🛠 Mythbusting: Which is more important Air-Fuel Ratio OR Ignition Timing?

#afr #enginetuning #haltech
This is something you need to know if you're chasing horsepower - which is more important - AFR or Ignition Timing? Today we are going to tackle this hotly debated topic the proper way - with a test vehicle, a chassis dyno, and some hardcore theory thrown in. Strap yourselves in - it's gonna be a bumpy ride!
Read the website article here: www.haltech.com/ignition-timi...
Got a topic you'd like us to cover? Leave it in the comments section!
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Shortcuts:
00:00 Intro
00:40 Experiment Overview
01:44 Dyno pulls - Round 1
02:30 Round 1 results explained
03:50 What AFR does
07:20 Stoichiometric AFR
09:30 Why AFR doesn't produce more power
11:10 Dyno pulls - Round 2
11:50 Round 2 results explained
13:55 The Verdict
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[@cbdrift]

Aussie channel : "the crank bone is connected to the .......... Burnouts!" - well i cant argue with that one :)

[@Knackersjewels]

My tuner was teaching me the basics of tuning. He said "Power Enrichment doesn't add fuel to make power, it adds fuel _because_ it's making power"

[@quickcinema8031]

@@akinorhan4671 for cooling, upgrade your cooling system, not adding more fuel

[@MotoringBoxTV]

"Skip the foreplay and straight to the meat..." that's why we love you guys ❤

[@Old-n-slo-locked-n-leaned]

The best and most straightforward explanation of AFR vs. timing.

[@BIGGELATO]

Its always remembering that a 6000RPM rotates 100 times a second, and knowing there are cars with 10k rpm, bikes with 15-17k rpm, still pretty crazy till this day

[@jacquescrusan9500]

Old saying from my dad: "Time for torque, then jet for power." I always took it to mean that ignition timing is your rough groom that you do first, then changing the fueling is the fine groom to add finesse to the curve to finish optimizing. If you think about it, ignition timing more directly affects the timing of peak cylinder pressure in relation to crankshaft position than fueling. And cylinder pressure should be one of the main objectives for making power.

[@jacquescrusan9500]

I guess the purpose of his statement is that fueling doesn't have to be spot on at first to get within the ballpark. So it makes more sense to adjust the timing first with safe (albeit rich) afr's and build up the torque curve. Once that's done, trim the fuel to fine-tune the curve and keep temperatures in the green band. I've seen others take the opposite approach and it seems to trend towards taking longer to achieve a similar result.

[@huss9796]

Awesome coverage on a commonly asked topic! Thank you! Would love to see more in depth videos based on Rotary tuning !

[@dxrkout5677]

Nothing less from Haltech! You guys know how to present concepts simplistic and right on the head. Much love and respect, keep it up!

[@haltech]

Thanks for the feedback:)

[@grahamparsons1070]

Took the words right out of my mouth 👌

[@KHIJAPAN]

Perfect!! You helped me a lot, answering my question before I even ask you :)) Of course I watched some of your videos before and some from other reputable Australian companies.

[@BEYTEK]

this guy is very entertaining to watch! and very knowlageable

[@ciutarobert12]

Great video, defiantly the best explanation out there. Many thanks once again!

[@dlmperformanceandracing]

Defiantly or Definitely?

[@TurboHappyCar]

Fantastic video, thanks for doing these! 👍

[@kieranplowright7932]

❤ most informative explanation 😊 Thermal power and mechanical power, fuel, timing Makes so much sense now you put it like that, great vid.

[@dwolrdcojp]

Great explanation and the best engine management!

[@Phantom-mk4kp]

I believe the goal is for peak cylinder pressure at 18-20⁰ ATDC. There is a spark plug available that has a piezoelectric sensor that measures peak pressure

[@SooperKewl]

Great video. Really pulls AFR and timing concepts together.

[@doncarlson8391]

Maximum mechanical advantage is when the con rod is 90 degrees to the rod journal. Depending on rod length this may be when the ctank is more like 84 degrees after TDC not 90 degrees. Nice demonstration of timing vs afr. BTW, measuring egts and their relationship would be interesting.

[@Mineratron]

Simple, clear and entertaining. Enjoyed that. 😄👌🍻

[@lukeschannel650]

Well done! Best explanation ever. Keep ‘em comong

[@bcr1818]

Awesome video, i would love too see more of these. :D

[@jamesford2942]

Nice explanation so far. Engines of different design parameters take different ignition timing due to the time it takes for the flame to burn across the cylinder.

[@TURBOTRISTO]

yet another great video!!

