double06

On LS7 motor HCI, headers, MSD manifold and about 11.8-12.0 compression in a stick car. How much timing at WOT (5,000-6,000 rpm etc) is usually done. Pump gas 93 octane. I know there are some variations I am at 21 degrees with a safe tune. I have heard some at 25-26 degrees but that may be a swing for the bleachers type timing. Assuming no knock how much HP might one pick up at 600 rwhp - 10-15 hp at 25 degrees??? Thought someone might have been through this and a can shed some light.

roastin300

Start putting a degree in at a time and do multiple WOT pulls under different driving and environmental conditions (heat soaked engine bay after sitting at idle, cool and hot day, etc tec) and see if it knocks. Keep going until you see the start of knock activity and then back out a couple degrees. If its apparant on a hot day and not on a cold day then make your IAT ignition retard a little more aggressive that way you keep the power in it on the cooler days.

Another tip: eliminate the AFR timing advance table. Make it all 0. Then you can more consistently control timing using the main spark table, and the IAT and Coolant Temp tables.

double06

Your methodology above is what has been done on mine. I was just trying to survey what other people are running with regards to total timing at higher rpms with pump gas on an NA motor with cam headers etc.

TurboLX

BAD IDEA.

Flame propogation speed changes with AFR. It's physics, and this is why this table exists in the ECU. Dialing it to zero changes the delivered timing, but can NOT change the physics of what's happening inside your engine.

You would be better served to explore the options of running rich with more total timing vs lean with less total timing (as this table already helps compensate) and see which combination gives you best power without overheating anything (like the catalysts, O2 sensors, etc). Hint: GM already did a really good job of this.

Frans96ss

I've never seen an ls7 like 25 degrees unless the cylinder head is a pile of ****. Most like 21-22. Some even less

double06

Thanks Fran.

IansInGarage

Da Z06

Frans,

Can you expand on that statement? Why will a crappy head tolerate more timings vs a good head?

Very interesting.

Thanks!

Unreal

Chamber design, flow, etc all have big effects on timing a car can take, and be efficient at.

Asking questions like this online is an easy way to hurt a motor. Tune what your motor likes. Could be 15 degrees or 28 degrees. I've seen it all over. Even the cam timing can be off a few degrees from grind to grind, etc.

Frans96ss

The more efficient the cylinder head the less timing it will need. Old SBC stuff likes 36 or so degrees of timing while an LSX depending on head wont take more than mid 20's or so.

Pekka_Perkeles

So, since AFR is not measured (by the PCM), how do you tune this table?

Souds like a burst knock stuff to me.

Also agree with 21..22 degrees of timing.

TurboLX

The table input is COMMANDED EQ RATIO. If you have done the fuel injector characterization and airflow mapping (both MAF and Virtual VE) correctly, your actual AFR and commanded AFR should be the same thing.

Pekka_Perkeles

Now I understand. And they are after tuning.

I see your point though. But it's all about the money and most customers do not pay for tuning as much as GM does internally.

May I ask, how many hours (weeks?) it takes to tune a new GM engine?

Corvalex

This is the original GM "Max torque timing table" from a ´09 LS7 (without knocking):



At high revs with full-throttle (CylAirmass 0.80-0.96) i read the perfect timing between 24-26.

TurboLX

That depends. At the OEM level, starting from scratch all the way to passing emissions, meeting warranty and power targets, and drive quality tuning, it's THREE YEARS.

If you're talking about starting with a running LS3 (GenIV, fixed cam) and just adding a supercharger, cam, induction, and fuel system, it normally takes about 5 hours with the right tools to get the base mapping done, then a handful of cold starts later, followed by some minor tweaks to get to what most consumers here would consider an excellent tune. Adding variable cam or direct injection just adds more time on top of that. Starting with a known good calibration from the manufacturer is always nice.

Polishing some more in order to meet emissions on a CARB legal emissions package adds another week or so as long as nothing mechanical interferes. Having the right test environment and equipment is absolutely key here though. This is not something I do just driving around on the road with a scanner.

Pekka_Perkeles

My god.

Thanks Greg.

Agree.

I have always enjoyed your videos and how you have been very helpful for our tuning community.

Thanks again.

truth.b

Can you post some links to his videos, as I'm new to tuning and have just started to work with my C6 Grandsport with catted headers. The base tune was okay but now my plan is to go through it with a fine tooth comb over the next few months.

Pekka_Perkeles

https://www.youtube.com/user/eficalibrator/videos

TurboLX

My YouTube channel only has the demos (and some waterskiing). If you want to get the whole training video, you can order directly through our partners HERE. Summit Racing Equipment also stocks them.

Pekka_Perkeles

Indeed.

These are very good and worth the price. Ask me how I know...