PORT vs DIRECT vs DUAL INJECTION - a DETAILED comparison -EVERYTHING you need to know in 1 video

This is a detailed comparison of three different kinds of fuel injection. Port injection (or PFI), direct fuel injection (GDI or gasoline direct injection) and dual injection, which is a combination of port and direct fuel injection. We will see how each setup works, how they differ from each other and we will of course examine the benefits and drawbacks of each setup, so, let's get started.
So both port and direct injection essentially do the same thing - they inject fuel into the engine to create a combustible air/fuel mixture which when combusted creates combustion pressures which drives the piston downward causing the crankshaft to spin which then ultimately turns the wheels of the car.
As the name implies, port injection, injects fuel into the intake port of the engine, before the intake valve, whereas direct injection injects fuel directly into the combustion chamber, after the intake valves. This means that in the case of port injection you will usually find the fuel injectors somewhere on the intake manifold while in the case of direct injection the injectors will often be either on the valve cover or right underneath the intake manifold bolted to the cylinder head.
Both systems consist of essentially the same parts: a fuel tank, a fuel pump, fuel lines and injectors. However because direct injection injects into the combustion chamber it has to inject against the compression pressures of the engine which means that it must operate at much higher fuel pressures. Direct fuel injection often operates at pressures above 2000 psi or 140 bar. Of course to achieve such high pressures the direct fuel injection system must be more complex. It contains both a low pressure in-tank fuel pump and a high pressure cam-shaft driven fuel pump. The injectors themselves are also much more advanced and expensive because they must be capable of opening and closing extremely quickly against very high fuel pressure. They also need to be capable of surviving the harsh conditions created by combustion since their tips are exposed to it.
Direct injection has the advantage of enabling higher compression ratios because it supplies fresh cool fuel directly into the chamber and it injects it later which means that it spends less time inside the engine which means that it picks up less heat than it would in the case of 'port injection. Less heat means less chances of knock which gives direct injection engines more room to increase the compression ratio which can improve both performance and efficiency.
Another reason direct injection can improve performance and reduce emissions and fuel consumption is its location. Because the injector is inside the chamber it means that the amount of fuel injected is the same as the amount of fuel that gets into its chamber. Port fuel injection injects outside the chamber which means that the amount of fuel released isn't necessarily the amount of fuel that ends up in the chamber. Some of it may stick onto the walls of the intake, some may not make it into the chamber before the valve closes. This reduces injection accuracy and control which can negatively impact emissions and efficiency.
But port injection has the benefit of having the intake valves constantly exposed to fuel, a great solvent. Direct fuel injection never injects onto the back of the valves which over time leads to accumulation of carbon deposits and other gunk from the pcv system. This reduces performance and leads to rough running. Results of prevention methods such as oil catch cans and fuel system additives or valve cleaners are mixed and the need to eventually mechanically clean the valves is inevitable. This of course leads to increased maintenance costs for direct injection engines.
Another potential issue that can occur in direct injection engines is LSPI or low speed pre-ignition. This occurs at low rpm and high load (wide open throttle situations). At low rpm piston speeds are low which leads to poor fuel vaporization in direct injection engines. At the same time the high load means that the ECU instructs the injectors to inject more fuel into the cylinder. The other factor that needs to happen is a particle from the back of the valves or an oil droplet that makes it into the chamber and mixes with the poorly vaporized fuel. The mixture then gets exposed to the very high compression inside gdi engines and boom pre-ignition happens, often leading to catastrophic damage if allowed to persist.
A special thank you to my patrons:
Daniel
Daniel Morgan
Pepe
Brian Alvarez
Jack H
Dave Westwood
Joe C
Zwoa Meda Beda
#d4a #gdi #fuelinjection
00:00 Injection location
02:06 Injecting against compression
04:35 Timing
06:02 Compression ratio
07:48 Knock
10:13 Fuel injected vs Fuel combusted
11:09 Vaporization
13:09 Enough fuel for high rpms?
15:18 Intake valve deposits
17:22 LSPI
19:19 Stack the benefits loose the drawbacks

[@d4a]

Support the channel: driving-4-answers-shop.fourthwall.com/

[@fuckyoutubengoogle2]

6:30 Not a correct explanation of the efficiency gains from higher compression ratio. The Wikipedia articles for the Otto and Diesel cycles explain all this pretty thoroughly though it's too much physics for a general audience. The Wikipedia article for the Atkinson cycle doesn't give a detailed explanation. I still think driving 4 answers is a good channel. I enjoy watching the vids and I learn a lot from them.

