Lancer Nation

Honesty Always Welcomed!
 
Lancer NationLancer Nation  HomeHome  FAQFAQ  RegisterRegister  Log inLog in  

Share | 
 

 AFR : Air-Fuel-Ratio

View previous topic View next topic Go down 
AuthorMessage
Reverend
Admin
avatar

Number of posts : 355
Vehicle Type : Lansi
Registration date : 2009-09-08

PostSubject: AFR : Air-Fuel-Ratio   Wed Aug 25, 2010 1:33 pm

From recent discussions on topics here, I thought I'd share what I know about AFR because it appears some do not know what AFR can mean to a car's engine, its performance as well as reliability.

Theoretically, 14.7 : 1 (air : fuel) is a ratio deemed to be "perfect" i.e. perfect in the sense that this particular ratio means complete combustion. But this is theorectical because it will depend on air quality and petrol octane level.

Running "leaner" means higher figures while running "richer" means lower figures. For our Lancer, the stock factory AFR is 10 : 1, a pretty rich mixture.

Running leaner basically means better fuel effiency i.e. for the same amount of air, a leaner AFR means quantity of petrol used is used efficiently and hopefully to result in combustion without any petrol wastage. However, when good/perfect combustion is effected, temperatures will rise (i.e. compared to incomplete combustion, temperatures will not be as high, which makes sense, right?). So while better combustion = better performance, it also means higher temperatures bcoz while all the _fuel_ is being burned there will be excess _O2_ that causes temp to rise. Therefore how lean you want your AFR to be will be determined by a mixture of considerations i.e. performance versus engine protection vs long term engine reliability. Too hot and detonation can happen, engine kaput lo.

Also, whatever your car's factory AFR is, it is actually not a fixed ratio bcoz it can go very high/lean when braking and go very low/rich when, say, you WOT. That's why when you install some reflash or piggyback, the tuner will tune AFR according to the RPM range tested (usually 3000-redline/revcut). Like I said, AFR is not a set ratio that applies all the time.

Leaner AFRs usually means better performance and fuel economy (I know, it sounds strange but only if you don't understand... IOW, more petrol does not mean more power!). For example, after I removed my Unichip last Friday, my fuel consumption has increased (the MFD fuel meter drops so quickly over the next few days after de-mod, knn). It's not that I tekan more to get power (since no more Unichip)... I still drive the same way... but my car consume more petrol now because the AFR has become richer, using more petrol, wasting more petrol due to inefficient combustion. Now you ask the Q : Why stock cars have rich AFR? Refer to my explanation above i.e. for engine protection, so that engine temperature doesn't rise very high.

Hope this helps Smile
Back to top Go down
Elan
Member
avatar

Number of posts : 534
Vehicle Type : Lancer GT
Registration date : 2010-03-02

PostSubject: Re: AFR : Air-Fuel-Ratio   Wed Aug 25, 2010 3:03 pm

very good info bro.. thanks for clearing some of my doubts.
Back to top Go down
strike961
Member


Number of posts : 139
Vehicle Type : Lancer GT
Registration date : 2009-11-10

PostSubject: Re: AFR : Air-Fuel-Ratio   Wed Aug 25, 2010 4:22 pm

very good info Rev.

Sat in a Lancer GT which ran on 14.7 when idle and ~13 when WOT last week. The performance was impressive...and very fuel saving too.

An AFR monitoring device was plugged on the dash to show the actual ratio.
Back to top Go down
Reverend
Admin
avatar

Number of posts : 355
Vehicle Type : Lansi
Registration date : 2009-09-08

PostSubject: Re: AFR : Air-Fuel-Ratio   Wed Aug 25, 2010 5:11 pm

strike961 wrote:
very good info Rev.

Sat in a Lancer GT which ran on 14.7 when idle and ~13 when WOT last week. The performance was impressive...and very fuel saving too.

An AFR monitoring device was plugged on the dash to show the actual ratio.
Can you remember what AFR gauge was that in that Lancer? Where exactly was the AFR gauge attached to in the car? How sure are you what is shown is "actual"? Smile I'm just curious, s'all.
Back to top Go down
overdrive
Member


Number of posts : 3
Vehicle Type : What type of Lancer Vehicle do you own?
08 Lancer GLS
Registration date : 2010-01-14

PostSubject: Re: AFR : Air-Fuel-Ratio   Wed Aug 25, 2010 6:07 pm

Hi Rev, how have you been doing? I know I haven't been posting much but I'm always viewing the forum Smile
Anyway regarding the AFR topic, your Works Air Charger and Powerjet sorta thingys will also increase AFR (make it leaner) slightly, am I right? But you had unichip before to tune the AFR. So does this makes the Works Air Charger & Powerjet useless then with Unichip installed? And since you've removed your unichip, by right your 'actual' AFR should also be higher than stock assuming you still have the works Air Charger and Powerjet still installed.
Back to top Go down
donyong
Member


Number of posts : 308
Vehicle Type : Lancer GT 2.0
Registration date : 2008-07-18

