Interesting. How can the AYC send MORE power to a wheel than the engine's already producing, unless it's constantly limiting the amount of power going to the wheels? You know what I mean? Like if that's the case, doesn't that mean the AYC is somehow creating more power?

Thanks for the info

 

That's what I was thinking too, that it would be the chassis. But I didn't know it was THAT much stiffer.. just a good amount. Guess I should start saving up for some bars to stiffen up my chassis too.

+1 for a test of stock IX with Tre vs Stock X, but I would imagine a totally stock IX with just the tre would be kind of rare. The IX and the X were always really close on most tracks though, and I bet it would stay that way even with the Tre rear diff.

 

Does someone want to send me a TRE diff?

 

No

The center diff splits the torque 50/50 front and rear. so, 50 % of the power produced by the engine is sent to the back two wheels.

Then, that amount of power is split again by the rear differential to each wheel. So, under normal conditions, each wheel on the car sees 25% of the torque produced by the engine.

AYC can actively vary the power sent to each rear wheel, so its working with that 50% sent to the rear, and splitting it. Since it uses hydraulic pressure to force its clutch packs together, it can send more than 25% of the initial torque to the outside rear wheel.

 

So of the 50% to the rear, all 50% can be sent to one wheel? Can the math for that really be that simple?
if that's the case, wouldn't awd cars have some serious top speed/power issues, by virtue that 4 men pushing a boulder will be able to push it at a faster speed than 4 men each separately pushing a smaller boulder?
Or something like that? lol

 

Anyway that's kind of off topic but

basically: if a car has 200 hp and 4wd
and 100 hp is sent to the back, split 50hp each
AYC can move all 100hp to one of the rear wheels
while the Tre would just decrease the 50hp on the inside wheel?

If so, isn't the end result basically the same because physically, the 100hp pushing on one of the rear wheels will be limited by the amount of traction that tire has anyway?

 

i thought the new S-AYC /S-AWC/ can put more power on separate wheels then before.
So more then any CT9A car could.
Its kinda step forward, like it was from evo 4 to evo 6 or 7.
Am i wrong?

this link might help more understanding:
http://www.mitsubishi-motors.com/cor...003/15E_11.pdf

http://www.mitsubishi-cars.co.uk/features/ayc.asp

 

From about 50 laps of track experience with 325whp (Mustang Dyno) and a TRE 1 way diff, I have found the following:

Good: The car definately rotates nicely out of the corner. Just like everybody says, the front end no longer plows out of the corner like a FWD car. The rear will dance just as much as you can stand. However, you really need to be autocrossing if you are around my power level. My car just didn't have enough torque beyond 2nd gear to truly utilize the upgraded diff. Thats why I got a FP Red

Bad: The upgraded diff will make a lot of popping and grinding noise for a while. I talked to Jon @ TRE (awesome guy, a true encyclopedia of drivetrain info) and he said that it is perfectly normal. The clutch packs have to wear in. As of yet, I put about 500 HARD miles on it, and it still pops and barks around low speed corners, but it is noticeably better.

In all, this is arguably the most cost effective handling mod you can make. But again, unless you have 400wtq+, the autocross is the only place to enjoy this mod for those of us on stock turbos.

 

From how I understood that stuff, the s-ayc itself was the same, but what made the "s-awc" was the further development of the integration of all the parts working together, with the acd and the ebd and all that.. I thought I read that somewhere, could be wrong though

 

When you say "truly utilize," do you mean that, because you didn't have enough power, the car would still plow through the corner and the rear diff wouldn't do anything?

 

Kinda weird, mine has never made funny noises. Tires chirp at low speeds though.

I have to disagree with the lack of power thing. My car has 300hp on a dynojet (Pruven's). It has no problem rotating in 3rd or 4th gear.

