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

[ASAP]

Originally Posted by KennyPowers

no offense, but this post is ridiculous

the m3 isn't, never has been, and never will be a real sportscar. its well over 3000 lbs and is fattened up by a ton of luxury items.

who cares if the s65 is made by gnomes, elves, the "sondermotorenbau" or whatever. I don't even know what that means, or how its relevant to the performance of a given engine / car.

the m3 is also faster than most of its competitors because it is lighter and has a superior chassis and often times brakes. its not because the motor is more "tractable". if that's the case, then why is the gt2 rs so damn fast and blows the doors off a gt3? shouldn't be the case since the motor is turbo and too powerful and not "tractable" according to you, no?

fact is that modern turbo engines are not hard to drive on the track, even for novices like myself. my 997tt had zero lag problems, crazy driveability prolems or anything of the like. it basically felt like a really good chassis with a huge motor and great brakes.

you love the s65, that's fine. but get out of here with the notion that the s65 is somehow faster or better than the s55 in terms of performance. its not, end of story. game over. done.

Nah man, its not elves. It's a few guys with beards and overalls wearing traditional german outfits and enjoying heavy pilsner.

Originally Posted by bradleyland

I understand the love affair with engines like the S65. I'm waiting on the F80 to hit the market so I can snap up an E92. I want the S65, but I'm fully aware that it will be out performed by the F82.

I should probably make you aware that if you had a 135i even more so if it was tuned, a lot will irritate you in that car. Like someone said, the chassis is to heavy for the way the tq is delivered. I drove my friends DCT E92 M3 and I wanted to get out of it in 10 minutes because even with the amazing sound, it's street qualities were nearly useless under 100 MPH.

[Benstuck]

Originally Posted by CanAutM3

The N54/N55 was the design starting point, but the S55 is a brand new engine with very little parts in common with either the N54 or N55. It has a new block, oil sump, crank shaft, rods, pistons, head, turbos, intake, intercooler, etc...

Ah i see.

[Boss330]

Originally Posted by ASAP

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

Why can't the wastegates be fully closed during part throttle driving when in Sport and Sport+ mode?

During part throttle driving the volume of exhaust isn't big enough to over rev the turbos, and keeping the wastegates shut means that the exhaust is used to keep the turbos spinning, ready for action.

Obviously having them shut means more heat and higher fuel consumption, which is why the function is only available in Sport and Sport+

Or am I missing something?

[Benstuck]

Originally Posted by basscadet

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.

Yes, you can't appreciate that engine unless you rev it. Reminds me of my old RX-8. Only way to enjoy that engine was at redline.

[BMW M3 CRT]

Originally Posted by bradleyland

Simply swapping an S65 in to an F80 chassis is unlikely to produce the results you anticipate for many reasons. Not the least of which, the fact that the chassis and engine are tuned together for optimal handling and road holding. The F80 chassis is not tuned to the S65. Even if you were to tune it, the tractability of the S65 would have a difficult time overcoming the power deficit that it suffers against the S55.

Sorry, but thats not right. The only thing what is special tuned together with the S55 is the new M-DCT gearbox and the programming of the aktive M-Differential !

Because of this I worte "S65 with the old M-DCT gearbox" ... I´am shure the aktive M-Differential would work also with an S65 engine layout. All other (new) parts would work in the same manner either with the S55 or the S65. Both engines weights the same, so I could find no reason for other special treatment an S65 would need in an F8x to be fast.

[ASAP]

Originally Posted by Boss330

Why can't the wastegates be fully closed during part throttle driving when in Sport and Sport+ mode?

During part throttle driving the volume of exhaust isn't big enough to over rev the turbos, and keeping the wastegates shut means that the exhaust is used to keep the turbos spinning, ready for action.

Obviously having them shut means more heat and higher fuel consumption, which is why the function is only available in Sport and Sport+

Or am I missing something?

I don't quite understand it either. To me it seems, like it would make the car extremely jumpy (akin to driving at high revs or full boost consistently or extremely inefficient.) I want more explanation of that as well. I just don't see how a waste gate can be fully closed under partial throttle. That is akin to using fully turbo capability even at 25% throttle lol.

[CanAutM3]

Originally Posted by ASAP

I don't quite understand it either. To me it seems, like it would make the car extremely jumpy (akin to driving at high revs or full boost consistently or extremely inefficient.) I want more explanation of that as well. I just don't see how a waste gate can be fully closed under partial throttle. That is akin to using fully turbo capability even at 25% throttle lol.

I think that is the whole point.

