BMW M3 / M4 Engine (S55): Deep Dive and Interview

[e1000]

Originally Posted by turbo8765

I'm sure it's a bit of both.

Partially detuned to allow for the CP in a couple years.

A gearing comparison would help to compare the two graphs. The high revs and apparent lack of regard for fuel economy allowed the e92 M3 to have aggressive gearing… which made effective use of the available trq.

IIRC the ratios are published for the M4, does anyone know the percent difference in gearing between the old/new model? I'm too busy to look it up at the moment.

Keep in mind that if the new motor makes 20% more trq at a given rpm point but has 10% taller gearing half the trq delta is offset.

+9999999999999

[///Mangler]

The reason the power is flat up top is because the torque falls off at the same rate the RPMs are increasing. Remember that HP is derived from TQ and RPM. Tuners that get some larger turbos or more efficient wheels in the future will have it pulling all the way to redline.

T

[Powerslide]

Originally Posted by Kash

No offense. You may be a more advanced roller than I am. I agree.

But, What I meant was that the clunky feeling with E9x until you cross 5K RPM and then a sudden surge to a heavenly feeling when the car comes alive at higher RP is not very suitable for DD.

With the new engine; you get the intoxicating feel well in advance starting at lower RPMs in normal driving conditions . This doesn't mean you reach the full potential at low RPMs. I owned E90 M3 and I enjoyed it but Extracting joy in DD conditions that involves Downtown commute and local traffic was a challenge with that platform.

I think that is also well-stated. The E9x is a lot of fun even in commuting conditions (at least compared to the vast majority of cars out there), but you cannot get anywhere near the intoxicating feel that you get in the 5000-6000+ range in most driving conditions (except for a very short burst of speed from a stoplight - then you're up to 45-50 mph in no time flat, at which point you have to back off so as not to get a speeding ticket).

With the F8x - we will achieve a higher level of fun at the lower rpm range and lower speeds. (Again, however, I still cannot stress how much I love my S65 and how much fun I still think it is after 6 years and 75k miles)!!

[ASAP]

If anyone here has any experience or background w a tuned N54 you will quickly recall that this engine does not need to rev any higher than 5800. lol

An N54 protuned on e85 making 430 whp (aka the car in my sig) would scare almost everyone here. Sadly, I do not believe the s55 turbos have that much headroom.

[aus]

Originally Posted by Kash

No offense. You may be a more advanced roller than I am. I agree.

But, What I meant was that the clunky feeling with E9x until you cross 5K RPM and then a sudden surge to a heavenly feeling when the car comes alive at higher RP is not very suitable for DD.

With the new engine; you get the intoxicating feel well in advance starting at lower RPMs in normal driving conditions . This doesn't mean you reach the full potential at low RPMs. I owned E90 M3 and I enjoyed it but Extracting joy in DD conditions that involves Downtown commute and local traffic was a challenge with that platform.

You're points are valid and I've said the same thing about the 335 vs. M3, that in daily driving, the N54 is a better engine. Having said that, I really wouldn't call it "intoxicating" when you have torque at 2,500 RPM and it pushes you into your seat- I have a lightly tuned 335 N54 too- but it is nice when you want to get going quickly while driving in slow moving traffic, or when there's a little stretch of open road on the freeway.

IMO, having an engine suddenly surge forward and wake up a 5,000 RPM when most engines start to run out of breath (and just keep pulling until 8,000 RPM), combined with the scream of a V8 at 8,200 RPM... that's INTOXICATING. We'll see how the S55 pulls up top. A 7,600 RPM is pretty good for a turbo motor, but does it really pull up top??

.

[Kash]

Thanks for offering your perspective. Now, I miss my M3 E90 more than ever! Weep! Weep!

[basscadet]

Originally Posted by aus

A 7,600 RPM is pretty good for a turbo motor, but does it really pull up top??

.

Based on that graph, on the stock tune, it does not "pull up top". So much of this is going to be based on the gearing and turbo and not much else.

Personally I found the nature of the S65 extremely aggravating in day-to-day driving. It is an engine meant for a lightweight track car, not a heavy luxury sedan.

[e92stance]

kind of long winded techno babble but nothing new here. Don't believe the hype.

[GregW / Oregon]

Originally Posted by basscadet

Personally I found the nature of the S65 extremely aggravating in day-to-day driving. It is an engine meant for a lightweight track car, not a heavy luxury sedan.

I use my E92 80% as a DD and love it. Depends on your driving conditions and preferences I guess.

[3XTR3M3]

Originally Posted by GregW / Oregon

I use my E92 80% as a DD and love it. Depends on your driving conditions and preferences I guess.

Same here.

I agree a 335i is more comfortable in street driving without redlining, however, I didn't buy an M3 for this reason.

[Ioannis]

Awesome article

[Taigar]

Hi All,

Trying to learn something here. Engine wise, seems S55 is better every way than S65 - power, fuel economy. Why then did it take so long for BMW, Merc, Audi, VW and many others to jump on the Turbo technology only now? Is it turbo engines cost more to build, shorter life span, higher maintenance.. don't seem to be from my past Evo X experience.

Thanks for sharing.

[M4TW]

I'm intrigued by the power curve climbing steeply to a plateau at about 5500 rpm and then plaining out until about 7300. The power curve of the N54 took a dive at about 6000 rpm producing a noticeable "party's over" feeling when driving. Am I right in thinking that the S55 will still be in a fun zone at that high of rpm because that's where it is making its peak power?

[CanAutM3]

Originally Posted by JoeFromPA

The other thing he called out I thought was interesting: DCT gear shift changes result in no interruption in power delivery (i.e. amount of power on tap).

