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  1. #26
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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    Interesting comment to say the least...can you share what you did to study the ignition process of a DI system to see what exactly is happening to the fuel and where in the combustion chamber? Really not sure what you mean/could've done there with a borescope...i have one handy and can easily look in there but IMO if there hasn't been any severe damage/detonation in there there won't be much to see...in any case, you've got my curiosity up for sure and I'll definitely peak in there soon Click here to enlarge

    Its a known fact that AFR on DI can run leaner than port injection...from what you have seen/done with your car and your tuner what is your opinion on the AFR curve with everything you have currently on the car...what AFR do you target in low/mid/top range and do you modify it from one gear to the next?
    There is a lot of research done that is available online that you can access with a search. A lot of it has been done by Bosch during the design process. Read carefully how the fuel gets injected, where it travels to and at where in the combustion chamber it gets concentrated for when ignition occurs. I have also read a 5000pg document by VDO/Seimens that is N54 specific, this is not for public release and I could not get a copy.

    I am comfortable running between 13.1-12.5 Although there is no scientific proof that this is the correct amount but it doesn't show adverse affects when running this amount. Going richer has not added power or given any specific reason to do so.

  2. #27
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    Click here to enlarge Originally Posted by George Smooth Click here to enlarge
    There is a lot of research done that is available online that you can access with a search. A lot of it has been done by Bosch during the design process. Read carefully how the fuel gets injected, where it travels to and at where in the combustion chamber it gets concentrated for when ignition occurs. I have also read a 5000pg document by VDO/Seimens that is N54 specific, this is not for public release and I could not get a copy.

    I am comfortable running between 13.1-12.5 Although there is no scientific proof that this is the correct amount but it doesn't show adverse affects when running this amount. Going richer has not added power or given any specific reason to do so.
    Sounds right

  3. #28
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    Click here to enlarge Originally Posted by George Smooth Click here to enlarge
    There is a lot of research done that is available online that you can access with a search. A lot of it has been done by Bosch during the design process. Read carefully how the fuel gets injected, where it travels to and at where in the combustion chamber it gets concentrated for when ignition occurs. I have also read a 5000pg document by VDO/Seimens that is N54 specific, this is not for public release and I could not get a copy.

    I am comfortable running between 13.1-12.5 Although there is no scientific proof that this is the correct amount but it doesn't show adverse affects when running this amount. Going richer has not added power or given any specific reason to do so.
    I definitely won't be able to get a copy of that N54 specific document you've managed to get a hold of. It'd be great for the community if you could write up a short summary of what your findings were, obviously if you have time. Information like that is why I visit these forums in the first place, not bickering with Shiv. The more of that information on the forums the better it is for those that're willing to read/learn...

    You mention 13.1-12.5 as what you see as safe to run based on your analysis and what you've learned from reading documentation...that is very close to the stock AFR target in the top end which runs considerably less boost/cylinder pressures..I'm sure you're aware as stock runs about 12.7-12.8 up top, no need for a 5k page doc to know that...were you speaking low end/midrange or saying 13.1 low/midrange down to 12.5 at the top?

    Did you dyno your setup? What's the setup currently that you've run with the most power boost, nitrous, AFR, timing, meth wise?
    Click here to enlarge

  4. #29
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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    You mention 13.1-12.5 as what you see as safe to run based on your analysis and what you've learned from reading documentation...that is very close to the stock AFR target in the top end which runs considerably less boost/cylinder pressures..
    On the other hand high boost is ran on FBO + methanol. More octane + cooling, and less back pressure and pressure drop means that you can run a lot leaner, correct? Those should compensate for the increased boost. Only if you are seeing knock or dangerously high EGTs, you can conclude that you are running too lean.

  5. #30
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    Click here to enlarge Originally Posted by 654 Click here to enlarge
    On the other hand high boost is ran on FBO + methanol. More octane + cooling, and less back pressure and pressure drop means that you can run a lot leaner, correct? Those should compensate for the increased boost. Only if you are seeing knock or dangerously high EGTs, you can conclude that you are running too lean.
    I'd say so...one thing I really regret is not asking Rob@RBturbo to weld some EGT bungs to the turbo exhaust manifold...that would've been an awesome tuning parameter to have on this car and it could've provided TONS of insight into many of the questions we/I have still today
    Click here to enlarge

  6. #31
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    Good discussion. Very curious about DI pertaining to the N54. I have read before that the N54 is only homogenous mixture meaning injection during intake stroke, but on the forums it has been mentioned that it’s a stratified charge (only during low load I would think).

