Air/Fuel Ratio - How Does Being Rich/Lean Affect Your Engine?

Free Engine Tuning Lesson: bit.ly/KyleDrives_HPAcademy
In this video, we discuss air fuel ratio, why different fuels have different air/fuel ratios, what is meant by rich and lean, and what happens if you run your engine rich or lean. We also talk briefly about why you would target these conditions.
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[@lucywucyyy]

being rich means you can afford better parts and maintanance for your engine

[@KDD8]

being lean means you're a gym bro

[@Moparmaga-1]

Lol yep.

[@funnydubby6401]

@@TheRobertChannel so which gate vacuum line can get hot enough to melt lmfao, thats defiantly not how that works

[@funnydubby6401]

@@TheRobertChannel U said a vacuum line could melt lmfao, only way that would happen is if its too close to something too warm, u think hot air goes into a vacuum line?! XDDD

[@justinbryant237]

Nah, I think it's opposite : Fuel is EXPENSIVE, so if you run RICH, you spend MORE on FUEL, and have LESS MONEY to buy awesome NEW CAR PARTS...

[@stuartgilbert8308]

I think an interesting video would be explaining o2 sensors and what your exhaust can tell you about the health / efficiency of your engine.

[@JK-nd7ez]

the fuck he is literaly speaking about that all the time

[@AdonisMediaProductions]

Did you even watch the same video?

[@dennisrobinson8008]

Basically the O2's measure LAMBDA and what LAMBDA equates to depends upon the fuel type.

[@chiwong7943]

Diesel engines are not stoichiometric by design. stoichiometric simply means all the oxygen in the intake charge is consumed in a given combustion cycle. Diesel engines are lean burning in general and air/fuel ratio is varied to control the speed of the engine. Not all oxygen in each intake charge is consumed in a combustion cycle. This is the number one reason diesel engines tend to emit higher levels of NOx. The leftover oxygen in the cycle forms oxides of nitrogen which is AKA smog. This is mostly corrected by the SCR and urea (diesel exhaust fluid) injection. Diesel engines often also employ cooled EGR to reduce the oxygen level in the intake charge during part throttle conditions. Stoichiometric is only applicable to gasoline engines.

[@TaylrTownsnd]

+1

[@justarandomguy3969]

Nox is not technically smog, hydrocarbon is soot/smog

[@KYLEENGINEERS]

Hope you enjoy the video guys! Here's the link to the High Performance Academy Engine Courses, some are free, some are paid, but they are all great! bit.ly/KyleDrives_HPAcademy p.s. Seeing a few people comment on mass/volume, I would've thought it was pretty obvious, a 2.0L at 2000rpm, 50%VE sucks 1000L of air a minute, and clearly you don't burn 68L/min petrol under these conditions. But to clarify, AFR is by mass.

[@mas921]

KYLE.DRIVES can you please do a video on torsional rigidity? In japanese car shows i see the pro drivers they bring sometimes comment "oh this car feels rigid", and its not the that the shocks or springs are stiff! I googled the topic and got no where on how to "feel" rigidity and why is that a good thing for a sports car! Please make a video about this.

[@Kidzspeed]

Do a vid on the 812 superfast aero plz. thx

[@alienmechanic8696]

If you run a diesel to rich it will over heat 🔥

[@citypam7]

would love to see a video on what is the best path to take when designing aero for a race car for the grass roots racer. what will yeild the best resaults for the least cost, modifications ect. cheers

[@fanieschoeman2047]

Good information for those just starting to do some tinkering, or just curious. Thanks~!

[@reedstemen]

Thanks for the information!

[@mikef-gi2dg]

As a lifelong car nut.... this was very well done. I actually learned a few things. I have trouble explaining a/f ratios to others, I think I will use this video as a reference to that. I will definitely subscribe and look for more.

[@elonjun3327]

Thank you so much, as an aviation student, I could learn so much from your video related to the aircraft engine mixture system. Huge appreciate it!

