ignition timing and A/f Options

[ncgalant]

Alright, lets get down to it. I'm looking for power. Given that, which is better, a little richer and more ignition timing, or leaner and less timing? Currently I'm working toward the latter, but want some input from some that run fast.

Also, which is better for spool, lean or rich. I can't get my pre-boost #s into the rich range. If I do a 3rd gear pull from 1500-6500. My O2s will read .08 until 3500 or so when they jump up to .8 and then .9 around 4000. My setup is working, but I want it to be the best it can be. I can post up my SAFC settings if you guys want too. Their F'd up.

[KOU In3]

Spool should be better the leaner you are. Hotter egt's is going to mean more exhaust energy to spool the turbo at the same rpm.

There's a quote somewhere that says something to the extent that "youre car will never feel so fast as it does the moment before it liquifies it's pistons." You get the idea.

[ncgalant]

I know the stock O2 sensor is worthless, but I do know one thing < .5 is < 14.7. Won't it hurt spool to be that lean? I was thinking I want to get it around 14.7, but keep riching up the bottom end with no results. I'm thinking the only way I can get my setup tuned properly is with the SAFC going by boost in stead of throttle. I'm at -2 on the bottom and -35 on the top

[natedogg]

I'm pretty sure I have the map sensor (3 bar if I remember right) and casing that you need to run your SAFC off boost rather than throttle position. I was going to do this back when I had an SAFC. I'll check the garage when I get home.

If you have to choose between the two, leaner and less timing, vs. richer and more timing, I would choose the former as far as power goes. As far as engine safety goes the latter is probably your best bet. It just sucks that you can't see how much knock you are running with the OBDII set up. When Marcus and I would log his car and my old fwd, they both always felt quicker while running leaner on more boost and with less timing (due to knock readings causing the timing to get pulled). Not really the safest for the engine, but that's the rub.

If you want the best of both worlds try some xylene, toulene, or some 100 oct. I just logged my car on the way to work this morning and saw 27 to 30 degrees of timing at 26 psi and 0 knock while running 100 oct. My wideband 02's were reading right around 13.5:1 AFR. You will rarely if ever see a perfectly stoichmetric ratio on a turbocharged engine at WOT. Its just too lean. Hell, I think the 13.5 that I'm running is too lean, but she's not knocking and if I richen her up she just sputters and chokes on the extra gas.

[ncgalant]

I'm pretty sure I have the map sensor (3 bar if I remember right) and casing that you need to run your SAFC off boost rather than throttle position. I was going to do this back when I had an SAFC. I'll check the garage when I get home.

PM me with how much you want for it when you get a chance. That's the only thing I can think of that will get rid of my low boost bogging and strange SAFC settings.

When Marcus and I would log his car and my old fwd, they both always felt quicker while running leaner on more boost and with less timing (due to knock readings causing the timing to get pulled). Not really the safest for the engine, but that's the rub.

I'm not sure how your doing this whether it be by changing base timing or what. I have the advantage of a 2g ECU. The advantage being that the worst timing maps give you very little timing. I can introduce a load and have mine drop as low as 3 degrees and not get above 10 if I want. The only problem is if the boost spikes even a little bit I hit fuel cut.

If you want the best of both worlds try some xylene, toulene, or some 100 oct. I just logged my car on the way to work this morning and saw 27 to 30 degrees of timing at 26 psi and 0 knock while running 100 oct. My wideband 02's were reading right around 13.5:1 AFR. You will rarely if ever see a perfectly stoichmetric ratio on a turbocharged engine at WOT. Its just too lean. Hell, I think the 13.5 that I'm running is too lean, but she's not knocking and if I richen her up she just sputters and chokes on the extra gas.

I'm thinking that you need that kind of timing with that high of an octane rating. Not that I know forsure, that's why I'm asking these questions. So I guess I'll continue to lean it out and if I start getting to much timing, I'll just turn the boost up higher. As of now I'm seeing 19psi with 16 degrees of timing up top. If I take 1% out of my SAFC settings, I get knock and only see 11 degrees.

[ICGerms]

Another option is to turn up your fuel pressure, thereby increasing your timing (I'm pretty sure that you get more power with more timing). Then you can go leaner with your SAFC, and even possibly turn up your boost. So, you can't log knock? You might also consider putting it back on the dyno and adjusting your A/F ratio (depending on where it is right now)...several guys in STL are running around 11.8-12.2, even though 11.2 is "ideal."

