Max Torque Timing for Main Spark Advance?

[JasonGT]

Hello,

First time poster and new to hp tuners. I read Greg Banish's book several months ago and it got me hooked. I was looking a the Max Torque Timing table and thought it would be interesting to paste that table into the Main Spark Advance Octane table since it is "theoretically" the spark advance that delivers MBT. Before I go all guinea pig, I wanted to see if anyone had tried this, and if so, to what extent was the knock retard?

[ajamesbond007]

Subscribed...

[steeljaz]

I did some searching and found this thread:

http://www.hptuners.com/forum/showthread.php?t=5785

I'll try it out and see how it goes.

[jimmyblue]

That table would be GM's opinion of best timing given the
stock setup, the cylinder charge a stock motore can draw
and so on.

I would expect that filling-improving and extraction-
improving mods would want less timing.

[eficalibrator]

Two words: "Knock Limit"

With a perfect fuel (NOT pump gas), running MBT timing everywhere would be great. It's just not possible without experiencing knock in many cases, particularly high load and WOT.

[JasonGT]

Well I tested the theory and had some interesting results.

After pasting the Max Torque Timing table in the the HO table and blending some areas (not all RPMs from the HO table are in the Max Timing table), I monitored KR and logged absolutely zero KR, NOTHING. What's even stranger is that the car felt slower. Now I don't have a dyno and was just judging by the butt-o-meter, but it was noticeably slower.

Maybe I gave the GM engineers too much credit?

I wouldn't of tried this experiment if I had major mods, but since my car is fairly stock (longtubes, catless mids, exhaust, CAI) I thought it would be an interesting theory to test. Unfortunately it didn't work out, but at least it wasn't the other end of the spectrum and I still have an engine.

[Ed39]

I copied the table on my 07 classic Chevy and it made a huge difference. There was knock and had to make a few test runs to calm it down but it made a world of a difference. I would maybe look at your fuel? Maybe not the right fuel for the timing?

Ps: anyone know how to find the peak torque timing? I installed a new torque converter and its loose down low under 2000 which I expected. I've made timing changes and made it better. I'm just wondering how to adjust the timing for peak torque and not power? I would need a Dyno I assume? Right now I make changes log the data and make sure I have no knock some people will say its not right but not everyone has a wideband and a Dyno in there back yard

[JamesLinder]

in no way should you use max timing for your high octane or any other spark table. this is definitely not the optimal timing for your motor under actual operating conditions, plus you never want idle timing at MBT because you have nothing in reserve when the motor needs more power to operate engine accessories such as when the AC comes on.

[Ed39]

in no way should you use max timing for your high octane or any other spark table. this is definitely not the optimal timing for your motor under actual operating conditions, plus you never want idle timing at MBT because you have nothing in reserve when the motor needs more power to operate engine accessories such as when the AC comes on.

For making power I agree. But a truck with a tight converter and now low end worked well. I left the higher rpm range alone for power. Also at idle the computer references the idle spark table? So it wouldn't have that much of an effect? Right? Cause I've seen spark values off and not what I command and I have the tables 0d out

[JamesLinder]

do not zero out the base spark tables that are used for closed throttle timing; these are used when the vehicle is traveling below the speed established in the PCM below which the motor switches from the main spark tables to the base spark tables.

[JamesLinder]

You are probably seeing the result of the overspeed or underspeed timing adjustment feature doing its job when either too much or too little air is being provided at idle, which can be a serious problem on cold starts. A lot of folks enter too much timing advance at idle, say 28 or 30 when 22 is more reasonable.

[Ed39]

I left the idle tables alone. I zeroed out my afr table ect table the adder/ multipliers. I see the throttle timing table and how it works and when it's enabled for speed I left that alone. I'm just curious if there is a way to know best timing for torque with out I wideband or Dyno. Cause my method is advance the timing till I see knock then back out a couple degrees. Im no expert I come here for information.

[JamesLinder]

this is what ended up working on mine. 230 duration cam.