R56 N18 boost limits
#1
N18 boost limits
Ok, guys and gals, maybe a dumb question or two, but I have searched....
2011 N18 with JB+ and the list of mods in my profile. I see 19.2 max (so far) as far as boost goes on my ScanGauge2. My questions are these:
Does the ScanGauge2 read actual boost, or what the ECU "thinks" it sees? Since it plugs into the OBD2 port, I would assume it's what the ECU thinks it sees.
How much does the JB+ "fool" the ECU?
How much is too much boost on a stock N18? Seeing 19.2 on my Scangauge2 may indicate that I am possibly pushing too much boost for the engine. Yes or no?
I have no issues thus far, and LOVE my JB+. But, at 55k, I am trying to make this little rocket last for at least another 100k.
Can anyone with a similar setup tell me what their higher-mileage results were?
Thanks in advance, and feel free to answer my questions one at a time, or chastise me for not getting a proper Tune. I know I need a Manic Tune, just not in the cards right now....
Cheers, Chris
2011 N18 with JB+ and the list of mods in my profile. I see 19.2 max (so far) as far as boost goes on my ScanGauge2. My questions are these:
Does the ScanGauge2 read actual boost, or what the ECU "thinks" it sees? Since it plugs into the OBD2 port, I would assume it's what the ECU thinks it sees.
How much does the JB+ "fool" the ECU?
How much is too much boost on a stock N18? Seeing 19.2 on my Scangauge2 may indicate that I am possibly pushing too much boost for the engine. Yes or no?
I have no issues thus far, and LOVE my JB+. But, at 55k, I am trying to make this little rocket last for at least another 100k.
Can anyone with a similar setup tell me what their higher-mileage results were?
Thanks in advance, and feel free to answer my questions one at a time, or chastise me for not getting a proper Tune. I know I need a Manic Tune, just not in the cards right now....
Cheers, Chris
#2
Ok, guys and gals, maybe a dumb question or two, but I have searched.... 2011 N18 with JB+ and the list of mods in my profile. I see 19.2 max (so far) as far as boost goes on my ScanGauge2. My questions are these: Does the ScanGauge2 read actual boost, or what the ECU "thinks" it sees? Since it plugs into the OBD2 port, I would assume it's what the ECU thinks it sees. How much does the JB+ "fool" the ECU? How much is too much boost on a stock N18? Seeing 19.2 on my Scangauge2 may indicate that I am possibly pushing too much boost for the engine. Yes or no? I have no issues thus far, and LOVE my JB+. But, at 55k, I am trying to make this little rocket last for at least another 100k. Can anyone with a similar setup tell me what their higher-mileage results were? Thanks in advance, and feel free to answer my questions one at a time, or chastise me for not getting a proper Tune. I know I need a Manic Tune, just not in the cards right now.... Cheers, Chris
mQubed Motorsport, Manic Tuning Dealer
__________________
2013 GP2 #295, 270whp/310wtq, KO4 47mm Turbo, 18" NM Wheels, Alta intake, Manic Stage III+, HFS-3 Meth, 30% E85 Blend, Forged IC, Alta Hot Pipe, P&P/Ceramic Exhaust Manifold, m3 Extreme Ceramic DP, Vibrant mid res, 4" Double walled Tips, WMW/KW V3 CO, Alta Rear CA, CREE Fogs, Black out F/R Rings and Gas Cap, M7 CF Front Splitter, and No Stickers. MORE TO COME!! Previous 04Triple Black 17% Alta, MM Air/H2O, CAI, OBX Header, FBT Head, Shrick Cam, 234whp
2013 GP2 #295, 270whp/310wtq, KO4 47mm Turbo, 18" NM Wheels, Alta intake, Manic Stage III+, HFS-3 Meth, 30% E85 Blend, Forged IC, Alta Hot Pipe, P&P/Ceramic Exhaust Manifold, m3 Extreme Ceramic DP, Vibrant mid res, 4" Double walled Tips, WMW/KW V3 CO, Alta Rear CA, CREE Fogs, Black out F/R Rings and Gas Cap, M7 CF Front Splitter, and No Stickers. MORE TO COME!! Previous 04Triple Black 17% Alta, MM Air/H2O, CAI, OBX Header, FBT Head, Shrick Cam, 234whp
#3
Thanks, Mario. I thought it sounded a bit high as well. But, no problems. I always run Union 76 91 octane, the best available at the pump here. I was told by the dealer mechanic that my car felt quicker than other stock cars he had driven. He even asked if I had modded anything, and at that point I had not. He was impressed with how well it performed. I guess I got a good one. LOL. Wednesday car, maybe? Or just a good builder? No matter, just happy to have a crisp car. I am looking forward to your Tune, but like I said, not just yet. The JB+ is set at 70%, and feels strong!
#5
With the JB+ it has been recommended to stay at or below 18psi (S turbo) since you are using stock AFR maps, which are very lean for MPG. The manic tune adds more fuel so it is able to run more boost and timing, making more power safely. If you stay with the JB+ the limiting factor is octane, so people run race gas, E85 mixture, or meth injection to achieve that goal.
