[Ferruccio]

I've heard lots of things like a big limitation on parts like downpipes for the XI models. However, it'd be cool seeing what kind of launches you'd be able to get with the AWD traction.

What can the xi models handle in terms of horsepower/torque? I haven't seen much more than an occasional mention about that. What are the weak points, and what's out there that one can buy to strengthen those weak points?

[pits200]

Originally Posted by Ferruccio

I've heard lots of things like a big limitation on parts like downpipes for the XI models. However, it'd be cool seeing what kind of launches you'd be able to get with the AWD traction.

What can the xi models handle in terms of horsepower/torque? I haven't seen much more than an occasional mention about that. What are the weak points, and what's out there that one can buy to strengthen those weak points?

Hey, don't fault anyone for not getting many responses, the xi is like the redheaded step child.

I'm full bolt-on, no meth xi with coils. I haven't been to the track with my dps yet being that was after the track season was over. But with my other mods, I was getting 1.7x 60's and running around 12.4x. I don't have any issues with my tranny, differential or transfer case.

Knock on wood. I think most fbo xi guys are pushing out around 390awhp and 420awhp torque.

I think we may be seeing the max of what the transfer case can handle. As for the differentials I think we have a better chance being awd and the initial 40/60 split on launch.

[Beemw335]

Fbo is fine on x drive, add meth and your transfer case will blow, only a matter of time.

[Brey335i]

Originally Posted by Beemw335

Fbo is fine on x drive, add meth and your transfer case will blow, only a matter of time.

Did anyone tell jpsimon that?

[jpsimon]

my car is running strong, I don't go around launching at 5k rpm's at every stop light though

[amclint]

+1 on not doing hard launches, problem is that's one of the best parts of having an XI

[Syndicategt]

Originally Posted by amclint

+1 on not doing hard launches, problem is that's one of the best parts of having an XI

You don't need to launch hard to have a quick launch.

[nailer335]

More so than total power, I think it's the addictive AWD brake boost launches that batter the drivetrain. As long as you find a less abusive way to put your xi in motion, I presume that you'll be fine. If I can find track time soon, I'll test the difference in difference launches at 18psi, namely second gear launch, first gear no brake boost, and an aggressive brake boosted launch

AMClint I remember you threw out the idea of possibly fitting the transfer case from something like the X5M. Any more development on that idea? Are they different sizes? I'm sure BMW built them to be stronger than they built the AWD n54 transfer cases? Sorry to thread jack- just going along this train of thought because the transfer case seems to be the first part to break on really high powered AWD n54s

[pinky_and_me]

Originally Posted by jpsimon

my car is running strong, I don't go around launching at 5k rpm's at every stop light though

Have you done any 2500 RPM launches? I got the 2 step rev limiter relay installed but I'm scared to try it so I just use the NLS from time to time.

[jpsimon]

Originally Posted by pinky_and_me

Have you done any 2500 RPM launches? I got the 2 step rev limiter relay installed but I'm scared to try it so I just use the NLS from time to time.

I've done a bunch of 4000+rpm launches, just not every day. You shouldn't worry about 2500*





* don't blame me if you break something, but i've been fine.

[amclint]

Originally Posted by nailer335

AMClint I remember you threw out the idea of possibly fitting the transfer case from something like the X5M. Any more development on that idea? Are they different sizes? I'm sure BMW built them to be stronger than they built the AWD n54 transfer cases? Sorry to thread jack- just going along this train of thought because the transfer case seems to be the first part to break on really high powered AWD n54s

I'm of the opinion that the SUV transfer cases are a no go after I looked into it more, sizing is all different and I doubt it would work with stock DME software.

However not to be all bad news, there is one interesting option in the ATC350 from the 550ix, stock I believe the car is 400hp/450tq and is quite a bit heavier so the transfer case would have to be much stronger. A quick Google search finds some 500hp tune only 550ix cars, but not anything about failed transfer cases. The parts won't be cheap yet but at least the option is out there! I guess the question is now, who's going to be the first person to have to buy one of these things to try it out

335XI : ATC300

550ix: ATC350

X5 Gas: ATC450

X5M & X5 Diesel : ATC700

[NM_BMW]

Originally Posted by Beemw335

Fbo is fine on x drive, add meth and your transfer case will blow, only a matter of time.

Dumb.

[nailer335]

Lol. We have a prophet among us...

