Have you measured when the injectors...

[Lex]

Originally Posted by Scatt Nasty does this have anything to do with blown motors ?

I think that one very quick way to a blown motor is a poor/failing HPFP. That's something that a lot of people don't keep an eye on.

[superskaterxes]

lol PHEW!!!! that was a long last 2 pages to take in since i last read.

i understand where we are at right now but i still have a few questions:

1. adding secondary PI is silly expensive and to me seems pointless when considering a different solution: meth.

can someone explain why secondary injectors would be more beneficial then a giant meth nozzle with 100% meth?

-meth would be silly easy to calibrate because you have x flow of air + y added meth which will always be the same.
-meth ADDS octane where injectors wouldent (and alot of octane like 6-8 more full points)
-you can dial back the fueling of the stock injectors so u will have more spray during intake stroke + already mixed meth mixture which should = uber power.

so why use an expensive secondary injection system then u can just use meth?

i find it funny that RR thinks they have this all figured out yet their T67 is still falling at redline. if this all turns out to be 100% hard evidence true and we did our homework right, then this would be the biggest break though anyone has ever accomplished on this platform so far.

has anyone ever compared the HP fuel lines between us and say a BMW? im talking the ones whoosh and PTP had bored out. your always restricted flow wise by the smallest part of any system. so if these orifices are too small and we make them bigger then maby we can squeeze some more flow out of the injectors at the same pressures? just thinking out loud here. im also in the middle of doing a few calcs to calculate something and ill post up if i find it to be relevant.

[djuosnteisn]

Only thing that makes me cringe about any pre-TB fueling on this car is the dry manifold. there's already enough flow imbalance for air, i can't imagine how much worse it would be when we start flowing fluids through it.

[SSinstaller]

Originally Posted by superskaterxes lol PHEW!!!! that was a long last 2 pages to take in since i last read. i understand where we are at right now but i still have a few questions: 1. adding secondary PI is silly expensive and to me seems pointless when considering a different solution: meth. can someone explain why secondary injectors would be more beneficial then a giant meth nozzle with 100% meth? -meth would be silly easy to calibrate because you have x flow of air + y added meth which will always be the same. -meth ADDS octane where injectors wouldent (and alot of octane like 6-8 more full points) -you can dial back the fueling of the stock injectors so u will have more spray during intake stroke + already mixed meth mixture which should = uber power. so why use an expensive secondary injection system then u can just use meth? i find it funny that RR thinks they have this all figured out yet their T67 is still falling at redline. if this all turns out to be 100% hard evidence true and we did our homework right, then this would be the biggest break though anyone has ever accomplished on this platform so far. has anyone ever compared the HP fuel lines between us and say a BMW? im talking the ones whoosh and PTP had bored out. your always restricted flow wise by the smallest part of any system. so if these orifices are too small and we make them bigger then maby we can squeeze some more flow out of the injectors at the same pressures? just thinking out loud here. im also in the middle of doing a few calcs to calculate something and ill post up if i find it to be relevant.

The benefit of using separate port injectors is that you have sequential control and can time the fuel injection much more accurately. With an injector in each runner you have a much better idea how much extra fuel is actually reaching the cylinder.. With one large meth nozzle your extra fuel is going to follow the airflow in the manifold, and that will not be even across the cylinders...

What we need is an IM that angles the injectors properly, not the 90deg spray that RR has in their spacer...

[Darksun280]

I told you what you consider a large meth nozzle isn't big enough to substitute a fuel. PTP made an actual good post on him attempting it and the the fail that persisted.

[superskaterxes]

so what about PTP's intake mani with the individual nozzles tapped in each runner at an angle towards the valve? theres no way that multiple meth nozzles couldent provide the same needed flow as individual injectors. i mean you might have less control but we really only need this while in boost and at higher RPM.

[SSinstaller]

Originally Posted by superskaterxes so what about PTP's intake mani with the individual nozzles tapped in each runner at an angle towards the valve? theres no way that multiple meth nozzles couldent provide the same needed flow as individual injectors. i mean you might have less control but we really only need this while in boost and at higher RPM.

I'm sure it could be made to work, but your still injecting meth into all four runners at once--any time your in boost..

With fuel injectors and sequential control you'd have separate timing for each injector, you can also vary the duty cycle on the injector with much finer control than you can get with the methanol controller... You could dial back the direct injection so it only injects fuel during the intake stroke, then use your port injectors to make up the difference to hit your target AFR..

[Lex]

Combustion theory is not simple. There are books, papers, millions of dollars devoted to this.