#6
Thanks, Mario. I thought it sounded a bit high as well. But, no problems. I always run Union 76 91 octane, the best available at the pump here. I was told by the dealer mechanic that my car felt quicker than other stock cars he had driven. He even asked if I had modded anything, and at that point I had not. He was impressed with how well it performed. I guess I got a good one. LOL. Wednesday car, maybe? Or just a good builder? No matter, just happy to have a crisp car. I am looking forward to your Tune, but like I said, not just yet. The JB+ is set at 70%, and feels strong!
#7
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#8
Thanks, guys. I may just step the JB+ back to 50 or 60%. I am not sure that I understand how a JB+ works. I thought it lied to the ecm, understating boost, and therefore the ecm allows more boost. Is this anywhere near close? Also, if boost is added, leading to a lean condition, wouldn't the ecu compensate for this, based upon the input from the upstream oxygen sensor?
#9
Thanks, guys. I may just step the JB+ back to 50 or 60%. I am not sure that I understand how a JB+ works. I thought it lied to the ecm, understating boost, and therefore the ecm allows more boost. Is this anywhere near close? Also, if boost is added, leading to a lean condition, wouldn't the ecu compensate for this, based upon the input from the upstream oxygen sensor?
Here is a quick couple quotes from Terry Burger The DME targets load not boost. But, all the gauges we use read in boost as its an easier concept to get our heads around. Basically boost will change based on air density. The amount of information you'd need to truly understand the DME's internal operation is beyond what I have time or motivation to provide (sorry) but the DME is mapped on load (and torque) and translates that to boost as its final step in determine a boost set point at any given time. mQubed Motorsport, Manic Tuning Dealer
__________________
2013 GP2 #295, 270whp/310wtq, KO4 47mm Turbo, 18" NM Wheels, Alta intake, Manic Stage III+, HFS-3 Meth, 30% E85 Blend, Forged IC, Alta Hot Pipe, P&P/Ceramic Exhaust Manifold, m3 Extreme Ceramic DP, Vibrant mid res, 4" Double walled Tips, WMW/KW V3 CO, Alta Rear CA, CREE Fogs, Black out F/R Rings and Gas Cap, M7 CF Front Splitter, and No Stickers. MORE TO COME!! Previous 04Triple Black 17% Alta, MM Air/H2O, CAI, OBX Header, FBT Head, Shrick Cam, 234whp
2013 GP2 #295, 270whp/310wtq, KO4 47mm Turbo, 18" NM Wheels, Alta intake, Manic Stage III+, HFS-3 Meth, 30% E85 Blend, Forged IC, Alta Hot Pipe, P&P/Ceramic Exhaust Manifold, m3 Extreme Ceramic DP, Vibrant mid res, 4" Double walled Tips, WMW/KW V3 CO, Alta Rear CA, CREE Fogs, Black out F/R Rings and Gas Cap, M7 CF Front Splitter, and No Stickers. MORE TO COME!! Previous 04Triple Black 17% Alta, MM Air/H2O, CAI, OBX Header, FBT Head, Shrick Cam, 234whp
#10
#11
Thanks, guys. I may just step the JB+ back to 50 or 60%. I am not sure that I understand how a JB+ works. I thought it lied to the ecm, understating boost, and therefore the ecm allows more boost. Is this anywhere near close? Also, if boost is added, leading to a lean condition, wouldn't the ecu compensate for this, based upon the input from the upstream oxygen sensor?
#12
Thanks, Mario. I thought it sounded a bit high as well. But, no problems. I always run Union 76 91 octane, the best available at the pump here. I was told by the dealer mechanic that my car felt quicker than other stock cars he had driven. He even asked if I had modded anything, and at that point I had not. He was impressed with how well it performed. I guess I got a good one. LOL. Wednesday car, maybe? Or just a good builder? No matter, just happy to have a crisp car. I am looking forward to your Tune, but like I said, not just yet. The JB+ is set at 70%, and feels strong!
#13
Not sure if this is the correct thread for my posting, but this thread seems to be the most current and related to my query.
I recently bought a 2011 Countryman Cooper S and it runs well with no fault codes. I've datalogged it with the Torque app and I've come across something that puzzles me. I've been logging Speed, RPM, Boost, Air/Fuel Ratio, Airflow through MAF and Ignition Advance. Although the increase in speed and engine acceleration (i.e. RPM increase) appears to be linear, the plots for boost, and airflow through MAF are far from linear. To demonstrate my point, the graph below shows the plots of RPM and Boost during a 3rd gear acceleration.
I would've expected that the plot for boost would show some linear increase throughout the acceleration, or plateau, rather than rise/fall/rise/fall as is recorded. I know from datalogging other normally aspirated BMWs, that the ECU makes all manner of almost instant different changes to timing which produces very non-linear plots for this parameter, but I'm very surprised that the plot for boost is as variable as it is with my car. At the end of the day, the plot of acceleration is almost perfectly linear so it would seem that the ECU achieves consistent power increase by adjusting several different parameters to achieve a result.
