I have been reading another thread regarding an engine going Kaboom and I am wondering what timing advance is safe for the 55K? I have searched the subject and it seems that on some graphs from data logs it shows as high as -37 degrees? Others say "shouldn't be higher than this or that". I'm guessing that there are many things that come in to play (fuel, temp, AFR), but there has to be a "safe" limit right? What will the ECU allow? Can a tuner override the maximum adavance or reduce the sensitivity of the knock sensors?

Bunch of questions have come up in my mind, I haven't got a data logger yet but on a previous vehicle that I could datalog I was showing > -25 degrees from what I could remember on a NA motor.

 

Hopefully our new resident expert MBVert will chime in with his vast experience....

 

when I'm in close to 5 to 6k rpmps around 3rd gear

i'm bouncing from -25's to -30's degrees and a few spikes higher....

The logs are old.. over 6 months. and I was messing around with an intake back then.

Now I have removed the intake mod and i'm just running pulley, tune, mild exhaust mods, better H/e set up.

so I started data logging this week after the other thread of blown motor. Just for precaution.

I have had LET tuning for 18 months and no issues so far.

MY supercharger was replaced last week.. but I don't think those are 2 items are related at all.

 

Thanks TopGun,
Your experience confirms some info that I have seen on some graphs.

In the "other" thread one poster mentioned above by citylightva stated that he would never run more than 25 degrees advance, so I am trying to gather information as to what everyone is seeing and whether they are "tuned" or not.

 

I'm no help, since I have no idea what the Kompressors should be running. TopGun has certainly been around a while though

 

Old school logic from the 80-90's is/was ALL FI motors like timing and that MAGIC number is 35 degrees advance for MAX power. It DIDN'T matter who made the engine as BM, Weiand, and several others tested their blowers on ALOT of engines and ALL of them came up with this magical number

However, MOST engines can not take this much with our lovely gas sold these days, hence they turn it down.

The problem is that ALL engines, even built by hand, have differences in them. Hence 31 may work for one without detonation, and another may only take 28. Yes gentlemen there are tolerances in EVERY engine made.

Hence there is NO magical number you can use, as EVERY engine will be slightly different. The BEST tool for this is the DYNO.

AKA tweak the timing as high as you can, and once you reach detonation, back it off a tad.

In the old days, it was easy with a MSDS boost retard box, you simply turned the knob down to you heard some rattle, and then backed it off a tad.

Now, with all the ECU's, you really need a dyno or a GOOD knock sensor to see what is going on.

Interesting thread by the way

On a side note, B&M saw on their dyno that you only loose a little bit of power for each degree of timing pulled. I'll pull my old charts out and post the numbers, but it was only like 1% power for each degree of timing.

 

David,

My graphs you are referencing do show timing well above -30deg, but when people talk about "safe timing" they are talking about timing advance under load. 55Ks, even in stock trim, run timing as high as -40deg under light throttle conditions at high RPM, and that is completely normal (for reasons that are very long and complicated). If you look at my 100% load timing, my car runs VERY light timing compared to what other tunes are running.

-m

 

You know I love this forum! Such a wealth of information and experience readily shared.

Marcus, what is your timing under load, if you know it off hand? I don't see that you have listed whether or not you have a tune, do tell if you don't mind. BTW, you have one of the sweetest looking SL65's I have laid my eyes on, seriously, I love that picture.

 

Just looked at Marcus' graph again and at WOT your timing is around -5 to -15, wow. How do I see the duration of this run because it looks like you are at WOT for only a second or two and then out of it completely, at least on the graph I was looking at. I am interested to see what the timing is on a car at sustained WOT through at least a couple of gear changes. LOL, that might be what that graph is...

 

listen to this man!

 

I am by NOOOOO means a tuning guy (know intricate details) but I am just repeating over the years of hearing numbers come from tuners. I wonder if I hold the record for most tunes put on one car from different tuners. Gotta be over a half dozen so far over the years.

Seems like that timing number is the most coveted secret in tuning. I have had tuners change the subject on me when just asking what they run.

Anyway, it's my understand that under load like Marcus said, average numbers were running in the upper teens on most tunes.

Then tuners seemed to get a tick more aggresive and I had a couple slip and tell me they were running in the 20-22 range. Upon talking to some other tuners I was told that is on the edge of safety and to be careful around that range.

If someone is honestly showing -24 to 25 on a tune, according to what I have learned and ONLY talking about our E55's , it's a ticking time bomb.

Again, just repeating information.

Tuning could have changed a lot over the last few years....covering my A...blah blah blah

 

im going to do a 2nd gear pull now,is this up top or everywhere,if its over -22 im not going to redline it ect.

 

David,

Unfortunately I have an IAT issue with my car which can cloud my numbers somewhat. As you may or may not know, the ECU will pull back timing when it sees high IATs. My most recent log, from February, which is also with my most recent tune, shows roughly -15 to 0 timing at 100% load. Now if you look at that log (it is posted in the dataloggers thread - I know it's a bit difficult to read), the last "jaunt" (when my MAP sensor reaches it highest reading in the log), you can see my timing running in the single digits AND you can see my IATs hitting 185F (it was very cold outside). Something VERY important is to see that at initial WOT, before the IATs hit temps to cause the ECU to pull back, I hit -15deg. That's it. The ECU has plenty of room to pull back timing a few degrees (which is all it needs to pull back from those levels) to compensate for the high IATs.

