Air Fuel Ratios

[adam 32]

what sort of air/fuel ratios are people here running?

im after a balance of good power but also safeguarding against pinging/detonation on a hot day or as a result of some bad fuel, as happened last time if my turbo spikes it will blow the internals as im currently running the std fuel system. am going to upgrade soon but am going to boost it a little as 8psi and 10.8-11:1 A/F doesnt make for a very quick car!

ive been told 12-12.2 is the best range for a safe yet powerful air/fuel mixture, any thought/opinions?

thanks!

adam

[Grim]

yep I'd agree that around 12 is best. Using my SAFC I got my A/F ratio up to 12-12.5 right across the rev range and gained 20rwkw running 11psi.

[JimX]

With the S-AFC, does it "read" what your ratio is from your intake and tell you on the display? Or do you have to hook it up to diagnostic equipment in a workshop and the display is just used to program numbers into it?

I would like to hook up an S-AFC and experiment with it myself without having to necessarily worry about getting it tuned at a workshop, but if a workshop is really required to get any use out of it I won't bother putting it in until I can also afford the tune-up.

Can I easily hook everything up and just tell it to set the ratio at about 12-12.5?

JimX.

[Grim]

The SAFC doesn't tell you the AFR it only allows you to adjust the signal from the AFM to trick the ECU into adding more or less fuel. To tune it you need to hook up an AFR meter and drive around adjusting (or put it on a dyno) the SAFC until the AFM is around 12 across the rev range.

[JimX]

Oh ok. Can you hire an AFR and if so where from? Or can someone lend me one at some point in the future?

JimX.

[turbomad]

Dude the tune for an S-AFC would only set you back around $150, don't play around with A/F ratio's yourself unless your in the know or have rebuild money.

[JimX]

Ah fair enough, I thought it would be a similar price to reprogramming an ECU and I thought I'd be up for a few hundred.

Where's a good place to get it done in Sydney?

JimX.

[Grim]

Yep don't tune it unless you have an air/fuel ratio meter hooked up.

[Grim]

There's an article I've written about the SAFC unit and it's potential here.

[ninjadust]

would there be any benefits in putting the Apexi S-AFC on an N/A??? would there be any power gains??

[Grim]

Originally posted by ninjadust

would there be any benefits in putting the Apexi S-AFC on an N/A??? would there be any power gains??

Yes there definately would be a power gain because Skylines are set to run incredibly rich and once that is corrected you get a lot more power.

[Guest turbogtst]

I dont know about the dyno figures of 12.1 but i leaned my car out to 11.5.1 and it lost power on the road, I know use 10.5.1 under full boost 18 psi on the road, just because you get more power on the dyno at 12.1 does not mean it will be right across the rev range on the road, it was surging at 11.5 to 1

[JimX]

Once you have everything set up and tuned by the workshop, are you then able to tweak the ratios yourself without the meter hooked up? If you need the meter every time it might be worth buying one if they weren't too expensive. Even if they were, you could split the cost between a couple of friends because it's not like you'd need it every day.

JimX.