EGR delete survey

[Lex]

Originally Posted by bova80 here is my take on KR after cruising then WOT. So you are cruising and the car is doing its best to achieve great MPG's for you. Well when you go WOT its still using that ignition table for best MPG's so you'll see KR at first until it realizes hey this isn't the ignition table i should be using. something like that.

Not sure if I agree on that. If I roll into the throttle and see 5-10psi, the fuel richens up and spark timing drops and no knock. So it's no longer running in "efficiency mode." If I then romp on it (after rolling into it to 5psi) I see the same shot of knock.

I think the piston crowns become overheated with little fuel being sprayed in very localized regions during cruise. These then become detonation/preignition hot spots during WOT. Once the car has gone WOT once, the piston crowns have equalized in temperature due to the abundance of fuel and it takes some more hwy cruising to induce the uneven heating again.

[Fobio]

Originally Posted by Lex Not sure if I agree on that. If I roll into the throttle and see 5-10psi, the fuel richens up and spark timing drops and no knock. So it's no longer running in "efficiency mode." If I then romp on it (after rolling into it to 5psi) I see the same shot of knock. I think the piston crowns become overheated with little fuel being sprayed in very localized regions during cruise. These then become detonation/preignition hot spots during WOT. Once the car has gone WOT once, the piston crowns have equalized in temperature due to the abundance of fuel and it takes some more hwy cruising to induce the uneven heating again.

so if what you say is possible, it is likely to be exasperated by carbon build-up? perhaps on the piston itself?

[Lex]

Originally Posted by Fobio so if what you say is possible, it is likely to be exasperated by carbon build-up? perhaps on the piston itself?

I don't see why not. Hard to identify root cause but there are some sharp edges in the combustion chamber as well including the injector tip itself (thought it should be keep cooler by the fuel spray. This kind of analysis requires some pretty expensive lab equipment.

From what I and other have observed however - the high EGT (combustion temps) during cruising conditions result in detonation once cylinder pressure is quickly ramped up.

I am sure many of you see that a first WOT run usually has higher KR than subsequent runs (unless the intercooler is heatsoaked of course).

[06Speed6]

Ive worked with the crankcase breather and pcv system alot over the last few months and oil does not pool inside of it, that is total bs.

Also i think that the knock sensor goes to 0 at wot because the ECU isnt reading it anymore, not because the engine is running better.

[Lex]

Originally Posted by 06Speed6 Ive worked with the crankcase breather and pcv system alot over the last few months and oil does not pool inside of it, that is total bs. Also i think that the knock sensor goes to 0 at wot because the ECU isnt reading it anymore, not because the engine is running better.

The sensor goes death north of 5700 RPM.

What do you think is an effective method for lower EGTs prior to applying load during cruise? Start water injection early?

Reducing backpressure through a larger turbine should also lower EGTs.

Anything else I'm missing?

We're also not alone:
http://www.solsticeforum.com/forum/f...visited-61506/

[phillyb]

my car stopped throwing p0403.
i've had egr delete since august of 09.
now i only throw p0107.
does anyone else get that code?

[meatball18]

subbed for future reference

[06Speed6]

Why lower EGTs? If they arent north of 1700* at wot or ~1200* PT your fine. I dont think anyone on here is running those numbers. I dont think the knock is due to EGTs or running lean or spark plugs, I think its partly chamber shape and partly agressive ignition timing.

Ive never seen a high performance engine that ran more than 37* of timing max, and alot of forced induction guys run less than 20*... and some far less than 20*. I think the combination of high load and lean mix is fine for DI due to its inate cooling ability, but I think that throwing in 50* of timing on top of that is a blown engine waiting to happen.

Honestly before this car, I didnt know you could even run that much timing short of maybe a 18000rpm indy type engine due to the high rpm and low flame front speed from the race fuels.

Now if we were just talking about having a clean engine, I do think that a EGR delete is one of a few ways to help with that. I dont think that it has much if anything to do with blown engines.

EDIT: I also have no information regarding the effect of higher boost temps with higher EGT temps. I would personally lean towards it having almost no affect on EGT.

[djuosnteisn]

Originally Posted by Lex ...I think the piston crowns become overheated with little fuel being sprayed in very localized regions during cruise. These then become detonation/preignition hot spots during WOT...

I mentioned this like a year ago, but it didn't get much attention. But i agree fully with this. With a stratified, localized combustion strategy at highway cruise (much higher load than cruising around town from the gearing and wind resistance), it's obvious that some portions of the crown are gonna get real hot.

Originally Posted by 06Speed6 ..Ive never seen a high performance engine that ran more than 37* of timing max, and alot of forced induction guys run less than 20*..

+1. Stock tables have alot of high 50's, and even some 60's IIRC. It may seem like a ton at first, but maybe since the combustion strategy is indeed in a localized part of the combustion chamber, this high of spark advance is necessary. Maybe flame speed is much slower than normal PI, or the force is simply much less than a homogeneous mix in the combustion chamber.

