ACD Tuning Options - USDM CT9As, Read!
Jul 9, 2017, 03:33 PM
#542
no, not true... we tune both... Motec and other ACD controllers like GEMS are used on rally cars and those have to have a mechanical RS rear diff, hence those controllers do nothing for AYC.. Some rally drivers use mitsubishi Ralliart ACD controllers which are just stock units with diferent setup..
that's not how most of the evo tuners overseas feel about it -
http://www.motec.com/filedownload.ph...pdf?docid=4399
http://www.motec.com/filedownload.ph...pdf?docid=4399
exactly... u want to allow the speed difference on corner entry, and lock together on corner exit.. VCU can't provide that
Jul 9, 2017, 05:21 PM
#543
Anyone who thinks a nose heavy evo needs more stability is doing something wrong.
Jul 9, 2017, 05:28 PM
#544
the ACD is best tuned, not open:
Mid-corner on zero throttle, the diff is virtually open allowing the car to be very nimble, while under power there’s a good percentage of locking, close to the safe maximum, enabling the car to powerslide as its nose points in the intended direction. Confident drivers will quickly find that car speed isn’t limited by over or understeer, but by outright tyre grip – the ideal handling balance.
It turns in extremely fast, but the biggest difference – and it is a huge one – is the lack of stability under brakes. From the high-speed corners into the low-speed turns, there is a tendency to lock an inside front tyre – based on normal driving style – and the result is the need to be kinder and softer (and less
effective) on the brake pedal.
effective) on the brake pedal.
Last edited by kyoo; Jul 9, 2017 at 05:36 PM.
Jul 10, 2017, 01:33 AM
#545
Evolved Member
with regards to your motec comment.. I have read the article before and there is no mention of ayc... what I told you before is that we who choose to keep the ayc tend to remap both ayc and acd... Motec on the other hand is ACD only solution becuse the vast majotrity of race cars come with RS rear diffs... i.e. no AYC, so no need for that control.
Jul 10, 2017, 05:44 AM
#546
I have and the car is an understeering POS with open ACD (admittingly, the AYC was off too)
with regards to your motec comment.. I have read the article before and there is no mention of ayc... what I told you before is that we who choose to keep the ayc tend to remap both ayc and acd... Motec on the other hand is ACD only solution becuse the vast majotrity of race cars come with RS rear diffs... i.e. no AYC, so no need for that control.
with regards to your motec comment.. I have read the article before and there is no mention of ayc... what I told you before is that we who choose to keep the ayc tend to remap both ayc and acd... Motec on the other hand is ACD only solution becuse the vast majotrity of race cars come with RS rear diffs... i.e. no AYC, so no need for that control.
the aricle does mention that their tune disables AYC.
In some Evos, the MDC disables the Active Yaw Control, but compensates with added stability from the new diff settings.
::
that reminds me, you're also the second person i've seen mention that your car actually understeers worse with ACD off - and the other guy had a USDM car. very odd indeed, counter to the article's claim that open ACD oversteers more, as well as what I have seen and experienced myself.
Last edited by kyoo; Jul 10, 2017 at 05:50 AM.
Jul 10, 2017, 09:21 AM
#547
Evolved Member
that is very interesting, since the article notes the exhaust opposite with their car - it must be due to the AYC being "off" as well, which is also very interesting. JDM RS's have a clutch type 1.5 way IIRC, so there should be some lock-up on decel, meaning if anything they shouldn't be as loose as an AYC that is not functioning?
the aricle does mention that their tune disables AYC.
this matches what i've seen from other ACD tuners, including when I was speaking with English Racing as they were developing their ACD tune. but as you say, there could be other options. I'd personally love to see a test of stock 9, stock 9 w/ ayc, stock 9 with acd tune and rear diff, stock 9 with acd tune and ayc, think it would be really interesting to see that data.
::
that reminds me, you're also the second person i've seen mention that your car actually understeers worse with ACD off - and the other guy had a USDM car. very odd indeed, counter to the article's claim that open ACD oversteers more, as well as what I have seen and experienced myself.
the aricle does mention that their tune disables AYC.
this matches what i've seen from other ACD tuners, including when I was speaking with English Racing as they were developing their ACD tune. but as you say, there could be other options. I'd personally love to see a test of stock 9, stock 9 w/ ayc, stock 9 with acd tune and rear diff, stock 9 with acd tune and ayc, think it would be really interesting to see that data.
