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Old 10-07-2009, 06:42 PM   #1
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Default N/A AFR targets (yes, again)

I've been pondering about this since I was never a 100% happy with the way my AFR targets are setup in MegaTune. I scaled all the tables down to mapvalues used in a non-forced induction motor, but I feel there's more
to improve. Should I really be dipping in the 12.5 AFRs WOT? Not sure if I could lean that out closer to 13 at full load.

Car makes about 140 rwhp on a standalone, exhintake cam swap and dialed-in adjustable camgears.

My idle MAP is between 30-40 kPa, due to altitude and cam overlap, cruising on the highway is usually 70-85 kPa.

Anyone care to take a look at my current target table and the made I cobbled together so far? I attached both tables in the excel file, aswell as a screenshot of the table in MegaTune.

Thanks
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N/A AFR targets (yes, again)-afr-targets.jpg  
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File Type: xls AFR targets.xls (16.5 KB, 82 views)
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Old 10-07-2009, 06:48 PM   #2
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Seems awful rich for a naturally aspirated motor. (EDIT: Seems way rich for any motor)

Peak torque with gasoline is going to be between 12.5 and 13.7 if I remember correctly...so you're at the rich end of that range.
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Old 10-08-2009, 07:50 AM   #3
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My stock ecu goes 13.8 @ at low rpm, than drops towards 12.8 @ peak torque and goes back up to 13.2 towards redline.
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Old 10-08-2009, 08:46 AM   #4
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I firlmy believe that in an NA car, 13.3 should be the upper limit. I'd put my car at 13.1 unless the dyno suggests I go richer.
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Old 10-08-2009, 10:13 AM   #5
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We've found a lot of NA cars seem to run pretty well at WOT in the 13.0 region.
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Old 10-08-2009, 11:13 AM   #6
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on an N/A car there's no reason to go richer than 14s at less than 80kPa unless the motor suggests otherwise by knocking.
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Old 10-08-2009, 11:23 AM   #7
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Quote:
Originally Posted by y8s View Post
on an N/A car there's no reason to go richer than 14s at less than 80kPa unless the motor suggests otherwise by knocking.
Only they make more torque with more fuel, independant from spark adavance, lol.
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Old 10-08-2009, 11:31 AM   #8
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Quote:
Originally Posted by hustler View Post
Only they make more torque with more fuel, independant from spark adavance, lol.
To a certain point...and it starts to diminish around 13.0:1.

I can definitely see dipping below 14.0...I liked 13.8 when I was N/A.
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Old 10-08-2009, 11:48 AM   #9
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Some of the numbers look a bit funny because I was originally using a 12x12 in MLV and then just smooshed it down to an 8x8 in Megatune. Tuned to these targets I get about 33 highway mpg. Might be able to lean out the cruise cells a bit more but I'm pretty happy with it overall. On track with stock horsepower, part throttle is somewhat rare for me. Seems I'm usually either WOT or braking, so I don't need to target ~13:1 until 90+ kPa. Often times in traffic when I accelerate a little from a steady cruise the MAP will get up in the 80s, and it helps with the economy to not have it run so rich in that row.

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Old 10-08-2009, 11:52 AM   #10
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Those "targets" you're showing us are for closed loop EGO correction. Are you running closed loop everywhere in that table?

If you're cruising at 85kPa, why are you so rich there?
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Old 10-08-2009, 12:59 PM   #11
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Quote:
Originally Posted by hustler View Post
Only they make more torque with more fuel, independant from spark adavance, lol.
can you explain "makes more torque" in the context of "not at WOT on an N/A car"?

because I thought making more torque was as easy as pushing your right foot a little further...
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Old 10-08-2009, 01:38 PM   #12
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Quote:
Originally Posted by gospeed81 View Post
To a certain point...and it starts to diminish around 13.0:1.

I can definitely see dipping below 14.0...I liked 13.8 when I was N/A.
Let the dyno do that talking. I made more torque at 11.5:1 than 12.0:1 at 200kpa.
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Old 10-08-2009, 01:41 PM   #13
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Quote:
Originally Posted by y8s View Post
can you explain "makes more torque" in the context of "not at WOT on an N/A car"?

because I thought making more torque was as easy as pushing your right foot a little further...
i skipped over the 80kpa part.
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Old 10-08-2009, 01:50 PM   #14
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Quote:
Originally Posted by hustler View Post
i skipped over the 80kpa part.
that's cuz you live life at 200 kPa, paul walker.
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Old 10-08-2009, 03:00 PM   #15
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Quote:
Originally Posted by hustler View Post
Let the dyno do that talking. I made more torque at 11.5:1 than 12.0:1 at 200kpa.
you made my point
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Old 10-08-2009, 03:06 PM   #16
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Quote:
Originally Posted by hustler View Post
Let the dyno do that talking. I made more torque at 11.5:1 than 12.0:1 at 200kpa.
One day you'll understand that tuning efficient cruise and tuning for max power and both
-are entirely different concepts
-can be optimized on the same set of maps
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Old 10-08-2009, 03:37 PM   #17
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Quote:
Originally Posted by gospeed81 View Post
you made my point
I just stated this from experience. I suggest you put the car on the dyno and see what #'s it makes. It seems that quite a few think those #'s are set in stone.
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Old 10-08-2009, 03:39 PM   #18
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Quote:
Originally Posted by Ben View Post
One day you'll understand that tuning efficient cruise and tuning for max power and both
-are entirely different concepts
-can be optimized on the same set of maps
Do you really want to do this again? I still affirm that retarding spark, with constant fuel, will not yield max fuel efficiency.

BTW, I scored 26mpg on the last tank. lol
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Old 10-08-2009, 03:49 PM   #19
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No, I don't. I never said that and you're obviously beyond help.
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Old 10-08-2009, 03:52 PM   #20
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Quote:
Originally Posted by Ben View Post
No, I don't. I never said that and you're obviously beyond help.
I argued that once achieving target AFR, run the max spark angle and it will maximize fuel efficiency. You're a Down's baby.
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