[Lex]

I think the Mazda runs homogeneous all the time - remember when we were looking at injection timing Dustin - it always injected during the intake stroke - even at low loads. That doesn't mean we aren't seeing hot spots.

Lower timing during cruise will actually INCREASE EGTs. The problem is not during the cruise itself - it's when cylinder pressures go up and the chamber is heatsoaked. The intake manifold is likely heatsoaked as well with all that EGR running through it.

The exhaust restriction (aka small turbo) keeps things super toasty in there.

I see a lot of people that drive this car on the hwy lots with on/off periods of WOT have issues. Even close to stock cars seem to have gone to heaven this way. I think detonation has a lot to do with it and mitigating this WOT transition detonation would be great. I fucking hate having to baby the throttle - but if I don't I get the sweet KR and fall flat on face performance. It's that much more important to not have spikes here. The higher the gear the higher the spike however. I think you get the picture.

[djuosnteisn]

I remember it would actually fire the injector towards the middle of the int compression cycle, and as load increased, it would move toward the intake event, and then once it ran out of room, it would move into the compression cycle as needed.

Also, i never logged or investigated any long highway cruises, so for all we know, it actually may change strategy all together during a sustained cruise. Who knows.

And higher EGT's don't necessarily mean more or less heat soaked combustion chamber, right? If the EGT's are still within an acceptable range, wouldn't retarding the timing result in less heat soak?

[Lex]

the EGTs are read after the exhaust ports. Retarded timing causes the flame front to happen "closer" to the exhaust stroke making the EGTs read higher - also causes the turbo to spool and that's why we have negative timing at the onset of boost.

Really, timing is meant to generate best torque. Move it to the point that it generates most torque for the particular motor and that should be it.

I think high combustion temperatures are very common for sustained stoich cruising. With direct injection less fuel is sprayed on moving parts. For example the intake valves, the ports, that get no fuel - so they must run hotter. In PI, you must inject more fuel because fuel evaporates from these parts and does not make it to combustion. This evaporation removes heat.

In port injection there is a premixing between air and fuel that happens prior to it entering combustion. With DI, air and fuel only meet in the combustion chamber. More efficient - sure - but I think the thresholds are that much tighter for error. It may not knock at 14psi but may severely knock at 19psi on the same turbo.

This is why I was thinking a methanol "pre-spray" may cool things off if you're about to get on it. Not sure if this is enough because I imagine the prespray has to last long enough for it to be effective. Not sure what "long enough" means yet.

[djuosnteisn]

WMI tip-in enrichment, hahaha. Great idea, but would take some work to make something that does that.

Has anyone measured / logged the tip-in fueling enrichment? I know we have one, just not sure the amount.

[Lex]

Not even tip-in because that would be too short - something like an intercooler mister button that activates WMI for a few seconds.

[06Speed6]

I do alot of highway miles and I rarely get knock when I go wot to pass and I dont aways downshift either. I dont mind running full boost in 6th at 2000rpm and I regularly drive 40mph around town in 6th.

I think the ignition timing needs to go down agressively as load increases.

Im going to throw this out there too, regardless of what people are doing with their plugs, I think that actual combustion temps are alot lower than people think they are. I have seen absolutely no indication of any burned, blued, or melted parts ever on any MZR DISI engine so matter what level of boost or how lean the burn is. I think running higher EGTs with less timing would probably lead to a safer runing engine. I also think that we can probably run alot leaner than people think at WOT as long as EGTs are kept in check.... Of course this is all assuming that I am right and our knock isnt heat related and is almost totally timing related.

As a bonus, running higher EGTs should help to burn off some of the carbon buildup and make for a better running engine.

[Lex]

Originally Posted by 06Speed6 I do alot of highway miles and I rarely get knock when I go wot to pass and I dont aways downshift either. I dont mind running full boost in 6th at 2000rpm and I regularly drive 40mph around town in 6th. I think the ignition timing needs to go down agressively as load increases. Im going to throw this out there too, regardless of what people are doing with their plugs, I think that actual combustion temps are alot lower than people think they are. I have seen absolutely no indication of any burned, blued, or melted parts ever on any MZR DISI engine so matter what level of boost or how lean the burn is. I think running higher EGTs with less timing would probably lead to a safer runing engine. I also think that we can probably run alot leaner than people think at WOT as long as EGTs are kept in check.... Of course this is all assuming that I am right and our knock isnt heat related and is almost totally timing related. As a bonus, running higher EGTs should help to burn off some of the carbon buildup and make for a better running engine.

Hmm - I always see timing drop like a bomb when I go WOT. -3 to -5 degrees and ramps up from there. When you go WOT, what does your boost spike and settle to?