::
that reminds me, you're also the second person i've seen mention that your car actually understeers worse with ACD off - and the other guy had a USDM car. very odd indeed, counter to the article's claim that open ACD oversteers more, as well as what I have seen and experienced myself.
My experience with acd off might have been due to ayc not working too (the pump was off the car for service) but it is a fact that the ACD is very active in controlling the car. One more thing that I find iffy in the article is that they talk about torque split between axles, and this is not what acd does... it is just a active limited slip clutch..
I also urge you to try logging it.. you will see that is is very active all the time, much more than the usual presumption of it being open on turn in and closing slowly on exit.. It also reacts first to steering speed...
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alpinaturbo (Jul 10, 2017)
Jul 10, 2017, 10:12 AM
#549
yes, my point was that aftermarket ACD controllers do not work with AYC because their market is mostly rally and other race cars which are mostly run with RS rear diffs.. and not because AYC is better kept off... in fact if you were to try a euro/jdm evo 9 with ayc and a usdm e9 with the plate diff you get, you would see that the ayc car is much more "nervous" and turns in better and tends to oversteer on demand. I am just in the process of setting up a USDM e9 MR and while we did perform the diff restack it still doesnt push the nose in on throttle like the ayc car will.
My experience with acd off might have been due to ayc not working too (the pump was off the car for service) but it is a fact that the ACD is very active in controlling the car. One more thing that I find iffy in the article is that they talk about torque split between axles, and this is not what acd does... it is just a active limited slip clutch..
I also urge you to try logging it.. you will see that is is very active all the time, much more than the usual presumption of it being open on turn in and closing slowly on exit.. It also reacts first to steering speed...
My experience with acd off might have been due to ayc not working too (the pump was off the car for service) but it is a fact that the ACD is very active in controlling the car. One more thing that I find iffy in the article is that they talk about torque split between axles, and this is not what acd does... it is just a active limited slip clutch..
I also urge you to try logging it.. you will see that is is very active all the time, much more than the usual presumption of it being open on turn in and closing slowly on exit.. It also reacts first to steering speed...
Re: Torque split, that is essentially what limited slip differentials do - if there is a speed differential and a diff tries to clamp them together, it will experience a difference in torque distribution. Same between two wheels in the rear. There will be a torque shuffle to the outer wheel.
Also, re: logging the ACD - that is what I am saying. Stock tune, the ACD is active all the time - too active, maybe a safer setting. What the current set of available ACD retunes do is opens up the ACD, particularly on throttle off.
I'm actually glad to hear you are setting up a USDM Evo with rear diff plate restack - no it will not turn like it has AYC - but the ACD is key here. I would reach encourage the owner of the car to reach out to English Racing to retune the ACD. There will be some big differences in how the car behaves, PARTICULARLY in turn-in. The car will turn in much better. I'm curious to see how that feels for you vs the AYC equipped car.
https://www.evolutionm.net/forums/ve...cd-tuning.html
Originally Posted by Darrin
I had the opportunity to test the English Racing autocross tune ACD controller in my 2006 EVO IX today. After several laps at the autocross track I can say it was absolutely EXCEPTIONAL. The controller tuned out all under steer (push) and made car react to inputs better than any evo i have ever been in. I could plant the front end on a cone and get the back end to rotate around unbelievably fast. If I was told i could only have one upgrade to a evo that i was to race, this is the very first thing i would put on my list. It made a bigger difference than my ball bearing turbo, or even my Ohlins . On the lowest setting I picked up 2 seconds (50ish second lap) the next higher setting i picked up another 1 second. The highest setting was the cherry on top. I picked up .4 sec and continued to improve .2 to .6 each lap as i got dialed into it. I had Nationals and Regional winning champions dive my car as well to give me their feedback. They were astounded that it was even an evo, they couldn't believe how much better it was than their nationals winning EVO. Thank you Aaron O'Neal for giving me the chance to try this thing out. I can tell you that as Bremerton Sports Car Club autocross instructor, i am going to recommend this controller to every evo that i come across.
