Spark vs boost

[derfdog15]

Look at the dyno data I posted above, I want to say that was a 17 psi TIP command, to my 15.25 psi tip command. His spark was 16 degrees advance, vs mine being 18-20 degrees advance.

Granted, not a major spark difference, but still a pretty decent difference in power, and especially the torque.

[StealBlueSho]

Look at the dyno data I posted above, I want to say that was a 17 psi TIP command, to my 15.25 psi tip command. His spark was 16 degrees advance, vs mine being 18-20 degrees advance.

Granted, not a major spark difference, but still a pretty decent difference in power, and especially the torque.

RIGHT, but that is a 3rd gear pull on a dyno... not a multigear pull on the street or track where the IAT's are really going to climb. On a dyno, you are pulling one gear with a big ass fan in front of your car..

A long track run or on the street where IAT's are really going to come into play, that is what I am more curious about.. because again.. at what point do you start shooting yourself in the foot because of the hot air from high boost by our snails causing the IAT's to climb and pull enough spark to make a difference..

where does that line cross where running your turbos so close to efficiency that you start to loose ET because you are dropping spark due to IAT compensation? Again... its one of those.. I believe.. the answer to be.. "Well, try different tunes at the track.."

[derfdog15]

Like I said, once I get my times nailed down on current setup so I can apples to apples my time to the dyno numbers, I will work on checking a few other wastegate settings (it will be warmer so I can go higher on the spring).

I am running between 15 and 16psi now, with 20 degrees spark, after I know what I can do on these settings with my springs, I'll go down in boost, up in spark a bit for the track. If I get lucky and end up at a test and tune like the last one, where I can get 20 runs in the night, I can get a whole lotta comparison.

Of course doing so will require Brad to be patient with me, or us to make some arbitrary combinations/boost and spark desires, and then run the tunes. Will probably be march or april before tracks open and I am able, but I think it would be nice to see.

[FoMoCoSHO]

SBS, yes when iat's climb the spark compensations take over so at my last outing I was down a ton of spark, like 8-10 degrees depending on where you look. Ambient was over 100 and IAT2 was over 170.

Trying to gauge how much power 1 degree of spark vs 1 PSI makes will vary by platform due to the amount of work performed. Number of cylinders, compression ratio, etc will all have an impact on how much work the extra mechanical leverage will provide.

Thats some pretty harsh stuff to be running logs.. although.. I did the same LOL... Ambient was in the 115's once.. I should look at the logs again...

As far as the spark vs psi, I was hoping to reference only our platform for this.. as like stated, each platform is different, and so the equation would be different.

I like to know how my tune behaves in the worst conditions as well as the best.

AJP passed with flying colors. Trace of KR and it ran 12.6x. Corrected was 12.2x.

10 degrees x 4HP which is my best guess on what a degree of spark makes = 40 ish HP which jives with my time vs corrected time.

[AJP turbo]

SBS I don't think you have it wrong at all....Lots of good observations as usual...It's a tough riddle and stop making me look at logs lol...You antagonize me with data then I can't resist.

I just looked and yeah LMS does handle the boost spike well in 1st...But I'm curious how mine would've reacted when having a lower desired tip.....The boost logic is a P&I based...Proportionate and integral controller....So like I said things change when you request more boost because how the wastegates react is based on the error of where the boost is currently among other complex things.

Obviously I can't speak to what LMS does but they could have made some changes to improve the response of the gate.

I can say there are some changes I make to the gates to help with boost taper and that could've made the the boost ramp up faster....I can see that when you look at the spool up from 2600-3500 rpm mine was spooling up faster and higher boost in 1st gear than LMS...So maybe my boost logic had it spool up faster because something I did ramped on the gate more and that caused me to overshoot and spike....Could be good or bad depending on what you want...If you sping then it's bad.

LMS boost looks like it's smooth no doubt and handled well. Kudos.

I think my attempt to minimize boost taper helps thought..It looks like at the end of 2nd there is less boost fall off compared to what I am requesting...Even in 1st too but just a bit....It looks bad on mine but that's because the boost was too high so the slope is more severe.

See we can play nice.