We have a swirl type injector injecting at around 12MPa in a wall guided system. This is pretty much AS BASIC as it gets with direct injection.

When fuel is injected into the chamber, the fuel droplets must mix with air to achieve a homogeneous mixture that will light evenly. In other words the fuel must change from liquid droplets to vapor. In port injection this mixing happens before the fuel/air enters the chamber.

There is a time constant as to how quickly the droplets can mix with air and that time constant is based on temperature and pressure and the presence of oxygen such that the fuel can diffuse into it. Once all the fuel has diffused it becomes a vapor. Only at this point can complete combustion occur.

I have an SAE paper in front of me quoting 3ms for complete vaporization. At 6000RPM 3ms = around 110 crank degrees. If we are still spraying let's say even 40 degrees BTDC, that means unvaporized fuel will exist well past 70 degrees after TDC and by that point it's too late to get power out of it. We get soot.

Since nozzle swirl injector spray patterns are also affected by pressure inside the chamber we're messing with the combustion model when we're throwing more boost at it as well.

So in technical terms we end up with poor homogeneity of the air fuel mixture.

EDIT: Droplet size does change with injection pressure. The lower the pressure, the larger the droplets, the slower they will vaporize. So you can imagine how poor combustion will be if fuel pressure drops. This is to show how important a solid pump is on this motor. Many people have experienced this first hand.

[superskaterxes]

Originally Posted by SSinstaller I'm sure it could be made to work, but your still injecting meth into all four runners at once--any time your in boost.. With fuel injectors and sequential control you'd have separate timing for each injector, you can also vary the duty cycle on the injector with much finer control than you can get with the methanol controller... You could dial back the direct injection so it only injects fuel during the intake stroke, then use your port injectors to make up the difference to hit your target AFR..

yah but were also talking about a $2000 + solution vs a $500 dollar option. 2k isent exactly in the budget for most people who want to just make some power without going full race.

Originally Posted by Lex Combustion theory is not simple. There are books, papers, millions of dollars devoted to this. We have a swirl type injector injecting at around 12MPa in a wall guided system. This is pretty much AS BASIC as it gets with direct injection. When fuel is injected into the chamber, the fuel droplets must mix with air to achieve a homogeneous mixture that will light evenly. In other words the fuel must change from liquid droplets to vapor. In port injection this mixing happens before the fuel/air enters the chamber. There is a time constant as to how quickly the droplets can mix with air and that time constant is based on temperature and pressure and the presence of oxygen such that the fuel can diffuse into it. Once all the fuel has diffused it becomes a vapor. Only at this point can complete combustion occur. I have an SAE paper in front of me quoting 3ms for complete vaporization. At 6000RPM 3ms = around 110 crank degrees. If we are still spraying let's say even 40 degrees BTDC, that means unvaporized fuel will exist well past 70 degrees after TDC and by that point it's too late to get power out of it. We get soot. Since nozzle swirl injector spray patterns are also affected by pressure inside the chamber we're messing with the combustion model when we're throwing more boost at it as well. So in technical terms we end up with poor homogeneity of the air fuel mixture. EDIT: Droplet size does change with injection pressure. The lower the pressure, the larger the droplets, the slower they will vaporize. So you can imagine how poor combustion will be if fuel pressure drops. This is to show how important a solid pump is on this motor. Many people have experienced this first hand.

yah but that 3ms is prob based on PI injectors @ ~70psi vs our crazy 1800psi injectors. this is also why the PSI on the meth pump is important because the higher it is the more atomization you can get after the nozzle. something isent adding up here because if we spray meth even BEFORE a reg PI injector would spray (read before as in the Im runners rather then the head runners of PI) then we should have even more time to let the fuel atomize and mix. this might seem uber hard but when it comes down to it its still air + fuel = power. i wonder if we can see more rail pressure with modded fuel lines?

[Darksun280]

Well I had the fun of witnessing this first hand on the dyno trying to blow myself up with 28 psi. And if what you say is correct all the pretty hard parts in the world can't correct this issue so makes you wonder don't it?

[Lex]

Originally Posted by superskaterxes yah but that 3ms is prob based on PI injectors @ ~70psi vs our crazy 1800psi injectors. this is also why the PSI on the meth pump is important because the higher it is the more atomization you can get after the nozzle. something isent adding up here because if we spray meth even BEFORE a reg PI injector would spray (read before as in the Im runners rather then the head runners of PI) then we should have even more time to let the fuel atomize and mix. this might seem uber hard but when it comes down to it its still air + fuel = power. i wonder if we can see more rail pressure with modded fuel lines?

