S55 vs. S65

[Needsdecaf]

Originally Posted by swamp2

Good for performance and terrible for character due to the feeling of "running out of steam" all the way from 5500 rpm. Nothing exciting past that point.

Just sayin...

If the car makes peak hp to 7300, how will it feel like running out of steam at 5500? Rate of acceleration won't decrease.

I agree, it won't feel as peaky or as characterful as the S65. I do understand, I have a Car with a high RPM power peak I drive everyday. I also get annoys having to rev the nuts off it all the time.

[JoeFromPA]

Why are so many folks saying there is little/no improvement in HP? Are you kidding me?

There is a dramatic increase in HP available throughout the RPM range. Especially down low, you now have a dramatic increase in HP.

Further, genuine question, has anyone mapped out actual torque given the gear ratios/FDR we now know about for the s65 m3 vs. the f8x m3/m4? How much actual torque is going to be applied to the wheels in each gear after torque multiplication effect - this will also be important to actual WHP in gears 1-3 particularly.

[bimmerjph]

Which ever one is lighter.

[Boss330]

Originally Posted by BMW M3 CRT

I can understand and agree with the statement "Frist drive and then descide" ... and I am sure that the new F8x would be clearly "The best M3 ever build" ... but the engine is an total change in M Philosophy and that without an improvement in hp !!!

For my an M3 doesn't need the highest hp-numbers, but it also was never ever an car defined over high low end torque numbers ... so for me there is no reason to change the engine if ~430hp are enough.

430hp and 1572kg = 0,27hp/kg or 3,66kg/hp

420hp and 1655kg = 0,25hp/kg or 3,94kg/hp

To have a similar hp/kg ratio as the F82, the S65 would have had to make 446hp, same as M3 GTS/CRT.

So, BMW didn't need a big power increase (on paper) to achieve their goal. Instead they lowered the weight and gained handling and braking performance as well. Upgrading power output only helps for acceleration, lowering weight helps for acceleration, braking and handling!

Owning a M3 CRT (?), you should be familiar with the concept of lowering weight

[pkimM3r]

One question i have is if those dyno plots are even real. Or if its a concept that they were getting at. In reality, im wondering if the power starts to dip instead of flat lining that much. I mean they look like powerpoint charts lol.

The s65 isnt peaky, the s55 would be peaky if the above was the case.

[Ezio]

what would bug me is that the S65 option would without a doubt be a slower car.

although should be slightly faster than a E90 with a S65. because of weight loss. i would 100% take the 4.4 450HP S65 over a S55 any day of the week.

At the end of the day, i would probably take a 4.0L 414hP 295TQ S65 over the S55. only if i could do a full exhaust and tune on the S65.

[Denk]

I love the linear response of the S65. I love this motor, the S55 has big shoes to fill. On paper it looks great but I gotta date it first to see if there is any chemistry.

[swamp2]

Originally Posted by Needsdecaf

If the car makes peak hp to 7300, how will it feel like running out of steam at 5500? Rate of acceleration won't decrease.

I agree, it won't feel as peaky or as characterful as the S65. I do understand, I have a Car with a high RPM power peak I drive everyday. I also get annoys having to rev the nuts off it all the time.

Acceleration absolutely decreases in proportion to the falling torque curve.

Just compare the torque and power curves for the S65 and S55. That should help you understand how "running out of steam" applies to the feel (felt acceleration at high rpm) between the two engines/cars. I've also posted some simulations that show the acceleration differences. Yes the S55 offers more power and more acceleration but I am talking here about feel alone (which some might call qualitative but feel can be fully quantified as well). Cars with a huge knee in their power curves (typically accompanied by a very fast fall off of torque with rpm) feel a bit dead after the knee. Those with a linear power curve to redline just feel "linear" and although their acceleration also tapers off, it does much less so.

Furthermore, I think "peaky" is entirely the wrong term for the S65, again both quantitatively and qualitatively. It surely does not describe the shape of the cars power curve nor torque curve, which by the way, qualitatively, is far superior to the S55. It offers about 90% of peak torque from 2500 rpm to 8250 rpm, a nearly 6000 rpm spread. Peaky to me is a two stroke dirt bike...

