AFR's - Talk to me

i've learnt that standard is round 12.2 - 12.5: however under high boost levels you should give your engine lots of attention as you will need to run allot richer also around 30psi it's not uncommon to see arf of 10.5:1, but you need to have a well serviced engine, and should keep an eye on your spark plugs... is that right?

12:2 to 12:5 On a built engine.. maybe.. but even so v.lean....

i am busy learning all this, i bought a book called building and tuning high preormance Electronic fule injection by ben strader.

 

i've learnt so much, i've just finished tuning maps and basic engine calibration, next step is AEM and Motec , i need to get a laptop and get my hands dirty but there's so much to learn i'm considering doing some Motec course's.

 

any one here got any tips on where to learn more, any advise or help would be great

where did you get the book from? would love to read something like that as i know nothing

i've learnt that standard is round 12.2 - 12.5: however under high boost levels you should give your engine lots of attention as you will need to run allot richer also around 30psi it's not uncommon to see arf of 10.5:1, but you need to have a well serviced engine, and should keep an eye on your spark plugs... is that right?

Not learnt much then if you think 12.2-12.5 under boost is standard. Stock ECU will show a plot easily into the 10's at WOT and whilst it may sap some power, I'd trade that off against the risk of det. Most of the people here who have experience of running aftermarket ECU's would consider 11.2 as safe at WOT and nothing leaner than that. You run into the 12's on a single of even on twins at wot and you'll be looking at det or worse a melted piston.

no thats full throttle, what i have read has told me that most N/A engines will like a afr of 13.5:1, with the optimum beging some where slightly richer or leaner depening on the specific engine combination, where as high compression engines will want more fuel, to help them stay cool within limmits and good power output's, turbocharged afr mixtures run as rich as 12.2 - 12.5:1, and most air cooled engines will want to be slightly more richer, high boost levels will need more attention and again may be far richer then given numbers above, as i said its not uncommon to see a ratio of 10.5:1.

thats full throttle, i have only just started reading this stuff so dont shoot me down if im wrong, id rather you gave me helpfull tips.

where did you get the book from? would love to read something like that as i know nothing

amazon, it was a one i was by Jurgens brother he runs a tunning shop called Xo motor sports he mainly specializes in hondas, he maps car's and has done motec courses, so far i have read and learnt the following..

how carburetors work and pro's & cons and how they compare up to fuel injection

the basic's of electronics ( it really goes into detail so you understand how every thing works also teaches you formulas), voltag, amperes, resistance, catch a wave, ecu out put controle

tools and equipment so you can test or trouble shoot should you run into problems also helps to have the know how.

ecu inputs, that teaches you on all the sensors, map, maf, throttle position, coolant,intake,engine speed, camshaft position,knock, oxygen, exhaust, basicly teaches you how they work, what they do, what you can do to them, ie trick them, pro's and cons of mass airflow sensor, there so much in this book its a interesting read.

ecu output, ignition, relays, injectors, matching the injectors to the engine.

tuning maps and basic engine calibration

base fule maps,igniton,idle spark,coolant,air temp,altitude,acceleration, deceleration, basic engine calibration, idle fuel requirements, part throttle and full, understanding ignition timing and correction maps..

it also goes into details so you know how a engine works, under standing how it work what each thing is for, basicly teaches you stuff you dont need to know but is handy to know.

here's the book http://www.amazon.co.uk/Building-Tuning-High-performance-Electronic-Injection/dp/1884089798/ref=sr_1_2/203-9122844-0199940?ie=UTF8&s=books&qid=1193949958&sr=8-2

I would only contemplate running 12.1 - 12.5 AFR with good mappable water injection with all the fail safes, 11.7 is really as much as you want to push it, but you had better have a dam good timing map.

i have only just started reading this stuff so dont shoot me down if im wrong, id rather you gave me helpfull tips.

With all due respect, if you are looking for tips then a new thread would be wise in supra chat or similar.

You are replying in someones tech thread here though and people often assume these are gospel, so saying anything that isnt correct can have implications.

yeah your right soz, i was just trying to help, testing what i had learnt.

yeah your right soz, i was just trying to help, testing what i had learnt.

Sure no worries, always nice to see folk helping, its just bad when its not entirely accurate

i'm guessing the info i given must be accuratish to some point... i mean the guy who wrote the book know his stuff like.

You will probably find Matt that your map looks a bit like this below. This is what mine looked like after they mapped it and as you can see there is no trimming after 4500rpm therefore the car runs very rich or mine did 10:1 all day long. Since then i've corrected the map over and over again to run at 11:1 on WOT across the higher rev range. He may also have used high lag times on your injectors as well.

Not saying that they are wrong but was a bit worried about bore washing.

They didn't spend much time mapping that did they.

I found this word document helped me a few years ago to understand it a little better.

http://www.mkivsupra.net/vbb/showpost.php?p=536680&postcount=23

They didn't spend much time mapping that did they.

well yeah i suppose thinking about the amount of time i've put into it tweaking it. Saying that the car did run ok but it was really rich and i suppose safe.

