[benzy89]

Originally Posted by C ///M

I really appreciate the comments. I have a few specific questions for those familiar:

Fuel Economy. Really, I know comparisons are ridiculously difficult due to driving style, altitude, temperature, fuel type, etc... I mean the list goes on. But really, the N55, all things equal, is supposed to get better mileage, right?

What about maintenance? I'm not worried about the HPFP, because I'm certain that BMW's newest part has got to have the problem sorted, right? I'll make sure and get the newest part. However, what about other maintenance costs like when the turbos eventually need to be rebuilt? I guarantee that I'm only settling for somewhat lower mileage motors, like under 50k miles and in the 30's would be perfect. But if I do get a 50k mile motor and I'm half-way to a snail rebuild, what costs more? Two small turbos or the slightly larger twinscroll unit on the N55?

Most of the N54 comments are all about power, but maybe i wasn't clear that I'm really not interested in going much over 400 crank hp, obviously more torque would be nice. This is still an X3, so i'd like reliability, best fuel economy possible considering the type of performance, less maintenance cost if possible.

Fuel Economy: If drove both engines the exact same way or put them both on cruise control, the N55 should get better gas mileage. This is because of the Valvetronic system in the N55, which ironically enough is the reason why we haven't seen higher HP N55s. When tuners crack the Valvetronic-Tuning Nut, we'll see a very healthy bump in tuning numbers.

Maintenance: Both cars are direct injection, so walnut blasting/cleaning the intake valves is going to be a necessary evil every 35-40k. The N54 was plagued with HPFP problems, but majority of the cars now have had that part replaced with an update pump. Both the HPFP + Wastegates are covered under BMW Recall's if they go wrong & will be replaced if the car isn't heavily modified & doesn't cancel the warranty (so you'll prob have to find a mod-friendly dealer if you're doing the engine swap).

Install & Maintenance Costs: Both engines need to be actively maintained by the owner. These aren't Chevy small blocks that you can beat the hell out of & skip an oil change and expect them to be fine. What it sounds like is you're basically trying to make your own X3 M (which I don't see a problem with, if BMW wants to make an X5 M + an X6 M, there's no reason why the X3 or X1 should be left out). From a compatibility perspective, finding an N55 motor will probably be more difficult & expensive then buying a used N54 (or maybe not, the N54 is more sought after), but the N55 will work in the X3.

The N55 has been available in the X3 since 2010, so besides the fact that what you're looking for is already being made, but this is also concrete proof that an N55 in an X3 works with the transmission & xDrive system. Not sure if you've considered it yet, but maybe save yourself the headache & the cost of doing the engine swap and just buy an X3 that was turbo'd from the factory. Burger Tuning sells their N55 tune, but only the Stage 1 can be applied to the X3. It's still a very nice bump & you should be seeing around 340 WHP + 400 WTQ with the tune, intake & DP:


If that still isn't enough power for you, email Terry (BMS) & Shiv (Vishnu) and see what their tunes can do for an X3 with the N55. Regardless, you'll prob have one of the fastest X3's in the country since this would be a much more "stealthy" upgraded car than an 335

[boostd92]

Originally Posted by benzy89

Fuel Economy:This is because of the Valvetronic system in the N55, which ironically enough is the reason why we haven't seen higher HP N55s. When tuners crack the Valvetronic-Tuning Nut, we'll see a very healthy bump in tuning numbers.

This is misinformation at it's best.

The valvetronic system is not the reason why we haven't seen higher hp numbers, the restrictive turbine section of the single turbo is.

In the end, the valvetronic will help us make MORE power (not in and of itself, but the valvetronic heads have larger valves and longer duration cams), then an equally equipped (meaning same upgraded single turbo setup) N54.

[benzy89]

IIRC, Shiv or Terry commented how Valvetronic has gotten in the way with making adjustments to run higher HP. If the turbine was really the only thing getting in the way, why did they make the single-turbo upgrade for a car that came with a TT?

If you really want, I'll find the comment that mentions Valvetronic being the problem. Another difference between the motors: N54 comes with forged internals. N55, not so much

That's how come you can see FBIS putting down 650+ RWHP and the engine hasn't been cracked open to put in new cams, piston, rods, etc etc etc

[nkadisha]

I'm in the process of trading my car in right now for an N54, get the N54 100%. Gas mileage differs by something like 1-2 mpg, nothing really noticeable. The engine is less laggy, has more potential, and is just so much more satisfying to drive. N55 is great, but the N54 is just so much better.

[boostd92]

Originally Posted by benzy89

IIRC, Shiv or Terry commented how Valvetronic has gotten in the way with making adjustments to run higher HP. If the turbine was really the only thing getting in the way, why did they make the single-turbo upgrade for a car that came with a TT?