That 3ms time is for a direct injected injector very similar to ours. Not for port injection

Originally Posted by Darksun280 Well I had the fun of witnessing this first hand on the dyno trying to blow myself up with 28 psi. And if what you say is correct all the pretty hard parts in the world can't correct this issue so makes you wonder don't it?

The issue can be addressed but you'd have to go about it sensibly.

The simplest way is this port injection business because not many can make new injectors but I think it's not the most elegant solution.

I am thinking higher rail pressures are worth a shot as well.

It really comes down to what you want out of it and how much effort/money/time you want to put in it.

[06Speed6]

To the meth nut swingers: Meth is not fuel, octane is not fuel, water is not fuel. Meth lowers intake charge temps and raises the fuels relative octane. Meth does not solve any problems, it only bandaids them for people who are too cheap to fix them properly.

Net results of these logs:

The injectors flow inversely proportunate to rpm: 2*rpm = flow/2.
The duration of the injection event needs to stay in the intake stroke.
The fuel injected in the compression stroke is likely to turn to soot and not properly burn.
This improperly burned fuel could be skewing the actual a/f ratio in the chamber, possibly resulting in a leaner burn than indicated by EGTs and O2 sensors.
The injectors cannot properly atomize the fuel if rail pressures are low.
The injected fuel cannot properly vaporize when its injected in the compression stroke.
This vaporization process pulls heat from the chamber, if this process is incomplete it could result in higher chamber temps.
The flow rate of the injectors is lower as cylinder pressure rises, this is net rail pressure.


Dj, the points I would need are:
The earliest start of injection in crank degrees.
The latest start injection in crank degrees.
The time in ms for a revolution of 1 crank degree at say 2, 4, and 6k rpm.
Maf g/s for known hp, and known injection duration, at specific rpm points.

I bet even if you cheezed it off of some of your dynos it would be pretty close.

[djuosnteisn]

Originally Posted by 06Speed6 ... Dj, the points I would need are: The earliest start of injection in crank degrees. The latest start injection in crank degrees. The time in ms for a revolution of 1 crank degree at say 2, 4, and 6k rpm. Maf g/s for known hp, and known injection duration, at specific rpm points. I bet even if you cheezed it off of some of your dynos it would be pretty close.

I've just switched to a 3.25" maf and had to recal everything, so that somewhat throws off my maf per hp. If your willing to wait till i get my new exh manifold (any day now, i hope to god), i'll be hitting up the dyno shortly after. Give me a couple weeks (weld on EWG, street tune and then dyno) and i'll have everything for you.

[Lex]

Originally Posted by 06Speed6 This improperly burned fuel could be skewing the actual a/f ratio in the chamber, possibly resulting in a leaner burn than indicated by EGTs and O2 sensors.

This is something I have been wondering about myself. O2 sensors on the N54 motors show it running very lean. O2 sensors on our motor show it running very rich. The injection strategies are different but I am very curious if the actual mixture present in the combustion is quite a bit different than what the O2 measures during high loads. I am personally sticking to stock A/F ratios at WOT until I learn more.

Originally Posted by 06Speed6 Dj, the points I would need are: The time in ms for a revolution of 1 crank degree at say 2, 4, and 6k rpm.

I can answer this one.

The motor spins 2000 times per minute, which means 33.33 times per second which means 0.03333 times per ms. There are 360 degrees in 1 revolution so this means the motor will spin 12 degrees per ms. Each degree will be 1/12 of a millisecond

At 4k RPM, it would 1/24 of a ms per degree. Each ms, the engine spins 24 degrees

At 6k RPM it would be 1/36th of a ms per degree. Each ms the engine spins 36 degrees.

[06Speed6]

Originally Posted by djuosnteisn I've just switched to a 3.25" maf and had to recal everything, so that somewhat throws off my maf per hp. If your willing to wait till i get my new exh manifold (any day now, i hope to god), i'll be hitting up the dyno shortly after. Give me a couple weeks (weld on EWG, street tune and then dyno) and i'll have everything for you.

Hell yeah, see if you can log MAF g/s, crank trigger, spark timing, and injection duration when you dyno. I bet we would be nearly spot on if you get that maf sensor calibrated.

