BlueStreak
03-30-2012, 11:08 AM
This was posted on MSF by Bucker. One of many gearheads over there.
Good info.
I hear tons of talk about fueling this, fueling that, lean me out to make more power! etc. etc. I am here today to demonstrate that leaner mixes generate little to no addition power at the expense of a higher tendency to knock. The ONLY advantage to leaner AFRs I can find are increased headroom for fueling for those who are taxing the DISI fueling system.
I have seen this on my car running as lean as a 13.4:1 gas AFR compared to a 12.2:1 gas AFR that I daily drive. I really started to suspect it meant nothing more recently when I flashed a tune that commanded a 10.8 AFR with all other parts of the tune being the same. I did this because I am running nitrous and I need to be that rich to compensate for the increased O2. What blew my mind what that the tune ran exactly the same as my daily driven tune. The SAME. Logs and VD plots were identical.
I couldn't just say that was a good enough test, though. Other things fell in to line and a member that I am tuning came to me and asked to have me try something: make 2 identical maps, one with an 11.0:1 AFR and one with a 12.0:1. I obliged.
Attached are the logs, and below is the VD plot.
http://i.imgur.com/B7nez.jpg
Don't say it gained 5 peak WHP. It didn't. To confirm that, look at the lower and upper regions of the plot, where the richer run makes "more" power. What this says is that AFRs play a very minute role in power production for us.
Good info.
I hear tons of talk about fueling this, fueling that, lean me out to make more power! etc. etc. I am here today to demonstrate that leaner mixes generate little to no addition power at the expense of a higher tendency to knock. The ONLY advantage to leaner AFRs I can find are increased headroom for fueling for those who are taxing the DISI fueling system.
I have seen this on my car running as lean as a 13.4:1 gas AFR compared to a 12.2:1 gas AFR that I daily drive. I really started to suspect it meant nothing more recently when I flashed a tune that commanded a 10.8 AFR with all other parts of the tune being the same. I did this because I am running nitrous and I need to be that rich to compensate for the increased O2. What blew my mind what that the tune ran exactly the same as my daily driven tune. The SAME. Logs and VD plots were identical.
I couldn't just say that was a good enough test, though. Other things fell in to line and a member that I am tuning came to me and asked to have me try something: make 2 identical maps, one with an 11.0:1 AFR and one with a 12.0:1. I obliged.
Attached are the logs, and below is the VD plot.
http://i.imgur.com/B7nez.jpg
Don't say it gained 5 peak WHP. It didn't. To confirm that, look at the lower and upper regions of the plot, where the richer run makes "more" power. What this says is that AFRs play a very minute role in power production for us.