[@Fabio-jm9jq]

We use E100 since 70’s in Brazil. Ethanol is a bit aggressive to fuel system but keep the engines clean of carbonization, and not dissolve oil film like gas. The cars before flex ( ethanol only ) work with 13:1+ CR and is more efficient.

[@dennisrobinson8008]

What Max CR have you seen with Ethanol?

[@Fabio-jm9jq]

@@dennisrobinson8008 With pistons around 80-85mm bore and alloy heads water cooled, around 13.5:1 with stock cams and 15:1 with agressive race cams.

[@ejune98]

also b/c brazil produces alot of ethanol

[@mikef-gi2dg]

Wow that sound like a hot rodders Paradice. Unfortunately, here an America, the perception that we (USA) are the only ones who can have and create cool things. I know this isn't true, and I have known this for a very, very long time. This (your comment) is an example of an environment where a car/engine nut could go crazy and make power, but it isn't available in the USA. We don't always have the cool stuff, we could have.

[@mikef-gi2dg]

@@Fabio-jm9jq 13.5 to 15.5 you could make some power with that for sure!

[@Zspeed]

Awesome video, thanks for sharing this information! Awesome presentation!!!

[@mikebaylis5350]

Great video.have you ever heard of a chevy 350 with hyperutictic pistons breaking the ring lands between compression rings? Only on one side, I mean all 4 on left side! No damage to cyl walls, valve, or top of pistons! Compression ratio was 10.9. Ran 93 octane.

[@850t5m]

I am interested in a video covering the suspension differences in a "street performance" car like say the Z06 and a GT car like say a Porsche GT CUP car. I'm interested to know where the break point is for something like too much total dampening, or what real world usable spring rates would look like. I have a hard time finding an example to compare the overall setup / experience.

[@jf4872]

Today's ethanol blends alter the standard 14:7 stoich. With a typical E10 fuel stoich is roughly 14:2-14:4 and with a carbed engine it generally requires going a bit richer on the jetting from stock jets. At a steady state 'cruise' one can run cooler at an AFR of 16-17 than you can with an AFR of 13-13:5 (same scenario) non turbo or boost application. But you will need vac advance or an EFI set up for the leaner burn at part throttle condition (no/light load).

[@CalaisRider]

Just what I needed. With Lambda I wasn't sure if low was high or low and visa versa. "Thanks for taking the time and posting, it was a "great education for me". I have a custom LS engine where the overkill cam and high compression causes me Knock grief and blow-by has been way high since new. Running so rich now its sort of embarrassing with the fumes and overlap especially with forged almost everything in it.

[@rcdesmond]

Thanks, I needed that.👍

[@CHIBA280CRV]

Fantastic informative video thanks . Can you make a video on a vehicle with a afr and o2 sensor and how they work , also what the reading should be.

[@dangoe9908]

Most people go for that high miles per gallon of fuel. Where would I find this on the curve?Would that effect engine working life?

[@nurseratchet8535]

Solid explanation, cheers!

[@Zspeed]

Great video, thanks for sharing this information!!!!👍

[@MauriFunez]

Thanks for the videos mate

[@fasnuf]

great explanation, thanks

[@arfreedom]

Thank you, very informative from a very wide range of fuels. Can you do one on oil tempt and oil pressure and what to look for when reading the gauges thanks

[@jeremymurphy7320]

6:50 All the Hemi guys went nuts and then said "wait...four valves? Sorcery!"

[@creedence1819]

aren't all the Hemis manufactured from 2003 onwards 4 valve engines?

[@zephirexinvestments3195]

Thank you Kyle!

[@llewvirtue861]

Eng knock can also be avoided by running a higher octane fuel, don't get confuse higher octane does not mean higher volatility. Octane rating is an anti knock rating, developed in the second word war by the SAE to ensure that every batch of fuel for the spitfires was the same quality

[@axelriet]

llew virtue Correct except it was before ww2. Harry Ricardo came up with octane rating and his research got published in the early 1930. He also came up with the Merlin so yes you are correct, but it was earlier.

