Twin Clutch Mystery

[Phoenix]

I was wondering if anyone has heard anything about reprogramming the ECU to address the shift points for increased power output.

The GT-Rs twin-clutch transmission comes programmed from the factory with shift points, specific torque capacities, and firmness based on OEM TQ & HP curves (436 / 480).

It may get interesting as power is upgraded beyond the 70 - 80 HP from baseline, which seems to be about what the Spec V will see in terms of a power adder.

This speaks to another observation I have for some of the aftermarket tuners. If they are just increasing boost and/or torque curves to a certain AFR, and not adapting the transmission, then this may explain some of the longevity issues facing those cars placed on the track with big power losing their clutch packs. And it also may explain why some tuners have chosen to minimize their psi / bar increase to nominal levels and instead adjust the powerband (i.e. Mine's).

This limitation has also been expressed by the factory (for the standard GT-R), stating that the transmission can take up to a maximum power of 85 - 90 kgm. When you take all the factory and aftermarket tuner data together, it does seem like 600 HP (crank) and maybe 520 TQ is probably the maximum the OEM system can take and still retain longevity. The Spec V numbers (if they hold to what has been published) have about a 10% buffer before reaching limitation. Nissan is also probably making adjustments to the shift points and other capacities as well.

This is still good for 10s:thumbsup:

[AdamSupra]

Well, this just means that the key companies in Japan will have to build a stronger unit to hold the power :)

[Phoenix]

Well, this just means that the key companies in Japan will have to build a stronger unit to hold the power :)

Yeah, I just spoke with my mechanic and he seems to think that for BIG power applications only, that the gears should be swapped for a different set of ratios that are more focused on drag racing time attack.

ECU probably won't give much room for improvement.

I definitely think the launch control can be optimized for bigger power though.

[justinn]

Apparently the transmissions will not hold 650hp+ for any length of time. This has come from a pretty solid source, although until I break one personally, I will wait to pass judgement.

Justin

[Phoenix]

Apparently the transmissions will not hold 650hp+ for any length of time. This has come from a pretty solid source, although until I break one personally, I will wait to pass judgement.

Justin

crank or wheel?

[justinn]

crank, although I am waiting to hear what the limit is longetivity wise at the 650chp number. So far so good, and this is probably going to be the magic number for now. Until there is a better shift algorithm, we will have to wait and see. I am not sure if it shears one of the input shafts, or actually destroys the internals, but I will research it further.

justin

[Phoenix]

crank, although I am waiting to hear what the limit is longetivity wise at the 650chp number. So far so good, and this is probably going to be the magic number for now. Until there is a better shift algorithm, we will have to wait and see. I am not sure if it shears one of the input shafts, or actually destroys the internals, but I will research it further.

justin

Dude! haha

600 crank is safe. above that is accelerated wear. Nothing shears or is destroyed.

And who is your source!??! We don't have secrets here.:cool:!

[Phoenix]

crank, although I am waiting to hear what the limit is longetivity wise at the 650chp number. So far so good, and this is probably going to be the magic number for now. Until there is a better shift algorithm, we will have to wait and see. I am not sure if it shears one of the input shafts, or actually destroys the internals, but I will research it further.

justin

Sorry. I figured out who you were. :cool:

The Japanese tuners seem to have seen that ceiling, but it appears that Nissan is comfortable pushing 0.9 bar with the Spec V with minimal alteration to the transmission.

Are you going to do any lightweight pieces....maybe a high-quality CF hood or wing?

[justinn]

:D shhhh, don't tell anyone I'm here ;)

as far as the CF pieces go, I doubt I'll actually develop one for the car as other people usually take care of that type of product. I try to stick to the performance aspect of "tuning"

Just like the japanese, we don't let something go out the door that won't last, so that's why i touted the 650hp number. It's quite possible that I will push the limits of the stock transmission and shifting algorithm as far as it will go... depends how I feel that day :eek: However, I wouldn't want to have alot of unhappy customers because their transmission lasted 1000 miles before grenading.

Justin

[mindlessoath]

justin from ****tuning?

[Norman]

this clutch can hold 80kgm torque only,after that...it start to slip.
from one Japan Magazine

[mindlessoath]

actually nissan was quoted saying 90kg-m max via www.endless-r.com
BUT... thats max, thats how much it will handle in a short burst. and even then its definatly not safew. so what could you run safely rms wise?
i think about 70 to 75kg-m

but like you said, they start to slip really bad around 80kg-m as alot of tuners found out the hard way.

someone really needs to develop a few tranny mods, new clutches, hone some of the gears for better contact etc. thats the problem... upgrading the turbos will offer more performance but it goes out the window because of the trans.

Not only would the trans start to slip but it would be creating so much heat a trans cooler is required... also engine oil is going to cause overheating at such high HP numbers requiring annother stock oil cooler (ie the nismo R35 and cobb R35).

zele has created a trans oil cooler but is waiting because its starting to do some engine mods now and they feel a stock R35 doesnt really need an trans cooler atm.

[AutoLuxuryGTR]

Yeah working on oil cooler for engine and transmission. Possibly might be in production by winter.....so as i figure out what is the beat and most efficient way to cool the fluids i will post diagrams for mounting after i study some more airflow characteristics of the car....

[JaredPink]

Well, this just means that the key companies in Japan will have to build a stronger unit to hold the power :)

Who says it has to be Japan first?

[mindlessoath]

lol, ya! hear ya there! sofar usa is totaly whooping ass. tho i have to admit suspention and aero is japanese special!

here are some wind tunnel shost i found earlier in the month...

as you can see the air doesnt flow throught the black mesh as originaly thought. so placing the cooler lower in the air stream would be the only solution, cause other than that its hot as hell down there in that muffler area.

[mrplatinum]

nice pic

[mindlessoath]

sean morris just found this....
http://2009gtr.blogspot.com/2008/08/gr6-transmission-clutch-settings.html

and i know cobb tuning know about this. i wonder what will be the outcome when we reach higher levels of hp. this will certainly help limit the power to protect the clutches a bit more.

you need a consult III to mess with the TCU, i belive cobb's access port might have access to it (they have a consult3 too i thought).