Turbolarry - Timing Advice

3865 Views 9 Replies 5 Participants Last post by Fourdoor, Jul 4, 2005

Warrtalon

Discussion Starter · May 27, 2005

Turbolarry, I tossed on a 3" cat-back last night, then got together with ldstang50 to do some tuning. I was supposed to have my Hallman so that we could do some REAL tuning, but instead, it was just some light tuning, since the exhaust didn't invoke a need for many changes, nor did we have to worry about setting boost at a certain level. I already had the S-AFC tuned in really well to begin with, so we only made some minor changes, but I have now gotten to the point where my 02s are beautiful, and my timing advances wonderfully, but I'm afraid it's advancing too far. What are the ramifications of timing advancing too far? I originally worried that it would potentially raise my EGTs, but after reading on EvoM, I see that increased timing LOWERS EGTs, which at least relieved me for the moment. Take a look at these 2 logs, and let me know if you have any suggestions on some changes. I'm not sure how to keep the O2 curve flat while advancing the timing steadily without going over 20. I keep hitting 21 at 6700rpm or so...

RPM 02 Tmng AFC
3820 93 3 +3 (4000)
4199 93 8
4570 91 9 +2 (4500)
4929 91 10 0 (5000)
5273 93 9
5636 93 11 -1 (5500)
5953 93 14 -2 (6000)
6285 93 16
6597 93 17 -5 (6500)
6898 93 20 -8 (7000)
7164 93 20 -12 (7500)

Now, for the 2nd log, I tried to take the timing dip out of 5273 while leaning out 4500-6000 to the point of hitting .91. Above 6000, I wanted to stay at .93v all the way to redline just to be safe. I haven't been losing timing, so I didn't see a need to push the AFR in street mode.

RPM 02 Tmng AFC
4023 93 4 +3 (4000)
No reading
4593 91 10 +2 (4500)
5128 91 10 0 (5000)
No reading
5605 93 12 -3 (5500)
6000 93 15 -3 (6000)
6394 93 17
6718 93 21 -5 (6500)
7015 93 22 -8 (7000)
7308 93 23 -12 (7500)

I actually didn't even pay attention to the richness and suppressed timing at the 4k level, because it is usually leaner, but I think the turbo is spooling up sooner then hitting full boost sooner, so the 3800-4000 o2/timing needs to be addressed. I'm going to take a little fuel out of my 4k setting for next time, so that I get the timing advancing sooner and so that the o2 is .91v. After 5500, I still have a lot of room, but I am hesitant to pull out more fuel on the road. I'm happy with the power, and everything is running nice and smoothly. I could get the 5500-6500 down to .91, but then wouldn't the timing advance even more? What's the downside of having my timing go all the way up to 23 near redline?

Btw, thanks for all the help, Liam! Can't wait to go for a [email protected]

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turbolarry

· #2 · May 27, 2005

Warrtalon said:
What's the downside of having my timing go all the way up to 23 near redline?

Technically; high timing plus high boost levels equals a greater chance of serious damage. Keep watching what's going on with the timing while your subtracting fuel or adding boost. If your just starting to knock, it will get flat. If it get's worse, the ECU will pull the timing. That knock sensor and ECU are looking out for you too.
I think the second log looks OK with good advance after 4500 RPM's. What's your boost at readline?
When the boost controller goes on, just keep things balanced and make the ECU happy.

If your happy with the power at .93 volts, but want to take out a little more, shoot for a straight .92 volts.
How come there's spot's with no reading?

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ldstang50

· #3 · May 27, 2005

turbolarry said:
Technically; high timing plus high boost levels equals a greater chance of serious damage. Keep watching what's going on with the timing while your subtracting fuel or adding boost. If your just starting to knock, it will get flat. If it get's worse, the ECU will pull the timing. That knock sensor and ECU are looking out for you too.
I think the second log looks OK with good advance after 4500 RPM's. What's your boost at readline?
When the boost controller goes on, just keep things balanced and make the ECU happy.
If your happy with the power at .93 volts, but want to take out a little more, shoot for a straight .92 volts.
How come there's spot's with no reading?