[natedogg]

I'm not sure how your doing this whether it be by changing base timing or what. I have the advantage of a 2g ECU. The advantage being that the worst timing maps give you very little timing. I can introduce a load and have mine drop as low as 3 degrees and not get above 10 if I want. The only problem is if the boost spikes even a little bit I hit fuel cut.

I'm just saying that if your timing is getting that low at WOT your knock sensor may be going crazy. It just sucks that you can't see for sure if its the knock bringing down your timing or your airflow readings. I guess I fail to see how low timing is an advantage, at least when it comes to making power anyway. I've always tuned for the maximum possible timing from the maximum possible boost without getting too lean or out of the compressor's efficiency range, both of which obviously lead to knock and therefore less timing. To me this is the safest way to get the most possible power out of the engine. It seems to me your car is setup similar enough that you should be able to tune it the same way. I'm not knocking your 2G ECU, but I see the 1G ECU as more advantageous because it offers more possible timing at WOT and it allows me to monitor knock. So I can keep turning up the boost or leaning out the mixture until I see knock. In my case I'm already getting plenty of timing, so turning up the boost is my doorway to more power at WOT. Then, if I need to go a click richer to deal with more boost I will. I simply tune my fuel around the boost pressure that I want to run as long as that pressure is still within the turbo's efficiency range and amounts to an airflow that my fuel system can physically handle as far as fuel pressure, fuel flow, Inj. duty cycle, and injector size are concerned.

The reason my ECU is willing to give me all that timing is because the engine is flowing what it believes to be normal amounts of air (airflow input adjusted and dampened by the translator) at WOT and I'm not knocking at all, so its not pulling any of my timing. It would do the same thing for me if I put 93 octane in her and turned the boost down. What the ECU understands to be valid airflow readings + no knock = good timing.

[ncgalant]

I can make my timing at 6000 be anywhere from 10-25 degrees depending on fuel pressure and SAFC settings. Althingh I might not be able to go that high anymore with my boost cranked as high as it is. My SAFC is near maxed. I'm seeing 2350hz on my 2g MAS right now. My question was, which was partially answered(maybe I just don't word well), If I'm tuning to knock, am I better off with 10 degrees up top and 12.5 A/F or 20 degrees and 11.5:1 A/F. Right now I'm somewhere in between.

[ICGerms]

...If I'm tuning to knock, am I better off with 10 degrees up top and 12.5 A/F or 20 degrees and 11.5:1 A/F....

I think it depends on why you're at 10* when running that lean: if it's being pulled back to that because of knock, I'd either richen it up or turn down the boost. Otherwise, if that's just where it's at (no knock) that might be OK.

I guess the bottom line is that you really want as much timing advance at WOT as you can get without knocking. I've heard people say that they can actually feel their ECU pulling timing because the car has noticeably less power. But, then again, if you've got too much advance that can be bad too (not exactly sure on WHY, though, sorry. I think that you're safe to turn up the boost if you've got 17* of timing or more...I don't recall where I read that, though.

[ncgalant]

All of those are assuming knock <3 counts. I'm not seeing the timing flatten or drop. The good thing about running 10 degrees is that when in the worst timing bracket(most load), the ECU pulls timing at a drop of a hat. When I am pulling the load and getting more timing, timing doesn't get pulled as easily. I guess you guys are also thinking in terms of 1g ECUs. For a 1g, 17 degrees is quite average, for 2gs that's pretty good.

[ICGerms]

I'm not seeing the timing flatten or drop. The good thing about running 10 degrees is that when in the worst timing bracket(most load), the ECU pulls timing at a drop of a hat. When I am pulling the load and getting more timing, timing doesn't get pulled as easily.


I guess you guys are also thinking in terms of 1g ECUs. For a 1g, 17 degrees is quite average, for 2gs that's pretty good.

Not sure what you mean by that first statement: it seems to me that you're saying that with more timing, it's less apt to get pulled. Is that right? That suggests to me that you'd want more timing. Unless I'm misunderstanding

Hmm, actually 17 is a little on the high side for a 1G. There are a lot of guys w/2Gs that have 22-24* timing advance at WOT and seem perfectly happy w/that. Seems like it's kinda high to me, though.

