What AFR am I aiming for across the rev range?
Turbo Mini Forums

I have finally got my mini on the road with the AFR gauge working.

I think I've worked out how to log the SU dashpot piston deflection real time so I can compare the
needle dimensions with the AFR results to calculate what I need. I'll write this up if it works.

I plan to start trundling along in 3rd and slowly accelerate (so the dashpot damper doesn't affect the mixture) to map the mixture against engine revs/ needle position.

What AFR am I aiming for across the rev range for good driveability in a normally aspirated 1275
(standard engine) ?

Thanks for any pointers,

Nial.

i believe i dont have much of a clue so take what you want lol others will correct me if im wrong i hope =/
you want it lean at declaration kinder lean at cruse/coasting no load constant speed then ritchen up as you actually make power ie start pulling away/boosting thats in order to have good econamy but when i do my car ill be well ritch and work to the lean side of things for safety

12.5-13 AFR on WOT and cruise more around the 14-15 range, it all depends on spec of the engine as to what it runs best at. If you're running mapped ignition then before you go mad on filing the needle, it's worth advancing / retarding the ignition as you go as that will have an effect on you AFR readings.

You may find that you have Fueling set up perfectly but then when you adjust the ignition timing, (if its not already optimised) that it will lean out slightly.

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1/4mile in 13.2sec @ 111 terminal on 15psi

Thanks Matty.

I'll aim for 14 ish at part throttle 'rising' to 12.5 - 13 at full speed.

Ignition's standard 1993 1275 distributor at the minute. I am planning mapped ignition at some point in the nearish future but would like to
get the fuelling nearer being sorted so I can drive the car without constantly mucking about with the choke cable!


Nial