I did re-stack my rear diff and i would say that this re-flash affected rotation 500% more than the re-stack did. I welcome people to come to any BSCC autocross events and i will give the a ride and let them feel it.
I had the opportunity to test the English Racing autocross tune ACD controller in my 2006 EVO IX today. After several laps at the autocross track I can say it was absolutely EXCEPTIONAL. The controller tuned out all under steer (push) and made car react to inputs better than any evo i have ever been in. I could plant the front end on a cone and get the back end to rotate around unbelievably fast. If I was told i could only have one upgrade to a evo that i was to race, this is the very first thing i would put on my list. It made a bigger difference than my ball bearing turbo, or even my Ohlins . On the lowest setting I picked up 2 seconds (50ish second lap) the next higher setting i picked up another 1 second. The highest setting was the cherry on top. I picked up .4 sec and continued to improve .2 to .6 each lap as i got dialed into it. I had Nationals and Regional winning champions dive my car as well to give me their feedback. They were astounded that it was even an evo, they couldn't believe how much better it was than their nationals winning EVO. Thank you Aaron O'Neal for giving me the chance to try this thing out. I can tell you that as Bremerton Sports Car Club autocross instructor, i am going to recommend this controller to every evo that i come across.
I did re-stack my rear diff and i would say that this re-flash affected rotation 500% more than the re-stack did. I welcome people to come to any BSCC autocross events and i will give the a ride and let them feel it.
Jul 10, 2017, 10:38 AM
#551
Evolved Member
Jul 10, 2017, 10:47 AM
#552
That's a fair comment. I don't know the scenario of the testing - if they got to a certain level, then changed it, then hit another wall, then changed it and picked up speed or not. I'm not saying it will, from your fastest run, with just the switch drop 2s. But I'm looking at the rest of the commentary, as well as reviews, and seeing that there is consistent improvement in laptimes. His is just one anecdote, there are many others in that thread.
Jul 10, 2017, 11:11 AM
#553
EvoM Guru
iTrader: (1)
I never quantified my results objectively with lap times. But I have swapped a stock ACD ECU in/out of my car at autocrosses and track days, car feels worlds better when the ACD is running the ER tune. Handles much more like a RWD car with all the grip than a pushy AWD when the ACD is tuned.
Jul 10, 2017, 12:08 PM
#554
I'll blatantly blow the horn on behalf of knowledgeable but restrained genius,
You should know that Kikiturbo tunes ACD maps, and optimizes others ACD maps, aside from building all mechanicals, turbo kits, porting, tuning, and more.
So be assured his feedback based on the experience with ACD+AYC "rest of the world" Evo, and USDM Evo models, as well as successful rally Evo's which are a lot like USDM- ACD with RS rear diff.
Getting back to FRONT LSD:
I discussed with couple of highly experienced road race Evo chassis specialists, and both advised that Wavetrac is only front LSD they use, and pointed out how plates (wear) material in Plated Mechanical LSD gets into gearbox oil, and generally mechanical LSD plates require different oil(somewahat opposite requirements) oils not recommended for gearbox.
For race car the oil issue is moderate compromise, but for more club level and dual purpose car, Wavetrac is easier the better choice.
As far as performance, neither felt that Wavetrac gave up any performance to Plated Mechanical LSD on track, or road.
This is theirs point of view, their experience, and preferred method.
You should know that Kikiturbo tunes ACD maps, and optimizes others ACD maps, aside from building all mechanicals, turbo kits, porting, tuning, and more.
So be assured his feedback based on the experience with ACD+AYC "rest of the world" Evo, and USDM Evo models, as well as successful rally Evo's which are a lot like USDM- ACD with RS rear diff.
Getting back to FRONT LSD:
I discussed with couple of highly experienced road race Evo chassis specialists, and both advised that Wavetrac is only front LSD they use, and pointed out how plates (wear) material in Plated Mechanical LSD gets into gearbox oil, and generally mechanical LSD plates require different oil(somewahat opposite requirements) oils not recommended for gearbox.
For race car the oil issue is moderate compromise, but for more club level and dual purpose car, Wavetrac is easier the better choice.
As far as performance, neither felt that Wavetrac gave up any performance to Plated Mechanical LSD on track, or road.
This is theirs point of view, their experience, and preferred method.
thanks!