[@importanttingwei7747]

get Toyota to design the direct injection engine they're the best company in the world

[@tigerpjm]

@Trevor Brannon No. Watch the video.

[@tigerpjm]

@@fuckyoutubengoogle2 @thph No, he's correct. The higher the compression ratio, the more force acts upon the piston. Lower compression ratios mean more energy is lost into the fuel/air mixture as gasses are compressible whereas solids (the piston) are not.

[@LikaPyramid]

how does this work with diesel engines? do diesel engines also have direct/ indirect and dual injection systems or are they completely different? and if they are the same do direct injection systems also have the same negative effects on the intake valves?

[@georgelincolnrockwell14]

Man every one of your videos gets cleaner and more polished, I've really enjoyed watching the channel grow over time. You present very technical subjects in an interesting way. Thank you for sharing!

[@billert_bone5663]

One of the best in this

[@johnkodera9926]

+1 on this. Keep it up!!

[@krimsono4746]

Easy to follow aswell, while still covering a topic in great detail!

[@abrahamgnanaraj4263]

All are very informative one. Great job.

[@Katiethekitten]

My thoughts exactly

[@MarkSmith-js2pu]

This is the best presentation on ANY subject I’ve heard in all my 70 years. Stunning.

[@overstack7128]

Honestly, best car and ICE channel out there! Highly detailed and accurate yet understandable Small detail: when a gas is compressed, it doesn't pick up heat because of friction between air molecules when they bump in each other, the bumping itself IS the heat !

[@d4a]

Thank you. Yeah, I know the explantion isn't really scientifically accurate but I keep using the friction thing to help people visualise it. Can be a bit confusing without it. But you're right, I should still change the explanation and figure out a better way to say it.

[@AtaruMor0boshi]

That's right. During the (nearly adiabatic) compression phase, you put work (== energy) into the charge, so you get an increase in its temperature.

[@ThisRandomUsername]

@@d4a Please pin OverStack's comment. These bots are plagiarizing the top comment and using their 'verified' tick to get upvotes. I don't know what they're on about, but something fishy is going on. Otherwise, great video. I didn't know of the improvement in heat of the air-fuel mix in DI engines. It makes sense now.

[@Larslegos]

@@d4a The vibration of the air itself is heat. A lack of vibrating molecules results in no heat, which is why space is very very cold. There's hardly any particles in the vacuum of space.

[@user-jq4mu8vk3q]

Couldn't agree more. Definitely the best video out here explaining Port and Direct Injection Techniques.

[@AtaruMor0boshi]

You left it implicit that the fuel passing by the inlet port will vaporize and take away substantial amounts of heat from the valve, its seat, the piston top and marginally from the whole combustion chamber. That's also the reason why sometimes the ECU will spray (and waste) MORE fuel than can actually be burnt, especially at high RPM and loads: a rich mixture will directly cool down those parts exposed to the combustion heat, out of the reach of closed circuit cooling system. Conversely, direct injection allows for a leaner charge (lower fuel consumption) and hotter combustion, without incurring in pre-ignition or knock, but this has to be carefully weighted against the thermal limits of the engine components. I find the content on your channel is very well made, complete and pleasing to watch. Cheers from Italy and God bless.

