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

[Roadkiller]

Originally Posted by Oakleyguy

This is my favorite line:

"In stark contrast is the SPORT PLUS mode, which pays absolutely no attention to any comfort factors"

Was thinking the same. €

[Powerslide]

Exactly - I absolute love my S65 to death - best engine I've ever personally owned. But don't get me wrong - but you're making 414 hp only at a single, discreet "point in time" - i.e., at 8300 rpm. With the S55 - you may only be 11 hp peak hp better - but you're there for a heck of a lot longer period of time - 5500 to 7300 rpm over and over again (1st through whatever gear you're at when you decide that you don't want to risk going to jail). I agree that this engine will be much faster - given that you can be at a virtually constant 425 hp as you accelerate (assuming you shift at 7300 rpm) - whereas the S65 you have to wait until 8300 rpm just to get to 414 hp, then when you shift at 8300-8400, your rpms drop what - 1800-2000 rpm (so now your hp just instantly dropped from 414 to 325-350, or whatever it is, gradually building back up to 414 by the time you again reach 8300)...

With naturally aspirated engines, peak horsepower used to be the most important single factor for acceleration (relative to the car's weight and other factors too, of course). Now, with turbos making very wide, flat power plateaus over a wide rpm range - it seems the most important single factor for acceleration is for how wide of an rpm range (or for how long of a period of time) can the peak power be maintained?

[Bowser330]

Originally Posted by Powerslide

Exactly - I absolute love my S65 to death - best engine I've ever personally owned. But don't get me wrong - but you're making 414 hp only at a single, discreet "point in time" - i.e., at 8300 rpm. With the S55 - you may only be 11 hp peak hp better - but you're there for a heck of a lot longer period of time - 5500 to 7300 rpm over and over again (1st through whatever gear you're at when you decide that you don't want to risk going to jail). I agree that this engine will be much faster - given that you can be at a virtually constant 425 hp as you accelerate (assuming you shift at 7300 rpm) - whereas the S65 you have to wait until 8300 rpm just to get to 414 hp, then when you shift at 8300-8400, your rpms drop what - 1800-2000 rpm (so now your hp just instantly dropped from 414 to 325-350, or whatever it is, gradually building back up to 414 by the time you again reach 8300)...

With naturally aspirated engines, peak horsepower used to be the most important single factor for acceleration (relative to the car's weight and other factors too, of course). Now, with turbos making very wide, flat power plateaus over a wide rpm range - it seems the most important single factor for acceleration is for how wide of an rpm range (or for how long of a period of time) can the peak power be maintained?

nicely put

[dpgfunk]

This makes me and my S65 sad

[Ezio]

They still make some n/a engines that have a power across the rpm range. Your point would only be valid if all n/a engines were like a s65. Go drive a c63 amg v8 power everywhere.

[BhamDavid]

Originally Posted by Ezio

They still make some n/a engines that have a power across the rpm range. Your point would only be valid if all n/a engines were like a s65. Go drive a c63 amg v8 power everywhere.

Yes but they do that with 6.3 liters of displacement.

[humpday]

Awesome article. This engine is going to be beast.

[keno]

I'd love to see the S55 's power chart compared to something like the current C63's V8

[ASAP]

Originally Posted by Ezio

They still make some n/a engines that have a power across the rpm range. Your point would only be valid if all n/a engines were like a s65. Go drive a c63 amg v8 power everywhere.

that requires serious displacement...ls7

[biglare]

The day to day driving pleasure of this engine is what most people will be excited about. You have more power and torque available at a lower RPM. Of course this range of max power will help at the track, but the day to day driving pleasure factor just went up ten-fold in my opinion. It will be similar to the 1M daily driving compared to the E9x M3, the daily city driving is must more fun with power available down low! Just my two cents and cannot wait to get my hands on one!

[Sir Loin]

With this power curve chart, I thought it is kind of weird that it has a flat top between 5500 RPM to 7200 RPM. Unless BMW somehow clip the engine output, the HP should peak at 460 or higher at around 6500 RPM if you ignore that flat top and hand draw a curve between the two end points on that flat line.

Is this how BMW under-rates their engines?

