Anyone running 12:1 afr on 91 for daily use? I was playing around with my afr and tuned it to 12:1 through most of a 3rd gear pull. I did not get any more knock than my previus 11.3:1 tune. Also according to my ECU+ dyno I picked up a few ponies and flatened out my torque curve. The big concern for me is that I am not monitoring egt so I am guessing that 11.3:1 my be a better bet. Mods are 3 inch tbe, blitz intake cover, green filter, mbc set to 22 psi that tapers to 19 and sun hyperforce. Any input?

 

I would bring it back to 11.5, it will be alot safer and a few hp is not worth the risk.

 

12:1 for 91 seems to be too lean for that octane. But then again you have no knock what are you using to measure knock and afr? Then again I am no expert either....

 

Heres a plot of my 11.3:1 afr.

 

I have a ECU+ piggy back that monitors the knock sensor voltage and I have a LC-1 wideband.

 

Here are all three maps:

 

The lowest plot averages at 11.25, the middle is about 11.6 and the top is around 11.9.

 

12 is too lean for that boost! it will only take 5 seconds of knock under specific conditions and you will have a dead motor... 11.3 if you are over-cautious, 11.5 is a good for your mods.

 

How does you timing curve look like? post a log for us of your Evoscan timing. It is a trade off between AFR and timing. If you lean the AFR, then you retard the timing. If you are concerned that you might get knock, then back off your timing and stay @ 12:1. Personally, I would not run @ 12:1 on 91 pistane gas. But it can be done if you back off the timing to stay in the safe zone under varied weather conditions.

 

I can post my timing map. I use a ECU+ for logging instead of evoscan. Currently I have switched back to 11.3 afr and bumped the timing a little.

 

sounds like a better idea for a few ponies! you could add a lil more timing before the boost spike and then keep your values from 4k-5k the same to drop the timing back down to prevent knock on the spike

 

Trust me when I say the knock voltage is not telling the whole story. I was using ecu+ alone for logging and thought I had a good knock free tune, until I logged a few runs with evoscan.

 

Every once and awhile I run evoscan just for a sanity check. But I am going to stick with the 11.3 afr for safety. I am really concerned with leaning out the afr without egt measurements. Thanks for the input guys.

 

man is it just me or does his timing map look way too conservativle.

 

Its pretty conservative.. Its more or less the type of timing I run to do a sanity check on my bit turbo.. But its actually good that he's starting low and working his way up..

We also don't know what load cells he's hitting.. Its possible he's also hitting those lower load cells due to the ECU+, he may be altering the MAF reading to do that since it indirectly leans out the fuel and timing by running in lower load cells.

In any case, even at lower load cells, the tune is conservative for the most part.