Spark vs boost

[SHOwoosh]

Would it be possible to have both? Request more boost/reduced timing at lower/mid rpm and reduced boost advanced timing at higher rpms? Seems plausible but then I really don't know anything anyway.

[StealBlueSho]

Would it be possible to have both? Request more boost/reduced timing at lower/mid rpm and reduced boost advanced timing at higher rpms? Seems plausible but then I really don't know anything anyway.

LMS has a way to curb the boost spike in first gear only which helps with traction off the line... not sure if that level of granularity can be continued... if needed..


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[AJP turbo]

Would it be possible to have both? Request more boost/reduced timing at lower/mid rpm and reduced boost advanced timing at higher rpms? Seems plausible but then I really don't know anything anyway.

LMS has a way to curb the boost spike in first gear only which helps with traction off the line... not sure if that level of granularity can be continued... if needed..


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I've seen boost spikes are much more manageable and easily mitigated when desired boost is less than 190 kpa....In fact when the desired TIP is in the high 180's I don't even see boost spikes that would require a 3 bar map sensor. And you don't even run lean when you get a boost spike over what the map sensor can read because the 02 sensors would just add the fuel....It's not what you want but but that's what would happen so the idea that you automatically go lean if you exceed the map sensors range is wrong.

[AJP turbo]

Would it be possible to have both? Request more boost/reduced timing at lower/mid rpm and reduced boost advanced timing at higher rpms? Seems plausible but then I really don't know anything anyway.

I would never increase boost and reduce timing....Boost and spark are meant to increase cylinder pressure which is what makes power.....Sometimes on big turbos in low rpm you might reduced spark to get the turbos to spool but that's not needed with the baby turbos the SHO's have.

Spark follows load tables with the ecoboost. So yea you can command any spark at various loads at various RPM

[AJP turbo]

When I dynoed from stock boost to 18.5 psi I ran the max spark that the fuel could tolerate and made more power at each boost level until about 18.5 psi....18.5 psi was only a few hp more than 17.5 so it wasn't really worth it.

I don't really think that less boost and more spark is necessarily a tactic for max power but rather a guarantee that you can rest easy knowing that people won't have inadequate fuel pressure and less problems and complaints coming back to your company since data logging is not required which is smart in my book. Because strangely enough not all SHO's have the same fuel delivery capabilities.

I've seen some SHO's look fine at 16 psi and some borderline at 13-14 psi.

When operating in an efficient zone of a given turbo, I've never seen a car make more power at lower boost compared to a higher boost when both are running max spark the fuel can handle

I would never send a tune without datalogging and run more than 13 psi.....Of course if I was only running 13 psi I wouldn't even run a 3 bar, there is just no need.

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

I think that sums up my take for now until I am provoked by the forum which happens a lot which is why I enjoy the forum lol

[StealBlueSho]

Would it be possible to have both? Request more boost/reduced timing at lower/mid rpm and reduced boost advanced timing at higher rpms? Seems plausible but then I really don't know anything anyway.

LMS has a way to curb the boost spike in first gear only which helps with traction off the line... not sure if that level of granularity can be continued... if needed..


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I've seen boost spikes are much more manageable and easily mitigated when desired boost is less than 190 kpa....In fact when the desired TIP is in the high 180's I don't even see boost spikes that would require a 3 bar map sensor. And you don't even run lean when you get a boost spike over what the map sensor can read because the 02 sensors would just add the fuel....It's not what you want but but that's what would happen so the idea that you automatically go lean if you exceed the map sensors range is wrong.

I agree that the boost spikes would be much less with lower desired TIP at 186.23kpa which is what the 4+x LMS tunes has. HOWEVER, Torries tunes and your tunes even when the desired tip was 201kpa I had boost spikes in first gear around 4000 rpms or so... 

Look at these LMS logs that were pulled from my car... in first gear the boost just...plateaus without a spike? while in second gear and third gear I see the normal looking boost curves with a peak. I know the are using the throttle to control load output... but can that be adjusted to allow different amounts of load in different gears at different RPMS?