[jaehshim]

let's ask the guy again.
so, what is special about this new engine? besides it being basically a 335i engine

[CSanto]

Originally Posted by biglare

The day to day driving pleasure of this engine is what most people will be excited about. You have more power and torque available at a lower RPM. Of course this range of max power will help at the track, but the day to day driving pleasure factor just went up ten-fold in my opinion. It will be similar to the 1M daily driving compared to the E9x M3, the daily city driving is must more fun with power available down low! Just my two cents and cannot wait to get my hands on one!

+1

Driving at 5/10ths vs 5/10ths I feel the 1M is much more fun than the M3

10/10 vs 10/10 the M3 edges the 1M out. IMO

[Ezio]

Originally Posted by BhamDavid

Yes but they do that with 6.3 liters of displacement.

There is no question small turbo engines are the new way of business let me first say. All I am saying is power being at any rpm is nothing new from a n/a engine or Turbo engine.

[Sir Loin]

Originally Posted by CSanto

+1

Driving at 5/10ths vs 5/10ths I feel the 1M is much more fun than the M3

10/10 vs 10/10 the M3 edges the 1M out. IMO

How can you make these statements before you have driven the new M3/M4? Or have you already driven the new Ms? Give us the juicy details!

[jphughan]

Originally Posted by Sir Loin

With this power curve chart, I thought it is kind of weird that it has a flat top between 5500 RPM to 7200 RPM. Unless BMW somehow clip the engine output, the HP should peak at 460 or higher at around 6500 RPM if you ignore that flat top and hand draw a curve between the two end points on that flat line.

Is this how BMW under-rates their engines?

I'm figuring that flat top occurs because all turbo engines back off the turbo pressure as the engine approaches redline, so perhaps BMW has simply tuned the engine so the power drop from the turbo dropoff is exactly canceled out by the power increase courtesy of rising engine speeds, yielding a constant horsepower in that range.

[ASAP]

Originally Posted by Sir Loin

With this power curve chart, I thought it is kind of weird that it has a flat top between 5500 RPM to 7200 RPM. Unless BMW somehow clip the engine output, the HP should peak at 460 or higher at around 6500 RPM if you ignore that flat top and hand draw a curve between the two end points on that flat line.

Is this how BMW under-rates their engines?

I can only think of two things-

a) the turbos r too small to hold more boost up top
b) the car is detuned

I would be willing to bet it's a combo of both but definitely leaning towards A.

[turbo8765]

Originally Posted by ASAP

I can only think of two things-

a) the turbos r too small to hold more boost up top
b) the car is detuned

I would be willing to bet it's a combo of both but definitely leaning towards A.

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.

[aus]

So he basically said everyone's butt dyno doesn't work because it's all about sound as the main determinant in "feeling" you're going fast? Given that torque curve and power curve, I'd expect it to be the feeling of the driver being pressed into the seat. :/

Also, no mention of this "pre-charge" they mentioned before to keep the turbo's spooled up?

.

[jphughan]

Originally Posted by aus

So he basically said everyone's butt dyno doesn't work because it's all about sound as the main determinant in "feeling" you're going fast? Given that torque curve and power curve, I'd expect it to be the feeling of the driver being pressed into the seat. :/

Also, no mention of this "pre-charge" they mentioned before to keep the turbo's spooled up?

At higher speeds, sound can actually deliver a more convincing sensation of going fast. Few cars have the ability to push you truly hard back into your seats if you're already doing near highway speeds, so even fairly large percentage differences in torque may not translate into an especially noticeable difference in push -- sound is much more obvious. Also, the push only happens when you're actually accelerating, whereas you can have a thrilling, speed-suggestive symphony even when you're driving at a constant or only moderately changing speed.

As for pre-charging, the interview specifically mentions that in Sport or Sport Plus, the wastegates stay closed to keep the turbos spinning.

[Sir Loin]

Originally Posted by aus

Also, no mention of this "pre-charge" they mentioned before to keep the turbo's spooled up?

This?

So what are the differences between the EFFICIENT, SPORT and SPORT PLUS modes?

In the SPORT and SPORT PLUS modes, the waste gates remain closed under partial load and the mass flow is routed through the turbines, to ensure that the turbo chargers are already rotating at a higher base speed even in standby. Moreover, certain special engine control functions are brought into play that accelerate activation of the turbo chargers. This means that the car responds more closely to the accelerator in SPORT and SPORT PLUS modes.

[ASAP]

I have no idea how you can keep wastegates fully closed all the time lol. He probably means partially closed.