    EGTs will actually decrease if you are detonating. I don’t think you should target the lowest temp, but don’t run with excessively high EGTs.

    As far as shifting, I have been playing with fueling on the procede. I have a manual though. And have found post-shift is very dependent on the open loop table. There has been a drastic difference in my shifts now when I try targeting positive trims across the revs and MAP points. No bog, no worries about shift timing really… fast, slow… always crisp now. There could be some effect with an auto also.

  7. #32
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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    Good discussion. Very curious about DI pertaining to the N54. I have read before that the N54 is only homogenous mixture meaning injection during intake stroke, but on the forums it has been mentioned that it’s a stratified charge (only during low load I would think).
    You in the right direction. The engine runs three different cycles. It runs stratified charge up to medium load with high lambda values, it then transitions into homogenous lean charge mode where the lambdas are around 1.5 and then transitions into homogenous charge mode where the lambda target is 1. The trick to all of this is that in all three cases the spray pattern from the injector is different.
    A good read of the VW system that is similar to the N54 can be read here http://www.volkspage.net/technik/ssp/ssp/SSP_253.pdf

  8. #33
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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    I definitely won't be able to get a copy of that N54 specific document you've managed to get a hold of. It'd be great for the community if you could write up a short summary of what your findings were, obviously if you have time. Information like that is why I visit these forums in the first place, not bickering with Shiv. The more of that information on the forums the better it is for those that're willing to read/learn...

    You mention 13.1-12.5 as what you see as safe to run based on your analysis and what you've learned from reading documentation...that is very close to the stock AFR target in the top end which runs considerably less boost/cylinder pressures..I'm sure you're aware as stock runs about 12.7-12.8 up top, no need for a 5k page doc to know that...were you speaking low end/midrange or saying 13.1 low/midrange down to 12.5 at the top?

    Did you dyno your setup? What's the setup currently that you've run with the most power boost, nitrous, AFR, timing, meth wise?

    I am going to get the doc and try do some cliff notes and post some information up. The crunch of the matter is maintaining stock fueling characteristics as what the injector is doing is not as simple as people think. It is also not a matter of how much fuel you burn - AFR but where the fuel is burnt in the combustion chamber. It went in depth about the sting of fuel and NOX values which is the basis of the whole ECU logic. Keep in mind though that 99% of Seimens effort went into what happens when you not full throttle.

    The last dyno I did was 509whp on a Mustang type dyno with a .34 jet and 16psi at 5500ft. At 19psi no nitrous I am seeing 470whp regardless of Procede or flash, boost is boost I guess. I have run a .47 jet with thumb sucking the fueling jet for about six bottles. We then scoped the engine to see signs of heat and it was fine, hence the not a big worry about fueling unless we masters and we got it right.

  9. #34
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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    As far as shifting, I have been playing with fueling on the procede. I have a manual though. And have found post-shift is very dependent on the open loop table. There has been a drastic difference in my shifts now when I try targeting positive trims across the revs and MAP points. No bog, no worries about shift timing really… fast, slow… always crisp now. There could be some effect with an auto also.
    "target positive trims across the revs and MAP points"? How do you do that? What is the drastic difference in shifts?

  10. #35
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    Click here to enlarge Originally Posted by George Smooth Click here to enlarge
    I am going to get the doc and try do some cliff notes and post some information up. The crunch of the matter is maintaining stock fueling characteristics as what the injector is doing is not as simple as people think. It is also not a matter of how much fuel you burn - AFR but where the fuel is burnt in the combustion chamber. It went in depth about the sting of fuel and NOX values which is the basis of the whole ECU logic. Keep in mind though that 99% of Seimens effort went into what happens when you not full throttle.

