 v6. :D 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.

Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 643386)
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. :D It can be a country-specific thing, but X1 (Series 1) Xantias had this engine, and also a turbocharged version called "Turbo Constant Torque".

Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 643386)

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 03-02-2021 12:15 AM

Quote:

Originally Posted by octinum (Post 643403)
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.


Quote:

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/CitroŽn 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.


Quote:

I don't think Citroen themselves remember all the engine options they sold with Xantia. :D 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.


Quote:

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 03-02-2021 05:15 PM

Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 643435)
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/CitroŽn 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.
Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 643435)
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. :D

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. :D

cRiPpLe_rOoStEr 03-03-2021 06:57 PM

Quote:

Originally Posted by octinum (Post 643466)
Dynamic qualities of these Citroens are precisely the reason I bought these cars.

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


Quote:

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.


Quote:

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 :D


Quote:

Oh, I remember people fitting kitchen type LPG tanks in the boot here. :D
It used to be more common here in Brazil too, even though nowadays it's mostly done in small towns without a CNG supply.


Quote:

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).


Quote:

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 03-04-2021 02:26 AM

Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 643533)
CitroŽn 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.
Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 643533)
AFAIK the 1st generation is still made in Argentina, where it seems to have effectively fulfilled the role as a replacement for the 2CV :D

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

Originally Posted by cRiPpLe_rOoStEr (Post 643533)
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. :D

cRiPpLe_rOoStEr 03-04-2021 03:13 PM

Quote:

Originally Posted by octinum (Post 643556)
I'd prefer some boot between the rear bumper and the child seat at the back.

No wonder some models available only as a hatchback in Western Europe often had a sedan bodystyle for markets such as Turkey.


Quote:

Never driven a deux chevaux myself.
Neither did I.


Quote:

Small turbo engines rely on very rich mixtures under high load conditions to prevent preignition.
Direct injection became so prevalent on newer generation of turbocharged engines because it doesn't require such a very rich air-fuel ratio. Downside is an increase to NOx emissions, and even some particulate matter buildup which used to be previously seen as more troublesome to Diesel engines than to spark-ignited ones.


Quote:

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.
Either going through the evaporator or being allowed to vaporize naturally at the intake manifold, an amount of the charge air would always be replaced at a port-injection engine operating with LPG. With the cooling effect, there is a lower NOx emission, even though the AFR could still be leaner than with a vapour-phase injection.


Quote:

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 have only found mentions to the usage of stock injectors for direct-injection engines. Port-injection ones may still require supplemental injectors only for the LPG, just like the 5th-generation CNG conversion setups.

octinum 03-04-2021 04:46 PM

Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 643576)

Direct injection became so prevalent on newer generation of turbocharged engines because it doesn't require such a very rich air-fuel ratio. Downside is an increase to NOx emissions, and even some particulate matter buildup which used to be previously seen as more troublesome to Diesel engines than to spark-ignited ones.

Right, missed that point. Though that's limited as well, I remember reading that small VW engines with both turbochargers and direct injection consume more than larger NA engines with similar output. However, this comment might be for an older generation TFSI.

Alfa Romeo JTS engines suffered from some soot buildup; long time users say equally maintained Twin Sparks (port injected) "keep" their performance longer than JTS because of this.

Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 643576)
Either going through the evaporator or being allowed to vaporize naturally at the intake manifold, an amount of the charge air would always be replaced at a port-injection engine operating with LPG. With the cooling effect, there is a lower NOx emission, even though the AFR could still be leaner than with a vapour-phase injection.

You're on spot again. :) But fuel vaporized in the intake manifold would also help a denser charge, lowering charge temperature. The injectors could provide more fuel per cycle as well; as the vaporization would happen _after_ injection. I believe it would be beneficial in any case; better than vapor injection at least.

Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 643576)

I have only found mentions to the usage of stock injectors for direct-injection engines. Port-injection ones may still require supplemental injectors only for the LPG, just like the 5th-generation CNG conversion setups.

I haven't found any references to supplemental injectors too. I have a feeling that the manufacturers never bothered with port injected ones when the trend is toward direct injection, and the extra cost for liquid injection tech would be harder to justify for an already mature market of port injected vapor phase kits.

This is not a problem for me though. I already want to be able to switch to "stock" when required, so I'm not touching the gasoline hardware. :) I want to play with the sequential LPG kit on my car. If anything goes wrong (short of a fire that is :D ), I want to switch to the virgin fueling system from the factory, at least until I'm safely home. :D

octinum 03-04-2021 05:16 PM

OK now, thanks to the very welcome provocation from @cRiPpLe_rOoStEr, I think I now have enough posts accumulated for me to post links. :D

So let me tell you about my car, which (AFAIK) was never imported to the countries that I presume most of you live. It's a 1997 Xantia X1 (pre-facelift) VSX, hatchback. The same body shape as the following, but in dark blue:

https://www.citroenorigins.co.uk/en/cars/xantia

Not as aerodynamic as its bigger brother XM, but with a very aerodynamically dirty underbelly, I believe it has potential. :)

The highlight of this car is its suspension. There were 3 types of suspensions on Xantias, one was the regular hydropneumatic suspension, second was Hydractive II (my car), and third was the Activa, which still is the top car on the famous Moose Test.