Originally Posted by Lex This is something I have been wondering about myself. O2 sensors on the N54 motors show it running very lean. O2 sensors on our motor show it running very rich. The injection strategies are different but I am very curious if the actual mixture present in the combustion is quite a bit different than what the O2 measures during high loads. I am personally sticking to stock A/F ratios at WOT until I learn more. I can answer this one. The motor spins 2000 times per minute, which means 33.33 times per second which means 0.03333 times per ms. There are 360 degrees in 1 revolution so this means the motor will spin 12 degrees per ms. Each degree will be 1/12 of a millisecond At 4k RPM, it would 1/24 of a ms per degree. Each ms, the engine spins 24 degrees At 6k RPM it would be 1/36th of a ms per degree. Each ms the engine spins 36 degrees.

I threw that out there some time ago before I even had much information to go on, but no one paid much attention since there were no hard numbers to back it up.

Nice work on the numbers.

[SSinstaller]

Originally Posted by superskaterxes yah but were also talking about a $2000 + solution vs a $500 dollar option. 2k isent exactly in the budget for most people who want to just make some power without going full race.

I consider anyone trying to make more than the ~400whp the direct injection will make going full race... If someone can't afford the 2K port injection solution, that person can't afford to blow a motor--and he shouldn't be pushing the envelope anyway??

Originally Posted by superskaterxes yah but that 3ms is prob based on PI injectors @ ~70psi vs our crazy 1800psi injectors. this is also why the PSI on the meth pump is important because the higher it is the more atomization you can get after the nozzle. something isent adding up here because if we spray meth even BEFORE a reg PI injector would spray (read before as in the Im runners rather then the head runners of PI) then we should have even more time to let the fuel atomize and mix. this might seem uber hard but when it comes down to it its still air + fuel = power. i wonder if we can see more rail pressure with modded fuel lines?

During the compression stroke cylinder pressures get so high that the injector pressure differential decreases dramatically, at that point direct injection becomes very ineffective.. Dumping meth in the IM will never be the equivalent of a controlled addition of fuel via port injection..

I have upgraded injectors and just about every other fuel mod available. I see rail pressures of about 550psi at idle, when I get the car back on the road and start tuning I'll see where I'm at at WOT. I haven't taken the car past 5~6K yet..only have about 50 miles on the new motor..

[Lex]

Also each tooth on the crank trigger wheel measures 6 crank degrees.

[KoukiS14]

Originally Posted by Lex At 4k RPM, it would 1/24 of a ms per degree. Each ms, the engine spins 24 degrees At 6k RPM it would be 1/36th of a ms per degree. Each ms the engine spins 36 degrees.

That jives with the 8ms injection duration at WOT. 8 x 24 = 192* and 8 x 36 = 288*

[djuosnteisn]

Okay, i kinda want to establish one more thing about the ecu logic. One the way home i took a few pics of the injector beginning relative to missing tooth, and found that the injectors open anywhere from 30 to 35 ticks away, 60* - 90* after TDC under light load.
31 counts


33 counts




As soon as i go wot, the injector timing shoots left, right up to the point when the intake valve opens. Here's a vid of me goin wot and yelling out rpms:

goodvidtocount.flv video by djuosnteisn - Photobucket

goodvidtocount.flv video by djuosnteisn - Photobucket

Here's my VVT table:


The table is just a look up, real life VVT varies somewhat. But (if your willing, or you can take my word lol) if you stop the video at different rpm calls, and count the pulses, you'll see that the injector doesn't start spraying before when the valve is open. Assuming (and i know it's not proving, but this certainly strengthens the argument) that the VVT table is in crank degrees.

It could prove interesting when trying to squeak out the last bit of power, but could only be done on a dyno.

[superskaterxes]

ok so i did some math tonight.

i had dustin take a log for me of MAF g/s, inj mg/cyl, actual AFR, commanded AFR, and RPM. note he was also using a D05 meth nozzle starting at 5lbs of boost with full at 16. dunno his mix ratio. what i was trying to do was figure out what his ACTUAL AFR was by dividing MAF g/s by fuel. this would tell us what % of fuel was left unburned and seen as erroneous by the WBO2 sensor. after the necessary calcs this is what i came up with using excel.

Pull 1:



Pull 2:

GRAPH EDITED i diddent have it going long enough lol sry




as you can see the actual and commanded afr seen my the car is different and the calculated AFR is WAY different. now because meth is added into the mix this wont really tell us anything but i thought it was interesting none the less.

[Lex]

I agree that given the fact that the intake cam retards as RPMs go up, advancing it might give us a little more headroom.

EDIT: In the video at WOT I am counting around 20-22 pulses meaning the injection starts pretty much right after TDC on the intake. How are the cams timed on this car - anyone have the numbers? When does intake open versus exhaust close?

