Subaru Legacy Forums

Subaru Legacy Forums (http://legacygt.com/forums/index.php)
-   Tuning (http://legacygt.com/forums/forumdisplay.php?f=84)
-   -   Per-Gear Tuning (http://legacygt.com/forums/showthread.php?t=202958)

SeeeeeYa 03-06-2013 06:24 AM

Per-Gear Tuning
 
While per-gear timing may not be available on LGTs, from what I know, per-gear boost tuning for many LGTs certainly is. My STi, as well as several other model ECUs, have the dormant ability for both per-gear boost as well as per-gear timing. Seems the provisions in the ECU, revealed not all that long ago, are leftovers from capabilities in JDM versions. Figures.

The thread I made on IWSTI has had but two people reply... one is LittleBlueGT. :lol: I don't expect many will undertake this, but this is to let you know it is possible. Apparently, people have yet to envision the possibilities. I can tell you this, without per-gear tuning you are missing out.

To begin per-gear tuning all one needs is an EBCS and the tuning software of choice. I use the Tactrix/Prodrive EBCS and ATR. The tuning, however, is arcane. There is virtually no direct information anywhere, with only hints here and there if you search.

I accidentally came across per-gear looking for a solution to a common, potentially destructive, result of a Stage2 tune... inadequate boost control at the uppermost limits, where the stretched OEM ability becomes inadequate. Many Subarus die on racetracks due to precisely this. Initially I bought an EBCS and a MBC, to implement "hybrid boost tuning" on my car, which would have been a solution. Along the way I was made aware there was a better solution, one where I could have safety in any gear and at any speed, PLUS more power and superior everyday performance to boot.

A short time later I had per-gear tuning, and a car with a difference in feel like it did going from stock to a good tune, only it already had a good tune. Something this rewarding to drive, that protects my valued Suby no matter the weather or driving extreme, should not remain a secret.

RomRaider has had a number of per-gear threads, and definitions that revealed pertinent tables. Some tuners have boasted about it, then kept understandably quiet. It has been incrementally revealed and has been promised in future tuning software revisions. Some esoteric tuning softwares have long embodied the ability. Per-Gear Tuning is coming, yet, at this time, there is no access for the bulk of the Community. Time to change that.

Here's that IWSTI thread I made:

http://www.iwsti.com/forums/ecu-tuning-performance-electronics/254298-power-safety-driveability-per-gear-boost-per-gear-timing.html

Here are informative threads:

http://www.airboytuning.com/archives/130

http://forums.nasioc.com/forums/show....php?t=2189089

Thanks, rtbrjason, for all your help and guidance.

bnguyenbb6 03-06-2013 08:44 AM

I'll have to look into this when I have more time. The hybrid boost might work for rolling dynos but it'll overboost/boost spike in higher gears if you are shifting fast. Mine will hit 22-23psi going from 3rd to 4th(in Mexico of course); its supposed to only hit 20.5psi.

BAC5.2 03-06-2013 09:01 AM

Seems like a reasonable idea. Load changes with respect to gear ratio, so it's logical that you tune for the load conditions each gear will ultimately result in. You can do a LOT with per-gear tuning, including developing a REAL snow mode (low boost and pulled timing with high throttle sensitivity in low gears, and low throttle sensitivity and higher boost and more aggressive timing in higher gears).

Big power, street-tire STi's could even benefit by mitigation of wheelspin off the line without sacrificing dynamic response or closing the throttle.

Question: How does the ECU determine gear?

GTTuner 03-06-2013 09:30 AM

I would assume gear determination would be RPM/road speed

SeeeeeYa 03-06-2013 09:32 AM

Quote:

Originally Posted by BAC5.2 (Post 4326279)
Seems like a reasonable idea. Load changes with respect to gear ratio, so it's logical that you tune for the load conditions each gear will ultimately result in. You can do a LOT with per-gear tuning, including developing a REAL snow mode (low boost and pulled timing with high throttle sensitivity in low gears, and low throttle sensitivity and higher boost and more aggressive timing in higher gears).

Big power, street-tire STi's could even benefit by mitigation of wheelspin off the line without sacrificing dynamic response or closing the throttle.

Question: How does the ECU determine gear?

I had to find it again...

http://www.iwsti.com/forums/3258960-post6.html

You certainly get it, even adding to the list of potentials I've read about.

SeeeeeYa 03-06-2013 09:33 AM

Quote:

Originally Posted by GTTuner (Post 4326316)
I would assume gear determination would be RPM/road speed

Ding ding :)

fahr_side 03-06-2013 09:56 AM

I've been running per-gear boost control on my WRX for a few years now, since Eric Minehart pioneered the definition of those tables. Everything you need to know is here: http://www.romraider.com/forum/viewt...hp?f=25&t=7048

The ECU calculates gear position from engine rpm and vehicle speed via a 2D table of thresholds.

BAC5.2 03-06-2013 10:17 AM

Quote:

Originally Posted by SeeeeeYa (Post 4326321)
Ding ding :)

So that causes some problems then. Gear changes would have to be interpreted quickly (especially for drag racers), and changes made accordingly. You'd have to give some thought to the gear transition (which wouldn't be as easy as having step-function changes). Things like FFS and LC would interfere.

You also can't compensate for clutch slip. Ideally, you'd know that clutch slip occurs and would drive responsibly. But the ECU wouldn't know that you are launching, or slipping the clutch intentionally in the dirt or snow. You'd have to account for that, and there's some different ways to do that (i.e. default to wastegate or low boost when gear position is undefined).

But you could also use that to your advantage, by retarding timing when road speed is greater than zero, and there is no matching ratio (i.e. during shifting). That, along with target wastegate boost, you could effectively build FFS into the ECU without having to rely on either clutch switch.