Hi Larry, I was with Clayton last night helping him tune.
The stock boost gauge is really hard to read. He was spiking 1.4bar (20.3lbs) then falling to 1.2bar (17.4lbs). Thats pretty much were it stayed. There were 1 or 2 runs were it looked like the boost came back up to 1.3bar (18.8lbs). With a MBC this boost 'problem' will be solved and he won't have the fluctuating boost like he has now.
We would love to have the car tuned at .92v but his logger only reads in odd numbers. So its either .91 or .93.
The reason for the blanks is the logger was throwing out rpm numbers that the AFC was not exactly set for. So what it looks like to me the way he has it written down is the AFC was running say +2 fuel from 4000rpm to 4500rpm, but the log showed 4200rpm.
One thing is for sure, with just and at back and AFC, his car pulls hard as sh!t!! I was very impressed.
Clayton, if you get your MBC today, let me know, we can go out again tonight and get that set.

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Warrtalon

Discussion Starter · #4 · May 27, 2005

turbolarry said:
Technically; high timing plus high boost levels equals a greater chance of serious damage. Keep watching what's going on with the timing while your subtracting fuel or adding boost. If your just starting to knock, it will get flat. If it get's worse, the ECU will pull the timing. That knock sensor and ECU are looking out for you too.
I think the second log looks OK with good advance after 4500 RPM's. What's your boost at readline?
When the boost controller goes on, just keep things balanced and make the ECU happy.
If your happy with the power at .93 volts, but want to take out a little more, shoot for a straight .92 volts.
How come there's spot's with no reading?

But is 23 too high? Do I have to induce knock at the higher rpms to keep it from advancing too far? I'd have to add fuel in the high rpms to induce knock to keep the timing from advancing as much, and that will rob power, but if 23 is ok, then I can stay where I am. I really wanted the timing curve to climb like it does but end up at 20. I'm just not sure how to keep it from advancing so aggressively during the 6-7k range without DETUNING it. I even have room to squeeze out more power by tuning those ranges down to .91v, but I'm afraid it will give me even more timing.

Yeah the boost was consistently spiking to 1.4 bar then falling to 1.2 or so. This tells me that the stock gauge is reading perfectly (if not, then my factory boost isn't right). Because of this, I'm very eager to see how much I can gain with a Hallman set at 21psi that doesn't taper...or at least that doesn't go below 1.4 bar. That, combined with the fine tuning of the S-AFC in addition to the MBC, is how I hope to get a 12.4.

As for the blank spots, I'm not sure. I was recording the readings, and somehow there were no intermediate readings in those 2 spots, whereas in the first run, there were readings. Since the logger reads based on certain time increments, I guess it's possible I was accelerating faster through that rpm range. In basically the same rpm range, I went from 11 readings to 9...hmm.

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ldstang50

· #5 · May 27, 2005

Warrtalon said:
As for the blank spots, I'm not sure. I was recording the readings, and somehow there were no intermediate readings in those 2 spots, whereas in the first run, there were readings. Since the logger reads based on certain time increments, I guess it's possible I was accelerating faster through that rpm range. In basically the same rpm range, I went from 11 readings to 9...hmm.

Thats what it was, the computer couldn't keep with ludacris speed! lol
There really is not rhyme or reason for it to miss reading like that. If thats the case, then the logger wouldn't work if you added more mods. Hopefully it was just a fluke thing.
If you were to add fuel at higher rpm, that would richen it up and maybe take away timing. You didn't try adjusting up there yet so maybe on the way home, add 1% at 7000rpm and log to see what she does. No harm in trying.

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turbolarry

· #6 · May 27, 2005

At 1.2 bar, the peak 23 degrees of advanced timing is fine.
Once the MBC is in, you'll add more air, so add more fuel. Which means turn down the AFC (ECU sees more air) and you'll see less timing.
Ludacris speed! :laugh:

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ldstang50

· #7 · May 27, 2005

With the boost set at 21lbs all the way through, I would think top end you would want to add about 2% fuel. Sound like a good starting point?
Larry, Clayton brought up a great point with the settings he has on his AFC.
He starts tuning at 4000, then goes 4500, 5000, 5500, 6000, 6500, 7000, 7500. He said he choose these settings because he is never below 5000rpm at the track. For track tuning, those are great numbers to tune with. It really allows him to fine tune where his rpms are.