You will probably find Matt that your map looks a bit like this below. This is what mine looked like after they mapped it and as you can see there is no trimming after 4500rpm therefore the car runs very rich or mine did 10:1 all day long. Since then i've corrected the map over and over again to run at 11:1 on WOT across the higher rev range. He may also have used high lag times on your injectors as well.

 

Not saying that they are wrong but was a bit worried about bore washing.

I think you have hit the nail on the head there rob, that makes perfect sense.

Ive done a bit more monitoring tonight (you forget that your doing like 120 when you observing the gauge!! then you think, umm, maybe i should slow down!) oops!

Anyway, it appears to be just like you say, its a nice 11.2 up until the higher RPM', then it just drops and drops to 10! bit rich from what people are saying isnt it?

Cheers bud

OK Guys

Before 'slagging off' any more of our mapping work I'd like to explain why the tuning is done like it is.

Firstly, we use a laboratory grade Autronics, £1500.00 wideband, not a £200 AEM one that most of you guys are referring too! You wouldn't beleive the difference in the two...chalk and cheese. The sensor alone costs more than the AEM kit. The AEM's are OK if you want to keep an eyen things but I wouldn't take them as gospel and I certainly wouldn't map a car on one!

Secondly, if you run a car anywhere near 11.5 - 12.0 it will blow up. Period. I am certified by the EFI University tutored by Ben Shrader, who gave us a good example when on one of the courses. A 911 runs 10.7 AFR WOT makes 630BHP, and then remapped at 11.2 and make 640BHP, but lasts 500 miles before melting a piston.

A car will make very negligable power increases with a AFR of 10.5 or 11.5, though the car will be a lot safer at 10.5. There is no chance of bore wash on an engine that has 60,000 miles on it running an AFR of 10.0 or 10.5! All power if made through boost / timing increases and surprisingly little through AFR.

Please let us do what we do best, without any unsavoury comments from 'armchair critics'.

Thanks, Chris

OK Guys

 

Before 'slagging off' any more of our mapping work I'd like to explain why the tuning is done like it is.

 

Firstly, we use a laboratory grade Autronics, £1500.00 wideband, not a £200 AEM one that most of you guys are referring too! You wouldn't beleive the difference in the two...chalk and cheese. The sensor alone costs more than the AEM kit. The AEM's are OK if you want to keep an eyen things but I wouldn't take them as gospel and I certainly wouldn't map a car on one!

 

Secondly, if you run a car anywhere near 11.5 - 12.0 it will blow up. Period. I am certified by the EFI University tutored by Ben Shrader, who gave us a good example when on one of the courses. A 911 runs 10.7 AFR WOT makes 630BHP, and then remapped at 11.2 and make 640BHP, but lasts 500 miles before melting a piston.

 

A car will make very negligable power increases with a AFR of 10.5 or 11.5, though the car will be a lot safer at 10.5. There is no chance of bore wash on an engine that has 60,000 miles on it running an AFR of 10.0 or 10.5! All power if made through boost / timing increases and surprisingly little through AFR.

 

Please let us do what we do best, without any unsavoury comments from 'armchair critics'.

 

Thanks, Chris

That Porsche needed some timing removed then

Turbo Race cars run 12.5:1. This is where the most power is to be had. But engines don't last long. Tuning a road Supra to this would be suicide.

Corky Bell, A. Graham Bell and other well established tuners/authors and they all recommend 11.3-5:1 for a good mix of safety whilst still maintaining good power. This is what I've always used. As long as det cans are used during the mapping session to make sure det is not incurred then all should be fine on a road car. 10.5:1 is safe and rich which is fine...as it means that no matter what the enviroment you're driving in the car would be safe (*might* even allow for a lower grade of fuel).

But for a Supra owner who only puts in V-Power etc I'd be only concerned if it went leaner than 11.7:1.

Hmm a little touchy there i think, all i did was comment about the limited adjustments in the piece of the map that is shown, i have similar spec and just fitted larger injectors, and spent thirty minutes tweaking my EMU map and already i have far more adjustments than that! oh and all the injectors are flow tested at less than 5cc of each other.

As for wide bands well most people and tuners tend to use sensor setups based around the Bosch LSU4 which

is used by a lot of major manufacturers for their std ECUs, i myself use the Innovate which is recognised as one of the best on the market, in fact their system of calibration is about to become an industry standard!

Interestingly i have run my last two cars at 11.2 - 11.5 AFR on my less than perfect wide band, and they surprisingly never blew up, but then i don't just tune by AFR alone.

so apologies from an armchair critique:rolleyes:

My car runs 12.5 at WOT and has been checked on SRR dyno with no det. (should I be worried?? )

Yes mate - wouldn't want to run that lean on WOT ! What are your egts like ?

Was your AEM gauge reading 12.5 or the dyno?

Was your AEM gauge reading 12.5 or the dyno?

Both the same

Mate you have one of my favourite Supras on here, be gentle to her and get those WOT afrs down to early 11's

Both the same

Thats a good start

Who mapped it?