    The last dyno I did was 509whp on a Mustang type dyno with a .34 jet and 16psi at 5500ft. At 19psi no nitrous I am seeing 470whp regardless of Procede or flash, boost is boost I guess. I have run a .47 jet with thumb sucking the fueling jet for about six bottles. We then scoped the engine to see signs of heat and it was fine, hence the not a big worry about fueling unless we masters and we got it right.
    Those are some awesome numbers, probably record numbers for the N54 if you calculate a minimum 8% correction for a Mustang dyno, you're at ~550whp STD on a Dynojet at close to sealevel I think..

    Whenever you do get the time I'd love to read a summary you put together from that doc you read...I understand that 99% was emissions related, understandable, and that's part of the reason I'm not convinced yet that DI's leaner AFR targets are indeed safe to be used for big power especially given your comment about 99% of the documentation dealing with situations when you're not WOT (i.e. not high hp, performance applications)...
    Click here to enlarge

  11. #36
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    Click here to enlarge Originally Posted by George Smooth Click here to enlarge
    You in the right direction. The engine runs three different cycles. It runs stratified charge up to medium load with high lambda values, it then transitions into homogenous lean charge mode where the lambdas are around 1.5 and then transitions into homogenous charge mode where the lambda target is 1. The trick to all of this is that in all three cases the spray pattern from the injector is different.
    A good read of the VW system that is similar to the N54 can be read here http://www.volkspage.net/technik/ssp/ssp/SSP_253.pdf
    thanks for the link. I just did a brief search and apparently the n54 doesn't have stratified charge mode due to US gas, NOx, and potentially the injector solenoids. Not 100%, and could be only in the US.

  12. #37
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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    thanks for the link. I just did a brief search and apparently the n54 doesn't have stratified charge mode due to US gas, NOx, and potentially the injector solenoids. Not 100%, and could be only in the US.
    This could possibly be correct, hence why US Flash tuners initially had no flash tune files for foreign cars. I would also become cautious with various terminology used as our cars are VDO/Seimens controlled vs the Bosch stuff I posted. It could possibly be that none of them run it as it requires a specifically designed piston although I do recall reading they have something which works in a similar way in principal. Its actually quite scary that we messing around with such complex systems, luckily most the changes we do are full throttle.

  13. #38
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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    thanks for the link. I just did a brief search and apparently the n54 doesn't have stratified charge mode due to US gas, NOx, and potentially the injector solenoids. Not 100%, and could be only in the US.
    According to a recent post from Rob@Cobb N54 does have stratified charge mode but only under low load situations...it was over on e90
    Click here to enlarge

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    I have read all this information about 4 years ago when I helped with fuel pump development for my old DI platform. Honestly you guys are reading to much into it. DI could slightly burn leaner down low at wot and low load situations, however DI technology goes OUT THE WINDOW once rpms climb, the car still needs the traditional fueling afrs to stay happy. When I mean slightly leaner under low load/lower rpms I am talking half a point or so.

    As for when the fuel is sprayed, that is a big one, because if the injector timing is off, you will report a FALSE rich conditions due to overlap. This gets a little more involved but it is not as complicated as the 5000 page manual suggests lol. Like George said, the majority of those reports focus on emmissions, not power so take what they say with a grain of salt.

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    Click here to enlarge Originally Posted by Laloosh Click here to enlarge
    the car still needs the traditional fueling afrs to stay happy.
    What happens if it does not get the traditional AFRs but the typical DI AFRs? How do you reckon the car is not happy?

  16. #41
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    For WOT, AFR really depends on the tuning and how well A/F can mix. I don’t know the specifics, especially when approaching the thermodynamics of the actual reaction. BUT we enrich basically to ensure fuel is distributed throughout the cylinder and able to mix with O2. DI is much better in this respect. The other reasons for fueling is cooling and burn rate. Speaking purely on energy production, 14.7:1(or stoich) will give the most power considering consistent mixture and no spontaneous combustion due to heat. The thermodynamics get complicated (for me anyway), but with a richer mixture you use more of the available O2 in the first reaction… apparently combustion is 2 parts… and thus less energy potential.

    I’m sure there’s much smarter peeps that can explain better.

    I would really be interested in leaning my AFR, but first would want to gather data from external WB, or at least see other AFR traces to compare… and you all have kinda scared me that maybe I’m leaner then the logs state… good job. I may try targeting 12.5:1.

