Talk:Gasoline direct injection

carbon build up

Users of various forums talk of carbon build up due to direct injection. Here's an example article on the subject from Edmunds, written in 2011 Edmunds - Direct Injection Fouls Some Early Adopters. Is there solid research anywhere into this alleged drawback of direct injection? It's easy to find anecdotal evidence from individuals on forums, most of it "friend of a friend" but I'm having a hard time finding hard research. 75.158.93.71 (talk) 17:37, 10 June 2013 (UTC)

I added that most of the carbon buildup comes from blow-by past the piston rings (or the crankcase oil itself, if fossil based), not from air through the air intake filter. Products of combustion steadily leak past the piston rings into the crankcase. This pressure has to go somewhere so it's routed into the intake plenum. Some engines have separators to remove liquid component of this mixture but they might not work as designed under all situations. So a mist of fossil/synthetic oil and blowback carbon gradually cooks onto the hot intake valves and manifold. — Preceding unsigned comment added by 204.128.192.34 (talk) 02:30, 12 March 2016 (UTC)

Merge proposal with Stratified charge engine

Since no-one appears to have started a discussion on the proposed merger of Stratified charge engine into this article, I shall begin the discussion:

Oppose: The concepts may be related, but they are not identical. Two notable stratified charge systems, Honda's Compound Vortex Controlled Combustion (CVCC) from 1975 to 1983 and Piaggio's system as used in the Vespa ET2, use carburetors to vapourize the fuel. Sincerely, SamBlob (talk) 13:40, 27 May 2013 (UTC)

• Oppose It's nonsense to even suggest this. We might as well merge clutch and carburettor. Andy Dingley (talk) 17:26, 27 May 2013 (UTC)

Clarification needed

The merger proposal has been rejected but I think some clarification is needed concerning Gasoline direct injection, Stratified charge engine and Turbo fuel stratified injection. Are the following statements correct?

• a Gasoline direct injection engine may, or may not, use Stratified charge
• a Stratified charge engine may, or may not, use Gasoline direct injection
• a Turbo fuel stratified injection engine is a Stratified charge engine with a turbocharger

Comments please. Biscuittin (talk) 18:14, 9 May 2014 (UTC)

• delete all. All three articles are crap that convey nothing and are so badly written that an honest clean start would be an improvement. Stratified charge engine is particularly awful as it's hopelessly confused with the Diesel cycle.

BTW, TFSI is a stratified charge engine(sic) with a turbocharger and an Audi badge.

'Stratified charge' BTW has been in commercial use since the days of Prosper L'Orange. It was most noted around 1990, when there was considerable interest (and a lot of money was wasted on snake oil salesmen) in using stratified charge as a means of achieving a lean burn engine – at that time, a really lean burn engine. This never happened. We should distinguish though between "engines with some degree of stratification" (common and old tech for diesels, as a means of improving initial combustion and establishing the flame front), "lean burn engines of crazy optimism" (they never happened, and they certainly couldn't be done with the control systems of 25 years ago) and the sort of thing that is increasingly common over the next few years, where some rational degree of stratification is used to give advantages to the overall combustion (and so improve efficiency and emissions, more than just making the engine run more smoothly). I don't think WP is capable of explaining any of this though. Andy Dingley (talk) 19:51, 9 May 2014 (UTC)

Since you are the expert, perhaps you could re-write the articles. Biscuittin (talk) 22:16, 9 May 2014 (UTC)

I can't be arsed. Wikipedia is too broken to waste time on. Maybe too broken to fix at all. Andy Dingley (talk) 22:27, 9 May 2014 (UTC)

Why do you post here then? Biscuittin (talk) 09:32, 10 May 2014 (UTC)

Because it's quick and easy to post here. Rewriting stratified charge would take a few evenings at least, time I just don't have.

