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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > The Basics of Tuning and Timing



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      02-24-2011, 12:51 PM   #45
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strong post -- and good explaination of how it all works ...

one thing i would like to add:

for timing to be efficient it must occur within a set window of opportunity --
when engine speed increases the time it takes the piston to reach TDC is shortened. now if you add a load factor to the speed increase the cylinder pressure must be kept at optimum levels to sustain proper engine output.

if the timing occurs too early in the process (under load) cylinder pressures rise to a unacceptable level -- ie knock events start to occur. now if you add pressurization to the equation (boost) you make the engine more susceptible to knock. simple way to put it --> cylinder volume -> pressure --> start of ignition --> piston speed. with more volume and speed -- time if initial fuel/air ignition is reduced (required) -- a knock event is an indication of cylinder overpressurization and lack of combustion control ..

this is one reason most engine builders/tuners search hard for the best timing under the knock threshold.

so with the increase in load, and piston speed timing is moved backwards to reduce the peak pressure reached TDC -- having the ability to move (graduated increases) the timing back up to an efficient setting is far more advanced than the old way of power timing (under load till it knocked and then back it off 2-3 degrees).. and believe you me, you never wanted to power-time a forced induction engine -- unless you had a lot of spare parts laying around and nothing to do but teardowns and rebuilds

again -- great post and good information
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      02-24-2011, 01:07 PM   #46
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Quote:
Originally Posted by shifterboy45 View Post
strong post -- and good explaination of how it all works ...

one thing i would like to add:

for timing to be efficient it must occur within a set window of opportunity --
when engine speed increases the time it takes the piston to reach TDC is shortened. now if you add a load factor to the speed increase the cylinder pressure must be kept at optimum levels to sustain proper engine output.

if the timing occurs too early in the process (under load) cylinder pressures rise to a unacceptable level -- ie knock events start to occur. now if you add pressurization to the equation (boost) you make the engine more susceptible to knock. simple way to put it --> cylinder volume -> pressure --> start of ignition --> piston speed. with more volume and speed -- time if initial fuel/air ignition is reduced (required) -- a knock event is an indication of cylinder overpressurization and lack of combustion control ..

this is one reason most engine builders/tuners search hard for the best timing under the knock threshold.

so with the increase in load, and piston speed timing is moved backwards to reduce the peak pressure reached TDC -- having the ability to move (graduated increases) the timing back up to an efficient setting is far more advanced than the old way of power timing (under load till it knocked and then back it off 2-3 degrees).. and believe you me, you never wanted to power-time a forced induction engine -- unless you had a lot of spare parts laying around and nothing to do but teardowns and rebuilds

again -- great post and good information
Nice. You pretty summarized the 50 page long thread.
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      02-24-2011, 01:31 PM   #47
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trying to help --

i worked as an instructor at a local tech school for a little bit, the guys i worked with were really clueless to onboard electronic controls. but just like everything else technology, some people get caught in the past. like the guys i used to wrench with, they said i was stupid for taking personal time to go to fuel injection classes -- cars would ALWAYS have carburetors ..

still gotta dig through some tech stuff and get that info --
i think it will benefit everybody on specifics of the N54
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      02-24-2011, 02:59 PM   #48
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You and I def show the same understanding of how tuning should be applied. The difference that I have a low tolerance for ignorant spiteful members who know they are wrong but continue to post because they feel the need to justify their incorrect logic.
I'm assuming you don't have kids?

I have a two year old son... and that kid has taught me more about patience and learning to let things go than any other experience I've ever encountered haha!! I'm a fairly technical person in many regards, but man, try being logical with a toddler!!

That combined with being a moderator on other boards for a couple years (most mods/admins get called out/talked trash to on a fairly regular basis haha), and spending a good amount of time in Nasioc's OT section (talk about a number of fairly clever, foul-mouthed, trash talking, yet strangely comical reprobates there are over there haha)... well, what another anonymous person says online doesn't bother me nearly as much as it used to!

The way I figure it, if people really want to learn, they'll at least make an attempt to listen to what another person has to say (even if they're wrong), but otherwise, not much you can do about it IMO.

Just my $.02
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      02-24-2011, 03:02 PM   #49
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Quote:
Originally Posted by JPSlick View Post

Edit- If you read a few peoples post in this thread you will also notice that sleeping on the knock sensor isnt necessarily the most efficient power. More ignition isnt always more power.

There is a certain point where you increase ignition, and make no more power. That is where you want to place your ignition, if not a degree or 2 less.


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Originally Posted by shifterboy45 View Post
strong post -- and good explaination of how it all works ...

one thing i would like to add:

for timing to be efficient it must occur within a set window of opportunity --
when engine speed increases the time it takes the piston to reach TDC is shortened. now if you add a load factor to the speed increase the cylinder pressure must be kept at optimum levels to sustain proper engine output.

if the timing occurs too early in the process (under load) cylinder pressures rise to a unacceptable level -- ie knock events start to occur. now if you add pressurization to the equation (boost) you make the engine more susceptible to knock. simple way to put it --> cylinder volume -> pressure --> start of ignition --> piston speed. with more volume and speed -- time if initial fuel/air ignition is reduced (required) -- a knock event is an indication of cylinder overpressurization and lack of combustion control ..

this is one reason most engine builders/tuners search hard for the best timing under the knock threshold.

so with the increase in load, and piston speed timing is moved backwards to reduce the peak pressure reached TDC -- having the ability to move (graduated increases) the timing back up to an efficient setting is far more advanced than the old way of power timing (under load till it knocked and then back it off 2-3 degrees).. and believe you me, you never wanted to power-time a forced induction engine -- unless you had a lot of spare parts laying around and nothing to do but teardowns and rebuilds

again -- great post and good information
Thank you both for the submissions! We are very much in concurrence.
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      02-24-2011, 03:03 PM   #50
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No kids here...don't want any for at least 3 years either. Your name sounds familiar from msf.org.
Quote:
Originally Posted by roninsoldier83 View Post
I'm assuming you don't have kids?

I have a two year old son... and that kid has taught me more about patience and learning to let things go than any other experience I've ever encountered haha!! I'm a fairly technical person in many regards, but man, try being logical with a toddler!!

That combined with being a moderator on other boards for a couple years (most mods/admins get called out/talked trash to on a fairly regular basis haha), and spending a good amount of time in Nasioc's OT section (talk about a number of fairly clever, foul-mouthed, trash talking, yet strangely comical reprobates there are over there haha)... well, what another anonymous person says online doesn't bother me nearly as much as it used to!

The way I figure it, if people really want to learn, they'll at least make an attempt to listen to what another person has to say (even if they're wrong), but otherwise, not much you can do about it IMO.

Just my $.02
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      02-24-2011, 03:21 PM   #51
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Good post. Were the subarus you mention closed loop all of the time? Because if not, then you can't compare the two. I know the rx7s weren't, and you had to rely on user maps. These types of piggybacks would never have worked on an rx7. Just like the S-afc would not work-safely, that is. Maybe that's the reason for the confusion here?

It's also the reason you can't just slap on DPs an exhaust, and an intake and make 50hp with no tune. With an rx7 there was the 3 mod rule. Ever heard of that? Three airflow mods: intake, exhaust, downpipe. Any more than that and BOOM. Actually sometimes not, and sometimes even with less than three the engine went boom anyway. All it took was a hot day, or a bad tank of gas. Why? Because the ECU wasn't able to react. That's not the case here.

You're also incorrect in saying that the knock sensor is setting the BASE timing map. BMW sets the base ignition map and it does indeed look similar to the one you posted and does decrease timinq with load. I may be oversimplifying things here and somebody correct me If I'm wrong because I'm only repeating what I've read here, but it's my understanding that the flashes rely on the knock sensor as well, but with a 3 degree "head start".
Most of these guys have a hard time getting their heads around closed loop timing which as far as I can tell is exclusive to the N54 platform. It's a complete game changer. This thread belongs on a Subaru forum somewhere.

Mike
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      02-24-2011, 03:37 PM   #52
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No kids here...don't want any for at least 3 years either. Your name sounds familiar from msf.org.
I've had a few different screen names over the years (mostly this one and arctic_blue83), but never spent much time on msf.org. Back when I rocked my MS6, I mostly frequented mazda6club.com until a few buddies and I setup coloradomazdaclub.com (CMZC), at which time I spent a lot more time on local boards that I did national boards. I just preferred working with people locally, putting faces with screen names ect.

You're Laloosh right? I remember you being a bit of a guinea pig for CP-E back in the day lol. I actually worked with Jordan at CP-E back in the day and introduced the idea of developing an upgraded HPFP back when those cars were running lean around ~3500rpm or so when upping the boost (yeah, that long ago haha)... but sadly I sold the car prior to the release of their HPFP. I also soldered in the first Standback in a MS3 in this state (CO) in my buddy Josh's car... their first variation, I remember not caring for the axes (I think they were referencing TPS or something to that effect for a load reference on the original version?!? That takes me back...), but I know they eventually updated it to use a real load reference. I won't lie, I was never a big fan of Mazda's ECU's.. ridiculous throttle plate partial closure at high RPM's, horrid stock tunes, finicky at best ... and don't get me started about the piss poor, heat soak laden TMIC design haha! I'm glad to see the aftermarket has addressed most of those issues for that community though
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      02-24-2011, 03:42 PM   #53
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You're all wrong. Everybody knows tuning is all about adding forced induction and raising boost until something shatters into a million pieces and then blaming the manufacturer of the turbo / engine. Geez. I'm gonna go start my own tuning company now. Who wants in?

We'll name it BOOM Ferrari Tuning

On a serious note. It would be great if those who did understand this and tuned their own cars could post some more about it so other members can get more familiar with the process. I'm not saying Joe Plumber should go tune his own $50K car. But it's never hurt anyone to have more knowledge
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      02-24-2011, 04:04 PM   #54
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Quote:
Originally Posted by Brey335i View Post
You're all wrong. Everybody knows tuning is all about adding forced induction and raising boost until something shatters into a million pieces and then blaming the manufacturer of the turbo / engine. Geez. I'm gonna go start my own tuning company now. Who wants in?

We'll name it BOOM Ferrari Tuning

On a serious note. It would be great if those who did understand this and tuned their own cars could post some more about it so other members can get more familiar with the process. I'm not saying Joe Plumber should go tune his own $50K car. But it's never hurt anyone to have more knowledge
Most tuning "programs" are pretty basic.

Load VS RPM usually

Tables for fuel
Tables for ignition
Tables for Cam Profiling/advance if applicable

What sets them apart is the amount of control they have and any other features they might offer.

Lean Protections
Knock Protection
Idle
Rev Limits
Gear Compensation (ignition/fuel)
IAT Compensations
ECT compensations
Oil Compensations

ETC ETC

Not much to "teach" for this platform until a company releases software and tune for the end user.

Que Cobb ATR.
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      02-24-2011, 04:07 PM   #55
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In fact, it's the other way around. Subarus have predefined maps which means they make the same power even when the conditions vary (to a certain degree, of course). N54 is more dynamic and calculates many of the values "on the fly", whereas other ECUs have predefined values. That's why some days you feel the car a bit slow, some days you feel it is a beast.
Subarus have tables set up for ideal conditions. IE 68* F, sea-level. They then have a number of compensations tables to account for variances in atmospheric conditions. They do NOT make the same power with varying conditions and they are not designed to. They are designed to make safe maximum power for the conditions they are operating in.

For example, on the stock ROM for my 2006 LGT, the map calls for 13.54 psi manifold pressure at 95.4% and above throttle plate opening at 3,600 RPM. The ECU then applies a compensation to this based on altitude, which applies a multiplier of .05208 to the current observed atmospheric pressure and then adds an offset of .25 to that product. This is then used as a multiplier to the original requested boost target to compensate for barometric pressure. Take two examples:

14.5 psi atmospheric pressure:
14.5psi*.05208 = .75116 +.25 = 1.00516
Requested boost of 13.54 psi * 1.00516 = 13.609 psi requested boost corrected for atmosphere.

12.5 psi atmospheric pressure:
12.5psi*.05208 = .651 + .25 = .901
Requested boost of 13.54 psi * .901 = 12.199 psi requested boost corrected for atmospheric pressure.

My understanding of the N54 logic, which is still very limited, is that it would try to maintain that same 13.54 psi of manifold pressure, despite a drop in ambient pressure of 2 psi. Remember that the 2 psi drop in atmospheric pressure at the same manifold pressure will increase pressure ratio at the turbo. This makes me question how viable the OEM logic is for tuning the platform well beyond the factory power levels.
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      02-24-2011, 04:11 PM   #56
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Quote:
Originally Posted by biz77 View Post
Subarus have tables set up for ideal conditions. IE 68* F, sea-level. They then have a number of compensations tables to account for variances in atmospheric conditions. They do NOT make the same power with varying conditions and they are not designed to. They are designed to make safe maximum power for the conditions they are operating in.

For example, on the stock ROM for my 2006 LGT, the map calls for 13.54 psi manifold pressure at 95.4% and above throttle plate opening at 3,600 RPM. The ECU then applies a compensation to this based on altitude, which applies a multiplier of .05208 to the current observed atmospheric pressure and then adds an offset of .25 to that product. This is then used as a multiplier to the original requested boost target to compensate for barometric pressure. Take two examples:

14.5 psi atmospheric pressure:
14.5psi*.05208 = .75116 +.25 = 1.00516
Requested boost of 13.54 psi * 1.00516 = 13.609 psi requested boost corrected for atmosphere.

12.5 psi atmospheric pressure:
12.5psi*.05208 = .651 + .25 = .901
Requested boost of 13.54 psi * .901 = 12.199 psi requested boost corrected for atmospheric pressure.

My understanding of the N54 logic, which is still very limited, is that it would try to maintain that same 13.54 psi of manifold pressure, despite a drop in ambient pressure of 2 psi. Remember that the 2 psi drop in atmospheric pressure at the same manifold pressure will increase pressure ratio at the turbo. This makes me question how viable the OEM logic is for tuning the platform well beyond the factory power levels.
N54 targets load, so its not targeting manifold PSI.
IDK the specific limitations but the N54 Logic is designed to make ~300HP in any conditions.

So if its scorching hot out, and 2000 ft elevation, it will allow for more boost to make up for it.

If your at Sea Level, 30 degrees, it will lower boost, to achieve only 300 HP. So the car never really has that much of an advantage in cool weather as some people would like. It also pushes the car pretty hard if conditions arent ideal to get the HP back.

What this does is make a really good day, the same as a really bad day.

Not ideal for tuning for max power, as you could imagine, tuning in 30 degrees at sea level would yield a lot more power efficiently then at 90+ degrees in high elevation.

To the tuning world, its A$$ backwards.
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      02-24-2011, 04:16 PM   #57
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i doubt you can run map 7 on JB4 on pump gas without seeing timing drops . Would be nice to see this logs.
I saw logs on jb4 running 15.5 psi on pump full stage 3 with 5C temps and there were timing dips in 4th and 5th .
Here are some logs from a run between me (GIAC S2) and my buddy (JB4 map7, no methanol). Outside temperature was about 1 degree Celsius. Look at the ignition timing. Seems pretty much ok (first picture is the GIAC log, second is JB4). Logs are 2-3-4-5 gear. Second gear is a mess because there was no traction.
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      02-24-2011, 04:29 PM   #58
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Most of these guys have a hard time getting their heads around closed loop timing which as far as I can tell is exclusive to the N54 platform. It's a complete game changer. This thread belongs on a Subaru forum somewhere.

Mike
Please explain how the Subaru system is not closed loop.
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      02-24-2011, 04:31 PM   #59
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Please explain how the Subaru system is not closed loop.
Isnt it closed loop on low load(short term) trims and open loop WOT?
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      02-24-2011, 04:41 PM   #60
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Please stop fucking up a perfectly good thread.

OP, you said things perfectly for a basic understanding of tuning and timing. Whether this DME does/doesn't do things isn't for this tread.

Please people, just keep this on topic, no marketing, no vender bashing, no product boasting, etc.
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      02-24-2011, 04:43 PM   #61
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Quote:
Originally Posted by Mike@N54Tuning.com View Post
Most of these guys have a hard time getting their heads around closed loop timing which as far as I can tell is exclusive to the N54 platform. It's a complete game changer. This thread belongs on a Subaru forum somewhere.

Mike
Interesting concept... Please enlighten me sir. Fuel is closed loop under light accel/idle on all modern cars. This is done through the use of either a narrow-band or wideband O2 sensor(s) that constantly monitor AFR/lambda & adjust fuel accordingly in order to try and target around 14.7:1 AFR. These cars (N54/55) are unique in that they apply this basic function under heavy load/WOT... they have x2 WBO2 sensors last I checked, and an adaptive ECU/DME, that combined with a more detonation resistant DI design (injectors point almost directly at the spark plugs), it's no wonder that they're able to run such lean AFR's under load, or run closed loop fuel under WOT.

Fuel is fully closed loop on these cars, there's no debating that.... but timing? If this is truly your belief, please breakdown how you believe this "closed loop timing" works. No sarcasm intended, I would truly like to hear your theory.

Are you implying that the DME is constantly attempting to advance timing with no maximum load based values? If so, that would mean that running something like VP 110 (or any other designer racing fuel out there) would advance timing with no theoretical limit... and there would be no extra power to be made by advancing timing (manually/tune ECU for more timing) when octane permits (via race gas, meth ect) as the DME should constantly max out timing values based on knock input with no load based limits at any RPM... is that what you're suggesting?

If so, do you happen to have a technical write-up of some sort we could take a look at?

If not, well, '07 AP support and ATR will be out soon... I suppose I'll find out for myself
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      02-24-2011, 04:49 PM   #62
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N54 targets load, so its not targeting manifold PSI.
Understood. MAP is the main factor in determining load. If we look at manifold pressure on an N54 at a given RPM and IAT at sea level and then at 5,000 ft. ASL, with the same IAT and RPM, we should see almost identical manifold pressure and therefore load, no?
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      02-24-2011, 04:51 PM   #63
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Isnt it closed loop on low load(short term) trims and open loop WOT?
Fueling yes.
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      02-24-2011, 04:53 PM   #64
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Originally Posted by roninsoldier83 View Post
Interesting concept... Please enlighten me sir. Fuel is closed loop under light accel/idle on all modern cars. This is done through the use of either a narrow-band or wideband O2 sensor(s) that constantly monitor AFR/lambda & adjust fuel accordingly in order to try and target around 14.7:1 AFR. These cars (N54/55) are unique in that they apply this basic function under heavy load/WOT... they have x2 WBO2 sensors last I checked, and an adaptive ECU/DME, that combined with a more detonation resistant DI design (injectors point almost directly at the spark plugs), it's no wonder that they're able to run such lean AFR's under load, or run closed loop fuel under WOT.

Fuel is fully closed loop on these cars, there's no debating that.... but timing? If this is truly your belief, please breakdown how you believe this "closed loop timing" works. No sarcasm intended, I would truly like to hear your theory.

Are you implying that the DME is constantly attempting to advance timing with no maximum load based values? If so, that would mean that running something like VP 110 (or any other designer racing fuel out there) would advance timing with no theoretical limit... and there would be no extra power to be made by advancing timing (manually/tune ECU for more timing) when octane permits (via race gas, meth ect) as the DME should constantly max out timing values based on knock input with no load based limits at any RPM... is that what you're suggesting?

If so, do you happen to have a technical write-up of some sort we could take a look at?

If not, well, '07 AP support and ATR will be out soon... I suppose I'll find out for myself
As I said the N54 platform is pretty unique which is why people who come from other backgrounds always have your strong opinions until they do the tuning themselves. Fueling is closed loop during WOT using wideband sensors. Boost is vacuum controlled with a default open position. Timing is closed loop. It uses what we refer to as "maximum set points" and continually adds timing, listens for early knock, and removes timing, until it hits its maximum set point. Which are set so high that it would take race gas to hit them on a stock car. It uses short term trims (knock) and long term trims (octane) analogous to long and short term fuel trims. This is in addition to all the other factors that influence the timing mapping. If you add race gas you will automatically increase advance in a factory stock or tuned car as they are all running on this knock threshold system. As you get close to not being able to support your boost with your octane the DME logic starts overreacting with 3 degree drops instead of small 1/4 degree drops and you know it's time to dial back the boost. This is the basis for piggyback autotuning.

Mike
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      02-24-2011, 05:00 PM   #65
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Originally Posted by roninsoldier83 View Post
Although over the long-term, mild to moderate detonation can exasperate particle wear, which can cause various parts to wear prematurely as particles are carried throughout the oil system prior to being trapped in the oil filter.

Just my $.02

-Brandon
Great post Brandon!

Would like to repeat myself from some of the other threads and emphasize your point quoted above. People who subject these engines to excessively agressive tunes owe it to the future buyer to do an engine oil analysis at least once a year. Search for some of the Mr. 5 threads on the subject to get baseline numbers by which you can judge the effectiveness of your tune and put all of the hypothetical arguments for and against one type of tune or the other to bed. Some dude doing WOT runs as a part of his daily drive on a mild flash tune is probably doing the same engine wear damage as a guy who is rarely gets into it with a JB3 on off-brand cheap gas. But it's easy to find out.

I find all of the hypotheticals rather tiring because the reality is that none of us know the Siemens MSD80/81 control logic well enough to have any real idea as to what it's capable of doing or not.
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      02-24-2011, 05:00 PM   #66
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N54 targets load, so its not targeting manifold PSI.
IDK the specific limitations but the N54 Logic is designed to make ~300HP in any conditions.

So if its scorching hot out, and 2000 ft elevation, it will allow for more boost to make up for it.

If your at Sea Level, 30 degrees, it will lower boost, to achieve only 300 HP. So the car never really has that much of an advantage in cool weather as some people would like. It also pushes the car pretty hard if conditions arent ideal to get the HP back.

What this does is make a really good day, the same as a really bad day.

Not ideal for tuning for max power, as you could imagine, tuning in 30 degrees at sea level would yield a lot more power efficiently then at 90+ degrees in high elevation.

To the tuning world, its A$$ backwards.
While the DME is setup to attempt to make the same calculated torque regardless of conditions, I can attest that it is unable to make the same torque/peak power numbers at high elevations as it does at sea level.

I say that because I've seen several 335's at a local drag strip (Bandimere Speedway), which has an elevation of about ~5800 ft. The average trap speed for a stock 335 up here seems to be around the 95mph mark, which is a far cry from the 100-105mpg trap speeds most people seem to be pulling at sea level. 91 octane piss water and uber-thin air FTL
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