[@Adrenalfix]

really awesome and informative video, thankyou. I may investing in a haltech soon, just have to justify it :p

[@AngerIsAnEnergy]

I'm glad you did this video. I have had my current Evo 8 for about 5 months and have been wondering if the previous owner's A/F setting was overly rich. I am pretty sure now that it is and when I get it re-tuned I plan to remedy this. I put out noticeably more black smoke than similar cars when wide open and am fairly certain I could dial it back a tad without killing my engine or sacrificing power.

[@UzumakiGarage]

Great explanation. Thanks Matt

[@xyzconceptsYT]

Well done lads!

[@haltech]

Let's settle this once and for all: Which is more important when tuning for power - AFR or Ignition Timing? Today we are going to tackle this hotly debated topic the proper way - with a test vehicle, a chassis dyno, and some hardcore theory thrown. Strap yourselves in - it's gonna be a bumpy ride! Read the website article here: www.haltech.com/ignition-timing-vs-air-to-fuel-ratio/ ----------------------------------------------------------- Liked this video? Here are more like it: Volumetric Efficiency Explained: kzbin.info/www/bejne/e2qZo3V_r7-Sqac Volumetric Efficiency Tuning: kzbin.info/www/bejne/q4HNeoZvicxraa8 Nitrous Injection Explained: kzbin.info/www/bejne/g5acn5-frrahfq8 ----------------------------------------­---------------- Don't miss out on our next video - subscribe to our channel. ----------------------------------------­---------------- For more Haltech goodness check out our: Website: www.haltech.com Facebook: facebook.com/HaltechEngineManagement Instagram: instagram.com/haltechecu

[@DBatty]

Excellent video 👌🏻

[@baxrok2.]

Well done. Thanks!

[@MartinMcMartin]

I think like a caveman, AFR burns pistons, bad timing hammers bearings and throws conrods.

[@haltech]

Hey, you're not wrong so we won't argue:)

[@GoldenSim27]

very informative thank you

[@mikejarden3679]

Top work really enjoyed the VE videos as well hopefully convert some tuners into the modern age. Could you do a video on the importance of injector data/dead times. I have a mainline dyno too and recently noticed there is a tool in the software for injector deadtimes but iv never used it would be cool to see how that works. I do have a injector flow bench and a scope but its a lot to just check if the data you have is right or wrong. I tuned a f6 g6e the other day and managed to get 390kw only mod was a new dump pipe but maxed out fuel system so i put some new injectors and fuel pump in.

[@N1SMO32]

That Falcon comes on boost *HARD*

[@BjornFSE]

Awesome, Good Work, Keep em Coming (More Advanced next? lol)

[@lukedrakogiannskis8386]

Amazing learnt heaps from this vid

[@TurboS-gh5wc]

These videos are highly appreciated thank you

[@haltech]

Thanks for the feedback:)

[@mikeymasi]

Great stuff cheers

[@antonamalfi]

Nice explanation

[@johnnydoodles88]

Top Vid man.

[@Terribleguitarist89]

I'm so envious of the Holden's and cool stuff y'all get down there... I want a ute :(

[@ericn7698]

I like this Matt guy. He's very knowledgeable about EFI tuning. Maybe he should go work for an aftermarket ECU manufacturer...

[@jasonc950]

Fair dinkum fantastic info, it explains why a VF GTS is also rich up top stock and why it is lethal on a cold morning when the timing is not retarded, thanks so much for a absolutely fantastic 15min of knowledge now understanding the horror stories heard personally about melting pistons, blown new engines and popping ring gaps all due to poor tuning chasing numbers for a $ tune, cheers

[@simonschmidt7327]

Good stuff

[@discipleoftheword1785]

Thank you

[@whitewalker9622]

So how do you make a car drink the most less amount of fuel? Great ep!

[@TheJamesLykins]

Great sounding Ute

[@haltech]

It is:)

[@hyper8545]

Thanks

[@bryanne92]

Yall having too much fun explaining car stuff... 🚗 KEEP AT IT 🤳💅

[@whatsreallygoingon253]

Man id love to have a turbo falcon you Aussies get all the cool cars

[@wailingalen]

That hair and makeup moment was perfect 😂 👍

[@mathewboyd3746]

I'd be interested to know how different the AFR & timing would typical be for an aircooled engine versus a water cooled. Air cooled has an extra challenge to managing heat in the combustion chamber I believe?

[@Ismcoyote12]

Ignition advance is starting the burn earlier before Tdc though so technically the peak cylinder pressure would be closer to where cylinder volume is smallest .

[@TurbineResearch]

Well done lads

[@haltech]

Thanks:)

[@andiszile]

One could use EGT to fine-tune AFR. That''s a way to get some idea of cylinder temperature. If EGT start to get too high, make it richer.