[@mb7050]

e85 for the win when turbocharged

[@jasonmajere2165]

Leaner burn is more NOx emissions, not sure what Mazda does with the spcci engine though, probably a special cat. Rich burning to cool down the cylinder is common when the load is above 10%(guess). F150 EcoBoost was so heavily criticized as mpg was terrible pulling anything. And another Mazda skyactiv engines to increase mpg in real-world driving tried to raise the point where it needed to inject more fuel, but that doesn't reflect in EPA numbers. Porsche oversized turbo and than expand the intake charge before going into the cylinder is interesting also.

[@jasonmajere2165]

@@mb7050 e85 has its own problems, the cylinder wash down effect is worse, and can cause problems with the intake valves.

[@AtaruMor0boshi]

@@jasonmajere2165 NOx is taken care of downstream with special catalytic converters, exaust cooling and EGR. And yes, it's a big problem, as it will "clog" converters and require their "regeneration" (wasting fuel) every 100s/1000s km...

[@electric7487]

@@AtaruMor0boshi That's particulate matter you're talking about.

[@bikergirl8750]

As a graduate student in a piston engine class, I thank you greatly for this video. It made so many things my professor has been talking about clear. ❤

[@calevel]

So far you sir are the Best gear head speaker person I’ve ever heard explaining how things work in such a nit and clear way. Thumbs way up!!

[@kevinb5717]

I've said this before, your channel and EE are the ones I watch for detailed information on vehicles. I learn so much from ya. Thank you so much for spending your time teaching us.

[@emrah1313]

The most detailed and easy to understand video I have watched so far. Simultaneous narration with visuals is great. Instructive as a lesson. Thank you

[@hardstyleboy]

So much in-depth knowledge on your channel! Best car related channel on KZbin imho! Keep up the good work!

[@dsilvermane_]

For someone whose first language obviously isn't English your videos are absolutely brilliant. Each and every one is an invaluable learning experience, thank you!

[@professorscrim5303]

I cannot describe in words, how grateful I am for your channel.

[@ilgarkarimov7110]

never ever saw anything on the same level not in english not in russian language over youtube. Not even red such immersive and light to digest info in net. Watching your videos sometimes with pausing, but all info is getting into the brain in a straightforward manner. No twist and turns in logic. Very Clean!

[@quintoncarter26]

These are the best videos on KZbin explaining automotive theory

[@venugopalnair7597]

Amazing video! Being from a non-Engineering background I could still understand the whole concept to a great extent by watching this video. Fantastic job man - keep it up.

[@johnathankozloff212]

Thanks for putting that together, you just answered all my questions in 20 minutes that I've been trying to understand for the last two days!

[@MAYURGUPTA9]

This is perhaps one of best channels for those who wants to understand concepts of IC engine in simple language

[@carlyleroberts3995]

I have to rate this as one of the greatest most well explained videos on KZbin ever. Excellent presentation. This video made me subscribe.

[@rishijai]

I went back to the simple port injection engine on the Toyota. No direct or dual injection for me. I like reliability and durability.

[@MurCurieux]

Harder and harder every year. Every manufacturer is making over complicated vehicles these days. The Corolla is the only vehicle that keeps it simple and it is still overly complicated.

[@lifted_above]

@@MurCurieux You can thank the globalist billionaire bankers and their sub-system regulatory cabals for making things stupidly expensive and complex under the pretense of earth-harm. They create a theoretical thesis way back in the early 1900's, pump the information streams with the theory for 120 years, and build their legal and regulatory systems to control the dickens out of manufacturing, engineering, and scientists while the public never cry out because the public are fed the same unproven narrative. Oh and they bought out the legal system too. It's like an international version of Al Capone's Chicago.

[@jimgoff1170]

@@lifted_above lucky for you, you haven’t fallen for any unproven narratives!

[@lifted_above]

@@jimgoff1170 Luck is superstition. I'm not a fan. I'd rather research and use critical thinking, observation, get to know history, and not lean on all the self-proclaimed experts, especially highly paid Marxist educators with a political agenda.

[@jimgoff1170]

@@lifted_above now is as good a time as any to start

[@CountryFarmBoyUSA]

Another great and well explained video! I remember the old style Bosch CIS fuel injection from my 1981 VW Scirocco S. It continuously injected fuel into the intake. It didn’t need a mass air flow sensor, just a metal plate that raised when the airflow increased which then allowed the metering valve to open and allow more fuel. It was basically a teetotaler and very ingenious!