It fails the basic WP editing model: you can't write an article on stratified charge by just googling up a few sentences and pasting them in in order. Instead someone needs to understand the principles of what stratified charge could be used to achieve, to thoroughly understand topics like fuel injection and the Otto / Diesel cycles, to avoid the confusions that have already made it into this article, and then to construct a sensible narrative for the overall article. Fragments like "The Mercedes 300SL had gullwing doors" just aren't important in explaining such a narrative – and what's in here already about the 300SL's fuel injection is no better. TFSI shouldn't even be an article - it's an Audi label for their current state of the art. It should be part of an overall narrative on stratified charge, where it can fit into that narrative and add something to it. However it's easier to write, "I like Audis. A car mag used "Audi", "stratified charge" and "<buzzword>" on the same page. OMG!" in the traditional WP fashion. Andy Dingley (talk) 10:14, 10 May 2014 (UTC)

I have done some tidying up on Stratified charge engine and added a merge tag to Turbo fuel stratified injection. I agree that a lot more references are needed and I will see what I can find. Biscuittin (talk) 11:53, 10 May 2014 (UTC)

Stratified charge details

Hi Johannes Maximilian. Thanks for adding all the well-sourced info to this article, it is a good improvement.

I have some questions/comments about a few details please:

1. Regarding "which is why most car manufacturers have abandoned the stratified charge concept", could we have some examples of production engines which previously used stratified charge but now don't?
2. Is it also possible to get some examples of engines which use wall-guided, air-guided and spray-guided injection? It would be helpful to show whether there are trends over time for/against each method.
3. In the "Charge Modes" section, I believe that "Combined mode" is more of an operating strategy for stratified engines, rather than a separate mode. Therefore I would like to move the text from Combined Mode into Stratified Charge Mode (with wording tweaks so that it fits nicely)
4. The "Homogeneous charge mode" section states that a lambda of 1 is mostly used. Could you please supply quotes to support this? I think it should be explained which engines use a lambda of 1 (eg after a particular year or for some markets), given that lean A-F mixtures are common on indirect injection petrol engines at low loads.
5. If you have any statistics on current GDI usage, it would be great if "approximately 45% expected production for model year 2015" could be updated with something more recent (and less speculative!).

Thanks, 22:23, 8 November 2019 (UTC)

Hello 1292simon, thank you for your comments.

1. Car manufacturers often make different engines for different markets (for example: BMW offered the direct injected N53 engine in coutries with low sulphur fuel availability only, in markets with bad fuel quality, they put a completely different engine (manifold injected N52) in cars they sold at the time). I have recently talked to one of the engineers who developed the Mercedes-Benz M 256 engine, and he told me that it uses a homogeneous charge almost all the time, and that Daimler has pretty much abandoned the stratified charge concept. The engine runs on a leaner (but still homogeneous) mixture when it burns the soot in the particulate filter, but only on one cylinder at a time, and it is not "very" lean, rather $\lambda <1.2$, so it doesn't burn its valves. The predecessor, the M 276 series, used a stratified charge mode, but well, instead of making the M 276 into a homogenous mixture engine, they decided to develop an entirely new one. So I'd argue that it's hard to say whether or not engine manufacturers "update" their existing engines – some use different engines in the first place, some develop new ones, and then there are these manufacturers like Volkswagen who keep updating their existing engines over the course of several decades. And interestingly, there was a variant of the VW EA 111 engine (1.6 FSI, 81 kW) that came with a stratified charge mode from the factory, but after one of the inspections at VW, they updated the ECU to use a homogeneous mode instead. That was, because the engine was not running smoothly enough, and because it had very bad throttle response. Also, it needed 98 RON petrol in order to function properly, and many people just put in the wrong fuel... The engine code of this particular engine is "BAD". I wonder whether or not that is coincidence...
2. Some of the books that I have give some examples. The general trend is towards the spray-guided injection, because it offers the best engine efficiency.
3. I would not mind a combination of the "combined mode" and "stratified mode" sections. I have not done so to make it more clear that there are several different operating strategies.
4. In Richard van Basshuysen, Fred Schäfer (ed.): Handbuch Verbrennungsmotor. 8th edition, Springer, Wiesbaden 2017, ISBN 978-3-658-10901-1, Chapter 12, p. 647: „Bei den ersten Direkteinspritzsystemen wurde mittels Schichtung von Kraftstoff und Luft durch Einspritzung während der Kompressionsphase ein relativ mageres Gemisch eingestellt mit einer fetten Gemischwolke in der Nähe der Zündkerze, die eine sichere Entflammung gewährleistet. (...) Die Mehrzahl der heute in Serie befindlichen Direkteinspritzsysteme werden stöchiometrisch betrieben.“ "The first direct injection systems used fuel and air stratification by injecting the fuel into the compression stroke to obtain a relatively lean mixture with a rich cloud of mixture near the spark plug in order to achieve good ignition properties. (...) Nowadays, most series production direct injection systems use a stoichiometric mixture." A stoichiometric mixture means $\lambda \approx 1$, so I think it's safe to say that in the homogeneous mode, $\lambda =1$ is used. We don't need to be super precise since we want to explain how it works, and it is a completely different and difficult story why $\lambda =1$ doesn't exist in a real eninge (well it does, but hardly).
5. I agreee, the statistics should be updated. However, I don't have any at hand. In Austria, more than 50 % of all all passenger cars (does not include lorries and agricultural/industrial vehicles) have Diesel engines, in Hungary, virtually every car you see is either a Suzuki Swift MA or one of the former Eastern Bloc heroes (Trabant 601, Škoda 742, Dacia 1300, Жигули), and all of these have carburetted engines. But well, personal and subjective claims don't count in Wikipedia articles. Best regards, --Johannes (Talk) (Contribs) (Articles) 12:35, 9 November 2019 (UTC)