[@shotamakarashvili3714]

How about AFR being too rich in combination with retarded ignition timing resulting in very high EGT? What is it going to tell you about combustion chamber temperature?

[@bvward]

Matt, for us in the 'States, could you talk about the stoichio-Imperial ratio? Gallon per cubic mile?

[@233kosta]

If you can spare the dyno runs, you can do some RSM to find the ideal relationship between the two.

[@martinrodger9565]

🤔 Matt introduces by saying his last vid was VE. I thought that was Scotty… Matt and Scotty are never seen on camera together… Matt could fit into a Scotty suit but Scotty couldn’t fit into a Matt suit… WHAT HAS MATT DONE WITH THE TUNING FORK?! 😬

[@haltech]

Matt has done VE Part 1 and Scott has done Part 2. But you're right, we've never seen them on camera together.... queue suspenseful music 🤔

[@haltech]

Your cue will be the sound of suspenseful musing being queued. Just watch out for that reversing beep:)

[@RaksasaMentawai]

Nicely explained 💪👍

[@haltech]

Thanks. Glad you liked it:)

[@Andersljungberg]

If you question it, you can ask the question what was the octane value in MON. When you performed the test. And the horsepower and torque at lower rpm can be interesting for some people

[@mikejarden3679]

Another quick question do you use bosch lsu or ntk o2 sensors? also do you use the dyno wideband controller or ecu data via CAN

[@isidrosevier1125]

Should you change spark values at cruising speeds? Is there any benefit to doing so? Should they be changed on a big cam engine when using a high stall convertor? If max timing at WOT is 24 for my engine, but I'll see 40-41 when cruising. Should I lower those a few degrees?

[@HidRomail]

Nice information!! Next one up, would be good to understand how to make EGT's a bit lower ;)

[@npharkes]

I would LOVE to see you turn DOWN the boost so you can UP the timing - and compare that for power! Thanks!

[@marlo0oty213]

The forbidden theory 😂

[@martykath4427]

Take a look at Banks power clips.

[@Bacongrease00]

Generally safer to make power with more boost and less timing. Timing is great until it’s not and you open your wallet. All it takes is one bad fill up of petrol and an aggressive timing curve to relocate the piston ring lands

[@salloroc20]

I almost spit my beer at 11:ish

[@lockedinstreetracing6005]

Too much timing will separate the rods from the crank to little and it runs like a ford you have to find the sweet spot. I'm jk though this is a great video on afr and timing great video guys.

[@greybuckleton]

Just laying the truth on fast and hard!

[@hfr_ford755]

You wanna send one of those turbo Falcon utes over here to the U.S.? I need that car in my life

[@ShredCulture]

Another thing to consider is the effect that lambda has on laminar flame speed. It has been shown that any ratio richer or leaner than .90 lambda (roughly 13.2:1) will exhibit a slower flame speed. This means when the lambda is varied with fixed ignition timing, the point of maximum cylinder pressure will be at different locations.

[@wells2671]

Thanks for the great explanation, much appreciated!👍🏾 1 Question; If you dial in the fuel (AFR) throughout the RPM range first (using lower timing), and you then dial in the timing for more power, does the new timing change or affect the AFR that was previously set?

[@ennpty]

It shouldn't

[@chevyno1740]

My understanding is that you should go back and check/readjust the A/F after ignition changes, as the characteristics of the burn will change. It may be subtle but it is there.

[@Brenton656]

I can’t believe you did a power run before all the fluids were warmed up 😂😂😂

[@perpetualgrin5804]

I use 95 ron for more advance for my ' 380 '. She is a beauty.

[@bikergobrrr]

Fun video idea. Get a bunch of $300 wrecker barras and really push them with all the wrong things see what blows haha.

[@eggsandbirds2520]

Great job matt plan and simple to much details Could make it complicated. Question when will you be able to do a video on expansion modules For the elite series Unfortunately my 2500 is out of analog inputs need to expand my Ecu I noticed you still have the platinum series expansion modules will there be a release on a elite series expansion module or a updated version?

[@eggsandbirds2520]

Last will there be can bus switch panels for the elite series

[@haltech]

In the works as we speak:)

[@DATONALKY]

How flat are the Afr's on the dyno screen, nice work 👌

[@wadoryujh]

Great stuff, have a like just for the hair and makeup sketch

[@haltech]

Thnx, we'll take it!

[@gavinivers8941]

A very good video. If you want to know more, book your car in on Monday as the best answers come with a credit card number.....