[06Speed6]

I have stock boost control and the stock turbo is still on there so it hits about 15psi and drops to between 12 and 13 psi.

I dont butt rape my stock turbo up to 20psi like some members of this forum.

[Lex]

Originally Posted by 06Speed6 I have stock boost control and the stock turbo is still on there so it hits about 15psi and drops to between 12 and 13 psi. I dont butt rape my stock turbo up to 20psi like some members of this forum.

This is exactly why you don't see the famous knock. You're below the detonation threshold with that pressure.

With so many flow mods, how does your stock boost control maintain 15psi?

[phillyb]

wtf is this thread about?

[06Speed6]

Most of my mods are sitting on my bench and are not on my car.

You cant partially mod the car, you either replace everything or you dont touch it lol. Welcome to the future of car modding.

[Fobio]

Originally Posted by 06Speed6 Most of my mods are sitting on my bench and are not on my car. You cant partially mod the car, you either replace everything or you dont touch it lol. Welcome to the future of car modding.

I feel somewhat the same...you can't do single independent mods on this car, without doing like 2 - 3 supporting mods to keep it "safe"...

fucking car...lol...

[Lex]

A strategy would be to actually lower boost in the upper gears

[TRex]

^ive actually wondered about that too...looking at where our turbo operates on the compressor map i think this turbo would run a lot more efficiently at a bit lower boost...slower sure...but safer...and with less lag


also curious lex about what you said about the stock boost controller...it runs out of room with flow mods? at what point can it not control the boost (after DP? after upgraded intercooler)...and is the only way to cure this with a new boost controller?

Retarded timing causes the flame front to happen "closer" to the exhaust stroke making the EGTs read higher - also causes the turbo to spool and that's why we have negative timing at the onset of boost.

also curious about that statement...how does the flame front occurring close to exhaust help with turbo spool? is it because the gasses will be moving faster due to having just detonated so close to leaving the cylinder?

[djuosnteisn]

Originally Posted by TRex ^ive actually wondered about that too...looking at where our turbo operates on the compressor map i think this turbo would run a lot more efficiently at a bit lower boost...slower sure...but safer...and with less lag also curious lex about what you said about the stock boost controller...it runs out of room with flow mods? at what point can it not control the boost (after DP? after upgraded intercooler)...and is the only way to cure this with a new boost controller? also curious about that statement...how does the flame front occurring close to exhaust help with turbo spool? is it because the gasses will be moving faster due to having just detonated so close to leaving the cylinder?

Hotter exhaust in the exhaust manifold increases exhaust gas velocity and thus spool. Thermal differentials across the turbo are almost as important as pressure differentials (often they go hand in hand).


Have you really seen a compressor map for the k04 on our cars? There are several turbos out there labeled k04, but i've never seen the specific map for ours.

[Lex]

^ The stock TUNE will result in pretty big spikes and high boost. You can control it but you need an AP or an SB or some other boost controller.

And no, not detonated. The flame is hotter exiting the motor and more "efficient" at spinning the turbine. Without touching boost control you get several more psi of boost by JUST backing timing out 5-10 degrees but the car is slower overall.

Originally Posted by djuosnteisn Hotter exhaust in the exhaust manifold increases exhaust gas velocity and thus spool. Thermal differentials across the turbo are almost as important as pressure differentials (often they go hand in hand). Have you really seen a compressor map for the k04 on our cars? There are several turbos out there labeled k04, but i've never seen the specific map for ours.

Lol, that's what she said

[TRex]

^ic

i posted this in the k04 info sticky



not 100% sure...but when you do some calcs you find the operating range looks about right



this was done with the help of phate from m3f

these are the operating ranges for pressure ratios of 2.1, 2.2, 2.3, 2.4, and 2.5

i take the first green line going up from the bottom (2.2 PR with a boost of 17.64 (this is probably about what our turbo sees as im thinking we lose 2-3 psi in the intercooler)) as being our operating range which as you can see is right on the edge of choke....making anything much above stock a little dangerous as you get farther and farther into choke at earlier rpms (unless you upgrade intercooler and lower your boost loss)

again...i searched for this off google and the forums....is it exactly our k04? im not sure...but i figured it was fairly close

edit...i just found out and im almost 100% sure this is the map for the K04-2280 (K0422-881 & 882)

[djuosnteisn]

Yeah, i don't think it is ours I've seen that map before.

But your probably right, and it's probably close.

[TRex]

anyone know our exact k04 number?

[Lex]

^ This is why the boost drops in the higher RPMs. The turbo can't meet the air delivery requirements.

[TRex]

^agreed we start to choke like crazy

makes me wonder why so many want to throw 19+ psi on it....it just falls flat on its face and puts a lot of stress on the little guy

[Lex]

** This is quite off topic but I love an intelligent discussion **

You can throw 19psi at it at 4500RPM. Just don't be too aggressive with boost in the higher RPMs. I like 17-18psi in the midrange.

