Do I need the Speed Density COS?

[MisterGuru]

Hi all! I am Tim, new here. I have used LT1 Edit for a 95 F body very successfully.

I am putting an LSx engine into a rear engine dragster. I have been told at WOT I am in SD mode anyway... what's the deal about access to both spark tables using the SD OS? Can I use the SD OS and the two-sep feature simultaneously?

I am missing something, but I had just planned to leave off the MAF and tune it with a wideband first then take it to the dyno for final touchups and timing tweaking.

BTW - the LT1 liked 37 degrees total advance.... what are you guys seeing on 5.3 and 6.0 engines?

[joecar]

Hi Tim, welcome to the forum...:cheers:

You can run in SD and/or OL in the OEM OS... but in SD the PCM failsdown to the low octane table.

COS5 gives you extra features:
- uses HO and LO spark tables (when knock occurs, the PCM "slides" toward the LO table);
- boost VE/timing tables;
- nitrous VE/timing modifier tables;
- Alpha N (TPS vs RPM) VE table (if you need it);

If you're going to drag race it, you can just stay in OLSD (i.e. leave NBO2's and MAF off permanently).

[MisterGuru]

If you're going to drag race it, you can just stay in OLSD (i.e. leave NBO2's and MAF off permanently).

Yes... other than idling around the staging lanes, we are looking at 5.9-6.1 seconds of WOT at our 1/8th mile strips, and perhaps a few more seconds if I ever run the quarter.

I have a WB O2 - the "sweet spot" for the LT1 was 12.2:1 ratio. What has been your experience?

... the two-step OS would offer me more... since I can tune the LO tables and high tables the same for SD mode essentially ignoring Knock Retard, right?

(don't worry, I am not killing KR until I know the tune is safe! 36-40 degrees probably with 93 octane in a 1500 pound car and a 4500RPM stall. By the time the dragster is moving all the timing is in already!)

Hmmm I am going to have to show up at an LS1 meetup :-)

THANKS! Tim

[oztracktuning]

Its best tuned with TPS fuelling and target near 13.0 or maybe leaner at the strip. I would use less timing than 36 at WOT at peak rpm than that, how much less depends on the dynamic compression ratio. Some cams and dcr combos might not like more than 28 deg at peak power and less at peak torque.