Major differences between S55 and N54/55

[BPe90M3]

I wasn't sure which section to put this in but felt the general tab was my best bet. I'm taking delivery of my M4 this thursday and I'm more than excited. I just can;t help to ask, what are the major differences between the s55 used in the M3/4 vs the N54/55 used in the M235i, 335i, etc. Im coming from an e92 M3 which was a whole different engine altogether so its interesting to me. What really is the difference between these motors. Thanks in advanced guys.

[SakhirM4]

You can look here to start

http://f80.bimmerpost.com/forums/sho....php?t=1015603

[FogCityM3]

You should check out the BMW Sales Training/Tech guide for the M3/M4. It does a side by side comparison between the S55 and N55 in all relevant aspects. Pretty interesting reading.

[BPe90M3]

Originally Posted by FogCityM3

You should check out the BMW Sales Training/Tech guide for the M3/M4. It does a side by side comparison between the S55 and N55 in all relevant aspects. Pretty interesting reading.

I just looked at the tech guideline that the previous poster had posted but can't find this side by side comparison

[SakhirM4]

Originally Posted by BPe90M3

I just looked at the tech guideline that the previous poster had posted but can't find this side by side comparison

It is in the second document

[BPe90M3]

Originally Posted by SakhirM4

It is in the second document

Great! found it... thanks sakhir. It seems like the n54 and s55 are very similar. Would anyone happen to know what turbochargers are used between the two and if these are different? Its interesting that the n54 and s55 sound completely different even though they're so similar.

[SakhirM4]

You might want to look at this thread also

http://f80.bimmerpost.com/forums/sho...d.php?t=924954

[ES_TRADER]

Originally Posted by BPe90M3

Great! found it... thanks sakhir. It seems like the n54 and s55 are very similar. Would anyone happen to know what turbochargers are used between the two and if these are different? Its interesting that the n54 and s55 sound completely different even though they're so similar.

Mitsubishi

[STooK]

Simple, N54 sounds way better than N55 or S55 lol.

[m3rxn]

Both are great motors indeed and will be legends in their own class. Still in break in for the s55 so can't really compare yet to the N54, which pulls like a raped ape with current mods..

[ASAP]

The current big advantage that the N54 has is a decrypted and translated ECU that allows full freedom for flashing. Virtually everything else goes to the S55... everything. Better cooling, larger turbos, closed deck block, higher rpm... I could keep going for a day but the true capability of the S55 won't even be explored until a full flashing solution is offered.

[CanAutM3]

Originally Posted by BPe90M3

Great! found it... thanks sakhir. It seems like the n54 and s55 are very similar. Would anyone happen to know what turbochargers are used between the two and if these are different? Its interesting that the n54 and s55 sound completely different even though they're so similar.

The N55 (and N54 by default) was used as a baseline for the S55. But they are very different, most of the important components were changed in the S55 application. 25% of components are completely new designs, while other components were modified for the S55 application.

A tidbit a found interresting, is that it seems that they went back to a mechanical main pump for the engine cooling circuit on the S55. The N55 has an electrical pump.

[FTS]

@GrussGott has a nice thread on this:

http://www.bimmerfest.com/forums/sho...5&postcount=35

[Dalko43]

Originally Posted by FTS

@GrussGott has a nice thread on this:

http://www.bimmerfest.com/forums/sho...5&postcount=35

There was a lot of detail in that post, but he mentioned some things in there that I wasn't sure about.

For example, he said the S55 was mostly a dry sump. I'm not sure what he means by that nor am I sure that the S55 actually has a dry sump.

[JeffM-Houston]

Basically here is nothing similar to the two engine classes with the exception of the nominal displacement of 3 liters. But note that the actual displacement is not the same either.

Closed deck block
Larger bore
Shorter stroke
Arc spray cylinder liners
Forged crankshaft
Completely different turbo philosophy and design(N55 uses a single twin scroll while the S55 uses twin single scroll)

Etc., etc.. Basically there is nothing the same, and anyone that tells you different simply doesn't know anything about the two engines.

The N55 (and N54 by default) was used as a baseline for the S55.

I'm not sure what that means or where it comes from? Perhaps some of the external dimensions of the block are the same but nothing else as far as I can see.

[Dalko43]

Originally Posted by JeffM-Houston

I'm not sure what that means or where it comes from? Perhaps some of the external dimensions of the block are the same but nothing else as far as I can see.

The S55 evolved from the N55 which evolved from the N54. Yes parts/internals are differ between the all 3, but the concept, design, philosophy are very consistent with one another. This is widely accepted in the BMW community.

No one is claiming that the N54 is the same engine as the S55 or that it offers the same performance. But it did serve as the basis for the S55.

[JoeFromPA]

I would bet on the longevity of the S55 and powertrain components being better. Not only from ~7 years of learning by BMW, but because:

1. They reduced the oil change interval from 15k to 10k on ALL Bmw turbo engines effective on 2014 model years (lessons learned I guess)

2. The cooling of the S55 is ridiculous. The N54, from the factory and with the factory oil coolers, still had high degrees of oil temp fluctuation in aggressive everyday driving and definitely on the track. The S55 is far better in this regard, which I think is going to translate to better turbo life (among other things)

This is besides those technical differences mentioned

[Carl L]

Originally Posted by Dalko43

The S55 evolved from the N55 which evolved from the N54. Yes parts/internals are differ between the all 3, but the concept, design, philosophy are very consistent with one another. This is widely accepted in the BMW community.

No one is claiming that the N54 is the same engine as the S55 or that it offers the same performance. But it did serve as the basis for the S55.

Agreed, but what people forget is that M has almost always used regular-series engines as their base. The E30 S14 was based on the M10 block, the the E36's engine came from the 325i/525i, the E46 was just an evolution of that. While the E39 M5's engine was formed from the 535/735/540/740. So, when it's looked at, the only bespoke engine M have made since the E28 and E34 M5s engine (which was made for the M1 iirc) for street cars is the S85 V10. The S65 V8 was basically a 20% diet of that engine (and before people go nuts, yes they were lovely but would've been far better in lighter cars).

Just adding some facts to the revisionist history that goes on around here. Too many people who've never had grease in their hands think displacement is what defines engines.

[turbo8765]

Originally Posted by JeffM-Houston

Basically here is nothing similar to the two engine classes with the exception of the nominal displacement of 3 liters. But note that the actual displacement is not the same either.

Didn't BMW say >70% of parts are the same…

[turbo8765]

Originally Posted by Carl L

...the E36's engine came from the 325i/525i, the E46 was just an evolution of that...

In the same way that the upcoming 5.2 flat plane in the Mustang 350 is an evolution of a flat head.

[CanAutM3]

Originally Posted by JeffM-Houston

I'm not sure what that means or where it comes from? Perhaps some of the external dimensions of the block are the same but nothing else as far as I can see.

The N54/55 and S55 share the same bore, stroke (hence displacement) and cylinder bore spacing. The N55 served as a baseline for the design, ///M then modified, tweaked or redesigned the majority of the components to meet their requirements and specifications.

[CanAutM3]

Originally Posted by turbo8765

Didn't BMW say >70% of parts are the same…

According to the training documents, 25% of parts are "new development". Other parts have been modified/tweaked to suite the S55 application.