Shifting at 6k is probably optimal.

From Garrett:

The Choke Line is the right hand boundary of the compressor map. For Garrett maps, the choke line is typically defined by the point where the efficiency drops below 58%. In addition to the rapid drop of compressor efficiency past this point, the turbo speed will also be approaching or exceeding the allowable limit. If your actual or predicted operation is beyond this limit, a larger compressor is necessary. ◊ Turbo Speed Lines are lines of constant turbo speed. Turbo speed for points between these lines can be estimated by interpolation. As turbo speed increases, the pressure ratio increases and/or mass flow increases. As indicated above in the choke line description, the turbo speed lines are very close together at the far right edge of the map. Once a compressor is operating past the choke limit, turbo speed increases very quickly and a turbo over-speed condition is very likely. ◊ Efficiency Islands are concentric regions on the maps that represent the compressor efficiency at any point on the map. The smallest island near the center of the map is the highest or peak efficiency island. As the rings move out from there, the efficiency drops by the indicated amount until the surge and choke limits are reached.

[SpeedSixxx]

I did this about 6 months ago with my PNP intake mani and besides when I do seafoam I get much less smoke out the exhaust the car acts exactly the same.

I've always had during normal driving a 0.3 to 0.7 KR and on the highway I wouls sometimes see up to 1.2 KR but I never stumbled or had hesitationwhile flooringit on the highway after a cruise.

the highest KR ive ever seen on my car was a 1.7 and I'd say that is nothing.
isnt it true the computer is mostly adjusting for better mpg?

[Lex]

Originally Posted by SpeedSixxx I did this about 6 months ago with my PNP intake mani and besides when I do seafoam I get much less smoke out the exhaust the car acts exactly the same. I've always had during normal driving a 0.3 to 0.7 KR and on the highway I wouls sometimes see up to 1.2 KR but I never stumbled or had hesitationwhile flooringit on the highway after a cruise. the highest KR ive ever seen on my car was a 1.7 and I'd say that is nothing. isnt it true the computer is mostly adjusting for better mpg?

What octane fuel do you use? What boost do you spike to, and how closely do you watch KR?

East coast gas is better than what we get in the west.

[SpeedSixxx]

Originally Posted by Lex What octane fuel do you use? What boost do you spike to, and how closely do you watch KR? East coast gas is better than what we get in the west.

93 octane fuel

I spike to 16.5 and drop to 14 sometimes...colder weather?

I watched KR all the time untill it got boring...same old numbers 0.3, 0.7 and 1.2

[Lex]

Originally Posted by SpeedSixxx 93 octane fuel I spike to 16.5 and drop to 14 sometimes...colder weather? I watched KR all the time untill it got boring...same old numbers 0.3, 0.7 and 1.2

I am guessing your car's pretty much stock?

What we need is a turbo we can run at 16psi and give the same performance as the K04 at 20psi. We'd see a lot fewer blow-ups.

[djuosnteisn]

3071r is the right turbo for this car IMO. Even a 2871.


My car never felt better than when i jumped to bt and went from 19-20 psi to 17psi and made like 30whp.

[Lex]

^ True that. I'm going to have to map out the BNR turbos but a stage 3 might do the trick and it's bolt-on.

[SilverDemon]

I agree, I went to a 2871, made more power with less boost, but a bit more timing up top. I did the EGR delete a while back, but I started seeing more frequent and higher KR than I ever did before. With my set up prior to the delete I would never see cruising KR, after deleting the EGR KR seemed to come and go (upwards of 2.3 while cruising). I put the EGR pipe back in, and the car runs like it always did before.

[SpeedSixxx]

Originally Posted by Lex I am guessing your car's pretty much stock? What we need is a turbo we can run at 16psi and give the same performance as the K04 at 20psi. We'd see a lot fewer blow-ups.

I wouldnt say mostly stock
mildly bolted for now

CPE CAI, CPE TIP, BSD, EGR delete, TB coolant delete,vcts delete, PNP intake manifold, PTP IM spacer, ATP DP, SU RMM, TT FMM, denso itv24, blits tt, turbosmart mbc (not used)

things I HAVE and waiting to go on,

GT35R, CPE 4 inch tip, custom FMIC, PTP HPFP, Medievil Manifold plus 44mm Tial wg (how I forgot to add those last 2 the first time..???)

there are things i'm just forgetting on the car and off.....i'll update whenever.

I was told that me seeing a 16psi spike and then dropping down to 14 to sometimes high 13 psi was due to maybe the colder weather or my mods PNP IM...? the ecu reaching it's load without the required 15psi?

maybe now thats it's warm out i'll see a higher spike.

[djuosnteisn]

Damn, These seem quite pricey for what they are.

Maybe that's the price for no boost creep and drop in replacement.