[ncgalant]

1gs give out the timing easier. It was writen that way since the CR is lower. Anyway, It gives more or less timing based on engine load. If it sees the engine as VERY loaded, it will only give 10 degrees and drop to 0 at the slightest hint of knock(good thing). But if I'm running 20 degrees and therefore the engine is not loaded(or so the ECU thinks) then it won't pull as fast.

Personally I've never seen enough knock to see my timing pulled more than 2degrees at a time. It was like up 1 down 2 when I was knocking.

[ICGerms]

If it sees the engine as VERY loaded, it will only give 10 degrees and drop to 0 at the slightest hint of knock(good thing).

"VERY loaded" as in at WOT? I believe that it's based more on airflow, rpm and knock, which could be "converted" to load, I suppose. Even though you 2G guys can't read knock on a logger, it's supposedly still there, somehow.

I guess thats another difference between 1G and 2G: I don't want to go down to 0*, even if I'm knocking a bit. I try to keep my own timing around 14* or so w/o knock. I still think that more timing is better, though, so your 10* seems kinda low. But, if it puts a smile on your face when you drive it, that's what counts .

[ncgalant]

"VERY loaded" as in at WOT? I believe that it's based more on airflow, rpm and knock, which could be "converted" to load, I suppose. Even though you 2G guys can't read knock on a logger, it's supposedly still there, somehow.

yep, you hit the nail right on the head. By load I'm saying airflow/RPM. I can pull airflow with my SAFC and therefore pull load(less fuel, more timing) or vice versa. This really scared me when I first started tuning as I was seeing 28 degrees of timing at 12psi(fun byproduct of 720's). That was with it running really rich because I was afraid of running more timing.

Here is what I do know. Every person I've seen that makes good power on pump gas(450hp is good I'd say) is running 5-10 degrees of timing up top. I've never seen anyone run more. I am looking to do as much as I can on pump.

On a side note, I just want to make sure I'm comming off the right way. Sometimes I come off as trying to say that I'm right about something to people that don't know me really well. I'm just stating what I think to be right and am asking why its wrong. I'm always happy to be wrong, I just want to know why. You guys are being very helpful. Thanks gang, I just want to know what and why. I know I can make power. I just want to do it as best I can.

[ICGerms]

Every person I've seen that makes good power on pump gas(450hp is good I'd say) is running 5-10 degrees of timing up top.  I've never seen anyone run more.

Really?!? Is that 1G or 2G? And what about the knock counts? I may just have to start tuning a l'il differently .

On a side note, I just want to make sure I'm comming off the right way. Sometimes I come off as trying to say that I'm right about something to people that don't know me really well. I'm just stating what I think to be right and am asking why its wrong. I'm always happy to be wrong, I just want to know why.

Yep, I hear what you're saying, and I know that I'm here to keep learning about these damn cars, especially the tuning part .

[ncgalant]

Really?!? Is that 1G or 2G? And what about the knock counts? I may just have to start tuning a l'il differently

Well they also usually run a standalone. There are several of them running around on DSMtalk. What I do know is that you want maximum cylinder pressure around 14-16 degrees after TDC. Higher boost is going to make the charge burn faster and therefore need less ignition timing to make that happen. That being said, there's just as good of a chance of me having my settings perfect right now as you guys running 20 any other number and having it happen. I guess what it all comes down to is that I need some dyno tuning to run perfect.

[natedogg]

I don't know that there is any right or wrong way as long as what your doing is safely making power. In my mind and according to my buttometer, the more timing the better, but YMMV. The ECU will start pulling the timing on its own when it gets dangerous because it sees knock. If its not seeing the timing getting actively pulled during a run, the engine's probably not knocking (2G ecu guessing here).

There is a value stored in the ECU called the octane value. This value changes over time based on the amount of knock the car has seen over a long period of time. If this value is FF (highest value on the 8 bit hexadecimal scale), according to the ECU, the engine is running no knock over time and will give it the most possible timing at WOT, limited of course by the amount of airflow (load) that the ECU is registering. Conversely, if it is 00 (lowest value on the 8 bit hexadecimal scale) your ECU is going to give the engine the least possible timing, probably just enough to keep the car running. The other knock value is much more dynamic and affects the timing in realtime. This, of course, is what you see on the logger screen when the timing is pulled during a logger run.