[@BryanChance]

Excellent explanation. Thank you.

[@metaomicron72]

Can you do a video on older diesel engines? Before common rail systems. For example a Toyota BJ40 LandCruiser with a 3B diesel engine.

[@Kingswood7189]

Something interesting about diesel and gas is that the “combustion chamber” on the gas is in the cylinder head and on the diesel, its in the piston head. I dont know which is better for mpgs and/or power, i just thought that was neat.

[@MyLonewolf25]

Diesel is generally also regulated by timing of injection too

[@SoumilSahu]

That isn't really all that interesting actually. It just has to do with the fact that diesel engines operate at much higher compression ratios, and a straightforward way this is achieved is having a tiny clearance volume, ie; a cutout in the piston head.

[@farnarkleboy]

@@SoumilSahu I think it's interesting

[@Evs_Projects]

awesome stuff , good content, keep it up👍👍😀 need to get my car going too , the all in one option is a good one, boost, fuel and safety

[@walaypaglubadvlog6426]

Nice explanation

[@stanstudent9614]

Well explained

[@turbofan67]

Very well explained, good job.

[@steveforbin911]

Interesting video.. Maybe you might know the fuel to Kw produced per quantity of fuel.And how much kw of power you can get running lean and running longer with the fuel you save. Again the ability to get that spark to set off the mixture is very important. No bang and the engine must go around again and try to fire off. If it don't get a bang, it will eventually die off. Would a vapor fuel like natural gas be more likely to detonated on very lean mixtures?

[@Nzimports]

So if one were to say run a renesis rich via fuel tweaking and adjusting oil mix aswell it should be fine bar maybe needing sparkplugs and a oil service earlyer at the most ?

[@1darryloflife]

In order to better understand air fuel ratios you need to show the optimum air intake temperature for efficient burn . For example optimum temperature for petrol is 60 degrees Celsius and LPG is around 90 to 110 degree's Celsius. Of course all of the fore mentioned temperatures rely upon an exhaust valve that is under proper temperature control.

[@Seven-pl9rd]

Great vid

[@pinkdispatcher]

Cool stuff. This is relevant for small aircraft engines; these usually run very rich for takeoff to increase detonation margin, and lean off for cruise. In fact, most engines have manual mixture control, so it's useful to know what happens when you pull the red lever to lean the mixture for cruise. These engines have no ignition timing change (except a timing retardation for starting the engine); everything is simple and mechanical. Aviation gasoline still contains lead, but that will come to an end, and we will see how that works for high-performance engines, which still require an anti-knock index of 130 for takeoff power at full rich mixture. You say Diesel engine *often* don't have a throttle body. Are there Diesel engine that do?

[@MechInvent]

Thank you, I needed this answer.

[@CapablePimento]

I know aero is your specialty, but videos like this are great to watch too. Good format, good level of detail. Glad I watched it. Thanks

[@marycorner8275]

FamousMrAnonymous I

[@marineninga]

Hey Kyle have you seen the animated movie called "Redline"? Best racing movie ever and I'm sure you'd get a kick out of it.

[@SQUID_Road_Glide]

Subscribed.

[@jota5969]

I'd like to see a video about diesel tuning/efficiency, getting power w/out going too rich. Don't like rolling coal at all.

[@steven12395]

Gale Banks is the man to go check out if you are looking for diesel information, it is crazy the amount of knowledge that man has.

[@kikobarros76]

hello!! love your videos! concerning this subject, you must study about airplane engines running lean of peak or rich of peak! youre gonne love it!!! Best regards from brazil!

[@stevemcilroy9518]

Thanks, interesting

[@GardylooAlaska]

Neat video, thinking about a 5.7 C" gasoline boat engine and cruise at 3300 RPM or 75%, . Slightly rich or would consider that "steady state"...?

[@tunedom6488]

i have big black smoke on my tuned diesel when iam on full throtile but i have no smoke when iam chilling... what u think is it bad tune? will it damage the engine?

