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Discussion and questions related to the course Understanding AFR
I have tried to create a starting afr target map for my engine.(work in progress)
Its for a 4age 1600cc na engine with other cams(264 duration 8.3 lift) headwork pistons etc
I dont really care about emissions and/or fuel consumption that much since it will be used for rally.
Would the map in attach be a good starting point
(most people say 4age dont really like lean and for protection i made the map richer)
light blue=>dead zone
dark blue=>start zone
green=>idle and cruising
red=>full load na
brown=>high rpm vacuum
that would be a good starting point but I'd try and get your idle and light cruise closer to 0.95lambda/14:1 AFR, just to make sure your going to be running clean and not fuming the place out.
Once you get it data logged or on a dyno you'll be able to clean it up a bit. No engine likes to run lean unless it's designed for it, you will be able to run close to lambda safely but obviously this will take some testing and tuning
I'd probably suggest that if anything you target a little richer in the high rpm vacuum areas. 14:1 will not cause any ill effect but I'd typically be a little richer in this area to use the additional fuel to help cool the combustion chamber in this area where you aren't really concerned about outright power.
From my own experience with 4AGEs you will likely find the engine will run quite happily at 0.90 lambda at WOT with no detrimental effect but the dyno will be the place to decide. Certainly there is nothing wrong or dangerous with the targets you've got there.
thanks for the responses :)
So in summary:
idle and light cruise closer to 0.95lambda/14:1 AFR
little richer in the high rpm vacuum areas
0.90 lambda at WOT
Rest at the dyno
I have made a new map with these information in mind, would this be better then?
That looks like a pretty good starting point to begin tuning. Let us know how you get on.
ok thanks :)