By doing so, you minimize lag and get prompt throttle response. There is probably much more wizardry going on with the Valvetronic and DI though.

[NYAWE60]

Originally Posted by KennyPowers

you love the s65, that's fine. but get out of here with the notion that the s65 is somehow faster or better than the s55 in terms of performance. its not, end of story. game over. done.

DING DING DING, you just nailed it buddy. Couldn't have said it better myself. I too, love the S65 (A LOT, one of my top 5 favorite engines) but damn, the S65 nuthuggers need to get over themselves already. This is the same stupid argument that happened when the following cars evolved and in every case the successor was a superior vehicle in all regards, primarily performance:

E46 S54 I6 to E9X S65 V8
E90 N52 I6 to F30 N20 turbo 4
E6X M5/6 S85 to F10/F12 M5/6 V8 S63
R3X GTR RB26 I6 to R35 VR38 V6 TT

These are just some of many examples. Usually when huge automotive companies like BMW, MB, Audi, Porsche, Nissan, Toyota etc. develop cars, they ensure that the next generation car exceeds it's predecessor in every aspect.

[Boss330]

Originally Posted by ASAP

I don't quite understand it either. To me it seems, like it would make the car extremely jumpy (akin to driving at high revs or full boost consistently or extremely inefficient.) I want more explanation of that as well. I just don't see how a waste gate can be fully closed under partial throttle. That is akin to using fully turbo capability even at 25% throttle lol.

This is the "pre tension" part. The turbos are kept spinning (tensioned) and are producing meaningful boost at part throttle and are "ready to roll" at the blink of an eye, minimizing lag.

On a DI engine you can easily run an engine at stratified charge (more air than what is needed in relation to fuel injected) and still have no issues with detonation etc. Torque delivery is regulated by the fuel injected, not the amount of air going to the engine, or boost pressure.

To me, it makes perfect sense to do what BMW says they do in regards to running the wastegates shut. Turbos are ready to roll, eliminate lag and torque delivery is regulated by throttle input (and thereby fuel injected).

IMHO, this creates a more predictable (or NA like) power delivery since you don't have to wait for the turbos to spool up.

[ASAP]

Originally Posted by CanAutM3

I think that is the whole point.

By doing so, you minimize lag and get prompt throttle response. There is probably much more wizardry going on with the Valvetronic and DI though.

Originally Posted by Boss330

This is the "pre tension" part. The turbos are kept spinning (tensioned) and are producing meaningful boost at part throttle and are "ready to roll" at the blink of an eye, minimizing lag.

On a DI engine you can easily run an engine at stratified charge (more air than what is needed in relation to fuel injected) and still have no issues with detonation etc. Torque delivery is regulated by the fuel injected, not the amount of air going to the engine, or boost pressure.

To me, it makes perfect sense to do what BMW says they do in regards to running the wastegates shut. Turbos are ready to roll, eliminate lag and torque delivery is regulated by throttle input (and thereby fuel injected).

IMHO, this creates a more predictable (or NA like) power delivery since you don't have to wait for the turbos to spool up.

Got it! All the more reason, I want to drive this thing.

[Taigar]

Originally Posted by ASAP

I am gonna stoop the point of saying that you are starting to make stuff up or are blindly infatuated with an outdated motor.

Have you ever seen any of the following on a track?

Mclaren MP-12C?
911 turbo s?
Ferrari F40?
Nissan GTR?

All turbo cars with turbo engines that would blow away nearly anything NA... in fact the only credible NA cars around the Ring that are left are the Vettes, Vipers and the Lexus LFA. Two of those have gigantic motors that are unfit for an M3 and the latter is a $375K supercar.

Hi,

Based on what you said, thats my starting question - why didn't car makers all go turbo until now that turbo only starts getting popular? Thank for sharing.

[ASAP]

Originally Posted by Taigar

Hi,

Based on what you said, thats my starting question - why didn't car makers all go turbo until now that turbo only starts getting popular? Thank for sharing.

There was never a need. NA engines were sufficient for the last 30 years and technology has advanced tremendously during that time. 10 years ago, a 400 HP NA car was pretty much a world class sports car. Today, little 2.0L turbo engines are able to produce the same performance at half the displacement, lower mpg consumption, and much better low end tq delivery. It's a combination of horsepower wars, technology advancement and environmental factors. Today, in order to make a serious NA performance engine that can compete even with middle class turbo motors requires a massive V8, something that is simply unnecessary in most cars.

To add to that, the only serious NA performance V8 left in this world with less than a 5.0L displacement is the one found in the Ferrari 458 (a $300k car and even they are realizing the benefits of turbocharging.) Sound aside, I can't think of a single advantage to an NA engine.