[@tmmlam]

can you explain the the hatch back spoiler, "w/ slot opening" vs "No opening"; which offers higher down force & less drag? Thanks!

[@MrBrady691]

Wtf man

[@MunsKi]

hi, so they already have oxygen molecules in their structure. but they use energy for them to be disengaged right??

[@riccardo1796]

You need to first add energy to unsettle their balance and break up the chain

[@clevocamaro6238]

If you could produce some charts utilising a data logger like a LM-2 innovate motor sport wide-band meter, on a typical 350 small block Chev (mild built) with typical Holley vac sec Carb that would be awesome! There are heaps of resources out there for fuel injected cars, but not much for the older school cars. Seeings as technology is now cheaper and more accessible I think a lot more people will be using data loggers on their old cars like myself :)

[@bp6837]

Is it ok to tune my diesel engine just above the stoichometric ratio? The stock afr is around 22. Ive seen a known tuner in our area tune a similar engine to around 14.7 and increase the turbo boost as well.

[@ferrochinabisleri1587]

I have an engine light on and doing a OBD test on "measuring blocks" I have a continuous switching lean to rich mixture but with a preponderant rich mixture. I also have a P0420 catalytic converter error. Solutions?

[@painlesszm1421]

Is the ratio consistent between different types of engine. E.g. between a V8 and I4

[@wonderwalls3565]

So running lean air fuel ratio and adding hho in the fuel mixture would take care of the high temperature issue? as gas generated by hho systems is cooler?

[@MrDejast]

Wow I'm so stioced

[@Britton0932]

Can you please do an update to this video to show what it means when engines are using E10 fuel? Then, show how this impacts the 2022 F1 car power unit development

[@jimmygichohi7524]

Possible to show how to use diagnostic machine to adjust air/fuel ratio?

[@kennethjury9718]

I would like to know more about these mixtures running with a natural gas turbocharged stationary engine

[@jakethesnake1503]

Can you do me a video on the damages of an extra quart of oil in your new WRX by the dealership

[@dunaweezel]

Hi. I found a kit that I like its sold as a diesel kit. Will the same kit work for gas? Thank you in advance

[@stephenmwyatt2]

so whats the AFR for Septane or Hexane?, you know, a question you can't get with a google search.

[@p.c.h.6721]

Hi, anyone knows what’s the maximum EGT reading for a two stroke 125cc engine?

[@groomlake51]

We burn nitro 1:1 with air at about 2 gallons a second through a 140-150 GPM pump

[@jcoats1203]

Groom Lake Wow, thats some pretty bad mileage.

[@beqam9367]

you made this way more complex than it should’ve been

[@krusher74]

I would like to see a video on exhaust systems, how a manifold should be designed and what are the max hp per tube size is.

[@CalaisRider]

You don't get much power gain from headers and a tad bigger exhaust even with a 7 litre. Its "part" of the much bigger puzzle but on its own is only a minor gain. More for sound, show and pose.

[@tunedom6488]

hi mate. what is the best afr to tune diesel for power and safety?

[@OrangeDCTypeRAcuraRSX]

If you can make Video on How to Run Aftermarket Fuel System on K20A2 with RBC Intake Manifolds ported and Bored if you running Walbro 255 Fuel Pump and Aftermarket Fuel Pressure Regulator without IAV !!! Thx in Advance !!!

[@michaelramirez383]

I did a downpipe to my bmw the say that needs more fuel because its running lean what can you tell me about that infor.ation and that i can break a piston

[@Blockbuster2033]

Well, the exhaust probably has bettet scavenging, which draws more fresh air into the cylinder, which needs more fuel. But your car likely has enough headroom in cooling to handle it fine, however it would be better to get a custom tune for it

[@kovalenkoihor4325]

So, are you saying that any lambda between 0.75 and 1 is good, right?

[@SealineQatar.]

correct your lean/rich definition plz, check 4:29 Lean means more air compare to fuel, rich means less air compare to fuel.

