[chris719]

Tune it when it goes out of warranty only. It will be fast enough stock and S55 occasionally spins crank hubs.

[Bt12]

I guess, it’s never enough HP. That straight line is going to be fast.

[horsepower_and_hounds]

Of course

[ChrisK]

Originally Posted by M3_WC

The N55 in M2, is a N55 with some forged internals and higher boost. It is definitely not closer to the S55. They don’t even share the same block, the foundation of the engine.

I know, but the M2 N55 is not just an "N55"

[M-Pilot]

Originally Posted by SeanWRT

There's a bit of misunderstanding of S55 power here.

M4 base and M2 whp difference is 50-60whp, not more as many think. Detuned S55 with M2 Comp probably has 10whp less, that's around 45whp more over N55 M2, stock for stock.

As for tuning potential, on stock turbo and pump gas, breaking 500 with S55 is just as hard as breaking 400 with M2 N55. S55 also has a ugly top end when you push that hard.

Lastly, M2 N55 has just a bit more power potential than N54, given stock turbo.

Come on guys, fit a PS2 to match S55. Above 450whp I doubt you'd even care 10 or 20 more or less.

Breaking 500whp is difficult on S55 with stock turbos and pump? Total BS lol. Go check out BM3 thread to see how people are making 600whp on stock turbo and stock fuel system using E85. Hitting 500whp on S55 is easier than you think. It just needs a tune and maybe not even downpipes. No upgraded turbos or fuel system...

[SeanWRT]

Originally Posted by cntzl

Breaking 500whp is difficult on S55 with stock turbos and pump? Total BS lol. Go check out BM3 thread to see how people are making 600whp on stock turbo and stock fuel system using E85. Hitting 500whp on S55 is easier than you think. It just needs a tune and maybe not even downpipes. No upgraded turbos or fuel system...

Do you know the definition of pump gas and flex fuel?

[M-Pilot]

Originally Posted by SeanWRT

Do you know the definition of pump gas and flex fuel?

Yes, I do. 600whp on E85 was just an example to open your eyes. There are ton of people making 500whp with just a flash tune on pump gas.

Edit: If you wanna know what happens when you upgrade turbos and other components on S55, check this out --> 705whp on E85 http://f80.bimmerpost.com/forums/sho....php?t=1476933

Edit-2: To be fair, after checking several dyno threads of S55, most people are making around 490whp range on their stage 2 pump gas tune. It goes on a whole different level with E85 or an E30mix without requiring a turbo upgrade. Not sure if N55 can make 390-400whp with just a tune.

[SeanWRT]

Think what you want. I am no stranger to BM3 and M4 and speak mostly with the numbers that I see get put down same day same dyno.

Maybe my Dynojet don't read 420-430whp from a M4 base, could be why. If underestimating S55 power strikes your nerve, I apologize.

Have a nice day on M2 forum.

[arwin]

400 whp....500 whp....do we really need that much power? lol

Again...385 whp vs 400 whp on the N55
490 whp vs 500 whp on the S55...still a ton of power!

We don't need it but we don't mind having it!

[M-Pilot]

Originally Posted by SeanWRT

Think what you want. I am no stranger to BM3 and M4 and speak mostly with the numbers that I see get put down same day same dyno.

Maybe my Dynojet don't read 420-430whp from a M4 base, could be why. If underestimating S55 power strikes your nerve, I apologize.

Have a nice day on M2 forum.

You can say what you want and believe me it doesn't strike anything . Dyno charts, 1/4mile results are all easily accessible for both platforms. I'm just trying to point out the facts rather than making bold claims. N55 is great engine in its stock form and more than sufficient for many. I'm not trying to bash it or anything. All I'm saying is N55 definitely doesn't have as much tuning potential as S55 does.

[SeanWRT]

S55 is very tunable, a fact hard to not know.

What I was explaining is the s55-n55 power difference stock for stock and how they struggle to break 500/400 with stock turbo and pump gas.

I drive, tune, drag and dyno S55 and N55 more than most. And know a thing or two about them. I don't easily make wrong claims.

[M-Pilot]

Originally Posted by arwin

400 whp....500 whp....do we really need that much power? lol

Again...385 whp vs 400 whp on the N55
490 whp vs 500 whp on the S55...still a ton of power!

We don't need it but we don't mind having it!

If you can safely and consistenly put tht much power down why not? But in most cases, you can't... it's either too scary, jerky or the it's not consistent, which can cause "limp mode" (especially if you are pushing it around a track for example). Therefore, I'd rather stick to what BMW has tested and verified extensively under various circumstances. This doesn't mean staying completely stock as original CS or GTS maps are available from various tuners. I'll personally get a CS tune and call it a day.

[Spartan King]

Originally Posted by M3_WC

Drawbacks? S55 is more rev happy, higher redline, betting cooling, more robust oil system, closed deck, better throttle response...etc.

Only argument I see constantly is sound, which is completely subjective. N55 is a run of mill BMW engine, nothing special about it. In fact I'd rate the N54 over the N55.

The drawback of sound is subjective, but IMHO the S55 just doesn't sound a little different, it sounds horrible compared to the N55 and most other performance cars. Sound is a very important part of the sports car experience for me.

[mtoosexy]

^^^agree!!!

Dinan tune and parts will be installed at some point.
But first things first, gotta find a way to fix the S55 sound!!!!!!!!!!

[chris719]

Originally Posted by ChrisK

I know, but the M2 N55 is not just an "N55"

It pretty much is from a performance standpoint, sorry to say. The upgrades are for long term durability only. It makes the same power if running the same boost as other N55s. It still has the same basic turbo and fuel system limits as an M235i. It's still a good engine, but it's not close to the scope of changes in the S55.

[chris719]

Originally Posted by Spartan King

The drawback of sound is subjective, but IMHO the S55 just doesn't sound a little different, it sounds horrible compared to the N55 and most other performance cars. Sound is a very important part of the sports car experience for me.

Let's wait and see what it sounds like. The S54 engine in the E46 M3 sounds very raspy, but BMW tamed that rasp somewhat in the Z4M applications to sound sweeter.

I think the sound of S55 was at least in part deliberately engineered to sound raspy like the E46 for nostalgia. Just like the launch colors. N54 had two small Mitsubishi turbos and sounds nothing like S55. Maybe it would require a new exhaust header design, but the ZCP cars shows they can do something with the sound. I know the prototypes sounded similar but there may be a small chance. I didn't think ZCP M4 sounded that bad anyway.