RX7nonSEQ

Trying this post in a different section as it hasn't received much traction,

The main question I have is what is too much advance timing to where it becomes obviously dangerous? I'm running an FD 13b stock twin turbos non sequential, with Street port and Goopy Apex seals. Large SMIC intercooler with intake temps that peak at about 115 degrees F when ambient temps are approx 85 F. Pushing over 300whp at 11-12 psi.

Timing map 1 shows much more advance timing from 2500rpm to 5000rpm than timing map 2, the car builds boost on timing map 1 so much quicker(full boost @ 3800rpm) than the later timing map 2 which hits peak boost @ 5000rpm. Is the timing map 1 unsafe for my application? Should I be concerned with timing map 1, I've compared it to several other maps I've found online, including adaptronics basemap. But I understand timing plays a large role and varies depending on setup.

I also need about 15 degrees advance at idle to keep the motor running smoothly @ an AFR of 13.0.

arghx

iTrader: (3)

Can you post the logs from the two runs you are comparing between timing map 1 and timing map 2? It's hard to understand what actual timing is being used from just looking at a map. Furthermore, it's important to understand how it is interacting with your boost control. Can you give us some more details on your boost control? What are you using to control it, the ECU or some external device? What fuel octane are you using?

As far as the idle spark timing, there is an interaction between idle airflow (set by idle air valve and TB adjustment), idle spark timing, and accessory load such as electric fan, power steering, and A/C. What is your idle speed, what accessories do you have, how has your throttlebody been configured? When you say 15 degrees is needed, under what conditions?

Some Useful Concept of Spark TIming and Idle Tuning (non drive by wire)

Lower idle is more difficult to achieve and maintain. The higher the intended idle, the more forgiving the tuning is.

Accessory loads need some kind of compensation, or you just need a high idle in order to let it dip.

Baseline warm Idle speed can be achieved with more timing / less air , or less timing / more air . Less timing / more air gives you margin to use spark timing for accessory load compensation, but it also can reduce the stability of the idle.

Idle stability on deceleration depends on your baseline idle speed (higher base idle speed is easier as said before), clutch/flywheel combo (aggressive clutch and lightweight flywheel is harder to deal with), and any kind of dashpot on the throttlebody or by software setting of the idle air valve.

Cold start needs some kind airflow compensation, or again a really high idle set point. The airflow compensation can come from a mechanical fast idle valve like the stock FD throttlebody has, idle air valve tuning, or in some cases spark timing. Or if you want to hold your foot on the gas after cold start you can do that, but I'm not a fan of that.

RX7nonSEQ

I'm using a manual boost controller hooked up to the stock wastegate actuator. 93 Octane, with approx. 1-2 oz premix / gallon. I won't worry about the idle timing for now.

Attached are the logs of each, appropriately named. If it matters, for this I don't think so, Timing map 1 log shows 4th gear pull, Timing map 2 log shows 3rd gear pull. I don't have similar gear logs as most of the tuning associated with Timing Map 2 was done with 3rd gear pulls.

Timing 1 log

Timing 2 log

arghx

iTrader: (3)

Thanks for trying to make it easier by doing a screenshot of the log (that's especially helpful for maps as not everyone viewing the thread has the software to open up the ECU tune). Unfortunately these kinds of multiaxis graphs are really hard to read as a static pic. Also, there is not axis label for spark timing visible. So it's hard to make heads or tails of it. Can you export the two logs to some importable format (.csv , or better re-save it as an Excel format because it's smaller sized) and then tell us the timestamps you're looking at?

Second thing to consider: what exactly is your goal here? Tune for maximum response/spool ? Reduce risk by seeing what's the least amount of spark timing I can use and still have acceptable response? Get dyno number bragging rights?

Without knowing any more background, it looks like you're just sort of trying things and seeing what happens, without a methodical plan. The problem is that you have multiple degrees of freedom in the tune (primarily AFR, boost control settings, spark timing). So you have to do things in a certain order or you may find yourself chasing your tail, or you'll leave some aspect of safety and performance on the table.