[@KontoVonMir]

pumsjd Please think about your statement. Lean and rich is not about the absolute amount of air or fuel in the chamber, but merely about a ratio. Call it percentage if you will. At a given rpm and throttle position the engine will generally always suck the same amount of air into the chamber. With more or less fuel injected the condition can be either more lean or more rich. But the amount of air doesn’t change. So no, the purpose of a lean condition is not to have more air so you can burn more fuel. You actually lean out the mixture when you’re at part throttle in order to save gas and make sure that you don’t have any unburned fuel. The cylinder pressure is lower at part throttle and therefore you have slower flame propagation which means that it takes more time to burn up all the fuel particles, while your time window for combustion stays constant.

[@itzpro.]

@@pumsjd 😂he tried to copy engineering explained guy but hilariously failed🤣

[@RickyPisano]

On my scanner I have a FUEL AIR COMMANDED EQUIVALENT RATIO of exactly 1.00. So I guess I'm good? I have a 2005 Ford 500 Limited with the 3.0L Duratec DOHC V-6.

[@skaownz234]

Is H_vap of the fuel really the source of cooling that makes rich AF mixtures run cooler? Thing is, there’s so little mass of fuel being vaporized that I don’t think this cooling effect would make much difference. I believe the real reason lean mixtures cause knocking is because it burns slower, too slow at high RPM, which means less of that energy can get extracted as work and is therefore leaves your working fluid hotter which heats the engine to a point that can lead to knocking.

[@mr.adventure559]

What about ceramic coating on the piston tops and the combustion chambers to combat detonation?

[@axelriet]

Mr. Adventure It does not combat detonation at all. Just slightly increase the thermodynamic efficiency by keeping the heat where it should be.

[@amraceway]

What about LPG? Also when you lean out say a 2 stroke motor you get more revs and presumably more power.

[@wingracer1614]

Only to a point. Go too lean and you lose power. With your typical air cooled two stroke, they often are pretty lacking in cooling and depend on the oil in the fuel for lubrication so they are tuned rich to keep them cool and lubricated. Therefore yes, leaning it will make more power but again, only to a point.

[@KYLEENGINEERS]

You have to be careful with how you think about "leaning out", typically a "leaned out" two stroke is still running Lambda

[@Quintinohthree]

Bill Hollingsworth LPG consists of short chain saturated hydrocarbons with a slightly lower oxidation state than gasoline, but more importantly much smaller molecules and thus overall less oxygen needed per unit volume of vapour as compared to gasoline. Stoichiometric ratio between that of diesel and ethanol therefore, not exactly sure how to be honest though.

[@zacharymorris9917]

I think you're confusing the "air screw" adjustment on a 2 stroke for actually controlling the amount of air. It does not. 99% of the time all the screws on a carburetor control a fuel circuit. When people think they're leaning out the mixture by adding air with the "air screw" they are actually adding fuel. I've literally never seen a single 2 stroke that gained power by closing the "air screw" and leaning the AFR. 100% of the time, from factory settings, 1/8 or more turns out, richening the AFR, adds power and RPM. This is especially true for the last couple decades or so that the EPA has been meddling in the industry.

[@russellleahy]

Go to lean it will seize a bit rich is better

[@maxbify]

yo. make a vid on anti dive/squat geometry. other vids on youtube about that seem like they got some things wrong, to me.

[@KiriRose]

Is this one of the reasons my exhaust on my atv turns red hot?

[@albertseelig4776]

You probably dont have enough ignition timing.

[@bufalong]

how i know i setting carburetor on my bike is good

[@brianmathew09]

install new s/plug,,blast it,,view plug ,will tell you rich/lean,,,then AFTER that,,cruise its some and view plug again and will tell you if needles are correct hight

[@gazoline7093]

Stick a air fuel ratio gauge on the exhaust the days of reading plugs and guessing are over

[@yacineyassine3044]

I have problèm of hight egt in my diesel whats that mean i have lot of fuel or less?