 

To be more specific, tracking out of a higher speed corner (3rd gear+) my car did not have enough thrust to necessitate counter steering from lack of traction. With my driving style, I like to throttle steer out of every corner. Just enough wheel spin to let me know that I am slightly beyond the limits of adhesion.

Don't get me wrong, the car still tracks way better out of those corners with the new diff, I just feel that at my power level I really can't enjoy the benefit at higher speeds.

 

Is the S-awc the same way then, where you have to be giving the car throttle for it to be working?
Does anyone know what exactly the ayc is doing that is different from the tre rear? Is it the ability to transfer all power to one side vs. the ability to limit the power on one side?

 

Also, how does the Tre Rear Diff compare to the Cusco Type RS Rear LSD w/o AYC? (shown on AMS online store website)
Can anyone comment on pluses or minuses of this? As is why is it more than double the price/is it comparable/worth it?

 

In a nutshell, no its not that simple because you must take into account grip levels at each wheel, the power the engine is making, ect.. But, for these purposes, it is.

AYC cannot send ALL of the torque sent to the rear to one wheel, just more than 50%. a mechanical differential can only send a maximum of 50% to one rear wheel.


You are thinking about it incorrectly. First, HP is just a function of torque. torque is what differentials "split".

2nd, torque produced by an engine is dependent upon load. thats why load-bearing dynos are better. an engine will only produce its optimal torque under high levels of load.

Now, lets just look at it as a FWD vehicle making 200 lb-ft of torque. if both wheels have enough grip to not spin under acceleration, the engine will see enough load to create 200 lb-ft, and each wheel puts down 100 lb-ft of that total amount.

Lets create a scenario where one of the wheels is now on a surface that has 1/4the grip the other tire does, the other tire having the same grip as before.

Lets look at what happens with certain differential types:

Open diff:
So, we have one wheel on a slippery surface, and theres a certain amount of torque that will make it slip. since we said its 1/4 as grippy, it takes 25 lb-ft to make the tire spin. so, since the diff is a 50/50 split, that means the other wheel is getting 25 lb-ft as well. Because the one wheel is slipping now, the engine has no more load placed on it, and it is only making 50 lb-ft total. The car will still move forward because the one wheel is getting 25 lb-ft, but it wont move fast.

Mechanical LSD:
The mechanical LSD operates in the same way as above, except for one main thing: once the slippery side starts spinning, it "locks up". this does not mean it changes the 50/50 distribution, but rather it is transfering load from the tire with grip to the engine. The engine is now seeing more mechanical load.

This is where calculations get difficult, you would need to calculate the amount of lockup within the diff, ect. But we will just say that it is giving the engine enough load to make 100 lb-ft of torque now. thats split 50/50 again, so the wheel with grip will now get 50 lb-ft to put down to the ground. the car moves forward faster than with the open diff.

Active computer controlled differential (AYC):
Again, same circumstances as the open diff. But, this differential can cange is torque distribution. lets say it can transfer 75% of the torque sent to it to the wheel with grip. This gets even more complicated. But, here are the main effects of this:

Now, the diff is sending 75% of the power to the wheel with grip. The engine is also generating more torque. Because it can put more torque down, the engine sees more load, and generates more power.

Conclusion:
AYC is best, it can put the most power down when one wheel is experiencing decreased grip. So, because the inside wheel while cornering is experiencing less grip, the AYC can put more power down in a corner than both an open diff or an LSD. the fact that it can vary the amount of power it sends to the rear outside wheel means it can use that to alter the yaw angle of the car itself. this balances cornering loads, decreases steering imputs, ect. better handling, less driver feel.....ta-da.



DISCLAIMER: I am not a certified engineer, I have not graduated or been evaluated. This explanation has been very very simplified to get a main point communicated. Im not interested in arguing about it, if you would like to correct me, be my guest.





S-AYC started in the evo 8, it can transfer about 10% more torque than the original AYC. the evo x has the same S-AYC as the 8/9 had, but it is integrated into the S-AWC system.