[Former_Boosted_IS]

Originally Posted by farbmw

I am a little confused, while looking at what ACT has to offer, I don't understand the pricing, they have 3 clutches to choose from.

One is the street performance clutch which is good for ~467 lb of torque going for around $550 US and the other two are 4 puck and 6 puck race clutches which are cheaper at ~$465 US and both are good for ~560 lb of torque.

My question is why is the 4 and 6 puck clutches cheaper then the street performance? Because of more material?

Also putting in a better clutch, wouldn't that increase your torque? And right now the stock HP of the 335i and the torque numbers are almost the same (I think correct me if I am wrong), so if you are able to increase your HP to 500 then the torque would be lower then the HP but not by that much?

Unless your clutch is slipping, then you won't put down more power because of a clutch. It simply assures that the output from the engine successfully mates with your transmission without slip.

[Former_Boosted_IS]

Originally Posted by farbmw

Nice! And you are able to use this as a daily driver?

Twin Discs are pricey but very, very streetable.

[dzenno]

Former, have you ever done a burnout or took your clutch setup for any kind of racing?

[Former_Boosted_IS]

Originally Posted by dzenno

Former, have you ever done a burnout or took your clutch setup for any kind of racing?

I have done quite a few launches among other things. What part are you curious about?

[dzenno]

Just curious in general so with the twin disk which material is on the flywheel side and which on the pressure plate?

[R1000K3]

Originally Posted by Former_Boosted_IS

Uhhh, the crank torque will be considerably higher than wheel torque by probably 15%

Objection, the torque on the wheels is always much higher than crank torque since the gearbox and final gearing is used to multiply torque. The engine spins faster than the wheels on any gear, hence the wheel torque is higher than engine torque. The torque on the wheels are even higher than the crank torque on 6th gear even though this gear is less than 1 to 1, since the final gearing is about 3 to 1. In case the gearing on 1st gear is like 3 to 1 the total gearing is then about 9 to 1. In this case (first gear pull) the torque on the wheels is about 9 times higher than the crank torque. Tyre diameter also comes into play...

The 15% you mention is the estimated drive-line loss. It means the horsepower on the wheels is 15% lower than on the crank. In case the gearbox gearing actually was 1 to 1 (like the fifth gear is if I remember correct)) and the final drive was 1 to 1 (which it isn't on any car known by man) the wheel torque would be 15% less than crank torque.

Just my 2c

[Former_Boosted_IS]

Originally Posted by dzenno

Just curious in general so with the twin disk which material is on the flywheel side and which on the pressure plate?

Ah ok. The segmented kevlar disc (unsprung hub) faces the flywheel, then midplate, then full face ceramic plate (sprung hub).

[Penn999]

Is that what you are using?

[dzenno]

Interesting point on torque at the engine/crank vs wheels...it is completely valid...whp is indeed what sees drivetrain losses

[dzenno]

Excellent read on why torque at the engine is less than at the wheels (opposite of whp)...

http://danielmiessler.com/study/horsepower/

Oh and with upgraded turbos if you just manage to extend/hold boost longer to say 6500rpm instead of ~5600rpm-5800rpm which seems to be peak whp on stockers you can really see how much an organic clutch will hold in terms of whp, so same torque as before but held longer...example:

On stock turbos say you hold 400wtq at 5600rpm :
Whp = (400 * 5600)/5252 = 426whp

Now, imagine you upgrade turbos and now can extend that same torque curve by 1000rpm, here's what you get:
Whp = (400 * 6600)/5252 = 502whp

This is why clutches are rated for torque holding capacity and not whp (hp is calculated based on RPMs)...

So, theoretically speaking, on N54s with a top RPM of 7000rpm, if you managed to tune your car to hold ACT's claimed organic disc holding power of 456tq what does that mean in terms of PEAK whp possible on their organic on this TUNE:

Whp = (456 * 7000)/5252 = 607whp

Now all we need to do is find means of shifting the torque curve In all honesty I don't think these numbers are realistic but I wouldn't be worried about this ACT clutch even with a 35 nitrous shot....launching hard a lot will destroy any clutch prematurely...

I'll report back on the ACT clutch as soon as I'm through my break in..

[Enicinitas]

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