[Liamfosterr]

Im new to the forums but have been an avid reader of many N54-N55 posts.I currently own and daily ( ) an 08' AT trans E92 with some go fast goodies aka, Boost Concepts Stage 2 LPFP, MMP Inlets, Vrsf DP's, VRSF CP for re-located inlets paired with a TIAl BOV. I want to mention that the MHD OTS maps are a work of art as I have been playing around with the V7 E40 and E60 map and the new Beta V8 E50 map. I have been looking to pick up a MT N54 and start the project of a single Turbo kit. My Discussion topic is as follows,

Which platform will yield better and safer results, the N54 or N55? I do not wish to create an argument, I only want to hear and learn both sides.

:Which platform has a stronger powerband? For example, an upgraded twin turbo N54 generally produces a better low and midrange than a larger ST N54, while the ST pulls hard up top. The N55 platform has really seemed to be making some developments in the large turbo area. Im aware that some of the limiting factors to the N55 are the cast internals, but it also has some better flow designs (could be incorrect?) such as oil and fueling.

:Referring to a stock motor with a large turbo, is it possible for the N55 to reasonably run with the n54 guys? Possibly in the soon to come future? In the 600WHP range which car would perform better and more reliably, per say different tuning maps for different events such as a mild boost map for an autocross or track day, too a high boost map for 1/2 mile events.

:The N54 is often favored due to the forged crank and rods, but it has also been out longer and much more development has been done. someone said that they believed they found the N55's limit to be 650whp due to the cast parts and people bending rods. While others said that this could be due to the tuning.

:Largely I'm very very interested in torque/Power curve of these two platforms. My little self built garage project 335i has made many people unhappy when wanting to play around and they see my car walk away. From mustangs, camaros, M3's V8 a stock S55 and one lucky but very annoyed m550i owner. So am i right in saying that torque/power curve is king when it comes to efficient power vs a dyno king peak HP? Possibly this may be a pointless thread but iam curious to who may or may not comment or want to discuss this. (P.S. I'm a young 20 yr old whose father has his own VW Audi Porsche garage, that was sucked into the car world when I was four riding in my Dads tweaked 911 )

[Torgus]

N54 hands down.

[bradsm87]

Valvetronic is nice on N55. On the downside, I hear N55 solenoid injectors are no good once fuel pressure falls below about 1400psi where as N54 injectors are happy down to 1000psi so N54 has a little more fuel headroom. You'll want PI anyway so the injector thing is not really an issue.

I would go N55.

[Liamfosterr]

Originally Posted by Torgus

N54 hands down.

Well I'm for sure really liking my current N54 so i cannot disagree. Im just opening a discussion up as to which car makes more usable power, especially with some of the cars that the N55's are pulling on at 1/2 mile events even while not being a dyno king or having crazy high HP #'s.

[Liamfosterr]

Originally Posted by bradsm87

Valvetronic is nice on N55. On the downside, I hear N55 solenoid injectors are no good once fuel pressure falls below about 1400psi where as N54 injectors are happy down to 1000psi so N54 has a little more fuel headroom. You'll want PI anyway so the injector thing is not really an issue.

I would go N55.

So after PI neither car has much problems fueling wise from my understanding. So after PI the N55's can run with most of the N54's that are running larger turbos? The KRAKEN (N54 919WHP) from EMP tuning is certainly a different story and most of us wont ever go that extreme, but is it feasible to say that the PS2(or larger kits) N55 guys can run with the big turbo N54's? based off of linear power and power curve? Maybe this is a useless thread, I'm learning for when I eventually begin a project.

[bradsm87]

Originally Posted by Liamfosterr

So after PI neither car has much problems fueling wise from my understanding. So after PI the N55's can run with most of the N54's that are running larger turbos? The KRAKEN (N54 919WHP) from EMP tuning is certainly a different story and most of us wont ever go that extreme, but is it feasible to say that the PS2(or larger kits) N55 guys can run with the big turbo N54's? based off of linear power and power curve? Maybe this is a useless thread, I'm learning for when I eventually begin a project.

If you put the same single turbo and PI on both engines, results should be very similar.

[Chris@VargasTurboTech]

N54. It's not without issues, but they're fairly well known and able to be mitigated. Built N54's are starting to move out of infancy and showing some decent results. If you want to keep the motor stock and get some longevity out of it, be kind to her and be reasonable with torque and power expectations. Yes, there are 800+ whp stock motors out there, but no, they aren't going to last very long.

[Liamfosterr]

Originally Posted by Chris@VargasTurboTech

N54. It's not without issues, but they're fairly well known and able to be mitigated. Built N54's are starting to move out of infancy and showing some decent results. If you want to keep the motor stock and get some longevity out of it, be kind to her and be reasonable with torque and power expectations. Yes, there are 800+ whp stock motors out there, but no, they aren't going to last very long.

I've always leaned towards the N54's, some of the recent N55 development has made 600+WHP feasible. At this level can a N55 run with a 700ish WHP N54 due to power delivery? Maybe what i should ask is, how does the N55 compare to the N54 in power delivery. Will a 600ish N55 run with a 700ish N54 simply due to very linear power/torque delivery? I've been seeing the Fuel-It companies N55 135i walk all over cars that you would think it shouldn't. My thinking is that the N55 is making really good power from 3,500rpm-7,000rpm not just 5,500rpm-7,000rpm. I understand that in 1/2 mile events most of the time your between 5,000rpm-7,000rpm, but how the power is delivered is what i'm curious about and how the N54 delivers it vs the N55. Again maybe my question is silly but still, curiosity

[Liamfosterr]

Originally Posted by bradsm87

If you put the same single turbo and PI on both engines, results should be very similar.

What type of benefits are offered on the valvetronic on the N55 over the N54? Will 700ish be possible and relatively safe on the N55 platform in the future?

[YoungBlood]

Originally Posted by Liamfosterr

I've always leaned towards the N54's, some of the recent N55 development has made 600+WHP feasible. At this level can a N55 run with a 700ish WHP N54 due to power delivery? Maybe what i should ask is, how does the N55 compare to the N54 in power delivery. Will a 600ish N55 run with a 700ish N54 simply due to very linear power/torque delivery? I've been seeing the Fuel-It companies N55 135i walk all over cars that you would think it shouldn't. My thinking is that the N55 is making really good power from 3,500rpm-7,000rpm not just 5,500rpm-7,000rpm. I understand that in 1/2 mile events most of the time your between 5,000rpm-7,000rpm, but how the power is delivered is what i'm curious about and how the N54 delivers it vs the N55. Again maybe my question is silly but still, curiosity

I mean, n55 with a 62mm turbo and a n54 with a 62mm turbo, both with port injection, should put out very similar number and power curves. They’re the same displacement and compression ratio, both straight 6’s, not sure what you’re expecting. With oem or hybrid turbos their power delivery is definitely a bit different but big single takes that out of the equation