If you really want, I'll find the comment that mentions Valvetronic being the problem. Another difference between the motors: N54 comes with forged internals. N55, not so much

That's how come you can see FBIS putting down 650+ RWHP and the engine hasn't been cracked open to put in new cams, piston, rods, etc etc etc

How about we just stop regurgitating forum nonsense, and only post if we have first hand knowledge. Nobody has yet to verify whether N54 *OR* N55 are forged or not, and/or which individual parts are forged. It's purely speculation.

The larger valves and cam duration is a fact. It's documented in the technical information on the N55.

As far as Valvetronic interference goes, when you are WOT, the valvetronic system holds the valves all the way open. There really isn't anything to hold power back then (no different than N54). If you're somehow measuring N55 power delivered at partial throttle loads vs. the N54 (and have it documented as being greater somehow), I'd be glad to see it.

[benzy89]

Originally Posted by boostd92

How about we just stop regurgitating forum nonsense, and only post if we have first hand knowledge. Nobody has yet to verify whether N54 *OR* N55 are forged or not, and/or which individual parts are forged. It's purely speculation.

The larger valves and cam duration is a fact. It's documented in the technical information on the N55.

As far as Valvetronic interference goes, when you are WOT, the valvetronic system holds the valves all the way open. There really isn't anything to hold power back then (no different than N54). If you're somehow measuring N55 power delivered at partial throttle loads vs. the N54 (and have it documented as being greater somehow), I'd be glad to see it.

If you go to the Bentley manual (unless that's Forum Nonsense), it confirms that the crankshaft, connecting rods & pistons are all forged. The Valvetronic (or any additional system) is just another hurdle that gets in the way of aggressive tuning. So like I originally mentioned, until tuners like Shiv & Terry are able to take into account for all the Valvetronic variables & operating conditions (WOT & partial throttle), you won't see the full potential of the N55. I don't tune, I don't have a little "Bimmerpost Official Vendor" under my name, I wouldn't have data to illustrate the data you're asking. I also don't own an N55, but that's because I bought an N54 when I had the option.

In addition, the N54 has won the "Best Engine in the 2.5L to 3.0L" segment since 2007. While we're not talking about stock engines here, there's a reason why 5 years later than an engine that's been "outdated" for the past 2 years continues to win awards. YES, the N55 has better DD usable TQ. But if you're looking to for all around better engine, the N54 is superior.

[cstavaru]

Originally Posted by C ///M

What do you guys think? End goal is a ~400 crank HP vehicle.

Just make your end goal 450 crank hp...and you only have one option. Much easier to choose, and you will end up with a faster car

Originally Posted by benzy89

Which ever you can find -- I don't know if BMW NA sells the N54 or N55 motors to individuals (not like Mopar where you can order a crate Hemi), so you're prob looking at cars that are totalled & ripping the engine out.

Why are you jumping to conclusions without knowing the facts. Of course BMW sells engines to customers, like any other parts. I asked Tischer BMW like 2 years ago about the possibility of buying an extra engine, when a BMW-remanufactured N54 engine (long block !) was priced at only $3700, and they asked where to ship it...

[Beemw335]

N54 makes more power on less boost, so that right there should be your answer on reliability.
Most n55 users have maxed out their turbos and are making less power than lightly modded n54s.

[eyim1988]

edit: nvm

[NYC6]

The N55's single turbo is the bottle neck in the equation. It just doesnt flow as much air as the 54's twins.
The reason why a larger single on the N54 out performs the OEM twins is due to its size. An aftermarket unit doesnt conform to what BMW needs a stock car to. Idle, low end power, drivability, fuel economy, emmissions all suffer at the expense of top end power. Look at aftermarket Supra tuners, they've been doing it for many years.

[eyim1988]

Originally Posted by NYC6

The N55's single turbo is the bottle neck in the equation. It just doesnt flow as much air as the 54's twins.
The reason why a larger single on the N54 out performs the OEM twins is due to its size. An aftermarket unit doesnt conform to what BMW needs a stock car to. Idle, low end power, drivability, fuel economy, emmissions all suffer at the expense of top end power. Look at aftermarket Supra tuners, they've been doing it for many years.

yep.. Our turbos just don't flow enough up top.. past.. ~16.5 psi..

[N55]

I just traded in my N55 for a 2012 N54 335IS Yesterday. The tuning potential of the N55 is what made me get rid of it. I went from 08' N54 > 11' N55 > 12' N54 335IS

[C ///M]

I really appreciate both the information and opinions. I'll be honest, a big part of me likes the n54...