As a side note... see how rich they tune for at the higher RPMs? Would it possibly be beneficial to run rich at the higher RPMs when its easier for the HPFP to do so since its cam driven to cool and compensate for the boost spike after the shift to assist in mitigating knock? They also lean up a bit after the shift.. seems like an interesting theory at least... guess at this one?

But in short, LMS is a prime example of less boost and more spark... more logs to enjoy and consume...


::POKE::

[StealBlueSho]

When I dynoed from stock boost to 18.5 psi I ran the max spark that the fuel could tolerate and made more power at each boost level until about 18.5 psi....18.5 psi was only a few hp more than 17.5 so it wasn't really worth it.

I don't really think that less boost and more spark is necessarily a tactic for max power but rather a guarantee that you can rest easy knowing that people won't have inadequate fuel pressure and less problems and complaints coming back to your company since data logging is not required which is smart in my book. Because strangely enough not all SHO's have the same fuel delivery capabilities.

I've seen some SHO's look fine at 16 psi and some borderline at 13-14 psi.

When operating in an efficient zone of a given turbo, I've never seen a car make more power at lower boost compared to a higher boost when both are running max spark the fuel can handle

I would never send a tune without datalogging and run more than 13 psi.....Of course if I was only running 13 psi I wouldn't even run a 3 bar, there is just no need.

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

I think that sums up my take for now until I am provoked by the forum which happens a lot which is why I enjoy the forum lol

So would you be able to run the same spark of 20.5 degress at 13psi vs 16psi? Wouldn't knock become a factor? or are you more concerned about fuel pressure at point? If I am bass akwards let me know... but I assumed that there is a balance between the two?

[derfdog15]

AJPTurbo Delivers, in the thread, and in my inbox!

Here are some overlays of his big power pull vs. my pulls. An overlay vs. all three of my dyno runs (including the weird first one - lower power/torque) uncorrected and SAE. Also an overlay of his big pull vs. both of mine.

Note that the torque number is somewhat durring a boost spike like condition/tip in on his, mine is also at low end but more flat overall.

He ran more boost, less spark than I run on the pull, both power and torque are greater, but it shows that in this case boost was worth more power than spark.

SAE correction is a better comparison as it better accounts for weather, etc. His SAE correction factor is 1.04, due to his pull being at 78.94 deg F and 55% humidity.

My SAE correction factor is 1.01, due to 70.70 deg F and 33% humidity.

[AJP turbo]

When I dynoed from stock boost to 18.5 psi I ran the max spark that the fuel could tolerate and made more power at each boost level until about 18.5 psi....18.5 psi was only a few hp more than 17.5 so it wasn't really worth it.

I don't really think that less boost and more spark is necessarily a tactic for max power but rather a guarantee that you can rest easy knowing that people won't have inadequate fuel pressure and less problems and complaints coming back to your company since data logging is not required which is smart in my book. Because strangely enough not all SHO's have the same fuel delivery capabilities.

I've seen some SHO's look fine at 16 psi and some borderline at 13-14 psi.

When operating in an efficient zone of a given turbo, I've never seen a car make more power at lower boost compared to a higher boost when both are running max spark the fuel can handle

I would never send a tune without datalogging and run more than 13 psi.....Of course if I was only running 13 psi I wouldn't even run a 3 bar, there is just no need.

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

I think that sums up my take for now until I am provoked by the forum which happens a lot which is why I enjoy the forum lol

So would you be able to run the same spark of 20.5 degress at 13psi vs 16psi? Wouldn't knock become a factor? or are you more concerned about fuel pressure at point? If I am bass akwards let me know... but I assumed that there is a balance between the two?

I'm not sure what you mean exactly....If you were at 16 psi and 18 degrees on my tune and I lowered the boost to 13 then the spark would naturally rise because your load would go down which would request more spark.