Good find AMClint. I'll talk to the stealership about that option the next time I take it in. Should be within the next month or two. Im pleasantly surprised with my transfer case and transmission all together. Ive been hard on this car since day one. For some reason it still seems very strong (knock on wood). Depending on if fitting a stronger one is possible, I'll take one for the team and do a series of transfer case strength tests

Whens nitrous going in?

[Ferruccio]

Assuming you're not dumping your clutch (I'm really slow getting off the line. That takes skill and pretty much requires wrecking the clutch somewhat to be as fast as you can), would a hard shift from first to second on an AWD modded car be the true test for strength?

Honestly, with the traction of AWD, the 1st-2nd shift is the most satisfying to me. It just GRIPS, nothing seems to spin out. My 540i, despite having less power, easily spins the back wheels, losing that nice jolt that AWD can offer.

I'm kind of curious as to the ultimate weak point, especially with kits from HPF coming out, and whether there are adequate strengthened replacement parts. For instance, how might one strengthen the transfer case, in the specific case of the e90?

[nailer335]

The concensus seems to be the transfer case. IMO, I dont think we have a large enough sample to really determine any weakest links that are generally applicable to all AWD n54 cars. Truth be told, there just arent very many 335xi drivers pushing the limits. Only a small handful from what I see online

[Beemw335]

Originally Posted by Humtek

Dumb.

Wow, the people on this forum truly surprise me.
My friend is on his 3rd transfer case, xi fbo with meth..
Its not anything new, most xi owners k ow that its the weak point on their cars.

[MVested]

I had an 07 dme 80 fbo catless jb3 brake-boosting 19psi and blew front diff, forward output shaft and both front axles while brake-boosting from a dig in snow. boost, boost, boost, rears start to spin, then boom! obviously she tried to send power up front but since I was still on the brakes hard I assume that caused enough drivetrain shock to end my modded 335xi AT days..

set me back upwards of $9k at the dealer. it was pretty worth it since I got to beat up on my buddies R35 w dp's from a dig to upwards of 80mph!

since all that, I gave the xi to my brother and got an x6m. couldn't be happier with just a tune. God is she a beast!

forgot to add that same xi that I gave to my bro now has 86k on 'er as of this morning with jb4 and FMIC with original transfer case and is still going strong, no slips or strange noises! actually gonna switch cars w my bro for the day just to bring back old memories and get 30mpg on the highway! woohoo

[nailer335]

Originally Posted by Beemw335

Wow, the people on this forum truly surprise me.
My friend is on his 3rd transfer case, xi fbo with meth..
Its not anything new, most xi owners k ow that its the weak point on their cars.

I think he thought that was dumb because you basically said that ALL FBO + meth 335xi cars will have broken transfer cases... Which might not be a very universally applicable assertion, since it indicates that the mods themselves will lead to the broken transfer cases, independent of how the owner applies the additional power to his vehicle.

I'll be finding out either way probably... as I WILL get this damn car into the 11s at least once before I have to retire it

[amclint]

Originally Posted by Beemw335

Wow, the people on this forum truly surprise me.
My friend is on his 3rd transfer case, xi fbo with meth..
Its not anything new, most xi owners k ow that its the weak point on their cars.

The drivetrain was likely over-engineered to support 150% of the stock torque/horsepower, as is normal with manufacturers to reduce warranty repairs on the components in a car that take the most abuse. But I can tell you I have been actively looking for such failures, and have found more stock transfer case issues than tuned, different sample size obviously

But you are right about us knowing the limits of the drivetrain, on any 335 i or xi you have to deal with the trans/half shafts/differential and on the xi specifically we have an extra differential, double the half shafts and the transfer case. All designed for ~450whp/wtq (my opinion).

Here is your 600-700whp/wtq 335xi drivetrain, looks like $10.5k, who's first?:

1. 4 half-shafts $2k
2. Level 10 Trans $4k
3. ATC350 Transfer case: $2.5k
4. Rebuilt differentials: $2k

[nailer335]

Costly solution to a car that can't make that much power! (yet, to retain optimism...)

[amclint]

Originally Posted by nailer335

Costly solution to a car that can't make that much power! (yet, to retain optimism...)

Yeah I don't see myself building out for that power level, but you never know. I had a business trip last weekend so didn't put my mods back on my car, will be doing that this weekend and looking forward to my nitrous parts coming in the week after that

Going to do some full weight runs with the JB4 15ohm mod, only concern is how much trans fluid the dealership put in since Level 10 recommends overfilling for maximum life and the dealership tech probably just put in the amount from the service manual. Have you topped off your trans fluid before? Maybe I'll buy some just to be safe...

[David1]

I have seen 2 shatered transfer cases in 6 months.