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Fourdoor

· #8 · May 28, 2005

Warrtalon said:
But is 23 too high? Do I have to induce knock at the higher rpms to keep it from advancing too far? I'd have to add fuel in the high rpms to induce knock to keep the timing from advancing as much, and that will rob power, but if 23 is ok, then I can stay where I am. I really wanted the timing curve to climb like it does but end up at 20. I'm just not sure how to keep it from advancing so aggressively during the 6-7k range without DETUNING it. I even have room to squeeze out more power by tuning those ranges down to .91v, but I'm afraid it will give me even more timing.

Yeah the boost was consistently spiking to 1.4 bar then falling to 1.2 or so. This tells me that the stock gauge is reading perfectly (if not, then my factory boost isn't right). Because of this, I'm very eager to see how much I can gain with a Hallman set at 21psi that doesn't taper...or at least that doesn't go below 1.4 bar. That, combined with the fine tuning of the S-AFC in addition to the MBC, is how I hope to get a 12.4.

As for the blank spots, I'm not sure. I was recording the readings, and somehow there were no intermediate readings in those 2 spots, whereas in the first run, there were readings. Since the logger reads based on certain time increments, I guess it's possible I was accelerating faster through that rpm range. In basically the same rpm range, I went from 11 readings to 9...hmm.

If you are not getting knock then it isn't advanced too far. If you manage to run 40 deg without knock then you are fine.... it is all about knock, not about how much advance you are running.

The ECU is tuned from the factory to lower timing advance as the engine comes up on peak torque (highest combustion chamber pressures) and then advance it back up after peak torque as you go up toward redline.

Now if you start running substantially more than stock boost you may want to de-tune the fuel to reduce the timing at that point... but ONLY if you start getting knock. And that mainly depends on what fuel you are running.

Keith

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Claudius

· #9 · Jul 4, 2005

Fourdoor said:
If you are not getting knock then it isn't advanced too far. If you manage to run 40 deg without knock then you are fine.... it is all about knock, not about how much advance you are running.

Hi there

Long time no speak ...

Regarding the ignition advance settings, while you're right in practice on lowly tuned cars, IMHO the "correct" ignition advance setting depends on a bit more than whether the car detonates or not.

You mentioned combustion chamber pressures. As you know, the more you advance the ignition, the leaner the fuel mixtures and the higher the boost, the higher the combustion chamber pressures.

All that to say that, even if you may well run 30 deg of timing in the high rev range at relatively low boost levels like the aforementioned 1.2 bars relative, you will certainly make a few more hp, but also run much higher combustion chamber pressures and have less reliable an engine.

What's the 93 / 91 in the O2 column? Lambda values ie. 0.91 / 0.93 lambda ie. 13.4:1 or so AFR?!

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Fourdoor

· #10 · Jul 4, 2005

Claudius said:
Hi there

Long time no speak ...

Regarding the ignition advance settings, while you're right in practice on lowly tuned cars, IMHO the "correct" ignition advance setting depends on a bit more than whether the car detonates or not.

You mentioned combustion chamber pressures. As you know, the more you advance the ignition, the leaner the fuel mixtures and the higher the boost, the higher the combustion chamber pressures.

All that to say that, even if you may well run 30 deg of timing in the high rev range at relatively low boost levels like the afore mentioned 1.2 bars relative, you will certainly make a few more hp, but also run much higher combustion chamber pressures and have less reliable an engine.

What's the 93 / 91 in the O2 column? Lambda values ie. 0.91 / 0.93 lambda ie. 13.4:1 or so AFR?!

Hey Claudius,

About timing I was speaking in terms of tuning with an AFC and it's indirect effect on timing. If you actually have control of your timing it is a different story

Best way to adjust timing in a system where you have direct control is to use a load bearing dyno, and adjust timing until you see torque start to drop off... that is for max power, and you can take all those settings and back it down 3 deg or so at each point for a daily drivable tune.

About the O2 reading they are talking about, that is the voltage being read from the stock O2 sensor. The sensor reads from 0 to 1 volt and is only really acurate at stoichiometric ratio so any reading from it should be taken with a grain of salt. Anything above .93 is really rich, below .90 is pretty lean (for WOT operation)... but unless you have had your car data loged while on a dyno with a wide band O2 sensor you never really know exactly what those voltages equate too.

Keith

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