All that being said, what ECU are you using? Can you not hook up a boost control solenoid and at least run it open loop (just fill the duty cycle table with a fixed value)? Once you get the hang of it, even an open loop boost control solenoid is way better than a manual controller. The problem with a ball and spring controller is that you don't have any kind of way of knowing what's going on, and they can be especially sensitive to air temperature. You can at least log the duty cycle with a simple open loop controller. Not being able to datalog your boost control is a real disadvantage if you are trying to achieve consistent spool, and if your ECU has temperature compensation or closed loop control you can minimize the day to day boost fluctuations common from manual boost controllers.

So for example, here we want to understand the sensitivity of boost control to spark timing. That was your original question. You can do a series of 2nd gear pulls from say 2000-7000rpm with fixed solenoid duties at the very least, and overlay the results. So your test matrix goes like this:

Timing map 1 - 20% duty
Timing map 1 - 30% duty
Timing map 1 - 40% duty
Timing map 1 - 50% duty
Timing map 1 - 60% duty
Timing map 2 - 20% duty
Timing map 2 - 30% duty
Timing map 2 - 40% duty
Timing map 2 - 50% duty
Timing map 2 - 60% duty

All this can be done in one day if you have a safe place to run it and can keep the conditions somewhat similar. Now you can make a simple chart of Timing map, solenoid duty, peak boost, and say rpm at which 1psi boost is reached. Next step you can interpolate between the two maps and run the test again. So if you had 12 degrees on map 2 and 10 degrees in map 1 at a given cell, run 11 degrees. Now you have data for timing map 1, timing map 2, and a new timing map 3 that splits the difference.

This will actually help characterize the spark sensitivity relative to boost control. Right now you're just sort of turning a physical ****, hitting the gas, trying something else, hitting the gas. You can't get a real picture of the sensitivity to make a decision. These kinds of sensitivity tests are basically standard procedure for tuning engines on an OEM level.

RX7nonSEQ

This is all extremely useful feedback that I am able to learn from. Frankly and long story short, I've had my car remotely tuned by two different tuners. The rate at which things change with the car makes me want to learn to tune myself or be able to safely adjust the existing tune so I don't have to bug the tuner every other week. Since having my car tuned the 2nd time, the car runs smoother in certain areas, mainly up top but after several drives, my *** told me the car was slower in certain areas. In reviewing logs, I noticed boost does not build nearly as quick as the previous tune and in looking at the tune files, the timing on the slower to build boost tune the timing in the 2500rpm to 5000rpm (0psi to 17psi) cells is not as advanced as the timing (same cells) in Timing 1 photo. I'd like to keep my 2nd tune in play but somehow get my earlier onset of boost back as I had in Tune 1. Mechanically, nothing has really changed between the tunes and logs. And I don't think a 15 degree ambient air temp difference would be the cause for the change in building of boost. Attached are the log excel files. Car runs on an Adaptronic Modular.
For the Timing Map 1 log, beginning at 80 seconds are the cells worth reviewing in terms of onset and rate of boost (dyno pull).

arghx

iTrader: (3)

So the datalogs you pointed me to are two different pulls in two different gears (3rd gear and 2nd gear it looks like). So it's kind of apples and oranges. I don't see what you describe. Timing map 1 does not have more timing than timing map 2 on an rpm-basis in the logs you showed me. Do you have comparable pulls to compare? Also, I will say again that I don't know what your boost controller is doing as it is purely mechanical and can't be logged without putting a pressure sensor in the boost line or something.

I'm not saying your subjective assessment of the car's acceleration is wrong, it's just that you need to send the right datalogs. If you have a G meter as an analog input we could compare better that way as well.