As for fueling, grams/second calculated by the MAF has to be converted to grams per stroke where at each RPM you calculate how many seconds a stroke takes. I am not sure if you took this into account in your calculation.

[superskaterxes]

Originally Posted by Lex I agree that given the fact that the intake cam retards as RPMs go up, advancing it might give us a little more headroom. As for fueling, grams/second calculated by the MAF has to be converted to grams per stroke where at each RPM you calculate how many seconds a stroke takes. I am not sure if you took this into account in your calculation.

i did take this into account. i got mg/cylinder into g/cycle and then i did some fancy dimensional analysis to get MAF g/s into g/cycle. then just divide the two for AFR. i did have to multiply the final AFR by 100 but the order of magnitude shouldent matter.

i also did the calculation for mg/cycle and it diddent come out right so i then assumed it was mg/cylinder/cycle and just multiplied by 4 to get total mg/cycle. any insight on this?

EDIT: btw whats with the lean spike in dustins AFR? the act and cmd afr was taken right from raw data and not manipulated and its not a shift because RPM was constant before, during, and after the spike.

[djuosnteisn]

I don't want to add any of the VVT speculation to the OP until it's accurate. I have no clue when the intake opens relative to TDC with zero cam advance. I also have no idea when the exhaust valve closes relative to TDC.

I'd like to say something like exh closes 15* crank degrees ATDC, and intake opens anywhere from 0* to 30* crank degrees ATDC. But this would absolute bull shit, lol.

[fjames]

Originally Posted by djuosnteisn I don't want to add any of the VVT speculation to the OP until it's accurate. I have no clue when the intake opens relative to TDC with zero cam advance. I also have no idea when the exhaust valve closes relative to TDC. I'd like to say something like exh closes 15* crank degrees ATDC, and intake opens anywhere from 0* to 30* crank degrees ATDC. But this would absolute bull shit, lol.

How about taking a stab at explaining the following.

I've logged vvt a bunch lately. This I know - on my car, I can clearly see WG and boost rise as vvt drops - it correlates perfectly. So - to maintain load as vvt drops, boost increases.

If I smooth the vvt drop (raise it at higher rpms) then it maintains load with no or little boost increase. So - positive vvt values at high rpm maintain load.

If vvt is retarding intake, then buy having values there (high rpm) I'm pushing (losing) fuel toward the compression side (because fuel needs are first met by moving toward intake opening) and I'm losing dynamic compression. All the while maintaining load better than "0" vvt.

I'm not saying the above doesn't make sense, but can you explain how it might? Especially since if intake advance (as labeled) really was intake advance, then it makes perfect sense?

[jmhinkle]

Originally Posted by 06Speed6 To the meth nut swingers: Meth is not fuel, octane is not fuel, water is not fuel. Meth lowers intake charge temps and raises the fuels relative octane. Meth does not solve any problems, it only bandaids them for people who are too cheap to fix them properly.

Ummm.....since when did Methanol stop being a fuel? I'm not arguing for it's use over PI, but your statement above starts off with a blatant fallacy.

Here's what we need, but only real cars get stuff like this.

[djuosnteisn]

LOL, my brain is so fucking fried right now. The vvt stuff is still a little gelatinous in my brain. Some things i think i know about it are:
- as the lobes separate (more LSA), then the intake valve opens later, and closes later, thus reducing dynamic compression & chance for knock. I've read this tends to move the power upwards towards redline.
- as the lobes close in on eachother (less LSA), then more overlap occurs, dynamic compression increases (intake valve closes sooner), and i've read it increases low rpm torque.

Right now, lol, I believe the values in the VVT tables correspond to crank angle, and a higher VVT value = more crank advance (int valve opens later upto 30*) This is what i've been kinda noticing with the injector opening. This would mean the LSA is increased in the higher value areas of the table, thus reducing compression and pushing power up to redline. Maybe mazda did this to prevent low rpm knock?

But at redline i've noticed that the maps have significantly lower values, increasing overlap, increasing compression. Did mazda do this to allow the fuel to start earlier?

Man honestly it seems like my mind changes daily about this. I do know that when i increased the low value zone in my map into higher load areas around 2500rpm, my pt knock seems to have increased quite a bit. So this would support the lower values = more overlap and higher dynamic compession, more low end torque. I wonder if mazda put this low value area around 2500rpm to improve pep. I also think if people increased those values, they'd see a reduction in PT KR. When i get back to tuning, that's top of my list.