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    Click here to enlarge Originally Posted by 654 Click here to enlarge
    What happens if it does not get the traditional AFRs but the typical DI AFRs? How do you reckon the car is not happy?
    Same thing that happen on a PI car. Read up on how DI works and why it looses its "gains" at high rpm/load

  18. #43
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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    For WOT, AFR really depends on the tuning and how well A/F can mix. I don’t know the specifics, especially when approaching the thermodynamics of the actual reaction. BUT we enrich basically to ensure fuel is distributed throughout the cylinder and able to mix with O2. DI is much better in this respect. The other reasons for fueling is cooling and burn rate. Speaking purely on energy production, 14.7:1(or stoich) will give the most power considering consistent mixture and no spontaneous combustion due to heat. The thermodynamics get complicated (for me anyway), but with a richer mixture you use more of the available O2 in the first reaction… apparently combustion is 2 parts… and thus less energy potential.

    I’m sure there’s much smarter peeps that can explain better.

    I would really be interested in leaning my AFR, but first would want to gather data from external WB, or at least see other AFR traces to compare… and you all have kinda scared me that maybe I’m leaner then the logs state… good job. I may try targeting 12.5:1.
    In my case other people didn't need to scare me, i got scared of the sole fact they were being "calculated" off wideband bias and I just wanted to know true AFR..glad I did
    Click here to enlarge

  19. #44
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    Is there much N54 evidence to suggest running "lean" (13.8:1) in the midrange has any potential for damage? Things like melted plugs, valves, turbines, signs of preignition, etc? I've seen melted plugs/valves on two cars out of thousands and both of those had direct causes. Likely running > 16:1.

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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    Is there much N54 evidence to suggest running "lean" (13.8:1) in the midrange has any potential for damage? Things like melted plugs, valves, turbines, signs of preignition, etc? I've seen melted plugs/valves on two cars out of thousands and both of those had direct causes. Likely running > 16:1.
    Well you come from an ls1 background and they target 12.8:1 with PI in the top (I think)... they may change this when boosted, not sure. I'd love to see a dyno (with correct tuning) for 12:1 compared to 13:1 or even leaner.

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    Click here to enlarge Originally Posted by Terry@BMS Click here to enlarge
    Is there much N54 evidence to suggest running "lean" (13.8:1) in the midrange has any potential for damage? Things like melted plugs, valves, turbines, signs of preignition, etc? I've seen melted plugs/valves on two cars out of thousands and both of those had direct causes. Likely running > 16:1.
    Cobb stated on e90 that going richer at their boost levels has def taken away knock. Like anythign else its a balance. I wish cobb would present us with some data cause it sounds like they do things the right away and not just dyno a car and go "oh look, 100whp delta"

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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    Well you come from an ls1 background and they target 12.8:1 with PI in the top (I think)... they may change this when boosted, not sure. I'd love to see a dyno (with correct tuning) for 12:1 compared to 13:1 or even leaner.
    Boosted I'd always shoot for 11.8:1 across the board. Maybe richer. But a lot of that depended on the compression/boost/octane/advance curve used. NA you'd make the most power around 13:1 and knock wasn't a huge issue on good gas. The LS1 knock detection system is no where near as good as the N54s though.

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    Click here to enlarge Originally Posted by Laloosh Click here to enlarge
    I wish cobb would present us with some data
    I wish Cobb would have more of an official presence here personally.

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    2 out of 2 members liked this post. Reputation: Yes | No
    Hello! This is my best time 0-100-200 on the highway. Click here to enlarge
    Today it is very cold (+2C) also wheels slip to 140km/h.
    60ft 2.6, street tires 295/30R19 Advan AD08 with Rays CE28N.
    BMW335i AT, FBO+Jb4 map6+45meth (70/30mix),93oct, RBturbos, Full weight, Quaife.

  25. #50
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    Click here to enlarge Originally Posted by Tomaz Click here to enlarge
    Hello! This is my best time 0-100-200 on the highway. Click here to enlarge
    Today it is very cold (+2C) also wheels slip to 140km/h.
    60ft 2.6, street tires 295/30R19 Advan AD08 with Rays CE28N.
    BMW335i AT, FBO+Jb4 map6+45meth (70/30mix),93oct, RBturbos, Full weight, Quaife.
    Welcome.

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