I know on the 93 models they had a thing called speed density. Can anyone explain to me how this works. I would like to get a simpler way of keeping track of A/F ration rather than the MAF. I'd like to put a ram air hood on eventually but for now just stick a K&N directly on the front of the intake. Also I remeber hearing that speed density was something you could tune like with a laptop... is this true?

 

You can tune either a maf or SD system.
In a maf system, it measures the airflow directly and the ecm uses that number for the Air/fuel calc.
In SD, the airflow is calc'd based on MAP and various temperatures and values listed in the program.
MAF has poor lowspd (idle) measurement, and an upper limit on flow. The LS1's use a different MAF to get solve the flow limit along with a different method of handling the flow value internally.
Both systems have there quirks for tuning.

 

This belongs in DFI & ECM.

 

After having had both SD and MAF with my tbi, I prefer MAF as there are many fewer variables involved with tuning. On top of that, the MAF can directly measure the flow so its easier to keep track of the AFRs as youll know how much air is coming in.

Both systems will work equally well but given some of the shortcomings of the stock thirdgen MAF setups that came with the thirdgens, though, the SD setups are the clear winners. They dont suffer from having the junk bosch maf that cant register enough flow. Like most other bosch products, its unadulterated garbage. The delphi LS1 MAF is much better, but you cant just 'plug it in' as its set up for use with a pulse accumulator and not an ADC.

Both setups can be (and have to be) tuned with a laptop/PC. The speed density setup will be a lot more intuative to tune as youll actually see real life values like volumetric efficiency, pressure based timing tables, etc. rather then just a bunch of tables with airflow values, AFR percentages in them, and that LV8. But, youll definatly need to get a WB and do a good deal of test/tuning to get it dialed in. If your planning on a nice, healthy motor in the future, then migrating over to SD now and getting the hang of tuning with it wouldnt be a half bad idea.