[@irukandji___]

Phew! All this talk about melting pistons. Thank Felix I am a Rotary Guy 🤣. #ApexSeals

[@thedobermangang3503]

what is the best one to buy just rebuild my engine 5.7 1990 k5 blazer i got edelbrock carb on there i already have headers so the hole is there for the 02 sensor i converted it from tbi to carb.

[@chippyjohn1]

I use steel pistons and sit around 14.25:1 Lambda at full load. Makes a huge difference for economy. Soon enough, steel pistons will be common. If all cars were hybrid and used engines that ran around a fix rpm, they would be so much more efficient. Being able to design all aspects of an engine to run around a narrow RPM range make it so much more efficient and simple. No need for VVT etc.

[@supernice_auto]

that sounds awful for racing.....

[@sidecarbod1441]

At one end of the scale you have videos like this, then at the other end of the scale you have people that say 'twist the distributor until the engine knocks then back it off a couple of degrees' LOL

[@777MAV]

Why at 3:26 three graphs are in a strange order? 11.1 on top, 10.58 at the bottom and 11.7 is between them... Different axis? Also one of the graphs gave slower turbo spool, which one was that?

[@mattkoh]

Can you do another one of these with an NA engine?

[@aoeden83]

Would you generally play with cam phasing to determine max airflow before tinkering with spark and fuel tables?

[@GarageItYourself]

You'd have to do that in conjunction with modifying the VE table to see if you've actually changed the breathing capability of the motor. An engine is most efficient at a specific speed (RPM) which usually equates to it's maximum torque value and the cam phasing helps spread this peak point across a wider RPM band.

[@mikenco]

I'm watching this better learn how to use the air and ignition retard levers on my 1929 Matchless T4. Great video, thank you.

[@heavyweaponsguy21]

Will Haltech look into free valve tuning? I know it is early days for the tech and very niche.

[@haltech]

Just like with everything - if there's enough demand for it, we'll make it:) At this point in time, like you said, it's a very small, niche market.

[@heavyweaponsguy21]

@@haltech thanks for the reply. Love your hoodies btw. Excellent quality.

[@redteam77]

9k RPM going to 150 RPM per Sec is right for 2 stroke. But 4 stroke which the Ford runs is 75 RPM/Sec as it fires the sparklers every second revolution. That's okay, I'm still watching and learning.

[@GarageItYourself]

Nice video but maybe a bit more indepth on the ignition timing with info about too much timing creating knock due to cylinder pressures being too high before piston has reached the top of it's stroke and how ignition is tuned for maximum torque and stuff like that.

[@shotamakarashvili3714]

It's not the high pressure directly but rather high temperature heats up combustion chamber parts causing hot spots to initiate additional flame fronts after initial spark if the fuel in use can't resist it...

[@GarageItYourself]

@@shotamakarashvili3714 Yup, I'm well aware of this fact. Thanks.

[@shotamakarashvili3714]

Spot on as a lot of people get confused between knock and pre-ignition...👍

[@MrMajood1994]

Why we can’t adjust spark duration time on Haltech ECUs ??

[@ecuperformance959]

I prefer 10.5:1 because you can add more advance ...

[@theungoliant9410]

You can tune without a Dyno using vacuum numbers , at least for fuel economy.

[@drifting1O1]

Not me with stoichiometric efficiency tattooed on my arm

[@user9005]

I thought timing wasn't always set at peak torque but also removed as a cylinder pressure safe guard especially under boost?

[@Dirtypepants]

Have you done anything on turbo exhaust manifold pressure comparison to intake pressure I have run boost gauges on both and there is a big difference with standard turbos and upgraded turbos I guess my question is it must leave alot of boost still in the crown off the piston when the valves shut and effect the intake charge size if ex manifold pressure is higher than intake?

[@LaunchJoelRacing]