BUt if you mean you are running 20.5 degrees at both boost levels and are not getting KR then I would say you need more spark at 13 psi.

[AJP turbo]

AJPTurbo Delivers, in the thread, and in my inbox!

I am good at putting it in the box....I had a hot teacher in highschool and every morning she would tell us to put our homework in a box on here desk....She would say "stick it in my box".....No lie she was a legend in our school lol

[StealBlueSho]

When I dynoed from stock boost to 18.5 psi I ran the max spark that the fuel could tolerate and made more power at each boost level until about 18.5 psi....18.5 psi was only a few hp more than 17.5 so it wasn't really worth it.

I don't really think that less boost and more spark is necessarily a tactic for max power but rather a guarantee that you can rest easy knowing that people won't have inadequate fuel pressure and less problems and complaints coming back to your company since data logging is not required which is smart in my book. Because strangely enough not all SHO's have the same fuel delivery capabilities.

I've seen some SHO's look fine at 16 psi and some borderline at 13-14 psi.

When operating in an efficient zone of a given turbo, I've never seen a car make more power at lower boost compared to a higher boost when both are running max spark the fuel can handle

I would never send a tune without datalogging and run more than 13 psi.....Of course if I was only running 13 psi I wouldn't even run a 3 bar, there is just no need.

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

I think that sums up my take for now until I am provoked by the forum which happens a lot which is why I enjoy the forum lol

So would you be able to run the same spark of 20.5 degress at 13psi vs 16psi? Wouldn't knock become a factor? or are you more concerned about fuel pressure at point? If I am bass akwards let me know... but I assumed that there is a balance between the two?

I'm not sure what you mean exactly....If you were at 16 psi and 18 degrees on my tune and I lowered the boost to 13 then the spark would naturally rise because your load would go down which would request more spark.

BUt if you mean you are running 20.5 degrees at both boost levels and are not getting KR then I would say you need more spark at 13 psi.

The second portion answers my question.


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[AJP turbo]

And stealblue when you said my tune had boost spike in 1st gear when I was at 201 kpa desired is that when I had the throttle open and you were playing doctor boost controller LOL?...I think I wanted the gate to open and you wanted to delay the opening which allowed for a bit more spike which was ok because you had fuel pressure.

The throttle closures are awesome at mitigating boost spikes.

And there is a pretty big difference between 201 kpa and 186kpa....If I tune people at less than 185 ish I could keep the throttle open as boost spikes probably wouldn't go over about 215 is on the 2-3 shift.....But when I get into the 190 ish kpa then I need to use the throttle because boost spikes would exceed 220 kpa on the 2-3 shift and fuel pressure plummets and I'd rather not see that happen.

[StealBlueSho]

And stealblue when you said my tune had boost spike in 1st gear when I was at 201 kpa desired is that when I had the throttle open and you were playing doctor boost controller LOL?...I think I wanted the gate to open and you wanted to delay the opening which allowed for a bit more spike which was ok because you had fuel pressure.

The throttle closures are awesome at mitigating boost spikes.

And there is a pretty big difference between 201 kpa and 186kpa....If I tune people at less than 185 ish I could keep the throttle open as boost spikes probably wouldn't go over about 215 is on the 2-3 shift.....But when I get into the 190 ish kpa then I need to use the throttle because boost spikes would exceed 220 kpa on the 2-3 shift and fuel pressure plummets and I'd rather not see that happen.

Hmmm negative, I wasn't referencing the wastegate mod.. the difference in the first gear spike is noted here... here is the log when you were tuning my car and the desired TIP was 199... notice the difference in the boost curve in first gear.. yes, your tune is running more boost by 13kpa.. however, that spike in first is what i would expect to see... in LMS that does not exist... both tunes are using the throttle to control spikes.

IN ANY EVENT... regardless of boost spikes which is has been beat to death...

The reason for the spike vs boost question is simply this....

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?

or am I looking at this all wrong?

[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.

[StealBlueSho]

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.