RX7nonSEQ

That's a lot of info to analyze but to jump back to the basic timing maps that I attached originally, Timing Map 1 had more advance than Timing Map 2. Again, just comparing the timing in cells 0-12 psi, 2500-5000rpm, Timing Map 1 shows a slightly higher number than Timing Map 2 in the same cells. Do I understand correctly that is more advance timing...cell 2500rpm at 4 psi for Timing Map 1 is 17.6 deg BTDC, Timing Map 2 it is 15 deg BTDC. I just want to be sure I'm understanding the software corrrectly and have a generic understanding when too much advance becomes dangerous on the rotary in a set up like mine. The ignition is rpm and MAP driven. My boost controller is being a manual boost controller.

Regardless, this is going to push me into understanding and researching more about 1) Adaptronic, and 2) tuning in general.

The AFR deviation between the 2 tunes is minimal, although maybe a slightly richer tune helps build turbo spool down low.

Ultimately, I have two tunes. Tune 1 builds boost sooner and quicker. Tune 2 builds boost slower and reaches peak boost later. How can I go about safely adjusting the tune to get the early onset of boost back? Is it with the ignition map or the fuel map.

scotty305

iTrader: (2)

I agree with arghx, the engine tends to build boost differently depending which gear it's in. Now that you have Tune2 in the ECU, try doing one log starting at 2000 RPM in second gear and another log starting at 2000 RPM in third gear. Compare those two logs against each other. Unfortunately it's hard for someone to predict how much timing will be safe or dangerous, there is a trend in torque vs ignition timing (assuming boost and RPM and AFR are equal) but you're talking about small difference that would need a dyno to measure. Also the first step before using anyone else's numbers for ignition timing is use a timing light to double-check that the spark is happening at 10 degrees on the pulley when the ECU is commanding 10 degrees. That's easier said than done, but it's important not to get it wrong. And then hope (or ideally check) that the person who gave you the timing map had performed the same check on the engine they used for making their ignition timing numbers.

arghx

iTrader: (3)

In the timing map, a higher number is more advance (leading spark plug fires earlier). However that doesn't matter if the engine never runs in that cell. When it comes to building boost, there are sort of steady-state effects and transient effects. Steady state effects are basically the condition if the engine was "stuck" at that rpm, similar to how a dyno can hold the engine (or vehicle), and had unlimited time to spool. Transient effects are based on the inertia of the turbo and engine. That's where things like ball bearing turbos help you. So you might get 10psi at 2000rpm in 5th gear because you had enough time to spin up the turbos, but in 2nd gear at 2000rpm you might not even build boost. The thing that makes it more complicated is that -- and this is where **** gets weird -- sometimes less timing can give you more boost, but typically at only low rpm do you see that . Less timing --> hotter exhaust --> more energy to drive the turbine side (that's how some anti-lag systems work, by retarding timing). The spark plug fires later and the energy goes out the exhaust port instead of putting force on the eccentric shaft. The other thing to remember is the behavior of the boost controller. Is the ball and spring really behaving the same every time and in every gear? Maybe it is, maybe it isn't. It's an unknown factor in my mind.

So if we compare the two logs you gave me--of course timing map 1 has more timing than timing map 2 in the log. That's because timing map 1 is running at lower boost. So is it lower boost because of less timing or is it less timing only because of lower boost? Or is it not comparable because they are in different gears? My vote is, just go drive the car in 2nd gear at low speed, say 1500-2000rpm on tune #1 and on tune #2, as close to back to back as you can manage. Then post the logs.

To your point of how much timing is too much timing --> this can only be judged by looking for knock, which is pretty risky on a rotary, or by looking at the spark to torque sensitivity relationship as I mentioned before. There is a curve of diminishing returns between spark timing and torque. You want to figure out where you are on that curve. Just as I described before how you would try to find the sensitivity of boost/spool to spark, you basically do a bunch of dyno runs to figure out how much torque/power you are picking up as the timing advances. Then you settle on some number that you feel comfortable with in terms of safety margin, and that's ultimately a judgment call.