PostSubject: Re: AFR : Air-Fuel-Ratio   Wed Aug 25, 2010 6:08 pm

If some of you are constantly WOT with lean setup, becareful. Engine kaboom. Below 13 should be fine.
Back to top Go down
Reverend
Admin
avatar

Number of posts : 355
Vehicle Type : Lansi
Registration date : 2009-09-08

PostSubject: Re: AFR : Air-Fuel-Ratio   Wed Aug 25, 2010 6:36 pm

overdrive wrote:
Hi Rev, how have you been doing? I know I haven't been posting much but I'm always viewing the forum Smile
Anyway regarding the AFR topic, your Works Air Charger and Powerjet sorta thingys will also increase AFR (make it leaner) slightly, am I right? But you had unichip before to tune the AFR. So does this makes the Works Air Charger & Powerjet useless then with Unichip installed? And since you've removed your unichip, by right your 'actual' AFR should also be higher than stock assuming you still have the works Air Charger and Powerjet still installed.
Wah... bro overdrive, long time no c or hear man!!! How u doing? Ethan must be, what, 1.5-2 yo now? Everything OK? Working on second one? Razz Smile

TBH, I don't really have enough info about the Works AirCharger and PowerJet to make any conclusive comment. All I know is that PowerJet is supposed to make air going into combustion chamber cooler (which is always a good thing) but I don't really know how well it works... I simply spend money only lo Razz As for the Works AirCharger, all it does is make sure air sucked in by vacuum system goes in at higher velocity, and I also don't know how well it works (i.e. again, simply spent money!!! argh).

I do not think either/both products have any affect on AFR.
Back to top Go down
overdrive
Member


Number of posts : 3
Vehicle Type : What type of Lancer Vehicle do you own?
08 Lancer GLS
Registration date : 2010-01-14

PostSubject: Re: AFR : Air-Fuel-Ratio   Wed Aug 25, 2010 7:04 pm

Hey Rev, everything good here, yes Ethan is 2 now and 2nd one is coming soon, after this have to 'potong' already haha

Anyway yeah guess these 'minor' mods won't make a diff to the AFR, just thinking, our cars comes with a knock sensor, would it safe or maybe we can 'lean' the AFR until to the point that the engine starts to 'knock' then the knock sensors will kick in and retard the ignition timing? I'm just throwing ideas here Smile
Back to top Go down
strike961
Member


Number of posts : 139
Vehicle Type : Lancer GT
Registration date : 2009-11-10

PostSubject: Re: AFR : Air-Fuel-Ratio   Wed Aug 25, 2010 10:22 pm

Reverend wrote:
strike961 wrote:
very good info Rev.

Sat in a Lancer GT which ran on 14.7 when idle and ~13 when WOT last week. The performance was impressive...and very fuel saving too.

An AFR monitoring device was plugged on the dash to show the actual ratio.
Can you remember what AFR gauge was that in that Lancer? Where exactly was the AFR gauge attached to in the car? How sure are you what is shown is "actual"? Smile I'm just curious, s'all.

Bro Rev, the engine was reflashed to achieve that specific AFR. The device was attached to exhaust ?header if i'm not mistaken. The reading reflects the owner's setting..so should be "actual" gua Smile

How lean can actually stock 4b11 safely go (using RON97) when WOT?
Back to top Go down
Elan
Member
avatar

Number of posts : 534
Vehicle Type : Lancer GT
Registration date : 2010-03-02

PostSubject: Re: AFR : Air-Fuel-Ratio   Thu Aug 26, 2010 2:29 am

too lean AFR may lead to engine overheat. as donny said, 13 and below should be fine.
Back to top Go down
Reverend
Admin
avatar

Number of posts : 355
Vehicle Type : Lansi
Registration date : 2009-09-08

PostSubject: Re: AFR : Air-Fuel-Ratio   Thu Aug 26, 2010 8:06 am

strike961 wrote:

Bro Rev, the engine was reflashed to achieve that specific AFR. The device was attached to exhaust ?header if i'm not mistaken. The reading reflects the owner's setting..so should be "actual" gua Smile

How lean can actually stock 4b11 safely go (using RON97) when WOT?
It should be a wide band sensor, otherwise the readings will not be accurate. The sensor replaces our O2 sensor in the exhaust header, correct?
Back to top Go down
Sponsored content




PostSubject: Re: AFR : Air-Fuel-Ratio   

Back to top Go down
 
AFR : Air-Fuel-Ratio
View previous topic View next topic Back to top 
Page 1 of 1
 Similar topics
-
» Wideband Air/Fuel Ratio Meter
» Best Air Fuel Ratio at Full Throttle?
» Oil / Fuel ratio
» Air Fuel Ratio
» A/F Ratio Gauge....NEED HELP

Permissions in this forum:You cannot reply to topics in this forum
Lancer Nation :: Lancer Nation Garage :: 9th Generation Lancer :: Engine/Drivetrain : Engine, Transmission and Performance-
Jump to: