Why do I want a N55?

[Gangplank]

Originally Posted by HyeWarrior

I don’t want to derail this thread, but what are the pros and cons of the Dinan tune compared to other tunes like the MHD?

Yep. Let's not thread jack thus one. Everyone has their favorite tune method. Short answer is Dinan is tune it & forget it. You have it flashed and that's it. MHD is a handheld you do yourself and can be used to monitor things, log runs, retune/reflash or read codes. Some like all the tune-abilities (superpowers) it offers better. Others prefer the Dinan one-n-done simplicity.

If your goal is to extract all the power you can & custom tune you want MHD.

[gtjosh]

N55 owner just here to weight in. My N55 is not yet full bolt on but right now I am running MHD Stage 1 on a fairly stock car. I have taken it to the track twice. MY first track day was Harris Hill in the middle of august, so about 95 degrees out. By running MHD I am able to adjust the cooling of the motor through the app and I never saw any temps above 255. I saw the same at my second track day at COTA. I pushed the car hard both times and never once did it have an issue. I have changed the spark plugs out about 30k miles ago and right now my car has 79k miles. Its due for some maintenance but can still be daily driven no problem. I do have a water pump sitting on my shelf ready to go if mine fails but so far so good.

On the subject of power levels the N54 makes more at peak but what about the rest of the time? I think a pair of dyno graphs should be compared between a FBO N54 and a FBO N55 and don’t just look at peak power but the space under the graph. I have never driven a N54 car so I cant say anything about the way they drive or anything like that but I am extremely happy with the power level I am at now and the way the power comes on for both tracking and daily driving. There is still room for improvement for me and I am excited to see more power but for me I want to learn how to use the power I have before I add some more.

[Apex1.0]

Originally Posted by asiflicious

Either one will be fulfill your criteria. You can argue back and forth about the pros and cons all day but at the end of the day the right answer 99% of the time is "get the one with the lowest miles, most service records, and the color/options you want" imo

This is kind of where I am. Well except the arguing part. Condition and color, option will drive the search. From what I have seen, there are more clean n55 cars out there.

So initially I thought a n54 would be a better fit for me. The twins flow more, plus I like having power all the way to redline. After this thread and some other research, I am coming to the conclusion the n55 offers these benifits.

1) I like the idea of a single turbo for simplicity. Let parts, less mods, less complicated.
2) At the same modified power level, the n55 may be able to deliver track day power more consistently.
3) More total power and more top end power can be had from a simple single turbo swap.

The n54 still has obvious benifits, to me the above list just equalizes the two and bring me to prioritize other issues when searching for a 1er.

[atr_hugo]

I've owned an '08 135i and now a '13 135i. Liked the N54 a lot, like the N55 a lot - but there are differences. Out of the box the exhaust note of the '13 N55 was better than the '08 N54 - it got even better after installing the Performance Power Kit (PPK 1).

The N54 was unmodded, the N55, as stated, has the PPK 1 installed. Each turbo on the N54 receives an exhaust pulse every 240 degrees of crank rotation, the single turbo on the N55 receives an exhaust pulse every 120 degrees of crank rotation. The N55 feels somewhat more eager at lower RPM and I thought more turbine like through the power band (just my feeling).

But one big concern with the N55 is the addition of variable valve lift, Valvetronic, that wasn't on the N54. If I were going for big HP gains I'd avoid an N55. Just my 2 cents . . .

[Apex1.0]

Hmmm... why is valvetronic bad?

My goals are 400-450rwhp street and 300-350rwhp track depending on reliability. 93 octane pump gas.

[asiflicious]

Originally Posted by Apex1.0

Hmmm... why is valvetronic bad?

My goals are 400-450rwhp street and 300-350rwhp track depending on reliability. 93 octane pump gas.

Originally Posted by Apex1.0

Hmmm... why is valvetronic bad?

My goals are 400-450rwhp street and 300-350rwhp track depending on reliability. 93 octane pump gas.

If you're looking for 400-450rwhp then you should go with an N54. You can get to that power level easier and cheaper than you can with an N55. An N55 will need an upgraded turbo to reach those numbers.

[atr_hugo]

The N54 has a normal throttle and no monkey motion with variable valve lifters. The N55 varies the valve lift (another set of software parameters and mechanical complexity).

First is what an N54 valve setup looks like - there is VANOS variable valve timing but that's a phase shift of the camshaft.

Next is what the Valvetronic valve setup looks like.

[Gizmo135i]

Originally Posted by atr_hugo

The N54 has a normal throttle and no monkey motion with variable valve lifters. The N55 varies the valve lift (another set of software parameters and mechanical complexity).

First is what an N54 valve setup looks like - there is VANOS variable valve timing but that's a phase shift of the camshaft.

Next is what the Valvetronic valve setup looks like.

Other then it being “something else to break” I don’t see any issues with the valvetronic... yes it does fail occasionally, but the N54 has more pitfalls when it comes to reliability, especially when you consider they are older.

Performance wise stock turbo vs stock turbo, the N54 deffinatly pulls harder. The n55 will likely cost less to maintain.... money you can spend to upgrade the turbo on an n55 car. In my opinion that’s the way to go.

[Apex1.0]

Don't like the added complexity of the valvetronic. But fro, what I have read there are not widespread reliability issues.

Thanks

[atr_hugo]

Absolutely correct, Valvetronic isn't buggy - very reliable - and adds decent fuel economy gains. Its just one more complication if you want to get big HP/torque numbers

From a cost perspective in maintaining the car, one of the big problems with the N54 were the HPFP and the piezoelectric actuated fuel injectors. The N55 uses solenoid actuated fuel injectors. When the N54 was developed the solenoid direct injectors did not perform all of the functions required. When the N55 was developed the solenoid direct injectors had caught up. IIRC, the piezoelectric injectors are about 3 times as expensive as the solenoid direct injectors.

[Apex1.0]

What kind of boost can a factory N55 turbo deliver at redline?

What does the factory boost curve look like compare to FBO/tune?

[Toome]

Originally Posted by Apex1.0

What kind of boost can a factory N55 turbo deliver at redline?

What does the factory boost curve look like compare to FBO/tune?

Factory turbo can deliver around 12psi at redline.

Stock boost curve is 8-10psi throughout if I'm not mistaken.

[rominun]

Originally Posted by Toome

I believe only the early N54's have forged pistons.

actually people have always said that they have forged bits. the only thing the n54 has forged is the crankshaft. most people believe they have forged rods, but ive seen one out of my old motor and its definately not forged. nor are the pistons, which is why people pushing 750+hp usually crack a piston or two.

[Apex1.0]

Originally Posted by Toome

Factory turbo can deliver around 12psi at redline.

Stock boost curve is 8-10psi throughout if I'm not mistaken.

12psi??? That's it? Is that with 100% WGDC and full bolt on?

So either the factory turbo is just small or the N55 can gobble up a lot of air near redline.

I guess that explains why the N55 FBO cars are torque monsters.

[Toome]

Originally Posted by Apex1.0

12psi??? That's it? Is that with 100% WGDC and full bolt on?

So either the factory turbo is just small or the N55 can gobble up a lot of air near redline.

I guess that explains why the N55 FBO cars are torque monsters.

Yes 12 psi at 100% WGDC and FBO. It's undersized because it was only designed to run 8-10psi throughout the rev range.

[dleccord]

Originally Posted by Gangplank

N55 w/ Dinan tune for $800 you get 355 hp & 400 tq. Then just upgrade the charge pipe and intercooler.

Unless you really think an extra +12% bump in hp (355 vs 400) is really worth it.. personally I'm not sure I see the need for spending all that much more on FBO over the Dinan tune but to each his own.

i think 12% is comparing peak powers, not "the area" under the curve.

[Gizmo135i]

Originally Posted by dleccord

i think 12% is comparing peak powers, not "the area" under the curve.

Also comparing flywheel hp to whp is irrelevant lol. Dinan dynos closer to 310whp.

Not that there is anything wrong with the Dinan flash, it has its advantages.. just don’t expect a huge bump in hp

[dleccord]

Originally Posted by Gizmo135i

Also comparing flywheel hp to whp is irrelevant lol. Dinan dynos closer to 310whp.

Not that there is anything wrong with the Dinan flash, it has its advantages.. just don’t expect a huge bump in hp

just curious, do you personally have the dinan tune?

[BoosTonian]

Originally Posted by Toome

Yes 12 psi at 100% WGDC and FBO. It's undersized because it was only designed to run 8-10psi throughout the rev range.

I believe twisted tuning with mhd got 15
psi out of a stock turbo at redline. but that's all in and he wouldn't recommend using that daily. normal is 12-13psi.

[Gizmo135i]

Originally Posted by dleccord

just curious, do you personally have the dinan tune?

No but I have driven a lot of cars that have it... again nothing wrong with it, good for what it is.. smooth and stock like, no worries about breaking something, but doesn’t make the same power other options do

[FrostyDC4]

Originally Posted by Gizmo135i

No but I have driven a lot of cars that have it... again nothing wrong with it, good for what it is.. smooth and stock like, no worries about breaking something, but doesn’t make the same power other options do

Have you heard of any Dinan flashed N55 cars breaking any of the ancillary parts (fuel pumps, etc)?

[Toome]

Originally Posted by FrostyDC4

Have you heard of any Dinan flashed N55 cars breaking any of the ancillary parts (fuel pumps, etc)?

Dinan tunes are very mild and have quite a bit of R&D behind them (much like PPK). The chance of something failing is almost identical to stock.