[fjames]

Originally Posted by djuosnteisn LOL, my brain is so fucking fried right now.

Really? Why

Standard language for valve events is advance=earlier/retard=later ... just like ignition. Not sure what you mean about the stock tuning and 2500 rpm. The stock table provided by Cobb is 30 from 1K->3K, then 20 up to 4.5K (all this above ~1.0 load.) If you see it as I do (advance=earlier valve opening) then that makes sense. A lot of advance low in the rpm range to increase dynamic compression for better mileage, lower emissions and better torque. This is standard on most any car with variable valve timing I think. High rpm gets confusing to me ... back pressure from turbo is an issue, and I assume it's higher at high rpm. Bad for early intake opening. Plus less time to fill cylinder so none to waste with exhaust corruption. That adds up to open valve later to take full advantage of cylinder filling because it will close later.

It doesn't really matter, there's not much you can do with tuning just one cam. On a NA car it's pretty normal to get flow (overlap) from retarding the exhaust at high rpm. Doesn't the BMW have a pretty sophisticated system? Someone should take a look if they've cracked it, find out what they do with access to both cams on a turbo car. Turbo changes everything with valve timing.

Mind your emotions, you're starting to get a little frazzled. Don't make any rash decisions, like taking that shit our of your car until you've had a few days to settle

[superskaterxes]

dustin,

is there anyway to view the VVT on the scope? i know its a mechanical system but there was to be some sort of electrical check that knows where the VVT is at all times. can u log this vs crank angle? i think the VVT can give us a little more air up top so that maby we can inject fuel earlyer. i dunno wtf im talking about haha.

an another note:

can someone with a stock turbo and no meth and a dashhawk log something for me?

i need a 4th gear pull of:

MAF g/s
actual AFR
commanded AFR
inj mg/cly
RPM

make the pull from 3k to redline, and i mean redline like the tach is showing atleast 7-7.2k. also please only record this is your fuel trims are within +/-5. send me a PM before you do as well. i wanna plug it into my spreadsheet to make some more conclusions. more then one person is welcomed to do this as well, more data can only help.

[djuosnteisn]

Originally Posted by fjames Really? Why Standard language for valve events is advance=earlier/retard=later ... just like ignition. Not sure what you mean about the stock tuning and 2500 rpm. The stock table provided by Cobb is 30 from 1K->3K, then 20 up to 4.5K (all this above ~1.0 load.) If you see it as I do (advance=earlier valve opening) then that makes sense. A lot of advance low in the rpm range to increase dynamic compression for better mileage, lower emissions and better torque. This is standard on most any car with variable valve timing I think. High rpm gets confusing to me ... back pressure from turbo is an issue, and I assume it's higher at high rpm. Bad for early intake opening. Plus less time to fill cylinder so none to waste with exhaust corruption. That adds up to open valve later to take full advantage of cylinder filling because it will close later.

LOL, my emotions are minded, was just tired, and fiance was getting emotional. Too much car time, ha.

Yeah, i agree with you entirely on that being the logical operation for the VVT. And it definitely seems like it would make sense with the existing table in our map. that's how i believed it to work until i started looking at the scope logs. Basically i'm flip flopping right back and forth right now, until i can get some solid evidence (which i hope to do next weekend, muhahaha). 90% of me agrees with you completely.

The low value zone i was speaking about is in the lower loads. There are a bunch of zero's around low load 2500rpm area. This is where most people exhibit the PT KR, and i wonder if it's something mazda ran into, and tried to fix by dropping the compression in that area. I tried spreading my lower values into the higher loading areas (just a tad) and it seems to have made my pt kr a lil worse. It could be weather related though, so who knows, not concrete.

The benefits of the VVT are exactly as you described. I have read though, that there are decent gains to be had with turbo upgrades, and reduction in back pressure. You can increase the VVT value by like 3-7 degrees (increasing overlap & compression) and see some decent gains (10-20 hp, all depending though). It needs to be done on the dyno.

Originally Posted by superskaterxes dustin, is there anyway to view the VVT on the scope? i know its a mechanical system but there was to be some sort of electrical check that knows where the VVT is at all times. can u log this vs crank angle? i think the VVT can give us a little more air up top so that maby we can inject fuel earlyer. i dunno wtf im talking about haha.

You do know what your talking about, cause if indeed the injector won't open before the int valve (complete guess til proven next weekend), then opening the int valve sooner would help.

