What do you think about of tune to 12.0 A/F ratio?

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Adrian
Posts: 57
Joined: Tue Mar 13, 2012 1:57 pm

What do you think about of tune to 12.0 A/F ratio?

Postby Adrian » Thu May 24, 2012 9:05 am

I've found a intressting thread on the sr20-forum.

http://www.sr20-forum.com/tuning/16056- ... lcome.html

They say you should tune to a AFR of 12.0!

What do you think about and what are your preffered target A/F ratios?

RomChip200
Posts: 370
Joined: Mon May 11, 2009 7:58 pm
Location: FRANCE

Re: What do you think about of tune to 12.0 A/F ratio?

Postby RomChip200 » Thu Jun 14, 2012 11:08 pm

This is typically my real-life AFRs on E85:
(not WOT but 15.4psi reached below (TPpeak=80 with 740cc injectors on Z32, at WOT, my AFR goes quickly to 11.5-12, to go back to 12.xx)

Code: Select all

Time   RPM   Temp   Speed   TPS   Inj time (LHS)   Inj time (RHS)   Timing   TP   Lambda LHS   Lambda RHS   AFR   AFR RHS   TP (MSB)   Injector duty
05:38.0   3725   80   86   2.3   8.61   8.61   24   11751 [45]   1.06   1.07   15.72   15.74 45   26
05:38.1   3775   80   86   2.44   10   10   23   13481 [52]   1   1   14.77   14.77   52   31
05:38.2   3812   80   86   2.44   10.74   10.74   22   14429 [56]   0.82   0.82   12.08   12.17   56   34
05:38.3   3837   80   88   2.3   11.25   11.25   22   14997 [58]   0.8   0.82   11.86   12.08   58   35
05:38.4   3887   80   88   2.12   11.2   11.2   21   15035 [58]   0.78   0.8   11.52   11.86   58   36
05:38.6   3937   80   88   1.96   10.8   10.8   23   14516 [56]   0.75   0.79   11.12   11.75   56   35
05:38.7   3975   80   88   1.9   10.54   10.54   23   14205 [55]   0.78   0.8   11.58   11.86   55   34
05:38.8   4025   80   88   1.9   10.44   10.44   24   14126 [55]   0.81   0.84   11.98   12.37   55   35
05:38.9   4050   80   88   1.92   10.57   10.57   23   14329 [55]   0.82   0.85   12.17   12.64   55   35
05:39.0   4112   80   88   2.08   11.72   11.72   23   15273 [59]   0.84   0.87   12.4   12.83   59   40
05:39.1   4187   80   96   2.34   13.65   13.65   21   17465 [68]   0.83   0.86   12.23   12.78   68   47
05:39.2   4250   80   96   2.56   14.55   14.55   21   19334 [75]   0.79   0.86   11.74   12.68   75   51
05:39.3   4312   80   96   2.78   15.44   15.44   21   20529 [80]   0.79   0.83   11.64   12.34   80   55
05:39.4   4375   80   96   2.82   15.08   15.08   21   20010 [78]   0.79   0.82   11.65   12.2   78   54
05:39.5   4425   80   96   2.8   14.02   14.02   21   18595 [72]   0.81   0.84   11.95   12.48   72   51
05:39.6   4512   80   96   2.82   14.22   14.22   21   18881 [73]   0.84   0.89   12.36   13.14   73   53
05:39.7   4600   80   106   2.84   14.04   14.04   21   18629 [72]   0.86   0.87   12.74   12.93   72   53
05:39.8   4625   80   106   2.9   14.1   14.1   21   18706 [73]   0.85   0.87   12.55   12.86   73   54
05:39.9   4637   80   106   2.96   14.01   14.01   21   18562 [72]   0.83   0.88   12.34   12.96   72   54
05:40.1   4775   80   106   2.96   13.74   13.74   21   18297 [71]   0.83   0.88   12.33   12.98   71   54
05:40.1   4837   80   106   2.94   13.77   13.77   21   18332 [71]   0.83   0.88   12.33   12.96   71   55
05:40.3   4887   80   106   2.94   13.76   13.76   21   18327 [71]   0.83   0.87   12.06   12.93   71   56
05:40.4   4950   80   106   2.94   13.78   13.78   21   18354 [71]   0.82   0.87   12.06   12.93   71   56
05:40.5   4937   80   114   2.94   13.85   13.85   21   18344 [71]   0.83   0.87   12.33   12.86   71   56
05:40.6   5075   80   114   2.94   13.84   13.84   22   18341 [71]   0.83   0.86   12.3   12.78   71   58
05:40.7   5050   80   114   2.94   13.74   13.74   22   18191 [71]   0.82   0.86   12.17   12.74   71   57
05:40.8   5137   80   114   2.96   13.76   13.76   22   18212 [71]   0.82   0.86   12.14   12.68   71   58
05:40.9   5212   80   114   2.98   13.7   13.7   22   18141 [70]   0.83   0.87   12.33   12.83   70   59
05:41.0   5262   80   114   3.06   13.77   13.89   22   18212 [71]   0.84   0.86   12.45   12.71   71   60
05:41.1   5262   80   114   3.12   13.7   13.7   22   18131 [70]   0.84   0.87   12.45   12.9   70   60
05:41.2   5337   80   124   3.16   13.74   13.74   22   18187 [71]   0.85   0.87   12.52   12.9   71   61
05:41.3   5437   80   124   3.14   13.68   13.68   22   18107 [70]   0.83   0.87   12.3   12.84   70   61
05:41.4   5450   80   124   2.68   13.58   13.58   23   17977 [70]   0.84   0.87   12.46   12.83   70   61
05:41.5   5387   80   124   0.46   4.02   4.02   20   5007 [19]   0.79   0.8   11.71   11.9   19   18
05:41.6   5337   80   124   0.46   1.11   1.87   20   1653 [6]   0.77   0.67   11.4   9.96   6   4