On a more speculative note, it would be interesting to see other people with various tunes to see how their tunes compensate for high IAT situations, which we know are very common on these cars? I am personally not sure if the ECU scales back timing on a linear scale, or of it is target based - in other words... if the car is at -30deg, does the ECU want to just cut back a few degrees, because the map that deals with IAT-based timing pullback has not been scaled properly to match the increased timing? Or does the ECU always want to hit single digit timing advance values, inspite of what the main timing tables dictate? Details like this can easily lead to the loss of an engine.

My car is at CPT right now waiting on some mods to help with heat before I get back out there and log. I am very much looking forward to seeing if I have finally been able to track down my IAT gremlins. I don't want to let the cat out of the bag yet, but honestly it is something stupid and so easy to overlook (if this proves to be the issue) that it is enough to make you want to rip your hair out. I have had this IAT issue for almost 1.5 years. Unbelievable.

-m

 

Unfortunately David my datalogs are limited to the sample rate I get through the OBDII port. You can assume that the samples are a couple of seconds apart, but that doesn't really help. I can give you a bit more insight - look at the speeds, which are typically from 50-150mph (so roughly 1-2 gear changes). That's a good way, if you are going to datalog, to compare yours to mine, base it on speed, not on time.

-m

 

before I post any results.. let's see if I can summarize what I have learned..

1) timing can reach 30 and 40's under different engine load.. basically light throttle input

2) When somebody talks about timing being safe.. we are referring timing at a 100% load and or WOT.. for pull of a few seconds if possible.

Driving around town or quick jabs to 3k rpmps will not yield the timing issue that can cause detonation.

We are only talking about a pull around 2nd or 3rd gear that would hit 6k rpms and make the gear change in 4th...

so I'll need to post my results once somebody can confirm the proper method to test timing.

 

You can say that again.21-22 degrees on 93 octane under 100% load up top, +1 degree midrange would be a good start.Part throttle tuning and WOT tuning are two different worlds so please don't interchange the two as the data will then become more confusing.

 

I have a SRT-6 and last week I data logged during a 20 minute session. Ambient temperature was upper 90's. IAT's ranged from 132º to 172º during the session. ECT's reached 235º at its warmest. Timing advance depended on boost, throttle position, temperature etc. At WOT I saw 17º or 18º maximum advance but as boost climbed and revs built the timing backed off to 12º or less. I didn't always see 18º maximum at WOT, usually it was 15º. During the shifts timing went as low as 5º. At part throttle (30% throttle position) as revs climbed (6000 rpm) I saw over 30º with 10 PSI of boost. Maximum boost I saw was 17.9 PSI but it was only near redline and not every time. But it usually reached 17 PSI. I'll let others decide what to make of it. For me, it makes sense. What are tuned cars showing?

Mods - Needswings dual CAI and catch can, 1 gallon heat exchanger, separated cooling system, Code3 pulley, lots of suspension parts, Dashdaq, Michelin Pilot Sport Cups ..... that's all I can think of at the moment.

Les

 

If in manual mode (M5) in a high gear at low rpm as boost builds timing goes past 0 to +2 or + 4 on mine. Kleemann ecu/tcu and boost goes to 22psi max.

 

In the world of ECU tuning when talking about timing. There are two and really only two things you should and need to worry about. Those are "Safe" & "Not Safe". On pump gas there is no fine line. Most tuners dont share their timing numbers.. Honestly, you cant blame them either. Thats how they make their living.

What I feel is important is, if your car is pulling timing. You can spot this on a dyno graph without logging anything. If the HP flat lines prematurely or the car takes an early dive in HP as it nears redline. Those are signs the car is pulling timing.

Generally, the knock sensor is the key factor when it comes to adding/pulling timing. Basically if the car pulls or is pulling timing. The knock sensor has detected knock... Thus adjusting for it by pulling timing and/or adding fuel.

This whole thing can get very in depth, Like what your fuel trims are doing at WOT... In a nutshell, dead nuts tuning should add or pull no timing. If you are running the fuel the car was tuned for. Thats if all the sensors that relay info to the ECU are working as they should.

 

Unless your tuner has really messed with the ECU and removed timing modifiers, their are lots of factors that go into timing.

- Load, IAT, CLT, Trans, Ect.

For each day and load condition it may change. Depending on how many timing modifiers are left on, how much they are allowed to change the base timing table.

I am a "professional" tuner per say, and I can tell you there is no "magic" number as far as timing. It truly depends on each motors base design, and current combination. Just a cam swap alone can change so many factors depending on the cam specs. Cly heads are a HUGE factor in timing, since they change the base efficiency of the motor so drastically. (Timing is directly related to the combustion efficiency) I guess that’s what makes me get all excited about tuning a car, never are two the same.