My data points were all recorded at 1/10th second intervals, which is obviously faster than the polling rate of the ECU, as shown by the grouping of the plot points, but even if the data points were collected at 1/2 second intervals, it wouldn't change the basic shape of the plots. I've examined other plots of acceleration of my car and in other gears/speed and similar drops in boost seem to occur in mid-rev range.
Can anyone explain why boost on my car seems to drop in the rev range of peak torque? Have others seen similar plots with their N18 engines?
I recently bought a 2011 Countryman Cooper S and it runs well with no fault codes. I've datalogged it with the Torque app and I've come across something that puzzles me. I've been logging Speed, RPM, Boost, Air/Fuel Ratio, Airflow through MAF and Ignition Advance. Although the increase in speed and engine acceleration (i.e. RPM increase) appears to be linear, the plots for boost, and airflow through MAF are far from linear. To demonstrate my point, the graph below shows the plots of RPM and Boost during a 3rd gear acceleration.
I would've expected that the plot for boost would show some linear increase throughout the acceleration, or plateau, rather than rise/fall/rise/fall as is recorded. I know from datalogging other normally aspirated BMWs, that the ECU makes all manner of almost instant different changes to timing which produces very non-linear plots for this parameter, but I'm very surprised that the plot for boost is as variable as it is with my car. At the end of the day, the plot of acceleration is almost perfectly linear so it would seem that the ECU achieves consistent power increase by adjusting several different parameters to achieve a result.
My data points were all recorded at 1/10th second intervals, which is obviously faster than the polling rate of the ECU, as shown by the grouping of the plot points, but even if the data points were collected at 1/2 second intervals, it wouldn't change the basic shape of the plots. I've examined other plots of acceleration of my car and in other gears/speed and similar drops in boost seem to occur in mid-rev range.
Can anyone explain why boost on my car seems to drop in the rev range of peak torque? Have others seen similar plots with their N18 engines?
Last edited by exdos; 04-10-2016 at 11:03 AM.
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Flappy (11-19-2019)
#14
Someone can give a much smarter answer than me but here it goes. Boost is only what is needed to meet the calculated load and, as you know, is only one of many variables that is adjusted in real time and can vary by 2-3psi even under "identical conditions". You also have air temperature and altitude to consider.
I think boost would drop during the rev range of peak torque as not as much is needed to keep acceleration constant.
I think boost would drop during the rev range of peak torque as not as much is needed to keep acceleration constant.
#15
OK, still trying to figure out how a lean condition would not be read and compensated for. I get the fact that I may be overworking my knock sensor, but that deals with ignition timing, correct? So, if my upstream O2 sensor reads lean, the computer should compensate by adding fuel. I am sure to be missing something here. My point is this... no matter the lean/rich condition, nor the spark knock, the internal computer should be able to compensate, by either adding more fuel or cutting timing. It's not like I have taken parameters away, they still exist in the programming. There should be compensation. Right or wrong?
#16
OK, still trying to figure out how a lean condition would not be read and compensated for. I get the fact that I may be overworking my knock sensor, but that deals with ignition timing, correct? So, if my upstream O2 sensor reads lean, the computer should compensate by adding fuel. I am sure to be missing something here. My point is this... no matter the lean/rich condition, nor the spark knock, the internal computer should be able to compensate, by either adding more fuel or cutting timing. It's not like I have taken parameters away, they still exist in the programming. There should be compensation. Right or wrong?
#17
My AFR on my GP, with the JB+ and FBO was close to 13.0. Stage 3 and 4 Manic, my AFR's are around 11.3 and ignition is 5-6 degrees higher
mQubed Motorsport, Manic Tuning Dealer
mQubed Motorsport, Manic Tuning Dealer
__________________
2013 GP2 #295, 270whp/310wtq, KO4 47mm Turbo, 18" NM Wheels, Alta intake, Manic Stage III+, HFS-3 Meth, 30% E85 Blend, Forged IC, Alta Hot Pipe, P&P/Ceramic Exhaust Manifold, m3 Extreme Ceramic DP, Vibrant mid res, 4" Double walled Tips, WMW/KW V3 CO, Alta Rear CA, CREE Fogs, Black out F/R Rings and Gas Cap, M7 CF Front Splitter, and No Stickers. MORE TO COME!! Previous 04Triple Black 17% Alta, MM Air/H2O, CAI, OBX Header, FBT Head, Shrick Cam, 234whp
2013 GP2 #295, 270whp/310wtq, KO4 47mm Turbo, 18" NM Wheels, Alta intake, Manic Stage III+, HFS-3 Meth, 30% E85 Blend, Forged IC, Alta Hot Pipe, P&P/Ceramic Exhaust Manifold, m3 Extreme Ceramic DP, Vibrant mid res, 4" Double walled Tips, WMW/KW V3 CO, Alta Rear CA, CREE Fogs, Black out F/R Rings and Gas Cap, M7 CF Front Splitter, and No Stickers. MORE TO COME!! Previous 04Triple Black 17% Alta, MM Air/H2O, CAI, OBX Header, FBT Head, Shrick Cam, 234whp
#18
#19
Tis the magic of direct injection. We'd never be able to get away with it otherwise. The manic tunes run a little rich but better safe and leave some power on the table.
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