Would there be an advantage to changing the timing with edit with the mods i have? If so how much at what rpm, load? BTW im turning COT off and multiplying the MAF tap by 107%.

 

Absolutely. Advancing your WOT timing will can increase HP.

If you don't want to put the car on the dyno, ChrisB has a fairly good method for adjusting the timing curve.
His method can be found at the LS1 Edit FAQ.

 

ChrisB's faqs are down (if slowcar.net is it). Could anyone tell me what to do, which tabs etc.

 

Which table would i use to advance the timing?

 

I don't have my notebook on me, so I will be shooting from the hip on the equations, but to get you started...

The table that you want to be messing with is the High Octane Ignition Advance table. This is the table that the PCM is going to be referencing MOST of the time.

The table is referenced as g/cyl and RPM.

To start off, you need to know how to calculate g/cyl....

G/cyl =15 * (MAF / RPM)

You have to convert the MAF from lb/min to g/sec in order for the equation to work.

Now, go out and drive around a bit while logging some data. Do a few WOT runs and get familiar with where you usually put the petal to the metal (ie what RPM). After doing this a few times take a look at your data.
Using the above equation, calculate the g/cyl that you are referencing when the TPS (throttle position sensor) indicates 100%. It should be around .56 g/cyl
Then determine the RPM that you go to WOT.

Getting back to your timing table... locate the timing referenced with the above determined RPM and g/cyl. This is your starting cell, and from this point and up you want to increase your timing a couple degrees. Grab all cells to the right and down of your starting cell (you should have a highlighted blue box now with your starting cell in the upper left corner).

Click the "Use Selected Cells" check box. Enter 2 into the "Mult %" box, and then press "Add".

There, you've just added 2 degrees of timing to your WOT timing.

Go out drive around and log some data. Check to see if you are now generating KR in the upper RPM where you advanced the timing. If you are, then reduce the timing back to where you had it. If not, add another degree or two, and repeat the process. You should top out around 30 or 31 depending on how your car takes to the timing, gas, air quality.... Remember, conditions change so what you put in may not be good with another tank of gas, warmer air etc... Additionally, if you do go too nuts you will get bumped to the Lower Octane table (WOT timing get limited to 19) until you put more gas in your car. Just go slow, and make small adjustments at a time.

Don't worry too much about part-throttle tuning. Your knock sensors tune that curve for you every day.

Good Luck
<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

 

Take what I say with a grain of salt, but I added 2 degrees of timing to my stock timing tables and gained nilch. Then took 2 degrees away and lost nothing. So I ended up with stock timing tables. This was on the dyno of course. Maybe if I went even more to like 4 degrees of timing I might have saw something. Didn't try it. But anyway, my base timing is all around 27-28, that may vary from year to year or car to car (C5 vs F Body).

 

Timing is done as a diminishing return.

The more you increase your timing, the less you will gain. This is why some vehicles may gain more with advances than others.

Try reducing your timing to 20. Then increase your timing 2 degrees. I guarantee that you will see a noticeable increase HP. However increasing your timing 2 degrees above 27 total advnace may only net you a couple ponies.

Good Luck,
<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

 

Thanks for the advice NoGo, i really appreciate it, you're great.

<small>[ October 07, 2002, 06:45 PM: Message edited by: Zshark ]</small>

 

When I installed my ported heads I actually took away timing at the top end and added timing at peak torque. Unless you are on a dyno or out at the track there is no real way of knowing if you are helping yourself by changing the timing. Due to the extremely efficient combustion chambers of the LS1's, they don't need a lot of timing to max max power.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by John B:
<strong>When I installed my ported heads I actually took away timing at the top end and added timing at peak torque.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Your going to have to explain to me your reasoning behind this one.

If the engine can take the timing without running into detonation, why not run the advance at WOT? Sure some of these guys might run into trouble on a hot day if their timing is at the limit (and they zeroed the IAT table). But other than that, I cannot see a reason why not to run the most amount of advance that you can get at WOT.

<img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

A reduction in timing is just making the thermal to mechanical conversion more inefficient.

 

It's a given fact that a motor should make more HP at around a 13:1 A/F ratio as opposed to 12.8:1 ratio. As I began to lean my car on the dyno I would begin to see KR. The difference in power between 28° and running richer vs. 27° and running leaner was about 3 RWHP. So which would yo rather do <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />