Check your PM.
I don’t think anyone cares as far as other applications to be honest. The intake manifold and intercooler will change how much boost is needed to generate the CFM to pass the intercooler system. I think most know that.
I think just numbers in the intake manifold would be good enough. It was already noted that there was a boost gauge in the car. My cobra only sees maybe 1lb difference in the middle of winter vs the summer. SO ambient isn’t going to make a 10lb difference.
The RS4’s ECU strategy is MAF based, not speed density. You didn’t ask what the peak air mass flow was.
So I’ll ask you a fun question… What does the RS4 ECU use boost pressure for? (greater than 101kpa, or 1013mbar, or 0psig/14.7psia). 
I think almost everyone one here knows that about the MAF and speed density. Why would I ask what the PEAK air mass was when you can scale the MAF. Also We can all calculate CFM per hp Vs VE increase along with density altitude to get peak needed MASS Flow to support crank hp. As to not ask if or what you did or to ask too many questions the best thing is what everyone is looking for and that is the actual boost you guys needed to put this blower under.
We know the VE will rise expediently with the use of the 1740 but we also know the CFM needed. We all know the shifting of camshafts can help or hurt this. We also know you might want to bleed of boost post charge to cool down the cylinders. That with the added size of the cooling units APR is using Vs the competition we all expect higher boost numbers. This is a good thing as it shows the units are not too free flowing as free flowing isn’t the best for cooling.
While I do think that is a fun question. lets knock out one question at a time. Great work crazy driving and how much boost did you guys use.
Not taking anything away from what APR/R/TErnie have done, but that response was a pretty arrogant response to a simple question.
The man asking the question is also not some random idiot and probably has seen more 4.2l engines inside and out than anyone on this forum or anyone in the community besides maybe JHM themselves, so to try and stump him with foolish questions looks even more arrogant.
My post was not intended to be arrogant, nor suggest the question was posed by a “random idiot” as you suggest. My intent was to suggest a few reasons why boost pressure would be irrelevant while tuning a Supercharged RS4. Also to suggest why it would not be “scary” that the tuner could not recall the boost pressure several months after having an analog boost gauge in the car. I’m sorry if you feel threatened, that was not my intention. We’ll put that same analog boost gauge in the car today and let you guys know what the gauge says. ;D
R/TErnie, Welcome to AR! Nice work on the tune for the RS4 and very nice driving! Can’t wait to see what this blower does on my S4… Arin’s been tight lipped maybe you can share a little more? ;D LOL!
Welcome to the site. You shoudl ask the site admin to change your username to Eric@APR (on here and on all sites), as Arin has.
You’re not an Evo owner posting about his car anymore. You work for APR and are posting as their employee on sites where people may or may not know that.
The boost thing is pretty funny. I guess if you maintain that boost and knock aren’t important, that’s your prerogative. Definitely different.
Looking forward to hearing more. Thanks for the conversion rates for pressure measurements. If our google is ever broken, we’ll ask for you to help us out.
p.s. I don’t think euroswagr felt at all threatened. I think I would choose my language a little more carefully going forward. Maybe leave the snarky forum chat to Arin. You should instead focus on figuring out how to install a boost gauge that reads more accurately than ‘10-20 psig’.
Eric has not said knock isn’t important, so I’m not sure where that’s coming from. Knock very important. He’s spent months calibrating ignition all across maps and not just in key, such as full load. Compensational data in both hot and cold climates is important, and he’s collected data in both conditions with both normal and completely heat soaked cooling systems to ensure proper compensation. Likewise, he’s worked with poor quality fuel and great fuel to ensure no matter where our customers are, they’ll have a safely operating vehicle.
When it comes to boost, engineering’s targets were set using different size pulleys months back. That data will not change (Meaning unlike a turbo, we “control” boost, so to speak), but ambient pressure and some calibration changes will alter the values while producing higher or lower airflow levels.
It was in that EVO forum thread you told us to check out.
…again, explaining stuff most of us are well aware of instead of just giving us the simple answer.
Only “real” knock is important
Replies within.
Euroswagr,
Are you familiar with how knock detection is done? You can have a false positive. The sensor measures the amplitude of sound within a specific frequency range. If something else generates a frequency in that band with a magnitude high enough, you can false detect a knock event. This happens most time during aggressive shifts, while the throttle is actually closed.
It’s kind of weird how this is going. Is the boost number some embarrassing number? Or a trade secret? Should we assume 20 psig since that’s the upper end of the range you gave us? Want to post a compressor map so we can look at for ourselves?
There are certainly some variables that may marginally affect the boost, however you’ve already told the forum that
a) you had a boost gauge on the car
b) you forget what it said
I know a few calibration engineers, and the ones I speak to tend to have a pretty good understanding of what the hardware and software are doing, especially when applying boost to an RS4 or something similar. That’s an understatemtn. They know every detail about what they’re doing, in a near obsessive manner. I’ve never heard one say ‘I don’t know’ when asked what boost they’re running. It’s not a MBC controlled turbo, you’re right. It’s a controlled by the pulley size, the atmosphere, and the system. Thing is, you guys ran at sea level (density altitude), at MMP, last week. You had an APR SC and magnaflow HFC downpipes, and stock to no catback. Are you saying you have no idea what boost those runs were made on? Because all the variables you guys keep throwing around were KNOWN when you ran the car last week. So…what was it?>
As I said though, I don’t think you ‘don’t know’. I think you know it inside out. With each tune. With every hardware configuration you’ve tested. I just think you don’t want to say.
That’s fine in itself. Just say ‘none of your business’ (in nicer words). Being vague and pretending you’re thinking over everyone’s heads won’t work. Might work on audizine, but this site will tend to not let things like that slip. You’re singlehandedly undoing a lot of the good will that APR has built up with secttion of the site. Is that the goal here?
p.s. aligning yourself with Jason from AMD…yikes. There’s a feather in your cap lol.
Lol, I’ll stop being sarcastic and upset …and yes I am familiar with the magic of knock sensors. As an RF electronics technician I’m also well aware of the measurement of sound waves and the false positives that may be received or distorted because of some other mechanical event in or around the sensor. At work I deal with plenty of RF interference that needs to be dealt with by way of some type of signal filtering, but that is just HF radio system and SATCOM stuff…I leave my ECU calibration to the PROs.
This data is fairly pointless by itself, like we were saying, but here’s the peak figure from a pull minutes ago:
http://www.goapr.com/news/wp-content/uploads/2013/11/Screen-Shot-2013-11-18-at-2.36.58-PM.png
[quote=“sakimano,post:52,topic:4920”]
I think that’s coming form a lack of communication here. Like we were saying, a single boost value alone doesn’t mean anything. In my opinion, it neither hurts nor ben3fits anyone. It’s meaningless without a lot of other data.
[quote=“sakimano,post:52,topic:4920”]
I’ll be honest, I don’t know what that means.
[quote=“sakimano,post:52,topic:4920”]
Anyone can hook up a gauge when they buy the kit, so no, not really.
[quote=“sakimano,post:52,topic:4920”]
I’m sorry, but we cannot post this. This is currently still proprietary Eaton information. They have not release the graph to the general public yet.
[quote=“sakimano,post:52,topic:4920”]
I think this is where we have a disconnect.
There are many variables that will affect boost by several PSI, not just marginally. I think what your getting at is that, depending on a few things, we’ll maybe see a difference between -1 and 1 PSI… so that being true, we should be able to pull a value out of our hats. That’s actually pretty far off. There are quite a few things that will change pressure quite a bit.
Likewise, from tuner to tuner, same hardware, same vehicle, same time of day, etc, boost can be quite different.
[quote=“sakimano,post:52,topic:4920”]
What we’re saying is the data doesn’t change anything, so hooking up a gauge during the drag strip testing doesn’t matter. The ECU doesn’t use boost at all, so knowing what it was, exactly, during the pulls doesn’t change anything. We could simply lie and say “we know what it was, but it’s proprietary and don’t want to share”, and no one would be the wiser. However, I’ll be the first to say it doesn’t matter what it was, so no, we didn’t record boost figures during the passes.
[quote=“sakimano,post:52,topic:4920”]
I’m not sure I understand what you’re saying here. Sorry.
[quote=“sakimano,post:52,topic:4920”]
Off the tops of our heads, we will not know how much boost the supercharger is making at every RPM, in every weather condition, from a tapping location not specified (pre or post cooler). There are too many variables at play. No one will really know this, and as I said before, knowing it off the tops of our heads will not matter either.
I’ve posted a single data point above.
[quote=“sakimano,post:52,topic:4920”]
Sac, that’s the problem right there. I believe you think we’re trying to pull a fast one. As we’ve explained several times, we’re not. There’s nothing to hide, no one to trick, none of that. I hope I’ve explained why well above.
Replies within!
Euroswagr,
You got it. By running the car through the gears and at the track we can log these issues, identify them, and correct them (whether that’s hardware or software)… rather than just doing plain 4th gear dyno pulls. (which I do plenty of)
I haven’t read anything that was beyond the picture that Arin posted. You guys post too quickly or I type too slowly.
Eric what you dont know is there are only a few company’s that are honest and respected. You came into the forum at a time where we all ask the same questions. The con company’s hemm and hawww and dodge questions. The answers you gave made it look like you were doing that so more direct questions were asked. While we all get that you didn’t study the boost gauge and that you dont need the boost reading to do your job that still didn’t answer the question. Easy answer 14.5
14.5 off the gauge. That looks about what everyone thought and what it would take.
I as a shop would be hesitate to say boost too. Many might draw a false conclusion from just the figure alone.
Manifold before or after cooling?
I can understand why you don’t require a boost pressure reading for the tuning, but what about the effects of the pressure on engine components?
Running 10psi with a CR of 12.5 may be fine for long term use, but running say 15-20 psi will make a difference to how long your pistons, BE bearings, rings etc last.
As you say you can’t log it but you can at least get an electronic boost gauge with peak hold that you can check at the end of a run etc.
Interesting questions. I don’t think the makers of the high boost kits have answered those questions, ever. It’s another line of questioning that doesn’t go down well for some reason.
We get ‘10,000 miles and still running strong!’ but no mention of other things that may not be so awesome. We understand the rods haven’t turned into bent spoons. That’s not the only concern people have when boosting these engines well into the teens. We don’t get much feedback until we see videos where the car pounds out enough smoke to make you think the lens is fogged (AMD high pressure kti test car at the strip) or hear about sudden motor pulls (AMD low pressure kit test car).