I'll be scoping the cam signal next sunday, along with all the other things (4ch scope ftw). And i'm actually thinking i'll just leave the wiring in my car forever, so i can pull them out when ever and re-check this shit very easily.


Lastly i took a first stab at the OP, trying to summarize this thread, if anyone wants it changed or added to, pm me, or post it up here.

[Lex]

Make a synopsis at the top of the page stating:

The fuel system (injectors) is not adequately sized for producing more than around 350-380whp. At that point you're also looking at very poor combustion and efficiency in the upper RPMs.

So unless you're willing to address that first, bigger turbos, built engines, manifolds, etc. are only going to result in minimal gains.

[djuosnteisn]

Originally Posted by 06Speed6 ...the torque on on the MZR DISI dynos I have seen goes down past 4000rpm or so which indicates that the engine CFM for any given intake stroke is less at 6000rpm than 4000rpm. This lower air flow should require less fuel and if the scale of the graph on the scope remains the same. The graph should show a shorter injection period as measured in real time and not crank degrees between 4000rpm and 6000rpm when maf voltage and A/F is a constant...

Originally Posted by djuosnteisn ...My suspicion is that this: I agree torque falls off quite a bit near redline, and have been stating the fixed width looks odd, but attributed it to my boost creep. I didn't have creep on the dyno lex posted, and if you look at my recent maf logs, it parallels rpms (indicating same amount of air in cylinders) much more closely. ...so I do think there is a similar amount of air in the cylinders. ...

Originally Posted by djuosnteisn also lex, look at my recent maf curve like 2 posts up. Would you agree that the boost creep and linear maf curve would indeed indicate a similar amount of air in the cylinders, as opposed to the maf curve you posted from my dyno?

Okay, today at lunch i switched to a MBC and pulled out my pill. It's seemed to help slightly with my boost creep, and gives such a nice flat boost curve (which might not be sweet for a fwd 3, but on the 6 it's perfect).

You were right 06speed6 about how the afr's should have richend up with a constant injector pulse width in the higher rpms...
and i was right in that the added boost creep was adding enough air to counter intuition (and the point lex explained about the diminished fuel injected with increased cylinder pressure towards redline, but i've been thinking about that more and more, and with say 10:1 compression @ 20 psi & perfect VE, that's only 200 psi, which still leaves us with 1300psi pressure differential for the injectors), so i think the boost creep was the key ingredient into skewing the afr's & injector duration. Here's proof with a flat boost curve via mbc:





Look at the super fat afr's right where we'd expect them. Granted though, i didn't have the scope with me, but we've already seen the injector behavior on my car.

[SSinstaller]

Originally Posted by djuosnteisn Okay, today at lunch i switched to a MBC and pulled out my pill. It's seemed to help slightly with my boost creep, and gives such a nice flat boost curve (which might not be sweet for a fwd 3, but on the 6 it's perfect). You were right 06speed6 about how the afr's should have richend up with a constant injector pulse width in the higher rpms... and i was right in that the added boost creep was adding enough air to counter intuition (and the point lex explained about the diminished fuel injected with increased cylinder pressure towards redline, but i've been thinking about that more and more, and with say 10:1 compression @ 20 psi & perfect VE, that's only 200 psi, which still leaves us with 1300psi pressure differential for the injectors), so i think the boost creep was the key ingredient into skewing the afr's & injector duration. Here's proof with a flat boost curve via mbc: Look at the super fat afr's right where we'd expect them. Granted though, i didn't have the scope with me, but we've already seen the injector behavior on my car.

Before ignition at 20 psi of boost you have about 34.7 psi, after compression your near ~347psi, after ignition pressures would be well above 1000psi..

[djuosnteisn]

Originally Posted by SSinstaller Before ignition at 20 psi of boost you have about 34.7 psi, after compression your near ~347psi, after ignition pressures would be well above 1000psi..

Can you explain more? I want to understand where the 34.7 came from?

[Haltech]

Originally Posted by 06Speed6 To the meth nut swingers: Meth is not fuel, octane is not fuel, water is not fuel. Meth lowers intake charge temps and raises the fuels relative octane. Meth does not solve any problems, it only bandaids them for people who are too cheap to fix them properly. Net results of these logs: The injectors flow inversely proportunate to rpm: 2*rpm = flow/2. The duration of the injection event needs to stay in the intake stroke. The fuel injected in the compression stroke is likely to turn to soot and not properly burn. This improperly burned fuel could be skewing the actual a/f ratio in the chamber, possibly resulting in a leaner burn than indicated by EGTs and O2 sensors. The injectors cannot properly atomize the fuel if rail pressures are low. The injected fuel cannot properly vaporize when its injected in the compression stroke. This vaporization process pulls heat from the chamber, if this process is incomplete it could result in higher chamber temps. The flow rate of the injectors is lower as cylinder pressure rises, this is net rail pressure. Dj, the points I would need are: The earliest start of injection in crank degrees. The latest start injection in crank degrees. The time in ms for a revolution of 1 crank degree at say 2, 4, and 6k rpm. Maf g/s for known hp, and known injection duration, at specific rpm points. I bet even if you cheezed it off of some of your dynos it would be pretty close.