Most modern stock ECUs actually have those spark sensitivity curves built into the ECU to calculate how much torque the engine is making. Below is from an old Bosch paper that explains the principle of what makes an engine produce torque and how to understand. It's basically there's some theoretical amount of torque it makes with optimum AFR and Timing, but the engine doesn't normally run there under heavy load, so you want to get it close to ideal while still having safety margin for knock and high temperature. So for example if you are tuning a GM turbo engine, they have a complicated algorithm to maximize efficiency that adjusts boost and timing to achieve some target torque. It's based on ambient conditions and the concepts below.





I know that sounds complicated and a bit confusing. If that makes you more interested in diving in, then yeah you could consider trying to tune it yourself. There are a lot of DIY tuners among Rx-7 owners. Nobody will ever spend as much time tuning your car as yourself. Anyone you pay has more time constraint, but can hopefully make that up with experience. But As soon as you go on your own and unilaterally mess with one of your vendors tunes they would most likely withdraw support, understandably.

RX7nonSEQ

Sometimes we all have embarrassing moments in life, this is slightly one of them. From back to back runs on the 2 different tunes, boost built the same way, well, it turns out that after the more driving I did, it appears boost became later and later in the rpm band. On to looking for boost leaks. I can say that my (2) oem BOV's had less and less whoosh. Let's see what comes of this....

arghx

iTrader: (3)

ok, well keep hunting down the leaks.

dk_davis

Good discussion guys. Regarding looking for the boost leak, I've had a coupler once that would not leak until it got hot, it was a crack that was very hard to see and didn't easily open until the material was very warm. So close inspection of things may be required. Regarding logging, does your logging software have a trace view. I find looking at trace views very helpful when comparing just a few pull/runs and also for street pull/runs the trace if very helpful in letting you know if you were able to closely do the same things from run to run. Regarding logging and time/money, if you don't have the ability to log one or more data points that really let you know what is happening consider the economics of adding those sensors. Each run done takes your time and a few dollars in gas, wear-tear on car, and potential damage. Sometimes the cost of extra sensors can be a wise long term investment.

arghx

iTrader: (3)

Yes, looking at traces right after a WOT pull (or during one if you have an assistant) can be helpful. It's important to not have too many things going on your screen though, and to have usable scaling factor on the Y axis. So for example, if you are viewing Air fuel Ratio, technically it might go as low as 10.0 and as high as 18:1 or 20:1 during tip in and tip out of the throttle. That's not really what you care about though in a WOT pull, most of the time. you really want something like between 10.0:1 and 16.0:1 , or possibly a narrower range than that depending on the manuever.

Another useful thing is to consider how you want to handle the saved files. Do you want a few long files that you have to dig through and possible cut up into separate sections? Do you want to manually start and stop each pull? What are you going to name the files so you can keep track of them? Maybe you can set up an automatically triggered log with a buffer, so that for example every time Throttle is greater than 60% it logs a 40 second window, 10 seconds before and 30 seconds afterwards. That actual workflow of datalogging is important, or you end up chasing your tail re taking logs or having more logs than you can analyze in a reasonable amount of time.

j9fd3s

iTrader: (3)

too much data is a thing, i'd recommend just picking one thing, like AFR or boost and just working on that (or maybe two things)
way back when we had the OBD data in the race car, coolant temp, rpm, tps. then we started adding stuff, brake pressure, steering wheel angle, and its cool. we could see that Paul Ko eases into the throttle like you're supposed to, but Tommy waited a second or two, and then just matted it (Tommy is faster).

what we really wanted to do was to take a corner and compare all the drivers, and or see what is faster in a given turn. so we added the GPS, and then we have pretty much everything. Vehicle speed, Position, Rpm, Throttle position, brake pressure, steering input, we should be able to compare them right?

