WOT boost tuning

I have my drive tune pretty good and I'm ready to start on the WOT tuning. I just want to run some things by more experienced tuners and see if I'm on the right track.

I am commanding PE at 13:1 and BE at 11.2. Right now it's going really rich in boost. Is it best to keep working on the VE table to get the AFR numbers in the 11.2 range? For the drive tuning, I logged the AFR in the histogram and changed the numbers on the VE table to get desired AFR. Should I keep doing that for WOT? Or should I mess with the PE and BE numbers to get 11.2:1, then fine tune spots with the VE table?

Engine is an 2000 LS1, T56, 317 heads, ls6 cam and intake, TC76 turbo, Cobalt 2.5 map sensor, 80lb injectors, twin walbro 255s.

Let me know if anything odd sticks out in the tune. I'm a new guy learning.

Attachment 39540Attachment 39541

Change the VE until your fueling falls in line with your commanded. The other way is called "Raping" the PE or BE table and is not the way to go. If you rape it, you have no way of knowing your real AFR% error.

That's what I was thinking. Thank you for your input. Did you happen to look at the attached tune and log? Thoughts?

You're probably going to end up using more timing.

Log Commanded AFR in the same area as the WB. Modify the VE to make the WB AFR match commanded. Your VE needs a LOT of smoothing. Ideally you'd want to start at 1psi and work your way up to what you are planning on running all the time. Interpolate the areas in between.

You definitely need to pull fuel from 3k to redline. Use the charts to make adjustments NOT the AFR % histograms. They are great for cruising and all but the RPM is moving way too fast for them to give an accurate number. Compare the Commanded AFR and WB AFR manually at all RPM cells for a given boost level. 150-155kPa in this case.

Quote:

---

Originally Posted by Exidous

You're probably going to end up using more timing.

Log Commanded AFR in the same area as the WB. Modify the VE to make the WB AFR match commanded. Your VE needs a LOT of smoothing. Ideally you'd want to start at 1psi and work your way up to what you are planning on running all the time. Interpolate the areas in between.

You definitely need to pull fuel from 3k to redline. Use the charts to make adjustments NOT the AFR % histograms. They are great for cruising and all but the RPM is moving way too fast for them to give an accurate number. Compare the Commanded AFR and WB AFR manually at all RPM cells for a given boost level. 150-155kPa in this case.

---

I don't necessarily agree with your suggestion to not use the histogram considering it defaults to average the cell hits and you can make more than one hit to populate the cells, however it's important to consider time alignment whether manually dialing the car in or using histograms. Watch the throttle entry and exit points to get an idea of how much delay there is, if any. Also decel can populate your histogram and somewhat ruin it so when performing boost tuning, consider writing a filter for it to only populate when beyond "X"% throttle or only when it's in PE mode.

Good points. I forgot to mention watching for when throttle tip in and when the WB is reacting. Mines a little slow and have to shift the readings about 2-3 frames.

Every time I've looked at the histograms they'll say as an example that a 10% change is needed when only a 2-3% change is needed. I've found that at WOT the resolution just isn't there. So at say 4400 I'll read the AFR vs Commanded and again at 4800, 5200 and so on. Making very small adjustments. It's just so sensitive. Especially an LS3 MAF in a 4" tube.

The above explanation is mostly for the OP as at 1000+whp you know all that stuff. :-)

Good call on the filters. I'll set some of those up for my cruise tuning.