As far as knock goes, if you are seeing knock under WOT, that’s unacceptable in my opinion. The knock sensor is a preventive measure, much like a revlimiter. Its not something to rely on, or the motors safety will suffer. Sure under light load, some false knock will occur, however under WOT, there shouldn't be any with a proper tune. Fuel trims should all be with in + or - 5%, however their are no fuel trims under WOT, since the car is then in a open loop configuration.



EA

PS: I haven't posted much on here, but am planning on being much more active once I find the E55 that I am looking for. So, I hope I find her soon I am pretty picky on the color and options I am looking for, but hopeful I will find one soon.

 

Pretty standard for "most" modern cars these days, with good efficient cly heads, and exhaust systems. (Some cars run 10 deg, others are as low as 0 degrees, EVO's)

IAT's were likly changing that number the most.

Good old Torque managment, to help save the tranny. Takes power away for a moment to allow the tranny easier shifting. I personally can't STAND the way TQ managment feels... some love it.

Les you would be suprised how many cars these days follow pretty much exactly what you see. Awesome post, with killer info.

EA

 

I am amazed at the recent influx of people who, at least, claim to do tuning and at the same time are willing to carry on open conversations regarding the same topic. They will notice that in the Benz world, things are kept under lock and key and us, the public, are given a bucket of fish heads every so often to keep us happy. I applaud them if they are, in fact, who they say they are and continue to contribute to this forum.

With that said, the modifications that we do to our cars are so simple and straightforward compared to other tuning platforms that it is really much easier to talk about timing/fueling/etc. You take a platform like the GM LSx platform, that can go from monster cam, to twin turbos, to a blower and spray... you have yourself a real wide array of tuning approaches/etc.

With that said, the question at hand here is what is safe... and I think what people are really asking about is how ignition timing works - because what is safe is really a secondary question if you do not understand ignition timing on a rudimentary level. The explanation to that is somewhat complicated but not so much so if someone is trying to understand it at a fundamental level. In a few words, ignition timing in our modern cars (please note, mechanical timing is different in execution, but applies the same) is basically when your ECU tells your ignition system when in the combustion cycle do you want to ignite your air/fuel mixture. You are shooting for exactly the point where the combustion will deliver the highest amount of energy possible to the piston in it's downward stroke which thus turns the crankshaft and applies power through the transmission to the wheels.

Excessive timing advance, that is, sending the spark too far ahead of time is very dangerous (timing retard, while not as dangerous, can also cause problems). One of the major reasons it is dangerous is because if you ignite the air/fuel mixture too early before the piston reaches top dead center (TDC), you are actually exerting a force on it that opposes it's movement upwards. This force can cause failures on any number of parts and can destroy just about any engine, no matter how "tough" it may be. We have knock sensors on our cars which allow for the ECU to "hear" when the engine is "knocking" - knocking occurs when the combustion process goes awry, so to speak, as it will generate vibrations due to a number of erratic circumstances... such as preignition, detonation, etc. When the ECU "hears" knock, it will typically pull back timing because that is a very effective way of "relaxing" the engine and the stresses during the combustion process as to protect it from the failures I mentioned earlier.

Think of what happens to a baseball when a pitcher throws it towards batter, and the batter connects with the ball using his bat. The ball deforms drastically as the force applied by the bat transfers to the ball and changes it's direction... unfortunately pistons are made out of metal and they are not as pliable as baseballs. That "crack" you here when it makes contact - think of it as "knock", a LOT of it.

As I had mentioned previously, there are many factors that can dictate when in the combustion process ignition should occur, and the reality is there is no "definitive answer". These sort of discussions, though, do help a healthy discussion on what "works" and what "doesn't". I think that's the real question to ask, and it's one that Velociabstract has answered.

-m

 

M, trust me....

As soon as I find the "right" E55 for me to own/build. I will be much more active on this forum. I don't devoulge all my secrets, since that is how make $$$, however I am very good about making sure false claims and other mistruths don't get passed along. BTW: Killer post, I am sure even a novice will be able to read though it and have a much better understanding of what "timing" is, other then just a word and a number.

EA

 

Great post.

 

EA don't take my statement as a way to scare you off or somehow say you aren't who you say you are. I don't know who you are but please, by all means, contribute what you can to the forum. I, for one, welcome it. I am by no means a professional tuner nor do I plan on being one, however modifying cars is a passion of mine and I choose to be an informed consumer. A decade or so of trying to inform myself has taught me a thing or two, but I am still far from the levels of the actual professionals.

I don't think protecting your secrets is a bad thing, but at the same time this engine has a LOT more development to undergo (if it makes it that far) before I think your secrets will need to be kept secret. What I mean by that, is 99% of the cars on here that are modified are similar enough where their maps are not going to vary that much. I mean we now have upgraded throttle bodies and long tube headers are getting a bit more popular but it's not like we have bolt on head/cam packages and twin turbo kits abound. From a tuning perspective, IMO, an open and transparent tuner who really focuses on empowering the consumer and further developing the platform beyond the simple bolt on stuff is what this community needs, but that's just me.

-m