[@7301soulseekers]

I have a tsx I purchased recently I have a feeling there’s an issue with the mixtures of air and gas because of the lack of power when I accelerate hard. I don’t have a check engine light on, what can be the problem??

[@ronnieyoung8549]

Check the volts on the battery and altinater should be really close to 13 v mines at 13 5.btw Low voltage will cause power issue. Also vtec sensor that operates the oil flow when vtec hits but if it's bad you wont hit vtec just feels super flat power. It will throw a code tho. Cat could be blocked. Gas could be low on octane = old gas. If it's breaking up that's gonna be some type of sensor. Or wire - ground issue. if the motor is for sure good.

[@chanddon9068]

Bro what is the name software which is used to know what is perfect raito

[@jose15238]

I run water/methanol injection on my car. Can i run water/Ethanol injection instead? more energy

[@Matt_from_Florida]

What is the stoichiometric AFR for gasoline with a 10% ethanol mixture as we almost always have in pump-gas in the USA?

[@Matt_from_Florida]

Never mind. I found it: Pure Gasoline 14.7:1 10% Ethanol Gas 14.04:1 15% Ethanol Gas 13.79:1 E85 9.75:1

[@tilemahosberetis4417]

Hey mate, just a question. My bike, cbr 600 rr 2004, is lately stalling in neutral at stops even clutched in and also while riding will lose power for a second or two or will jerk forward sometimes as I deccelerate. Do you have any idea what the issue might be? Thanks

[@brianmathew09]

loose nut behind the wheel

[@GrumpyFelo]

What about the the gasoline that has like 10% ethanol in the mix at the pump already, do you go by 14.7/1 or not?

[@EB-dr4dd]

You are already wrong because each retailer has different additives which will make a fuel lean or rich. Some (gasoline) can contain all those fuels together at once.

[@ckryses3962]

Hmm..14:7 is mostly for cruising..below 13 or at 13 is for lil high speed.

[@dennisrobinson8008]

He said 10% ethanol gas has around 14.2:1 stoichemetry.

[@ProduceBOY939]

My 2003 supercharged mustang Gt is running all over the place. Some days I have 13.8 - 15.4 and days like yesterday out of nowhere I was getting 10.0... car died and drove home. What’s the cause? Maf? Iac? Egr?

[@FlickTricksOffical]

ProduceBOY939 Taking a shot in the dark I’d say throw a FRPS fuel rail pressure sensor at it.

[@Marco-nx5tj]

I recommend you use automaton the car company tycoon to help people understand ic engines

[@josephschaefer9163]

There should be an in depth revamp. Cam timing and ignition timing and a/f ratios need tables to be realistic

[@OffGridInvestor]

Lambda is also an engine name. For the Kia Carnival of all things.... it's a hyundai engine and the version 2 with GDI is in the genisis (except the V8).

[@axelriet]

Link Knight Irrelevant.

[@JORDIIMusic]

question: if my engine runs over-rich due to the use of a BOV on a MAF car, will this have some positive effects in that more fuel is being injected, resulting in cooler engine temps?

[@JK-nd7ez]

Yes more fuel = cooler engine. If you put air in a fire, its get hotter.

[@powerstroke0459]

That figure of 14.5: 1 with diesel is not correct with trucks about 17:1 is the smoke threshold also a huge factor of ambient air density before and after the turbo and intercooler

[@7sins979]

stoichiometric ratio for diesel is 14.5:1. all this means is that the ratio of fuel to oxygen is perfect for both reactants to be consumed in the combustion process. likely in the real world not all of the diesel fuel atomizes and burns so leaner ratios are in order.

[@Astrix_Jaeger]

Breathing: "how do I know if Im breathing lean or am I breathing rich?"

[@creedence1819]

Well, when the air goes into your lungs, it starts out mostly as regular air then the O2 content drops as the CO2 content increases. So depending on which one you want to define as lean or rich, it starts out as one and changes to the other. As the for the actual stoichiometry, the carbs and sugars get "burnt" in your body at the perfect stochiometric ratio as far as I know.

