Are stock VE tables purposely wrong? Or am I dumb?

[Supercharged111]

I've gotta stress first off that I don't have EFI Live in my hands yet, waiting on it to ship, but in the meantime I scrutinize my stock tune. One thing I noticed on it and a couple others is that the VE table doesn't peak where my torque peaks, and it's my understanding that torque peak is where the engine moves the most air per revolution. Why then does the table seem to differ from that?

[Redline Motorsports]

I've gotta stress first off that I don't have EFI Live in my hands yet, waiting on it to ship, but in the meantime I scrutinize my stock tune. One thing I noticed on it and a couple others is that the VE table doesn't peak where my torque peaks, and it's my understanding that torque peak is where the engine moves the most air per revolution. Why then does the table seem to differ from that?

In theory you are correct....in reality......well its reality! The LSX based engine typically makes peak torque at 4700 rpms +/-. Most in part to intake manifold design. The VE tables on many calibrations over 4000 tend to trend away from reality because there fuel calulation is biased more towards dynamic airflow (MAF based).

If you want to know when there peak torque is...........long dyn/cyl air mass!:hihi:

Howard

[TAQuickness]

Another thing to keep in mind is that stock calibrations are a compromise of performance and EPA calibrations.

[Supercharged111]

In theory you are correct....in reality......well its reality! The LSX based engine typically makes peak torque at 4700 rpms +/-. Most in part to intake manifold design. The VE tables on many calibrations over 4000 tend to trend away from reality because there fuel calulation is biased more towards dynamic airflow (MAF based).

If you want to know when there peak torque is...........long dyn/cyl air mass!:hihi:

Howard

My engine peaks at 2800RPM I think (L31) but the table keeps on climbing after that, so it's not coincidentally happening at the magical 4000 RPM mark where the MAF takes over. That is a handy little piece of info to remember though. . . what's long dyn?


Another thing to keep in mind is that stock calibrations are a compromise of performance and EPA calibrations.

That's kind of what I was thinking too, although you'd think they'd do their math in the fueling tables and not by fudging the VE table. I thought the OE's were the ones that did things properly!

[joecar]

I believe Howard was trying to say "log GM.DYNCYLAIR_DMA"...:)

[Supercharged111]

It has an X through it, what does that mean?

[joecar]

If it has an X thru it on the chart it means you haven't selected that pid for logging.

[Supercharged111]

It says it's not a valid PID.

[joecar]

If it has a grey X thru it on the PIDs tab, then either one of:
- you have to connect to vehicle and do Edit->Validate PIDs.
- that pid is not supported by your PCM.