I will address one comment, I have an E83 X3 with the N52. The F25 X3 is the only X3 to carry the N55 from the factory and in order to grab an F25 with M-sport, premium, cold weather, navigation, etc... That'd cost me almost $60k... Yea, ummm no thanks. I will likely be able to do the swap for under $10k unless I splurge on an expensive motor.

[Charleston335]

Ive had both (both with stage 1 tunes) and the N55 seems way more solid and not temperamental. One day my N54 would feel balls to the wall then one day it cant get out of its own way and i had to take it in allll the time for VANOS, wastegates, HPFF, air intake sensor, etc. I hate thinking there i always something wrong with it and its never at its full potential. That alone would make me never want to get another N54, or pre 09 one. The N55 sounds and feels more solid and once the tuners work everything out it will be N55>N54 in terms of overallness. Oh and the DCT is just

[Deadwrong]

Choose the N54 over the N55 for the same reason BMW did for the 335is and 1m....N54 ftw...

[Charleston335]

Originally Posted by Deadwrong

Choose the N54 over the N55 for the same reason BMW did for the 335is and 1m....N54 ftw...

Probably bc they can squeeze a lil bit more power without messing with the valvtronic system, reliability, etc and since they know the motor better for the additional output. Bet those type cars in a few years will get something similar to the N55.

[Black Gold]

Originally Posted by N55

I just traded in my N55 for a 2012 N54 335IS Yesterday. The tuning potential of the N55 is what made me get rid of it. I went from 08' N54 > 11' N55 > 12' N54 335IS

congrats, mate. you really traded up in 2 signifcant ways in terms of driving dynamics IMO

-rwd vs awd
-DCT vs auto

I test drove both the 335is and the 135i with DCT (which i now own) and thought that power and engine wise they felt identical, and they really didnt sound that different either. both cars sound really good. i loved both, and if the price point of the 335is was the same as the 135i, id have taken the is. as is, i saved 16 grand with similar options and love my car.

if anything, the 135i had more low end pull, possibly due to the lighter weight vs the 335is

bottom line is that the motors in stock form really dont feel that different at all, ive owned n54 and now n55 cars. the n55 does sound better imo, and currently the n54 has better tuning options.

people forget what it was like when the n54 was only 2 years old. no flash tunes, only half baked piggyback tunes that werent making nearly the amounts of power that they are now.

imo the same will happen to the n55 when it becomes the focus of the tuners. the car already easily makes over 350whp and 400wtq and not one company has a flash tune out for it, and none of them have truly focused all their energy on this platform.

once they do, the true potential of this car will be revealed.

and hell, even at 350whp and 400wtq, thats a fast car.

[boostd92]

Originally Posted by KennyPowers

and hell, even at 350whp and 400wtq, thats a fast car.

+1. But I'm one of those people who think there is no such thing as "fast enough."

For what it's worth, my N55 335 with just a tune and an exhaust went 12.8 on pump gas... sure it's not N54 record setting but it's still a quick car.

Since I installed the downpipe, the car spins the tires (275 Nittos) easily from any roll-on in 2nd gear. That's enough to make a fun street car. If you want to do highway racing, look elsewhere

[Dozhdbog]

Does the 335is have an LSD?

[benzy89]

Originally Posted by Dozhdbog

Does the 335is have an LSD?

Only M cars have LSDs

[C ///M]

So I'm sure you guys aren't dying for a follow-up, but I thought I'd provide one anyway.

So, taking in all the comments, I have to say you guys helped me choose, and it is because of this thread that I went ahead and bought an N54!!

A couple reasons:
-Having a real twin-turbo is so much cooler than "twin-power"
-If I want to build my version of an ///M car with only a choice between those two motors, I have to use an N54. N55 was never used in an ///M car. Sure there's that group of people that say the 1M wasn't a real M because of the motor, but I disagree. The U.S. E36 M3's used stroked versions of the M50 and M52 instead of the real S50b3.0 and S50b3.2 but they were still M3's. I won't get into that whole argument though...
-Finally, member cstavaru, you were absolutely right. Props to this guy for a brilliant answer, I'm changing my end-goal for power to 450 crank HP instead of 400. Haha, well, truth be told, I'm only going for 415 or 420hp, but we'll see.. Putting a limit of 400 crank on myself to start out with was pretty stupid.

So that's it guys. I really didn't plan to do the swap before this winter...so I'm not sure if getting the motor now means I'm changing plans and moving the swap up sooner, but I will certainly keep you guys updated on the project. I've listed it as completely as possible in my signature. I couldn't fit it all there, but you'll get the point. And the ONLY item I don't have is the Vanguard Titanium e9x M3 exhaust, so if anyone has a line on a used one, please let me know. I need to save some cash so I can't buy a new one for $2,500.... Help!

[Slops]

Thanks for the update man! Good luck with your project and be sure to start putting up pics of your progress