[@joseyox1]

Nature: rich City: lean

[@Astrix_Jaeger]

@@joseyox1 wahaha underrated. Good one.

[@fortnitedaily1042]

Stft, are -25% at full throttle, is this normal??

[@36trisix48]

Errr am i at Engineering Explain? Owhh im on alternate universe...

[@j1238066]

I have struggled to get 14.5 but my sbc won't run good the best for me is 12.7

[@xiaoxiaoxiao686]

Why does an engine running lean rev itself high? Is it because quicker combustion (less fuel)? And why does a lean engine produces more heat?

[@1Pitstop]

Gasoline also refrigerate the combustion camera.

[@axelriet]

Xiao Yáñez Fernández it’s not really that lean produces more, but more that rich produces less, as it takes more energy to vaporise the extra fuel, to the point that if you get rich enough some of the fuel does not evaporate at all and washes the cylinders.

[@jamiewolak]

Kyle I love the videos. Can you talk about the benefits of sealed side skirts? It seems simple but I never understood how much it could help with downforce

[@jean-baptistepicot3659]

Well I don't know if he did a video on it but as a simple explanation, if you have a car like an F1 which sits very close to the ground and has a flat undertray, it exploits the ground effect a lot thus there is a low pressure zone at the underside of the car. If you did not have a sealed side skirt or a barrier-like vortex running along the side of the car, the "outside" air and the high pressure air coming from the tyre wake would move and fill that low pressure zone. By sealing the side of the car, the low pressure zone is then sealed and it can then create a big amount of downforce at a really high aerodynamical efficiency (almost no drag created). Check the Lotus 78 and the Lotus 79 to see a real-life example of side skirts and ground effect.

[@husseinsuarez4501]

sir how many turns of air fuel screw in raider 150..

[@jawbreaker707]

I immediately imagined the tootsie pop owl in a tree looking down upon an amateur mechanic holding up a pair of carbs 😂

[@emune1111]

Can you do a carburetor explanation on how it works

[@MrBerru]

What about water injection... Have you heard anything about it?

[@EB-dr4dd]

Low IAT advance ignition for torque. High pressure mist lean for power.

[@xeigen2]

@@jzxtrd337 I fail to see how carbonic acid, an extremely weak acid, would cause damage when extremely acidic NO2 formed in combustion doesn't. NO2 is an acidic gas and also forms nitrous and nitric acid with moisture in the air.

[@em1ownerify]

I put k04 on my mk6 gti and reflagged and since the cars running super rich. I don’t know if it’s just the tune running rich or what. The whole fucking hatch will get like black soot covered on it after a good drive

[@technomage6736]

More fuel = lower temperatures? I don't understand because without an EGR system, or a stuck closed EGR, this causes the vehicle to burn more fuel, which increases combustion temps and increased Nox, contributing to knock. What am I missing?

[@Redtooth75]

A leaner air to fuel mixture burns hotter. Oxygen is necessary for a clean, hot, and fast burn. The more oxygen you have the better the combustion is. A lean burn will have more oxygen than a rich burn and will therefore burn hotter and faster. Same reason why cracking the oxygen valve on a torch makes the flame hotter.

[@technomage6736]

@@Redtooth75 I appreciate the reply. Would you happen to know a quick explanation of how then a stuck closed EGR will actually increase combustion temps? I'm wondering if it has to do with some sort of dampening effect a properly working EGR would cause 🤔

[@axelriet]

Techno Mage It does not “increase combustion temps” but it “fails to lower it”. EGR basically injects WATER back into the combustion process, as you know the exhaust gas is CO2 and H2O, mostly.

[@7sins979]

fuel vaporization lowers temps. an egr system introduces inert gas to the intake stream to lower combustion temps (less oxygen available to burn, therefore less fuel burned). oxides of nitrogen (NOx) are formed by high heat and pressure in the combustion chamber. a failing EGR will not contribute to knock, they only operate under very specific conditions and not under high load.

[@andgate2000]

This is why computerized fuel injection and computers in car came about.