[@d4a]

That's an airflow meter, I had one of those too. Even made a video that covers them: kzbin.info/www/bejne/mKnHqK2ip7eWbrc

[@aerialphotoeutin844]

@@d4a I think He is talking about bosch k-jettronic/ke-jettronic though 🤔 basically a mechanical fuel injection system

[@d4a]

@@aerialphotoeutin844 Oh you're right...I read metal plate and teetotaler and immediately thought of the flap on the air flow meter. K-jetronic has the round fuel distributor thing with a bunch of nozzles and the flap is in the intake if I remember correctly.

[@andycanfixit]

@@d4a yep, they work well when everything is good, but they are a pain when anything is a bit out of whack. The airbox typically has the fuel distributor on top with it's plate with steel braided lines going from it to the CIS injectors and you have a CIS injection fuel pump supplying the fuel to them at about 5 bar, 70-75 psi. Problems with the cold start injector or warm up regulator can make it really hard to idle when cold and they are really prone to vacuum leaks around the injector seals. Interesting concept for it's time but pure evil to work on today. :) The turbo versions were even more difficult.

[@GregoryVeizades]

@@andycanfixit the fuel injection lines are solid steel. Not steel braided.

[@tomharrison6762]

Excellent explanation, which has helped me tremendously in my business as a fuel Injector technician that cleans and flow tests both port and DI Injectors on a daily basis including piezo technology certification.

[@vr6gls]

I just installed MPI on my 2016 Golf GTI ( Not a factory feature on U.S. models) and this was a extremely informative video. It really helps me to understand the mechanics of the system, as well as address any future issues that may arise. Thank you for making this! 👍🏾🙏🏾

[@automotive_passion]

Very well made description of how the different systems work. Your explaining is very on point as usual, and easy to understand. Great work.

[@abdelatifmariche8771]

The clearest possible explanation in every single video 🤝. Good job

[@warriormonx]

Fantastic video; clear, comprehensive, well explained guide for a broad audience. Production quality and editing also outstanding!

[@JROC734]

Good video! Duel injection FTW! The ability to run a high CR and high RPM's without the need for race fuel is nice as is running a high CR and big boost without needing race fuel as well. Help with tuning giving bigger games as you can get more liberal with the tune seeing as you get the advantages of DI and PI, but each one offsets the others disadvantages. Not worrying about carbon buildup on the intake valves is a huge plus for people wanting an efficient and reliable daily drive as well.

[@JohnChuprun]

I have binge watched many of you videos - they are all excellent! Thank you for making these, you speak really well and know you stuff.

[@bradleygibson6887]

Man, you this channel is amazing bro. My brother in law and I are learning on our audi a4s 1.8ts and are continually coming back to your channel for information and resources. Keep up the amazing work!

[@dimikraa1135]

This is simply the best car channel on YT. Keep on making these great videos! This is always a Highlight on my Weekend. Greetings from Deutschland 😄

[@allprintcenter]

Summarizing all these information in twenty minutes that's a big challenge, great job.

[@pushhrodd01]

hey man good job on the video! you’re the best automotive content creator ever! thank you for your free knowledge!!

[@johnmacmillan3941]

I already know this stuff, but I must say it was hard back then when I learned about this stuff to find someone who explained it so well. Rly good channel for someone who is interested how stuff works in car engine

[@rushthezeppelin]

Port injection master race! All hail the clean intake ports and valves!

[@dmitrykhramov1832]

Best automotive, internal combustion engine channel ( if you want to learn and know stuff ) out there ! 👌👍💪

[@zweispurmopped]

That was a very thorough and well comprehensible explanation! Really, really good! 👍💪

[@SupraSav]

One factor you didn't mention, which I was actually curious to hear about; the increase in fuel temps from the higher pressures required by DI. N54 335i owner - thoroughly enjoyed this video.

