I remember reading about some guys swapping out the front o2s for a set of rear ones. They are supposedly more sensitive then the fronts since they are so far downstream. It seems that the people runnign speed density are the forced induction guys, their maf's run out frequency and cant meter the huge volumes of air that pass through. Other then that reason, seems there is no real advantage of speed density.

 

I think some people are a little confused. Open Loop does not equal (or require) Speed Density and vice versa. The MAF is just another means of calculating the mass of air coming into the engine. Based on this calculation of air, the VE table tells the computer how much fuel is required to produce 14.7:1 AFR. This is then adjusted by the O2 sensors (if present).

Many of the current proponents of SD tuning are doing so because the thought is that the MAF is not very accurate and therefore can't be trusted. Technically, if your VE table is right on, then there's no need for it. The MAP sensor does a jood job of calculating air mass based on load, ambient pressure, and temperature. In general, the LS1 uses MAP under 4kRPM and MAF over 4k. Althought there's an area somewhere in the middle where it uses a combination of the two.

Right now, I'm tuning my VE using the stock MAF but I'd like to see what I can do SD eventually. Without having to worrry about placement of an MAF; cowl induction, L88-style, would be pretty easy (and pretty cool)

-Matt

 

I ran open loop all the time because when you go WOT your computer takes the last reading of your o2s and adjust your wot richness off of that reading. It was giving me some inconsistant times between runs(meaning variations of .1 more or less between runs) due to leaving off of a two step which gave my O2s fits. Once I learned how to lock my BLMs at 28 under WOT no matter what the last reading was I turned the O2s back on. With the BLMs locked I get the exact same fuel each run. I tuned for it and now I can run within .02 at most between passes in the same condition with a 6 speed. If fact..last time at the track I netted 3 back to back dead on ets down to .005. Meaning I went a 10.973, a 10.977, and a 10.975 back to back. But I do agree that in open loop the car was so rich at idle it burned my eyes...I didn't tune alot for it though. But when i turned the 02s back on everything went back to normal for a cam my size.

I agree that the great advantage of fuel injection and computer a conputer controled system is the drivability and the ability for the computer to make adjustments for the driving conditions. I just mearly stated that if someone has a problem about O2 placement that is an alternative..may not be the prefered way and is much harder and takes more time to get the car right but it can be done.