Was going to post this as a responce to a post in Anthony's thread, but realized that we were getting pretty far off topic... so a new thread it is.

If anyone is interested in understanding X-tau better, I'd really suggest you watch the video here:
http://video.google.com/videoplay?docid=-1671092540772647555&hl=en

It's 20 minutes long, but X-tau is a complicated concept. I think he did a great job of simplifying it enough so that the average gear-head can understand but not over-simplifying it.

The video is of a presentation by Dr. Jim Cowart. From the megamanual:
(Dr. Jim Cowart is a professor at the US Naval Academy. His direct assistance on the X-Tau method has been extremely productive. For those not familiar with him, he worked for Ford calibration department for 10 years before moving on to obtain his doctorate from MIT in engine controls (dissertation was in evaluating wall wetting phenomenon). He reviewed our X-Tau implementation. His feedback we directly implemented in the current code and the user inputs.)

 

Great vid. Thanks for putting up the link. That last slide he put up for only a few seconds before he decided he was out of time looked interesting...

 

Nice vid. I had always realized that the fuel had puddled in a cold engine but never concidered the chenge in pressure. When the throttle is transioned very rappidly to WOT and you get a sudden pressure drop the fuel puddle increases in size. Hmmm I will have lots to play with on this new EFI conversion. I think the drivability will be worth it though.

 

Good listen. Anyone thing it may be a good idea to try and track this guy down and get his notes?

 

I paused on the slide he skipped. I think the message was that o2 sensors in the exhaust do not respond fast enough to be used to control the extra fuel added for the "accelerator pump" equivalent of the FI system. The second part seemed to suggest that the o2 sensor wasn't good enough to do the lab tests either for the transient behavior.