For analysis this in depth I think is where dyno are nice

I never really see LMS tunes add spark it just stays flat with the knock sensor...Which is GOOD....but I think they are shy on spark at times which is safe

I run the boost I do because what I see on the dyno..Well into the 400's for the torque...I've seen LMS tunes on the same dyno as the one I ran on and it was kyle04 posted here and it was either low 400's or even shy of 400 I forget but I like the torque my tune gave.

Although the peak power wasn't that much more so is there a benefit? I dunno...I still never really understand why derf and I can make so much torque but not the peak power? I guess because the turbos aren't moving the air because they are tiny?

And excuse some of my typos...I type pretty fast for a outdoor non office working person lol I'm not a receptionist...I'm proud to type with proper form at 30-40 words a minute lol

[Colorado-SHOBro]

If I am at the track, and my WGDC is sitting at 80% throughout the entire run my IAT's are going to climb yes? More so than if it was sitting at 60%?

IIRC the ecu scales back spark as the IAT's climbs?

So.. if I am running a tune that is originally targeting 20 degress of spark, but because my wastegate is running at 80% my IAT's climb, which by the time I am in 3rd gear, the ECU would scaling back on spark to 15 degress due to hotter air at the sensors which in effect would cause me to loose power?

If I am running a tune that is originally targeting 20 degress of spark, but my wastegate is running at 60% so my IAT's are not as hot, so when I am in 3rd gear, the ECU wouldn't scale the spark back as much if at all so I am still sitting at 20 degress of spark.. however, my boost will be lower but I maintain higher spark throughout the entire run...

So at which point is the breaking point? is 5 degrees of spark worth 1psi or so?

This is exactly the scenario that plays out in my head. I figure there has to be a happy efficiency range for these turbos that boils down to WGDC . . and i wonder if i'm not a good bit above it because of my boost level/altitude. . . but maybe not because i'm still getting 16-19* spark on straight 91 octane. But what if i was to dial back the boost and bring spark up to mean best torque levels? Happy turbos+good spark is where the power is at right?
Ignitions spark is mainly based on load/boost and IAT is just a modifier so load is gonna do the lions share in commanding timing, not to say IAT's don't have a relevant impact. My E20 tune commands just an extra 4.5 degrees of timing and holy hell can i feel it. I would safely say 25-30hp which inspires the thought that timing in this platform worth a little more.
As far as you mentioned earlier with LMS tunes commanding richer afr in the top end . . i've always felt throwing fuel to quench out kr is a cheap trick. Not to mention there's also a sweet spot for fuel at which you go richer it will make less power-much like MBT for timing.
Brad's gonna be a busy man this track season 

[StealBlueSho]

Stealblue on your car if we lowered boost the tables would've commanded more spark but since I'd say we were within the efficiency of the turbos we were moving more air at the higher boost and that coupled with running max spark is why I think it ran well

So spark follows load tables.. and based on datalogging the load PID, the load PID appears to follow the MAP pid or vice versa exclusively 99% of the time. I have seen cases during a log when I have had one my vacuum lines pop off (Thanks LMS for the weird blow off valve issues on the 4+x tune that doesn't allow the BOV to open correctly) causing the ECU to drop the WGDC to 0 effectively killing off all the boost.. which then because my load had just plummeted my spark advance went sky high I think into the 40's or so...

Point being, if spark follows the load tables.. and there has been mention that the logic in our vehicles pushes spark right up against the knock sensor as it scales it up, as a tuner, do you have control over how much spark gets added? In other words, can you program definitively that max spark would be 20 degrees for this given load?

Not exactly related to my original question... but curious non the less...

[Colorado-SHOBro]

Stealblue on your car if we lowered boost the tables would've commanded more spark but since I'd say we were within the efficiency of the turbos we were moving more air at the higher boost and that coupled with running max spark is why I think it ran well

So spark follows load tables.. and based on datalogging the load PID, the load PID appears to follow the MAP pid or vice versa exclusively 99% of the time. I have seen cases during a log when I have had one my vacuum lines pop off (Thanks LMS for the weird blow off valve issues on the 4+x tune that doesn't allow the BOV to open correctly) causing the ECU to drop the WGDC to 0 effectively killing off all the boost.. which then because my load had just plummeted my spark advance went sky high I think into the 40's or so...

Point being, if spark follows the load tables.. and there has been mention that the logic in our vehicles pushes spark right up against the knock sensor as it scales it up, as a tuner, do you have control over how much spark gets added? In other words, can you program definitively that max spark would be 20 degrees for this given load?