Hydropneumatic Citroens have steel spheres filled with nitrogen. They don't have steel springs and conventional dampers. Both springing and damping occur in the spheres, nitrogen gas acting as the spring and holes in the sphere "neck" acting as damper elements. The green thing is an example:
https://en.wikipedia.org/wiki/Hydrop...bol_Xantia.jpg

Hydropneumatic Xantias have 5 or 6 spheres, depending on version. 4 of these spheres are responsible for ride, assigned to each wheel.

My Hydractive II Xantia has 8 spheres (yeah, I know, my car has balls. 8 of them :D ). In Hydractive II system, there are 3 spheres responsible for ride on each axle. On "normal" mode, the car is suspended on 6 spheres, 3 front and 3 rear. Spheres on each axle are interconnected hydraulically.

An ECU tracks various sensors, such as speed, steering wheel angle, steering wheel angle change rate, brake pressure etc. When a sudden change in direction, or a high speed curve is detected, the middle spheres are disconnected from the system. This also cuts the connection between right and left wheels. So each wheel is now suspended by its own sphere.

The spheres for each wheel, also called "corner spheres" are stiffer than those on regular hydropneumatics (in other words, normal soft ride is provided by the middle spheres and the hydraulic interconnections). This decreases body roll. I believe maximum roll angle is around 2.5 degrees in this mode.

So, does this help with fuel economy? It does when traveling downhill, or when you want a little more rapid progress. I had this mountain pass in the city I lived before; I would just let the car go downhill, my foot off the accelerator. Most other cars, including modern and upmarket ones, would brake on every curve. I, on the other hand, would get to keep momentum.

This also goes when you're in a hurry. Again, where most "hot" drivers would accelerate until the curve and brake hard, I would just hold an average speed, with minimal if any braking on curves, and still keep up with them.

The power loss for the hydraulic pump is negligible.

Suspension is height adjustable, though only one out of four positions is intended for normal driving. The lowest and the highest positions are maintenance modes, and the high mode is only for driving over obstacles slowly.

But the "normal" driving position can be lowered or raised by tinkering with the height correctors on each axle. This no doubt would compromise comfort, but I don't think it would risk any damage to the car when done sensibly.

cRiPpLe_rOoStEr 03-07-2021 01:12 AM

Quote:

Originally Posted by octinum (Post 643581)
I remember reading that small VW engines with both turbochargers and direct injection consume more than larger NA engines with similar output. However, this comment might be for an older generation TFSI.

They're supposed to be more fuel-efficient than a larger naturally-aspirated engine with port injection, but they're not as easy to service. No wonder in some countries Volkswagen only offers the 4-cyl naturally-aspirated 1.6L for models available elsewhere with the 1.0 and 1.4 TSI engines.


Quote:

Alfa Romeo JTS engines suffered from some soot buildup; long time users say equally maintained Twin Sparks (port injected) "keep" their performance longer than JTS because of this.
Oily vapors from the crankcase vent would stick to the manifold and then trap some soot from the EGR in an engine with direct injection. With port-injection on the other hand, not only the fuel vaporizes and burns cleaner, but the oily vapors dillute more effectively with the air/fuel mixture than it would happen with charge air only.


Quote:

fuel vaporized in the intake manifold would also help a denser charge, lowering charge temperature
It will depend on the expansion ratio of LPG while it vaporizes. So, even with a colder charge, it might not get so denser at all.


Quote:

The injectors could provide more fuel per cycle as well; as the vaporization would happen _after_ injection. I believe it would be beneficial in any case; better than vapor injection at least.
Could absorb the same amount of heat from the ambient air with a fewer amount of fuel, which would be good for fuel-economy without too much harm to performance.


Quote:

I haven't found any references to supplemental injectors too. I have a feeling that the manufacturers never bothered with port injected ones when the trend is toward direct injection, and the extra cost for liquid injection tech would be harder to justify for an already mature market of port injected vapor phase kits.
When I refer to supplemental, it's what your car has. The injectors dedicated to operate with LPG are supplemental to the original fuel system fitted to the engine. And sure the trend toward direct injection may seem to not justify a switch from vapour-phase to liquid-phase on port-injection setups, but it's also worth to notice how pointless are some port-injection CNG adaptations on vehicles originally fitted with direct injection, which still require an amount of the original liquid fuel to be used in order to prevent damages to the stock injectors which are directly exposed to the flame spread.

freebeard 03-07-2021 03:44 PM

I'm just stumbling into the conversation, but can't the injectors be direct, in the port or in the throttle body?

