Datalog graph - AF vs RPM using mafterburner
#1
Datalog graph - AF vs RPM using mafterburner
Here is a recent (simulated, of course 3rd gear WOT run at 16 psi. The data was imported into excel to produce the graph below. Your thoughts on the AF ??
Last edited by brrgrr; 11-04-2012 at 07:46 PM.
#2
Too lean between 3-5K. It should be slopping down from 14.7 at 2K to 11.8-11.5 by 3.5K, then flat at 11.8-11.5 to 6.5K. Running +13 at 4K is begging for detonation. All my answers are of course, simulated
Last edited by Bri Bro; 01-15-2010 at 12:20 AM.
#4
Addict
Rennlist Member
Rennlist
Small Business Partner
Rennlist Member
Rennlist
Small Business Partner
Joined: May 2006
Posts: 5,252
Likes: 6
From: Denver
Peak torque (when boost first hits ~16psi), is where your richest spot should be. That is where you are most likely to knock...
I would shoot for mid/low 11's at peak torque, then hold 11.5-11.8 for the remainder of RPM.
-Rogue
I would shoot for mid/low 11's at peak torque, then hold 11.5-11.8 for the remainder of RPM.
-Rogue
#6
Drive-by provocation guy
Rennlist Member
Rennlist Member
Joined: Apr 2002
Posts: 10,439
Likes: 0
From: NAS PAX River, by way of Orlando
As I have learned from Rogue, it is more boost incumbent than rpm.
Think about it, an NA motor runs about 14.7 at idle and at 6K and no issues because there is no boost.
So a super quick spool would need to be in the 11-12's maybe by 2,500 and a laggy turbo maybe not till 4K.
How much room is there to lean it up to aid in spool up? I assume you would still want to be under 13 even for spool up?
Think about it, an NA motor runs about 14.7 at idle and at 6K and no issues because there is no boost.
So a super quick spool would need to be in the 11-12's maybe by 2,500 and a laggy turbo maybe not till 4K.
How much room is there to lean it up to aid in spool up? I assume you would still want to be under 13 even for spool up?
#7
The car has a Kokeln stage V turbo, 3" exhaust, MAF, LR Stage II head and intercooler, 65 lb injectors, MBC, LR DP wastegate, Tech edge WB, and a few other things.
This run was a 2500 rpm "roll on" to WOT - boost builds progressively starting at 2800 or so and hits 16 psi by 3400.
I will be adding a little fuel in the 3500 - 5000 rpm range to get into the low 12's. You actually tune using the MAF Voltage as a reference, so this is the graph I use to actually make adjustments......
This run was a 2500 rpm "roll on" to WOT - boost builds progressively starting at 2800 or so and hits 16 psi by 3400.
I will be adding a little fuel in the 3500 - 5000 rpm range to get into the low 12's. You actually tune using the MAF Voltage as a reference, so this is the graph I use to actually make adjustments......
Last edited by brrgrr; 11-04-2012 at 07:46 PM.
Trending Topics
#9
Daily use I am only displaying boost, AFR, and Knock counts on the dash so I can see when something blows up...
#11
I've been tuning my AFR on mine (LR 340 kit) with my laptop in the car with me. It seems that it's boost, or load, that dictates the AFR more than rpm. Is that correct? I can be running in 3rd at 4k rpms and be fairly lean (14 ish) since I'm under no boost, then when I dip into the throttle and boost builds, the AFR adds fuel in a nice curve towards 11-11.5 at WOT.
I say all this not as a pro, I'm learning too and just wanted to put some more info in the pot, but it seems like when we're off boost it's basically like an N/A car... right? So, higher rpms without load wouldn't necessitate a rich condition..
And yes, it is nice having all the gadgets to monitor and adjust everything... ;-)
I say all this not as a pro, I'm learning too and just wanted to put some more info in the pot, but it seems like when we're off boost it's basically like an N/A car... right? So, higher rpms without load wouldn't necessitate a rich condition..
And yes, it is nice having all the gadgets to monitor and adjust everything... ;-)
#12
I've been tuning my AFR on mine (LR 340 kit) with my laptop in the car with me. It seems that it's boost, or load, that dictates the AFR more than rpm. Is that correct? I can be running in 3rd at 4k rpms and be fairly lean (14 ish) since I'm under no boost, then when I dip into the throttle and boost builds, the AFR adds fuel in a nice curve towards 11-11.5 at WOT.
I say all this not as a pro, I'm learning too and just wanted to put some more info in the pot, but it seems like when we're off boost it's basically like an N/A car... right? So, higher rpms without load wouldn't necessitate a rich condition..
And yes, it is nice having all the gadgets to monitor and adjust everything... ;-)
I say all this not as a pro, I'm learning too and just wanted to put some more info in the pot, but it seems like when we're off boost it's basically like an N/A car... right? So, higher rpms without load wouldn't necessitate a rich condition..
And yes, it is nice having all the gadgets to monitor and adjust everything... ;-)
#13
It is total mass - airflow through the MAF that dictates fuel. As the total mass-air goes up, the voltage output from the MAF goes up, and it dictates a different spot on your "fuel curve" At high rpm and no boost - you are not pumping nearly as much air as high rpm and full boost.
To answer the earlier question on boost - No, I don't have the ability to log it - I know about where it falls on the fuel curve but it would be nice to see it exactly.
To answer the earlier question on boost - No, I don't have the ability to log it - I know about where it falls on the fuel curve but it would be nice to see it exactly.
#15
Drive-by provocation guy
Rennlist Member
Rennlist Member
Joined: Apr 2002
Posts: 10,439
Likes: 0
From: NAS PAX River, by way of Orlando