Not exactly related to my original question... but curious non the less...

doubt it's your my opinion your looking for but from my interpretation. .
to command a max 20* for given load i believe you'd have to set your base spark to 20* and then essentially disable the knock sensors adaptive capabilities as to not add or subtract spark advance based on what they're seeing. i'm sure the expert will be here soon to elaborate but the tuner can control if and how much the knock sensors adjust Spark.


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[AJP turbo]

Not sure if this will be what you are looking for exactly but...You can set a max spark advance or total spark advance allowed by load and RPM.

And you can set how much spark can be pulled or added by load and RPM via the knock sensors.

Sometimes if you see your knock sensor go flat during a pull it's not because the spark is dialed in perfect and it's neither adding or pulling but  rather because it may want to add more spark but is not allowed because you have reached a max allowed spark value so the knock sensor lost it's authority.

For instance...If you left the spark strategy stock and ran E85 and you added a few degrees of spark you would probably see your knock sensor flat and you would expect to see the knock sensors add spark but since the spark was added to the tables possibly putting you up on a spark limiter then the knock sensor would not be allowed to add spark over that.

[Livernois Motorsports]

Stealblue on your car if we lowered boost the tables would've commanded more spark but since I'd say we were within the efficiency of the turbos we were moving more air at the higher boost and that coupled with running max spark is why I think it ran well

So spark follows load tables.. and based on datalogging the load PID, the load PID appears to follow the MAP pid or vice versa exclusively 99% of the time. I have seen cases during a log when I have had one my vacuum lines pop off (Thanks LMS for the weird blow off valve issues on the 4+x tune that doesn't allow the BOV to open correctly) causing the ECU to drop the WGDC to 0 effectively killing off all the boost.. which then because my load had just plummeted my spark advance went sky high I think into the 40's or so...

Point being, if spark follows the load tables.. and there has been mention that the logic in our vehicles pushes spark right up against the knock sensor as it scales it up, as a tuner, do you have control over how much spark gets added? In other words, can you program definitively that max spark would be 20 degrees for this given load?

Not exactly related to my original question... but curious non the less...

The tune is essentially doing what it should, it kills off the boost if the situation warrants it and if there is no boost timing is increased because the load fell off.
That's how it's written so I'm not sure where the question is that?

[StealBlueSho]

Stealblue on your car if we lowered boost the tables would've commanded more spark but since I'd say we were within the efficiency of the turbos we were moving more air at the higher boost and that coupled with running max spark is why I think it ran well

So spark follows load tables.. and based on datalogging the load PID, the load PID appears to follow the MAP pid or vice versa exclusively 99% of the time. I have seen cases during a log when I have had one my vacuum lines pop off (Thanks LMS for the weird blow off valve issues on the 4+x tune that doesn't allow the BOV to open correctly) causing the ECU to drop the WGDC to 0 effectively killing off all the boost.. which then because my load had just plummeted my spark advance went sky high I think into the 40's or so...

Point being, if spark follows the load tables.. and there has been mention that the logic in our vehicles pushes spark right up against the knock sensor as it scales it up, as a tuner, do you have control over how much spark gets added? In other words, can you program definitively that max spark would be 20 degrees for this given load?

Not exactly related to my original question... but curious non the less...

The tune is essentially doing what it should, it kills off the boost if the situation warrants it and if there is no boost timing is increased because the load fell off.
That's how it's written so I'm not sure where the question is that?

LMS, I was using an example of something that happened to my vehicle to help clarify and give context to the next portion of my post which contains the question. Which is based on a statement that spark follows load... and to help MY understanding of how these cars determine how much spark is needed and if in tuning these ecoboost motors, the tuner has the ability to define what the maximum amount of spark at any given point. OR if the knock sensor will keep adding additional spark if it can... which AJPTurbo answered for me.

Yes, the tune did exactly as it was supposed too, I was not saying it didn't.. I am sure it follows what the stock settings allow for as well..

And yes, its a known issue with the 4+x tune that the BOVs don't open/close on time causing that weird duck call like sound.. sometimes they don't open at all... causing the excess pressure to stay in the system.. which again.. caused my vacuum line to pop off which helped me learn more about how these cars handle a no boost situation!