IIRC some race cars had the injectors above a throttle body for each cylinder, with almost no intake runners. [citation needed]

cRiPpLe_rOoStEr 03-08-2021 01:00 AM

Quote:

Originally Posted by freebeard (Post 643719)
I'm just stumbling into the conversation, but can't the injectors be direct, in the port or in the throttle body?

Unless it resorted to individual throttle bodies, which BTW might be as much of a PITA as multiple carburettors to deal with, it's not worth to use throttle-body injection with LPG in that car. On a sidenote, when GM started certifying CNG conversions in Brazil, it already resorted to port injection for the gaseous fuel system even though the stock fuel injection was a TBI.

octinum 03-10-2021 01:25 AM

Quote:

Originally Posted by freebeard (Post 643719)
I'm just stumbling into the conversation, but can't the injectors be direct, in the port or in the throttle body?

IIRC some race cars had the injectors above a throttle body for each cylinder, with almost no intake runners. [citation needed]

For multi-point injection like this particular car, intake runners are the preferred location. The LPG injectors are mounted on holes, drilled on the runners before the petrol injectors (i.e. closer to the plenum), as close as possible to them to minimize injection timing issues. The LPG controller ECU uses the vehicle's ECU injector signals as a template.

Single point injection ones used to use throttle body I think.

octinum 03-10-2021 02:50 AM

I somehow omitted to click "Submit Reply" so typing again. :)

Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 643694)
They're supposed to be more fuel-efficient than a larger naturally-aspirated engine with port injection, but they're not as easy to service. No wonder in some countries Volkswagen only offers the 4-cyl naturally-aspirated 1.6L for models available elsewhere with the 1.0 and 1.4 TSI engines.

I must have been distracted, of course you're right, they are much more fuel efficient for city driving and low load conditions. I meant, they would inject more fuel under than a larger engine would under load. Consider a 1.4 TSI, producing roughly the same power of 150hp with a 2 liter NA. When under load and producing same power, the TSI would inject a little more fuel just to prevent preignition.

Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 643694)
It will depend on the expansion ratio of LPG while it vaporizes. So, even with a colder charge, it might not get so denser at all.

Could absorb the same amount of heat from the ambient air with a fewer amount of fuel, which would be good for fuel-economy without too much harm to performance.

Now I have to refer to my books from 15 years back in the university. :D The effect would mostly depend on heat of evaporation of LPG. I think stoichiometric ratio for LPG was around 16:1. This could lead us to an equation which we might solve for a known amount of air, making a lot of assumptions of course. :D

Quote:

Originally Posted by cRiPpLe_rOoStEr (Post 643694)

When I refer to supplemental, it's what your car has. The injectors dedicated to operate with LPG are supplemental to the original fuel system fitted to the engine. And sure the trend toward direct injection may seem to not justify a switch from vapour-phase to liquid-phase on port-injection setups, but it's also worth to notice how pointless are some port-injection CNG adaptations on vehicles originally fitted with direct injection, which still require an amount of the original liquid fuel to be used in order to prevent damages to the stock injectors which are directly exposed to the flame spread.

I also meant that, but apparently omitted in my distraction. :) What is unknown (to me, and at the moment at least) is the extra injectors' ability to supply liquid fuel, in terms of both the amount of fuel they can supply and their reaction to a quickly evaporating fuel.

I don't know how they apply the liquid LPG injection with stock petrol injectors. It seems like a trial and error thing, which makes sense as all the liquid LPG aftermarket kits I know of are for specific models of cars.

If so, the way forward is:
- Find out if the extra injectors for LPG can use liquid LPG
- Set up the mechanism for adjusting fuel amount on the fly, and monitoring the AFR (invest in a wideband AFR sensor?)
- Start low, then find a ballpark figure for injector duty cycle under a generalized condition. Without knowing how much fuel our injectors can provide under a set pressure value, this could be the best we can do
- Continue optimizing. If I can, that is. :D Will require rpm, engine load, and possibly more parameters.

cRiPpLe_rOoStEr 03-11-2021 01:19 AM

Quote:

Originally Posted by octinum (Post 643892)
When under load and producing same power, the TSI would inject a little more fuel just to prevent preignition.

It might be more related to NOx mitigation, at the expense of the particulate matter emissions which now require them to resort to a particulate filter just like Diesels have been done for a while. Direct injection already mitigates preignition quite effectively even with a leaner AFR and higher compression ratio.


Quote:

What is unknown (to me, and at the moment at least) is the extra injectors' ability to supply liquid fuel, in terms of both the amount of fuel they can supply and their reaction to a quickly evaporating fuel.
Sure it will depend on the extra injectors being designed specifically for LPG.


Quote:

I don't know how they apply the liquid LPG injection with stock petrol injectors. It seems like a trial and error thing, which makes sense as all the liquid LPG aftermarket kits I know of are for specific models of cars.
Notice the liquid-phase injection through the stock injectors only applies to engines fitted with direct injection.

cRiPpLe_rOoStEr 03-12-2021 01:21 AM

Check this: https://gazeo.com/automotive/technol...icle,9297.html


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