I presume that means the 6MT is going to see a more notable decrease in boost between gear changes. I realize this is normal, but, sigh.

I don"t believe he was referencing losing boost we he mentions no interuption of power. But rather the fact that DCT does not interrupt power at the wheels during a shift. The same words were used with the E9X DCT.

[coloradoe92m3]

Gearing :
E92 dct
Final-3.154
1-4.78
2-2.933
3-2.153
4-1.678
5-1.39
6-1.2
7-1.0

F80-
Final-3.46--9% shorter
1-4.8 --same-----9% shorter overall
2-2.593 14% taller------6% overall tall
3-1.7. 21% taller_------12% overall tall
4-1.27----25% taller---16% tall overall
5. 1.0-----29%_--------21% tall overall
6. .84-----30% taller----21% overall
7. 0.67...---32% taller----24% overall

So check my math but 1st bear choice is crazy. I can't use 1st in my e92 due to traction limitations so talk about hard to launch. F80 will be really tough to put power down in first. 2nd gear is going to be downright freight train. But e92 is quite a bit shorter gearing from 2nd on.

So you can't only compare dyno plot as gears are the other half. If someone wants to create a plot with gear ratio differences taken in to account, the f80 will be way faster but not quite as much as it has seemed thus far.

Keep in mind at WOT you don't see below 6500 ROMs in e92 dct so you can't draw a line straight up as they do as you need to account for e92 power band .

So love to see area under curve of each cars WOT power band with gearing taken into account

[Thurman Murch]

I think it definitely will pull hard up top if it is anything like the N55 + MPPK + MPE... Now I only have experience w the 6mt in that config

In antithesis to the N54(T) the N55 (6mt) example doesn't have the same bottom end the taller gears used for gas savings means you really have to wring it out... Yes it is decent until you get up top

So I'm sure the bottom end will be ok... Even more so than the N55 but who knows how the gearing and turbo tech really affect the output given in a claim range

Now even though I suggest the 6mt for driver involvement and fun factor, the DCT may be the way to go for seamless power output

Hopefully the active noise can indicate rpm and power well but I still think the S65 is the right blend

[FogCityM3]

Tuned FBO S65 produces 400+ bhp (crank) from 6900-8600 rpm. If there isn't a big weight difference, think there won't be a huge difference in a track situation. Recall someone at BMW saying 10 secs faster than stock S65 M3 on the N-ring.

[Thurman Murch]

I was only saying S55 based on N55 as a starting block

Certain designs elements look as if the best bits are pulled from S54, N54T and S65 ... A little bit if this, add a dash of that

The one area I don't like is that air induction I feel that the engineers could have designed better intake snorkels

[pkimM3r]

Originally Posted by aus

You're points are valid and I've said the same thing about the 335 vs. M3, that in daily driving, the N54 is a better engine. Having said that, I really wouldn't call it "intoxicating" when you have torque at 2,500 RPM and it pushes you into your seat- I have a lightly tuned 335 N54 too- but it is nice when you want to get going quickly while driving in slow moving traffic, or when there's a little stretch of open road on the freeway.

IMO, having an engine suddenly surge forward and wake up a 5,000 RPM when most engines start to run out of breath (and just keep pulling until 8,000 RPM), combined with the scream of a V8 at 8,200 RPM... that's INTOXICATING. We'll see how the S55 pulls up top. A 7,600 RPM is pretty good for a turbo motor, but does it really pull up top??

.

aus, i think it will pull up top. the m5 and m6 do right?

my wife has a 135i and yes it is torquey but i am always in the right gear at the right time regardless of what car i am drivig.

kash, low end torque and shifting gears at 4k rpm to get to a given speed vs a screaming v8 in higher revs to get to the same said speed in city driving, add in heel toe shifting 100% of the time and it is still tons of fun.

new engine is no doubt better. i just dont understand the "potential in city" due to low end torque. shift if needed. thats what its there for!!

[FogCityM3]

If raise rev limit on an MT in FBO application, S65 upshift also occurs at 6500+ rpm at which point you're producing ~370 crank bhp, which is also pretty high..by 6900 you are at 400+. Pretty amazing in its own right as an N/A engine and multiply with shorter gearing and still a very fast car. TQ at wheels though still be higher in S55

Originally Posted by coloradoe92m3

Keep in mind at WOT you don't see below 6500 ROMs in e92 dct so you can't draw a line straight up as they do as you need to account for e92 power band .

[damnitBobby]

Originally Posted by Taigar

Hi All,

Trying to learn something here. Engine wise, seems S55 is better every way than S65 - power, fuel economy. Why then did it take so long for BMW, Merc, Audi, VW and many others to jump on the Turbo technology only now? Is it turbo engines cost more to build, shorter life span, higher maintenance.. don't seem to be from my past Evo X experience.

Thanks for sharing.

Most likely succumbing to pressures by BMW head honchos about improving fuel efficiency across the boards, including m cars

turbo cars are more efficient in that you get more hp/liter displaced.. especially when just cruising at relatively low rpm (e.g. 1.8k) turbo's really aren't in use and you are getting the fuel efficiency of a smaller displacement motor (3L vs 4L)

S65 was a marvelous engine.. i think it was just robbed of it's glory by the porky weight of the E92.. high rev motors shine in cars that are light on their feet (think rx8 and s2k).. both ridiculously fun cars to drive.. now imagine putting those motors in a car like a challenger... i think you get my point

[Thurman Murch]

Ok maybe second, but I'm not used to
Downshifting into 1

The dct/dsg in my other cars may have ruined this for me

I am more used to third gear as the go
To gear

Imagine downshifting and flooring like crazy in first w S55