[BMW M3 CRT]

Originally Posted by ASAP

I am gonna stoop the point of saying that you are starting to make stuff up or are blindly infatuated with an outdated motor.

Have you ever seen any of the following on a track?

Mclaren MP-12C?
911 turbo s?
Ferrari F40?
Nissan GTR?

All turbo cars with turbo engines that would blow away nearly anything NA... in fact the only credible NA cars around the Ring that are left are the Vettes, Vipers and the Lexus LFA. Two of those have gigantic motors that are unfit for an M3 and the latter is a $375K supercar.

All cars you listed plays in an much higher hp-class than the M3/M4 ... in this class you need really big N/A engines to realise such high hp-numbers.

And you simply forget one the best trackcars ever ... the Porsche GT3 and GT3-RS.

The only reason why for me S65 and S55 are comparable, is because they are in the same hp-class ... if the new M3/M4 would get an turbo engine in the ~500hp class, none ever would compare it with an S65 equiped car.

Yes I´am an fan of the S65, but I have nothing aganist turbo engine ... there are many really great turbo engines on the market, but with nearly the same hp like the S65 the S55 only change the driving charakter of the M3, there are many other, not engine related, improvements, that makes the F8x so much faster than the e9xM3 and to "the best M3 ever"

[Boss330]

Originally Posted by Taigar

Hi,

Based on what you said, thats my starting question - why didn't car makers all go turbo until now that turbo only starts getting popular? Thank for sharing.

Direct Injection (DI) has opened up new venues for the engineers to minimize turbo lag (as partly explained above).

Apart from that, recent EU emissions requirements means that there is less and less room for thirsty and big volume NA engines. Downsizing to meet MPG and CO2 emission requirements are major reasons manufacturers are looking at smaller engines with turbos.

(Apart from Mitsubishi that is looking at keeping large(ish) displacement but extremely high compression ratios to achieve the same thing. I believe they are at 16:1 on a petrol engine now!!!)

[ASAP]

Originally Posted by BMW M3 CRT

All cars you listed plays in an much higher hp-class than the M3/M4 ... in this class you need really big N/A engines to realise such high hp-numbers.

And you simply forget one the best trackcars ever ... the Porsche GT3 and GT3-RS.

The only reason why for me S65 and S55 are comparable, is because they are in the same hp-class ... if the new M3/M4 would get an turbo engine in the ~500hp class, none ever would compare it with an S65 equiped car.

Yes I´am an fan of the S65, but I have nothing aganist turbo engine ... there are many really great turbo engines on the market, but with nearly the same hp like the S65 the S55 only change the driving charakter of the M3, there are many other, not engine related, improvements, that makes the F8x so much faster than the e9xM3 and to "the best M3 ever"

I can certainly understand your reasoning... but

The Gt3 and GT3rs cost 1.5 x to 2 x an M3. They are much lighter cars and the engines are built on a completely different architecture with a completely different valve technology (one that costs double) as a Gt3 rs will cost nearly $140K usd.

I will ask a simpler question... in keeping with the NA motors, how could BMW have improved on the S65? Larger displacement? Honest question.

[clar]

The power graph seems to indicate that the new M3/M4 will not be a lot slower to my F10 M5 in the straights...

[bradleyland]

Originally Posted by ASAP

I should probably make you aware that if you had a 135i even more so if it was tuned, a lot will irritate you in that car. Like someone said, the chassis is to heavy for the way the tq is delivered. I drove my friends DCT E92 M3 and I wanted to get out of it in 10 minutes because even with the amazing sound, it's street qualities were nearly useless under 100 MPH.

I had a couple of opportunities to drive my 135i and a 6MT M3 back to back. I also owned a 24V VR6 powered GTI back to back with a 2.0T powered GTI. Those experiences gave me a really good feel for the differences between turbocharged engine power delivery and naturally aspirated.

The naturally aspirated engines deliver their power with far less urgency. There's a feeling of anticipation as you climb the RPM range, but the up-side is that (at least with the S65), it keeps making power all the way to the top. A turbocharged engine hits you with a lump of torque down low, and while power output is maintained in to the higher RPM range, torque usually drops off, so you get a very different feel.

I can appreciate both. I'm not interested in the E92 so much for its ultimate performance as I am the overall experience. I'm actually banking on the fact that most people don't have the same priorities as me I'm looking for a price drop. Of course, everyone who has the same priorities as me believes that the E92 is going to be some kind of collectors car and that no one is going to want an F82. I think that's preposterous. The mass-market doesn't give two-shits about the things that I care about.