The reason I can run 30 degrees of timing advance and 13.5:1 AFR and not fear that I'm going to destroy my engine (beside the rods being asked to handle too much power ) is because I'm not knocking. Even if I were, the ECU would help me out by pulling that timing away from me until I make the necessary adjustments. Running that high timing and that lean without knock tells me that my engine is using all the fuel available to it every combustion stroke to make as much power as it possibly can. Its efficient, safe power production.

We don't have direct control over the timing that our ECU gives us, unless we run a standalone ECM. The only thing we can do is fool the stock ECU by dampening the airflow signal to it with piggybacks like the SAFC or the MAFtranslator. This obviously will indirectly lead to more timing, but like I said before, if the ECU sees a lot of knock over time or even actively during a run its going to take that timing away from us anyway. I've seen it happen both ways. Marcus's car even when it wasn't knocking, would only max out at about 15 to 16 degrees of timing because his ECU's octane value was low from many knock happy runs. Whereas, my old fwd would max out around 20 to 21 degrees when not knocking because I didn't tune to allow as much knock over time and many runs. These were both nearly stock 14b setups.

This is my approach at tuning and it seems to be working pretty well for me. But, I know everyone does it their own way, so take it for what its worth. I just know its hella fun to be able to click a few switches, press a few buttons, or turn a knob to take a few tenths off your ET or make a few more hp on the dyno all while monitoring your engine's health with the logger.

[natedogg]

Higher boost is going to make the charge burn faster and therefore need less ignition timing to make that happen.

I can't wholly agree with this. More boost begets more fuel. Basically to get more power you are trying to stuff more of both in to the combustion chamber while maintaining a safe yet efficient AFR. Since we have more matter in the chamber altogether its going to take more time for all that matter to burn. Obviously we have less time every stroke as the RPM increases so the timing is going to have to advance to maintain an efficient mixture, lest we start throwing fuel out the tailpipe or even worse leave it in the combustion chamber to detonate or wash the cylinder walls. Now exactly how much the timing needs to advance, I don't know. The 5 to 10 degrees of advance may be what works well for the guys on pump gas since it burns more quickly than race gas anyway.

[ICGerms]

...The 5 to 10 degrees of advance may be what works well for the guys on pump gas since it burns more quickly than race gas anyway...

Wouldn't a faster burn be more likely to produce pre-ignition (knock) of the charge, though? Hmmm, unless you're saying that less timing shortens the "cycle" enough to sort of compensate for pre-ignition?

[ncgalant]

I don't know that there is any right or wrong way as long as what your doing is safely making power. In my mind and according to my buttometer, the more timing the better, but YMMV. The ECU will start pulling the timing on its own when it gets dangerous because it sees knock. If its not seeing the timing getting actively pulled during a run, the engine's probably not knocking (2G ecu guessing here).

Yes, this is what us OBDII guys have to do. The hardest part is determining the difference from knock and SAFC induced load when watching your timing drop off. When I first started tuning I went through this quite a lot. I would see timing drop 2 or 3 degrees and the more I added the worse it got.

I can't wholly agree with this. More boost begets more fuel. Basically to get more power you are trying to stuff more of both in to the combustion chamber while maintaining a safe yet efficient AFR. Since we have more matter in the chamber altogether its going to take more time for all that matter to burn. Obviously we have less time every stroke as the RPM increases so the timing is going to have to advance to maintain an efficient mixture, lest we start throwing fuel out the tailpipe or even worse leave it in the combustion chamber to detonate or wash the cylinder walls. Now exactly how much the timing needs to advance, I don't know. The 5 to 10 degrees of advance may be what works well for the guys on pump gas since it burns more quickly than race gas anyway.

I was more talking about your dynamic compression ration causing a faster burn rate. I can surely see what you mean though. If there's more air and fuel to burn that has to take longer to do it. So we can probably figure the actual burn rate is somewhere in between.

I think what I'm going to try for is running a bit more boost and seeing if I can keep my timing right where it is(17 degrees up top). All of this will be limited by knock of course. It curtainly makes sense that if the charge has more time to burn, then it would burn more completely and make more power with what you have.