With a standalone, you could build a controller so the ECU would be able to predict the next gear change based on current gear and the lower clutch position switch (i.e. clutch starts coming out, feedback RPM:speed to determine if the next gear is above or below the current gear, and select that boost and timing map).

SeeeeeYa 03-06-2013 10:19 AM

Quote:

Originally Posted by fahr_side (Post 4326367)
I've been running per-gear boost control on my WRX for a few years now, since Eric Minehart pioneered the definition of those tables. Everything you need to know is here: http://www.romraider.com/forum/viewt...hp?f=25&t=7048

The ECU calculates gear position from engine rpm and vehicle speed via a 2D table of thresholds.

Yep, two years ago he showed the way and made per gear boost tuning possible.

In 2008 Airboy discovered the timing compensations, that has made per gear timing possible. Here: http://www.romraider.com/forum/viewt...hp?f=25&t=3985

While I've often been outspoken in defense of the AP, versus OS, it is obvious that in doing so I've cultured a personal ignorance. Were it not for OS the abilities I post here may never have happened.

Now, isn't it time everyone, AP or OS, were made aware of their car's untapped potentials?

fahr_side 03-06-2013 10:46 AM

Quote:

Originally Posted by BAC5.2 (Post 4326414)
You also can't compensate for clutch slip. Ideally, you'd know that clutch slip occurs and would drive responsibly. But the ECU wouldn't know that you are launching, or slipping the clutch intentionally in the dirt or snow.

The gear determination thresholds are quite wide, so they allow for some degree of clutch slip or wheelspin, and they can be edited.

SeeeeeYa 03-06-2013 11:20 AM

I will say the tables in the emineheart RR thread above are significantly different from what I have to work with in ATR. It would be nice to edit tables like that, but I have to do extra manipulations to get the per gear torque breakout I need.

Can someone look with OS to see if those tables are still the same in a 2011 STi? If they're the same then "someone" at Cobb made the job for ATR folk not only more difficult, but have less resolution as well. I have to wonder why they would do that... if they did.

I've been kicking myself for selling my Tactrix cable. I only did so because Cobb had it locked out. Then, shortly after I sold it, they made it possible to use it. :( It is time for a new one if those tables are as detailed in OS now for my STi as for the 08 WRX in the RR thread.

It may be up to a skilled OS user like fahr-side to take this thread where people can actually use it. It's been a fairly complicated job of tuning for me to get where I am. That has been complicated by adding in per gear timing, which made a huge difference but means log/tune/log/etc multiple timing tables. Per gear boost, which most can implement, was made more complicated for me because I added an EBCS at the same time, and tuned multiple boost tables in sub-freezing temps. I bet those with an EBCS already would be ahead of the game to start.

BAC5.2 03-06-2013 12:47 PM

Quote:

Originally Posted by fahr_side (Post 4326484)
The gear determination thresholds are quite wide, so they allow for some degree of clutch slip or wheelspin, and they can be edited.

If that's the case, can you add columns to the table?

If so, you could build conditional boost/timing maps that would tailor those parameters based on what you are doing. Launching and shifting, namely.

fahr_side 03-06-2013 07:58 PM

No, it's a 2D table. Additional logic would need to be added to accomplish what you're suggesting.
A mate has already implemented LC/FFS on his standalone (works off the clutch switch as usual) but is working on an auto-blip function now. The trick to making that work is to monitor throttle pedal angle and the brake switch.
Gas pedal 100% and clutch down, ECU logic can determine you want LC or FFS based on vehicle speed. Throttle 0%, brake switch on and clutch down, you get a blip to rev match based on a table of rpm deltas between gears.
There are guys who could probably write a patch like this for the stock ECU but the place for that conversation in on Romraider ;)

SeeeeeYa 03-07-2013 06:07 AM

Sadly, from my limited OS experience and resources it doesn't appear there are complete definitions for the 11 STi. With official releases stopped years ago the only ones added have been individually provided. The one I've used in RR to look at the 11 STi isn't part of the official definitions, and does not include all the tables necessary to implement per gear.

So, unless I'm wrong which is very possible, it looks like for some OS is the tool to use and for others ATR is.

However, the point of this thread isn't a how-to for implementing Per Gear Tuning, but more to bring awareness that the option exists and has proven, undeniable benefits. Those who have the desire to pursue such tuning will find a way. Obviously, one way is to get a pro to craft the tune... with one here, fahr_side, who already has years of experience at it. I'm sure there are others, but not all.

I've been so preoccupied getting my own tune off the ground and safe that my knowledge of who can and who cannot do what is poor. Some only have the possibility for per gear boost... perhaps the most important of the two because it provides for more power and more safety than any other option I'm aware of. Some have the option of both per gear boost and per gear timing... the later providing driving and performance enhancements.

In my opinion, anyone who values their motor and has gone past Stg1 should find a way to per gear boost tuning, at the least. Far too many of these engines fail just because of one high speed run. The records show that track days kill unprepared engines. Many people who believed, just because their tune was "safe" and worked fine day after day in normal use, was also safe at a track or a few high speed rolls in "Mexico" have lost motors.

Proper boost control that eliminates spikes in higher gears can be done other ways effectively. But, per gear provides not only that, it provides for even greater performance in the lower gears as well. No other method does that, to the best of my knowledge. With per gear you can truly have your cake and eat it too.

iNVAR 03-09-2013 06:16 PM

Subscribed, and reading all linked threads you provided. Would love to get per gear boost control working on my car. Getting kind of annoyed by what seems to be a fairly wide gap between 3rd and 4th required WGDC and ability to achieve my targets... I ended up tweaking things more onto the safe end, while sacrificing 3rd gear and consequently every gear below that as well. :(


All times are GMT -6. The time now is 11:35 PM.


LegacyGT.com