I currently run a 75 shot and I want to up it to 125. I have read a lot of threads about how to run higher nitrous levels and see a lot of people referencing total timing and backing the timing off. I have HP tuners and finding the total timing doesn't seem that simple. The timing charts for low and high octane have numbers ranging all over the place. Can someone tell me how you know what the total timing is? The engine tune is stock. All I have changed is the shift tables and disabled down stream O2 sensors, emissions, etc.
Is the stock tune mild enough to accommodate a 125 wet shot? The engine is a 2002 6.0, rock stock. Thanks

 

If you log a WOT pull, you'll see the commanded timing decrease in lower portions of the spark table. The spots at the very bottom right is generally the 'total timing' that you're talking about.

 

By "total timing" I think they mean the spark advance after all the retards and advances have their say in the mix. For instance if the HO spark table says 34 degrees, but you engine coolant temp spark table is pulling 2 degrees, some other table is adding 1 degree, the IAT table is pulling 4 degrees, and there is some knock so timing retard is pulling 3 degrees, your "total timing" would be 34 + (-2) + (1) + (-4) + (-3) = 26 degrees.

 

Great, now it's just a matter of time before Custm2500 has something "brilliant" to say.

To the OP, how proficient are you at datalogging your runs? If you're not, I'd recommend that you get good at that(and reading spark plugs) before you decide to turn up the juice. When you datalog, there are histograms that will show you your ignition timing during the run, and knock retard(if there was any), and AFR error if you're using a wideband. Get used to reading & understanding these before you start getting more aggressive.

 

I was wondering who would point that out first

 

I have not used the data logger yet... I will do that first and do my best to become proficient. I'll log a few WOT pulls with no nitrous and then a few with the 75 shot. The instructions in my nitrous kit simply say to run a 125 shot, to pull 4 degrees of timing. Seems vague and reckless to me. Thanks everyone.

 

With 93 octane, it's not uncommon for a stock tune to handle a 125-150 shot. Using the scanner is the less reckless route to go though.

 

I've read about guys running shots of that size on the stock tune as well, but I agree that it's reckless.

If you're just hooking up a kit & spraying, you'll see gains, but it's risky. Do it right and TUNE IT AS YOU PROGRESS. That's why you have HPTuners, right? You'll have a safer AND FASTER combo when it is tuned properly.

If you need help or have questions about using the scanner, let us know.

 

I have looked at my tune a little closer and then I looked at a handful of different tunes on the HP Tuners Tune Repository. At higher engine loads, my high octane spark tables are ~20* less than the performance tunes on the repository. Seems like the factory spark tables are super conservative. At the highest load @5200 RPM, my high octane spark tables command 7*.
My next step is to log some data. So after I log a few WOT runs... then what? How do I know where I can safely add timing?
Sorry if this seems elementary to some, but I'm picking it up fast.