wrong! the starting line moves. because the track might be 2.1 miles (or whatever) if you go right down the middle, but we don't. the track has width, so if you go around the inside, its only 2 miles, but go around the outside and its 2.2 miles (just for example), so this lead to some books, and they got really thick really fast, and these people had whole careers analyzing data, and then my family friend who was a rocket scientist was telling me that is the same problem they had on their guided missile...

so after that, and some thinking, we just tell people to go faster.
really though Tommy looks at all his data, and it does let us quantify suspension changes (there is a spreadsheet, and after a lot of testing it becomes predictive)

with an engine, or any project the scope of the thing is usually bigger than we really have time (and money) to do, so you have to pick smaller pieces and work towards something
Autocross to Win (DGs Autocross Secrets) - Data Logging

RX7nonSEQ

So I ran into this POS this morning, because I knew it wasn't a coupler or turbo. I just knew it was something else but never considered the following until I removed the BOV hoses and saw it staring me in the face.

The shitty thing is, this can possibly be contributed to the Tune 1 file I was running, the lower than average AFR's only meant unburnt fuel burning in the turbo housings and the fuel enrichment setting in the tune during acceleration wouldn't help either. There's 1 sure way to fix stupid **** like this from happening, tossing the oem turbos and getting something built and designed in the 21st century.

scotty305

iTrader: (2)

Congrats, step one is finding the problem right? It's hard to tell from the angle of the photo, that looks like the wastegate arm?

I doubt Air/Fuel ratio will have enough affect on temperatures to make parts break or stay together. Spending a lot of time at high RPM and high load might do it. Imagine how many times the turbos and actuators have been banged around when they were removed/replaced, I suspect that's more of a factor. Also the OEM heat shields (or lack thereof) and the amount of airflow in the engine bay, and any sort of water splash that might thermally shock a hot metal part.

DaleClark

iTrader: (55)

Well, I've NEVER seen one do that before. Something happened there - either the turbos were dropped and hit that or something weird happened. That is totally out of the ordinary.

Hey, you found it right?

Dale

RX7nonSEQ

I can't certainly say but it was not because the housing was ever dropped. I'd like to contribute it to freeing up the intake restrictions (IC, pipes and proper intake) that it was boosting quick and flowing lots of air, to the point the wastegate would be closed and then would have to slap open. I think that repetitive slapping, maybe quicker and harder in nature than it does in an oem setup lead to its failure. I believe it was simply excessive heat numerous amounts of time and pushing the oem turbos harder than they were ever supposed to.

In the end, I thought they would go out differently, not the wastegate arm bracket twisting off. This is the 3rd primary I've destroyed, although this is the original housing that I've ported so its seen its fair share of dynos and twisties. If the turbo wasn't going to poop earlier, I was ready for it to poop at mid ohio on Monday.

I'll be coming back to this thread when the time is necessary, for now, I wait a few months and build the courage to commit to an EFR. Tired of chasing my tail with these twins. The time, effort, tuning, retuning and the way I drive does not add up to keeping the twins operational. Its almost a bittersweet time giving up on the stock hardware, but numerous people tell me single turbo is a game changer.

arghx

iTrader: (3)

yeah that's the basic point i was trying to make. Don't overload yourself with data, and when you are making charts, make sure they are manageable, whatever that means for the situation. Too much stuff and you can't see the trends as it's just a bunch of overlapping lines. Too few items and you have no context, i.e. you can have rpm but in OP's case, if I didn't plot rpm and vehicle speed I wouldn't have realized that his two runs were in different gears (because there was no channel for gear position).

arghx

iTrader: (3)

As someone who's spent a lot of seat time on basically stock FD's and significantly modified stock turbo FD's, I basically prefer stock turbos with almost stock everything else under the hood. Once you start raising boost for example or require porting of the wastegate, you are significantly reducing the life of components (which already don't last that many cycles) and the system becomes a house of cards. You've already gone pretty far so I think a single turbo would be simpler if you are buying a kit and don't have too much fabrication to do.