SOLD on buy it now. Thanks guys. Have lots more stuff, get in touch with needs. acp(at)acpracing(dot)com

Hey guys-

Just listed a new Ralliart ACD ECU I've had as a spare on ebay:

http://www.ebay.com/itm/110993747233...witem=&vxp=mtr

PS the GEMS ADC ECUs absolutely burn pumps - for fast response time they keep the pressure wound up constantly. I have a GEMS backup mounted in the car and use it to bleed the system or in case of ABS sensor fail, but it's a very aggressive strategy. After testing almost everything, we found (surprise) Ralliart knew what they were doing.

ACP

 

i'm wondering the same info as you. I plan to get a reflash with a stock setting, a autoX setting, and a drag setting. I would love to do a review, but it's pointless, as so much is changing over the winter it will mean absolutely nothing in regards to knowing what the ACD does.

the drag setting sounds good, but i don't know if it's just smoke and mirrors. reduced parasitic drag and all... the lockup on launch sounds good.

 

My guess is that it is all smoke and mirrors. Kind of like when people claim they feel a 10whp difference.

 

thinking about this. That claim, on the drag, should show up on a dyno. hmmmmm

 

in fact, in the snow, there is a dramatic difference between the remapped setting and original snow setting, for example... The car changes direction much much faster..
also, in the dry, it tends to lock up the diff sooner and "harder" and there is more grip on corner exit, one thing I missed on the track..

 

just to make sure it's clear. I completely buy into ACD reflashes helping with handling, it's the benefits for drag racing I am curious about.

 

aaah, sorry, did not get it.. To be honest, I have no idea about that one as I do not drag race..

 

Great thread, thanks all!

Had some idea of the potential tuning of the ACD in our cars, just didn't know people we're doing it now, which is awesome and news to me.

Subscribed..

 

I'll tell ya what, I've been tuning ACD units in both my own track cars and a lot of the local evos and its amazing. I don't know how I lived with out it. It's funny sitting in a car doing a custom setup for a customer and one pass is ok and the next is spectacular with only a few adjustments on the ACD maps.

I highly advise it and its definitely not a smoke and mirrors mod.

 

do you make any adjustments as far as the lockup being less/open on turn in and ramping up the lockup for corner exit? that's the "issue" with mine right now - a lot of lockup, all the time

 

Not sure if your asking how it works or questioning a certain aspect of it? Are you tuning yours or running a tuned ACD now? I've noticed some setups like the higher lock and others not so much but if yours is setup just to give more lock up then its gonna feel like crap. In my testing you have to play with all the aspects in order for it to balance out, not just the lockup percentage. The lockup reduction maps, the G-Force maps and ect. Maybe send me a PM and we'll talk.


I don't know what the claim was, but as for ACD at the drag... It's not going to make your car have 10 more whp and it won't show anything on a dyno unless your making enough power to create a condition for it to show up but it will feel faster with an ACD tune set up for drag settings. Its gonna give you back some of the power your losing while transering it from one side of the car to the other and keep the car more true. You would need to run the settings toward the aggressive and you wouldn't want to run it like that for a track day or AutoX but it would keep the car more stable and consistent with a more stabilized and one directional diff control. With a tune the ACD Ecu will instead be thinking "were going in a straight line, throw the fancy stuff out the window and full power ahead, Captain" instead of the stock method of, is this a turn?, how fast are we traveling in said turn?, what kind of geforces are we pulling? are we accelerating in said turn or decelerating?, are you sure this is a turn?, how hard do we lock up again?, can we start over cause i don't think that was a turn?.

Is an ACD tune on your drag car compatible to how awesome it is on a track car? I don't know but you'll definitely notice it more on your road race car. But if your a hardcore enthusiast, you'll be willing to take every advantage you can get.




P.S: ^ Ninja Edited cause no ones perfect.

 

Don't know what ACD set-up you are running and on what setting your modified map is on. But with the modified rear diff (TRE 12-plate) there is a fair bit of lock in the car. It is noticeable turning tightly in parking lots at slow speeds - bit like driving a track car w/ a race diff around the paddock - but I do not consider it a big deal given what else it does for the car. It drives way better anywhere else but the parking lot!!!

I have my most aggressive map on the tarmac setting. If I drop into the unmodified gravel or snow maps - yes I know they are also affected - the car will have less lock in it overall and seems easier to turn at very low speeds.

 

^ Agreed, if your adding more manual lock with with upgraded diffs and such then you may not want as much lock up in your acd tune. Thats where a less aggressive or a personalized tune my better fit your situation. Theres a reason why the car comes with three settings instead of just one, different scenario's require different adjustments, be it the track surface, tires, horsepower or the diffs them selves. I typically have tarmac and gravel as two different levels of lockup so pending the tire and track i can adjust to the situation. I reserve snow for a wet conditions tune which has come in handy once or twice.

 

Missed this great little convo going on - I'm usually running the "street" map from ACD tuning but even that is a little tight. I tried the other maps at AX and they just had a bit more lockup than what is optimal for turn-in/transition.

Well I think in general, you want as little lockup as possible on corner entry/turn in, for max wheel speed difference etc., and then ramp it up for mid corner and corner exit. if there is too much lockup all the time, the front and rear wheels will "bind" and car will resist turn in a little more - same with the rear diff, which may have a greater impact than the center diff. Some preload yes depending on setup, but in general you want low initial torque/lockup, which will then increase as you lay into it - otherwise, if there's too much, the left and rear wheel will resist turning at different speeds, and the car will then resist turning

Good picture (minus AYC):

 

The picture you show with the ACD opening up the diff for turn in and then locking up again in the absence of AYC is the issue in the understeer and FWD feel of the car. As far as I can tell from the feel - I have never seen the actual ACD maps - is that the with remapped ACD, there is less unlocking which gives the car better steering feel as well as diminishing the FWD feel. There are obviously other parameters that are changed.

It seems that people who have the AYC cars do not complain about understeer much. At the same time some people, but not all, prefer the RS diff we get over here on the USDM cars.

Anyway, if you feel you got too much lock, I would give Matt at ACD tuning a call and discuss. BTW, are you still running a CUSCO or TRE diff on your new car? Mine is a custom flash from Matt that is fairly aggressive but set up for the TRE diff. I do not have any squabbles with it. Indeed it has transformed things from FWD feel to RWD feel with loads of grip. Glad I never did the rear bar ...