• Johannes Maximilian: Thanks for all the info, and for your patience in carefully explaining the topic. I'll make some changes to the article. Feel free to make changes or discuss further if there's any issues.

  Just to explain my edit regarding item #1, I am wary about making global statements based on a few German engines. If there are examples from U.S. or Asian manufacturers, I'm happy for the wording to be broader. On the other hand, I have moved the stratified charge paragraph from the intro, because it is less widespread than I'd previously thought. Hope this is ok.

  PS Thankfully I found some stats on GDI usage in Stratified charge, so that ticks #5 off off the list. Also, that is quite amusing about the naming of the Volkwagen BAD engine! Cheers, 1292simon (talk) 23:40, 9 November 2019 (UTC)

• So it turns out that VW's Fuel Stratified Engines are no longer actually stratified?! Wow, that is quite a revelation! Thanks for fixing up my mistake, sorry I assumed from the name that they still used a stratified charge mode. Cheers, 1292simon (talk) 08:31, 11 November 2019 (UTC)

Yes indeed, VW's Fuel Stratified Injected (FSI) engines are not stratified anymore (stratification has been mostly disabled in the ECU), and the Turbo Stratified Injected (TSI) and Turbo Fuel Stratified Injected (TFSI) engines have actually never been stratified in the first place. This is why their pistons have a differently shaped piston bowl (it doesn't have the swirl cavity). In fact, even some FSI engines have never been stratified! Starting from somewhat in between 2002 and 2004 (I don't know the exact year), VW (or well, Audi) disabled stratification from the factory, and replaced the pistons in their FSI engines that used to have the swirl cavitiy piston bowl, with pistons that have a more traditional otto cycle four stroke petrol engine piston bowl (Germanic languages fortunately come with unlimited length compund words). There is some interesting information on this in Richard van Basshuysen (ed.): Ottomotor mit Direkteinspritzung und Direkteinblasung: Ottokraftstoffe · Erdgas · Methan · Wasserstoff. 4th edition, Springer, Wiesbaden 2017, ISBN 978-3-658-12215-7. pp. 436. Apparently, only in the Audi A3 8P, the 1.6 and 2.0 litre FSI engines were actually stratified, but only until 2006/2007, when they were discontinued in favour of the newly introduced homogeneous 1.8 litre TFSI direct injected and the (then already existing) homogeneous 1.6 litre port injected engines. But anyways, over here, people rather bought the Pumpe-Düse engines... Best regards, --Johannes (Talk) (Contribs) (Articles) 15:47, 11 November 2019 (UTC)

• Thanks Johannes. It is fascinating how few of the "FSI" engines actually used a stratified charge mode! Cheers, 1292simon (talk) 07:56, 12 November 2019 (UTC)