Quote:
Originally Posted by NvDiS
Hmm if thats so not that much more then the auto .. regardless its the engineers stating a safe margin ... but im sure the 6spd can relativity be pushed a little further
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The real advantage that a manual has, in regards to increasing torque, is that you can get/install a heftier clutch to handle the higher torque if you start getting slippage.
For AT you would need work done on the torque converter and I don't know that anyone has anything for it yet.
ZF has variations of the 8sp AT with different torque handling limits.
From Wikipedia:
name max. gasoline torque (N·m) max. diesel torque (N·m) examples
8HP30 300 300 -
8HP45 450 500 BMW 1 Series (F20), BMW 5 Series (F10)
8HP55 550 550 Audi A4 (B8), Audi A6 (C7)
8HP70 700 700 BMW 7 Series (F01), BMW X5 (E70)
8HP90 900 1000 Rolls-Royce Ghost[20], Bentley Mulsanne
F30 328i and 335i use the 8HP45
F30 330D uses the 8HP70
F10 5 series gas engines use 8HP45, same as the F30's.
F10 Diesels us 8HP70, which can handle up to 516lb ft.
Here is the chart from ZF:
Product Type of prime mover Speeds (forw.) Input torque (Nm)
8HP45 Standard /four wheel drive 8 500
8HP55A four wheel drive 8 650
8HP70H Standard / four wheel drive 8 700
8HP90 Standard / four wheel drive 8 1000
Interestingly Audi uses the 8HP55 in the A4, which has a higher torque limit.
It's an AWD application only, whereas the other variants are 2WD and AWD.
The 8HP55 torque limit is 406lb ft/550Nm for gasoline application,
and 479lb ft/650Nm for diesel, according to Wiki.
The chart higher from Wikipedia shows "gasoline" and "diesel" applications, but I don't know if it's 100% correct as it shows
550Nm for the 8HP55 in both gas and diesel.
ZF only shows the max torque limit with no mention of gas or diesel.
The 8HP45, used in the F30's, has a top torque limit of 500Nm, which is 369lb ft.
Wiki's chart shows 450Nm for gasoline and 500Nm for diesel.
450Nm is 332lb. ft, which seems too low to be used with the stock N55, at is shows greater than 300lb ft at the crank according to many dyno's.
I think the 369lb ft/500Nm number is likely correct, as that is what the ZF chart shows.
The 2.0T engine in the A4 doesn't produce more torque than the N20, and even less than the N55.
The 8HP55 variant is an AWD application only, so it's likely a special Audi spec
I wonder why BMW didn't spec a higher limit ZF 8HP variant?
I wonder if it's possible to swap the torque converter from one of the higher torque limit variants into an F30?
Maybe use the 8HP70 from the diesel F30 or F10.
That would be one way to get higher torque handling.
Although I'm sure it would be pricey. Or, find a wrecked car and see how much a used TC would be.