[Boss330]

Originally Posted by BMW M3 CRT

All cars you listed plays in an much higher hp-class than the M3/M4 ... in this class you need really big N/A engines to realise such high hp-numbers.

And you simply forget one the best trackcars ever ... the Porsche GT3 and GT3-RS.

The only reason why for me S65 and S55 are comparable, is because they are in the same hp-class ... if the new M3/M4 would get an turbo engine in the ~500hp class, none ever would compare it with an S65 equiped car.

Yes I´am an fan of the S65, but I have nothing aganist turbo engine ... there are many really great turbo engines on the market, but with nearly the same hp like the S65 the S55 only change the driving charakter of the M3, there are many other, not engine related, improvements, that makes the F8x so much faster than the e9xM3 and to "the best M3 ever"

The 991 Turbo S and GT3 have comparable performance and lap times (according to Sport Auto) but still employ very different engines (NA vs Turbo).

I think that it would be better to wait for test drives of the new car before we conclude that the S65 engine and DCT would be quicker in this car than the S55 engine will be. In fact, the S55 will provide significantly better acceleration times than the S65 would and only if the S55 is "un driveable" on a track would the S65 be able to claw that advantage back. And, there is nothing about the S65 engine that makes a F8x with a hypothetical S65 engine corner faster than a F8x with the S55...

Exactly where (which parts of the track) would a S65 powered F8x be faster than a S55 powered F8x?

[Black Gold]

Originally Posted by Boss330

The 991 Turbo S and GT3 have comparable performance and lap times (according to Sport Auto) but still employ very different engines (NA vs Turbo).

I think that it would be better to wait for test drives of the new car before we conclude that the S65 engine and DCT would be quicker in this car than the S55 engine will be. In fact, the S55 will provide significantly better acceleration times than the S65 would and only if the S55 is "un driveable" on a track would the S65 be able to claw that advantage back. And, there is nothing about the S65 engine that makes a F8x with a hypothetical S65 engine corner faster than a F8x with the S55...

Exactly where (which parts of the track) would a S65 powered F8x be faster than a S55 powered F8x?

and a gt2 (more or less same chassis as gt3 except engine) destroys the gt3 on track. so, not getting how the lower powered n/a motors are faster. seems more like desperate attempts to glorify the s65 by M3 CRT to me

[Taigar]

Originally Posted by Boss330

Direct Injection (DI) has opened up new venues for the engineers to minimize turbo lag (as partly explained above).

Apart from that, recent EU emissions requirements means that there is less and less room for thirsty and big volume NA engines. Downsizing to meet MPG and CO2 emission requirements are major reasons manufacturers are looking at smaller engines with turbos.

(Apart from Mitsubishi that is looking at keeping large(ish) displacement but extremely high compression ratios to achieve the same thing. I believe they are at 16:1 on a petrol engine now!!!)

Guys,
Thanks to all for responding and clarifying. I'm new to this and have certainly learnt from this forum. Cheers!

[bradleyland]

Originally Posted by BMW M3 CRT

Sorry, but thats not right. The only thing what is special tuned together with the S55 is the new M-DCT gearbox and the programming of the aktive M-Differential !

Because of this I worte "S65 with the old M-DCT gearbox" ... I´am shure the aktive M-Differential would work also with an S65 engine layout. All other (new) parts would work in the same manner either with the S55 or the S65. Both engines weights the same, so I could find no reason for other special treatment an S65 would need in an F8x to be fast.

Do they weigh exactly the same? I thought the S55 was slightly heavier. Also, torque output has an impact on suspension tuning. These might seem like minor points, but chassis tuning is a holistic process. That's why so many tuner cars handle so poorly.

Regardless, the subtleties of chassis tuning aren't what would make the big difference. The difference in power between the S55 and S65 is enough for the S55 to come out on top, despite your claims that it is some kind of wildly uncontrollable beast. I think you're just so in love with the S65, you can't think rationally.

[bradleyland]

Originally Posted by KennyPowers

and a gt2 (more or less same chassis as gt3 except engine) destroys the gt3 on track. so, not getting how the lower powered n/a motors are faster. seems more like desperate attempts to glorify the s65 by M3 CRT to me

Well put. The GT2 vs GT3 is probably the best apples-to-apples comparison you'll find of a turbocharged vs N/A configuration in the same production chassis, and it destroys the argument that the tractability -- or lack thereof -- of a turbocharged engine makes a car slower around a track.