Bernardd
Posts: 253
Joined: Thu Jan 26, 2006 3:20 am

Re: What do you think about of tune to 12.0 A/F ratio?

Postby Bernardd » Thu Jun 14, 2012 11:57 pm

I rely heavily on methanol injection for detonation control/octane and found that I lost a few horsepower at a high 10 afr and didn't gain anything by leaning out the afr's beyond 11.8. I tune for 11.2. Timing is critical and holds the key to power more so than afr's. YMMV

RomChip200
Posts: 370
Joined: Mon May 11, 2009 7:58 pm
Location: FRANCE

Re: What do you think about of tune to 12.0 A/F ratio?

Postby RomChip200 » Fri Jun 15, 2012 12:33 am

Agree about timing.
But I think fuel economy too.

bachig24u
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Re: What do you think about of tune to 12.0 A/F ratio?

Postby bachig24u » Fri Jun 15, 2012 12:37 pm

I think that one man's experience is never another's.

Try not to be blinded by science as it's far from reality at the best of times. (take global warming for instance)

I have personally proven that leaner mixtures make more power but to what extent?
well, in less than 3 seconds a perfectly healthy engine can become a $30K boat anchor. The owner neglected to tell me that the previous days blended fuel had not been blended the same for the current day. If the engine was on the safer side, would not have been a problem but the AFR's under load went up by just 2.1%

If you plan to push the boundaries (which we need to do atleast once) ensure to monitor/record every conceivable parameter.
When/if you get away with it, pat yourself on the back, spend the next few days understanding what happened in the engine to achieve the results. then, go out and prove your theory.
make 1 small change at a time and test it atleast 3 times in the same session to get best mean result.

good luck!!

Romchip E85's Stoich is 9.7:1 .. how does your AFR results come out so lean?

RomChip200
Posts: 370
Joined: Mon May 11, 2009 7:58 pm
Location: FRANCE

Re: What do you think about of tune to 12.0 A/F ratio?

Postby RomChip200 » Fri Jun 15, 2012 11:56 pm

bachig24u wrote:
Romchip E85's Stoich is 9.7:1 .. how does your AFR results come out so lean?



AFR are a matter of display of the widebands gauges.
I tuned E85 since the beginning having my widebands displaying the AFR values related to unleaded fuel and keeping the same references in mind.
Lambdas are consistent behind.

Image

This is just not to modify the parameters of my gauges when sometimes, I put some unleaded fuel in the tank b/c E85 is not available.
My widebands gauges are fixed installed in my car, so I always have an eye on them.

bachig24u
Posts: 662
Joined: Mon Jun 01, 2009 11:46 pm
Location: Austral, NSW
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Re: What do you think about of tune to 12.0 A/F ratio?

Postby bachig24u » Sat Jun 16, 2012 12:38 am

a viable workaround.


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