Actually, i have to disagree with you here. Reason being, Meth certainly is a fuel type, as in an enhancement to a properly engineered fuel system for the project you are building. However, it should not be used to substitute an over duty cycle system to keep you out of the red.

Meth's advantage is simple:

1) Raises octane for street level performance where race fuel is NOT an option due to:

A) Cost
B) Availability

2) Used to cool incoming boost temps

3) Lower combustion charge and burn fuel more efficiently

4) Increase the amount of boost and lower timing on the street

These are its advantages and it should be respected as such.

Originally Posted by Lex This is something I have been wondering about myself. O2 sensors on the N54 motors show it running very lean. O2 sensors on our motor show it running very rich. The injection strategies are different but I am very curious if the actual mixture present in the combustion is quite a bit different than what the O2 measures during high loads. I am personally sticking to stock A/F ratios at WOT until I learn more. I can answer this one. The motor spins 2000 times per minute, which means 33.33 times per second which means 0.03333 times per ms. There are 360 degrees in 1 revolution so this means the motor will spin 12 degrees per ms. Each degree will be 1/12 of a millisecond At 4k RPM, it would 1/24 of a ms per degree. Each ms, the engine spins 24 degrees At 6k RPM it would be 1/36th of a ms per degree. Each ms the engine spins 36 degrees.

Lex, have you investigated where the readings are being measured on the N54 and the type of sensor that is actually reading these voltage here?

[SSinstaller]

Originally Posted by djuosnteisn Can you explain more? I want to understand where the 34.7 came from?

20 psi boost plus the 14.7 psi ambient air pressure.

I can't find any hard info about DI peak cylinder pressures, but gas engines seem to range between 1000 and 2000psi peak pressure, and as high as 3000psi peak pressures in diesel engines..

[djuosnteisn]

Originally Posted by SSinstaller 20 psi boost plus the 14.7 psi ambient air pressure. I can't find any hard info about DI peak cylinder pressures, but gas engines seem to range between 1000 and 2000psi peak pressure, and as high as 3000psi peak pressures in diesel engines..

LOL, duh. I feel stupid ha, can you explain 2 + 2 now?

I agree, strongest cylinder pressures exist after ignition, so i would like to vote that if you keep the power (amount of air in the cylinder) such that the injector event doesn't go beyond the ignition event, your probably okay with our fuel setup. This is pure speculation, and neglects the proper atomization effects for proper burn, but it's just a very rough general rule.

Regardless, our fueling situation seemingly has exposed our stock fuel (or even upgraded fuel pump) systems power limits.

[06Speed6]

Originally Posted by Haltech Meth certainly is a fuel type However, it should not be used to substitute an over duty cycle system to keep you out of the red. Meth's advantage is simple: 1) Raises octane for street level performance where race fuel is NOT an option due to: A) Cost B) Availability 2) Used to cool incoming boost temps 3) Lower combustion charge and burn fuel more efficiently 4) Increase the amount of boost and lower timing on the street These are its advantages and it should be respected as such.

I agree actually, I should have said that meth isnt gasoline.

butane is a fuel too but I dont see anyone mixing it with water and injecting it

[Scatt Nasty]

Originally Posted by 06Speed6 I agree actually, I should have said that meth isnt gasoline. butane is a fuel too but I dont see anyone mixing it with water and injecting it

keep in mind that people actually use propane injection for performance...

[Lex]

Originally Posted by Haltech Lex, have you investigated where the readings are being measured on the N54 and the type of sensor that is actually reading these voltage here?

The N54 information I have seen was based on dyno runs and a sensor placed in the tailpipe. I realize those are so close to the outside air that they show a reading that is skewed towards lean. I am not sure what their stock wideband sensors measure.

[Haltech]

Originally Posted by Scatt Nasty keep in mind that people actually use propane injection for performance...

Propane is about equal to nitrous oxide in diesel applications