[@pauldmann1166]

Another very informative, interesting and enjoyable video. Your channel is the “go to” for an engine enthusiast such as myself. Keep up the amazing work 🙏🤘🕺🏾

[@daved3494]

Wow! I never knew there was so much to learn! Really well explained and the detail you go into is amazing. Thank you.

[@steveflor9942]

Great explaination of the difference between knock and pre-ignition. Outstanding video. Thanks

[@whykenneth]

This is one of the crazy detail videos that i ever come across. Well done sir!

[@lemzywonder]

no one does it better than this dude, he is truly gifted!

[@bamasciencekid]

After an argument with a friend, i decided to learn more about engines. This video was a great break down that i was able to follow!

[@lenkrenzler6560]

You have the most awesome in depth explanations I've ever seen. Great work!

[@just.for.the.downshifts]

Extremely clearly explained and easy to understand for a layman. Thank you.

[@p6102zrfxe]

Exactly the video that I looked to watch. Perfectly on time. Thank you!!!

[@carfo]

not an engineer or mechanic but this video was so easy to follow and understand. thank you!

[@charleslowe522]

Great explanation. The 2019 F150 has the dual injection setup. I the only drawback that I had known of with direct injection was the back of the valves not getting cleaned. Now I know the other drawbacks and when the port injectors are in use. One of these days if you get time maybe you could do a video on iconic cars with junk engine blocks. For example, the Grand National and the 5.0 Mustang in the 80's and early 90's.

[@802Garage]

Fantastic as always. I am so happy to see you succeed with each video. Thanks for teaching people real useful info. :)

[@micsub]

GReat video. Very informative as usual, explained in a simple way with detailed illustrations. A lot of work behind each video, thanks for sharing !

[@airmax90_king93]

This guy man.....you're knowledge is unmatched.

[@chalkster4723]

Fantastic video, even from a professional mechanics perspective. Great description & explanation.

[@danielrosllorens7049]

I don't speak english but listening to you it's easy to understand every second of the video

[@henkbaksteen8903]

Wooow great video again! Thank you so mutch, i really enjoyed watching it. Lots detail and i love you also talking about fuel pressures. Keep on the good work!

[@cowx73pw]

I'm putting a snow performance methanol injection on my GR supra and this Answered a few questions I had amazing video keep it up dude bravo 👏

[@zsz868]

You'are an European, vehicle engineering equivalent of an Indian guy who explains the most complex subjects of the computer programming issues in a very understandable way. Keep the great work!

[@nimam7986]

Thank you for the explanation. You are doing a great job. I know how much effort does it take to make such videos.

[@thomajaminwashadamilton]

That was top notch. Excellent substance and exceptional multimedia delivery.

[@jakebasa1517]

There was a discussion regarding this same exact topic near our place mostly engineers are in attendance which I attended out of accident. Topic last 3hrs never understood anything. You only took 21:46 mins and I understood. HELL YEAH!

[@supergiantbubbles]

This is a superb explanation of the differences of injection schemes.

[@nmc5h8MIZ]

Very nice and succinct comparison, that hits the main important points. Well done.

[@blanchbacker]

Your videos are really detailed and excellent, your speaking voice is very soothing as well 🙏🏼

[@samcoote9653]

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[@GLF-Video]

You are producing wonderful videos. Very informative. Thanks!

[@ailtonfogaca9377]

Trabalho a 32 anos com mecânica e nunca aprendi tanto antes de assistir seus vídeos. Muito obrigado.

[@Theferg1]

@ailtonfogaca9377 Hey bro not trying to be rude but if you have worked with mechanics for 32 years, and you learned more off of this video than in 32 years bro, you might want to find some new mechanics to work with because you should be just as educated as they are by now being 32 years deep into a trade!!

[@shubhabrata1979]

It's a very detailed video ..thanks 👍

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I went from a car nut who knows nothing about engine parts to having a comprehensive understanding of the entire operational cycle of an engine, just from this video alone! Thank you!

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Such an underrated channel. Amazing work, every video is absolutely didactic.