Im not haltech answering tho, but the answer is yes definitely, let me explain a few things! I have done extensive research and testing on this subject in relation to exhaust sizing and it directly affects the volumetric efficiency heavily which means you get higher potential for internal EGR(unfavorable 99% of the time) which is exhaust falling back into the combustion chamber and knock aswell(if running petrol). On E85 as engine doesnt knock so with high internal EGR you loose a tone of response on ignition timing and AFR changing the combustion flame speed leaving the car unwilling to make power. You basically raise the chamber pressure as the intake valve opens so you have less fill capacity and need more boost to overcome which is a vicious cycle if you just keep adding boost. It also decrease the amount of fuel that effectively can get inside so leading to overspraying of the intake ports which cause its own problems such as the fuel system is maxing out way too early. Decreasing combustion efficiency as we get worse atomization and inconsistent burns from partially burnt fuel residue etc. Too large exhaust cam duration wise and you cannot create an pressure difference large enough so you limit yourself. Exhaust cam on turbo cars is basically an balance between just enough flow and pressure control backwards into the cylinder, most run way too large vs what setup they run with no idea of their pressures through the chain. All in all it is basics of how a turbo system works. Boost is achieved through the pressure from the exhaust side running through the engine to the compressor wheel of the turbo so the more boost you have the more you will have at the crown of the piston pushing back on the intake charge trying to fill why it is best to have moderate boost levels and proper exhaust sizing with good ignition timing advance instead. If we take an full single 3'' exhaust on E85 at 600hp and internal gate we make an 0.8-1.2 bar of backpressure dependant on powerband, ignition timing and AFR(2.3L saab engine in reference here). In this scenario we run an turbine housing/turbine pressure ratio of 2.0:1 with and exhaust manifold pressure as baseline of 1.5 bar. The nominal pressure that the function of the turbine housing pressure ratio builds upon is the 0.8-1.2bar behind the outlet. This means to get desired pressure release and spool the exhaust manifold pressure is raised further ~1.5 bars. So if we have like without exhaust backpressure it may be 1.5bar exhaust manifold pressure and with exhaust backpressure it might be 3.0 bar exhaust manifold pressure. I've measured differences of cars reducing over 1 bar of exhaust manifold pressure by changing exhaust sizing it properly and removing only 0.3bar exhaust backpressure. Gained a tone of power on same airmass due to better volumetric efficiency, consistent burns and significantly decreased the fuel needed to make good AFRs so effectiviely dryer combustions. If we apply these principles that I mentioned we can make an small OE turbo stupid efficient without running out of the compressor map as we also the same time increase engines combustion efficiency so much. Made me be able to have my personal daily driver Saab 9-5 on E85 with TD04HL-15T to make 570nm at 1.5 bar to 373hp with 1.3 bar boost on the hubs(410-425bhp) for example which most likely is a world record(Video on my channel from that last dyno run). Most never get past 300-310hp at the hubs with them. This should hopefully shed a lot of light on your question.

[@Dirtypepants]

@@LaunchJoelRacing Thanks alot I have known this from practice but had not talked to anyone about the facts thanks for taking the time.

[@LaunchJoelRacing]

@@DirtypepantsNo problems! I was surprised that someone actually brought this up, almost no one ever talking about this nor pay attention to these specific very important things and understanding the whole chain.

[@MrWyza1]

Please more ignition videos! Rotary things!!

[@Andersljungberg]

But then perhaps you should also talk about the oxygen content of the fuel. And the purpose of, for example, a turbo is to push more air into the engine

[@yusufkarriem1074]

Very well explained... hope the make-up "artist" used a clean cloth... lol

[@haltech]

Play that part in slow motion - that cloth was the opposite of "clean"....

[@yusufkarriem1074]

Looks like it was used to wipe the dipstick

[@haltech]

LOL shhhh....

[@MRMOPARMAN0426]

The old saying, "ping is power". Myth confirmed.

[@MRMOPARMAN0426]

@Matt Wright that comes soon after

[@Harvy500]

Volumetric efficiency = brake horse power per litre/inches. Eg....car has 210bhp and is a 2.0ltr capacity. V/E for that car = 105 bhp per litre.

[@johnmurraycompton569]

Hair and makeup is spot on! lol

[@sidecarbod1441]

All of the AFR's tested were on the rich side, try going leaner than 13:1, then the BHP will start to fall off a cliff edge! Basically the 'bell curve' for AFR is not symmetrical, the peak BHP will be at around 12.8:1 or somewhere close to that (maybe richer for turbo), go richer and the power drops a small amount, go leaner and the power drops a large amount. Someone has already posted up that peak cylinder pressure needs to occur somewhere around 18-20 degrees ATDC, the figure I've seen is around 14 ATDC which is in the same ballpark. the RPM AND the VE of the engine effects when the plug needs to fire in order to get peak cylinder pressure at the right point in time (number of degrees) ATDC. In simple terms as the RPM goes up we need to fire the plug sooner but also if the VE is low (throttle just cracked open) we also need to fire the plug sooner, if the throttle is on the floor the VE will go up and we need to pull out some timing. In the old days this was with vac-canisters. One 'expert' on youtube that runs a 2 stroke tuning shop was arguing with me that peak cylinder pressure needs to occur at TDC! (words fail me!). In fact 2 smokers prove how important the VE is with regards to ignition timing, they run a retard curve! This is because the VE is rubbish at low rpm but then at high rpm they 'come on the pipe', the VE can go over 100% hence pulling the timing back even though the rpm is high.