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Bravo. Extremely well done. Keep it up.... The internet needs more professional, well researched, clearly articulated, orginized facts and less flash.

[@NiiHelium]

Thank you for great educational content. Now I'm really interested to hear about pre-chamber ignition from you.

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Super clear and understandable. Thank you for helping me understand my car better.

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One of dopest channels I have ever seen ....bro.....keep the good work up....so informative and the visuals so movie like....wow!!!!

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the best channel with this type of content for sure

[@r1madbrit]

Superb teaching with the best graphics to visualize and understand. Your analogies using force on a mobile phone were excellent to explain rocking motion. I thoroughly enjoy these videos.

[@WouterB76]

Twenty-one minutes very well spend, excellent video sir!

[@tigerpjm]

You're a legend! Dual injection in my AMG A45S! I knew all these concepts in a sort of ad-hoc way, but to have them all tied together is, as usual, brilliant. Another great vid!

[@youfube-]

Even Corollas have them.

[@tigerpjm]

@@youfube- Yeah, I watched the video.

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Top notch content and extremely detailed and clear visuals/explanation

[@Thommy_1983]

Your videos should have been presented in technical schools, if only my teachers were so detailed in explaining, awsome video

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Your videos are fantastic. I've never seen such clear and easily understandable explanations of the subjects you cover.

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Thank you, man. That was a great video. 👍 I was hesitant to buy a car because of my lack of knowledge on this matter. You helped me out incredibly I just subscribed to your channel. I'm looking forward to some more great videos.

[@V8anyday]

Loved the video. You do an awesome job explaining everything.

[@gerardmontgomery280]

7:45 this is a eureka moment for me. An amazing video as always.

[@TBD3.0]

Outstanding this video deserves an award and should be included in colleges that offer these courses, should be mandatory to watch this video.

[@clayp.e30_v86]

Fantastic presentation thank you. This channel is a great source of information 👏

[@speedy_pit_stop]

Thank you for this clear explanation of dual injection.

[@dyggiprahl9881]

Again, brilliant video to explain very complex systems in layman's terms... well done again driving4answers dude 👍👍

[@kavyapathirana2839]

hey, I'm from Sri Lanka. I have less English knowledge, but I also can understand what your explaining. Thank you very much for your content.

[@Scoots1994]

Been following for a while now and I enjoy your videos but usually I don't really learn anything new (engineer and car nut for a long time). This one though I didn't know and it was excellent. Really enjoyed it. Very clearly presented and explained.

[@Eduardo_Espinoza]

Asking where did you learn all of this without driving4answers's super high IQ videos?

[@Scoots1994]

@@Eduardo_Espinoza life

[@Eduardo_Espinoza]

@@Scoots1994 definitely believe u.

[@Scoots1994]

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You sir are a bad-ass teacher. Thank you for making every single bit of this easy to understand.

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this guy is so nice explaining things.... awesom videos

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That was the best explanation I have ever heard

[@Roadblock1396]

Just wow. Thanks for this lesson. Now I understand how feul injection works.

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Absolutely love your channel and can’t wait for project underdog!

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Thank you for another great video. Very informative and well made.

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[@thanziramukosi9932]

this was a fantastic video!!! The concepts were clearly explained. Thank you

[@tiagosilva.b5]

hey amazing video as always, please do a video on why there are pistons with different shapes on the top and what they change 💪🏾💪🏾

[@koksionglee7978]

Great explanation on why direct injection engines typically runs to lower RPM range.

[@olspanner]

Great presentation as usual. FYI {and no doubt YOU are aware of this]. Carburetted engines also produced heaps of intake valve deposits. Particularly in my era, pre emission control engines.

[@f5fstop]

Good video of how it works. Not sure if most people care or even understand what a fuel injector is. But that DI on GM engines is causing big problems with valves, and yet, some manufactures, such as Hyundai on their newer engines are using DI and PI as noted in this video. Best of both worlds.

[@christianmcdonald5658]

Excellent video, great breakdown and wonderful visuals!!