[Needsdecaf]

Originally Posted by swamp2

Furthermore, I think "peaky" is entirely the wrong term for the S65, again both quantitatively and qualitatively. It surely does not describe the shape of the cars power curve nor torque curve, which by the way, qualitatively, is far superior to the S55. It offers about 90% of peak torque from 2500 rpm to 8250 rpm, a nearly 6000 rpm spread. Peaky to me is a two stroke dirt bike...

Qualitatively better than the S55? OK, I'll bite. Show me the curve

[BMW M3 CRT]

Originally Posted by Boss330

430hp and 1572kg = 0,27hp/kg or 3,66kg/hp

420hp and 1655kg = 0,25hp/kg or 3,94kg/hp

To have a similar hp/kg ratio as the F82, the S65 would have had to make 446hp, same as M3 GTS/CRT.

So, BMW didn't need a big power increase (on paper) to achieve their goal. Instead they lowered the weight and gained handling and braking performance as well. Upgrading power output only helps for acceleration, lowering weight helps for acceleration, braking and handling!

Owning a M3 CRT (?), you should be familiar with the concept of lowering weight

Wrong and another apple vs. pears ... an F8x with the S65 would weight the same 1572kg as the F8x with the S55 !!!

Greetings BMW M3 CRT
P.S. ... very nice poll results!

[BMW M3 CRT]

Originally Posted by Ezio

what would bug me is that the S65 option would without a doubt be a slower car.

quod esset demonstrandum !!!

I guess it would be an "Dead Race" ... or the great M Philosophy of linear power output and driveability as the non plus ultra for track cars would be wrong for more than 20 years.

[Boss330]

Originally Posted by BMW M3 CRT

Wrong and another apple vs. pears ... an F8x with the S65 would weight the same 1572kg as the F8x with the S55 !!!

Greetings BMW M3 CRT
P.S. ... very nice poll results!

I was responding to a post about how the new car didn't have a rise in power, demonstrating that the F8x and S55 combination would be similar to a 444hp E9x M3 (NOT that the S65 in a hypothetical F8x chassis would need more power to get the same power to weight ratio...). Thought that was obvious...

And what is wrong about 1655kg for the E9x M3?

Both weights are EU curb weights with 6 MT.

To me, it's very clear that the power to weight ratio is better for the F8x than it is for the E9x. It has 10hp more (on paper) and weighs 80kg less (MT 6 versions). So a 10hp gain from the S55 and a "14hp gain" from less weight...

Meaning that a 1655kg E9x would need 444hp to have the same power to weight ratio as the F8x.

[vAnt826]

I've owned both an E92 335i and now an E92 M3.

One of the only things I missed from the 335i was the torque down low. I still to this day miss the lovely power available from low revs from a twin turbo engine (I had an N54).

I think the S55 will solve my thirst for torque, as it makes driving the car much more pleasurable and fun. The S65 is brilliant motor, but as I've gotten older, I find myself less likely to rev to the limiter, and more likely to go full throttle to around 6k RPMs for my spirited drives. This type of driving would be much better suited for the S55.

I obviously do not race or track my car, which I believe the S65 would be much more pleasurable to operate under (but if I did, I'd probably choose the S65!).

[swamp2]

Originally Posted by Needsdecaf

Qualitatively better than the S55? OK, I'll bite. Show me the curve

Qualitatively better. If you need my definition of "better" it is the width of the rpm band in which 90% of peak torque is available. In other words a flat torque curve. The S65 is remarkably more flat and holds a significantly wider band. This is a very common definition of a "good" torque curve, it's not just my pet definition...

To be crystal clear nowhere did I say at any particular rpm does the S65 make more torque, that is being quantitatively better.

[BMW M3 CRT]

Originally Posted by Boss330

I was responding to a post about how the new car didn't have a rise in power, demonstrating that the F8x and S55 combination would be similar to a 444hp E9x M3 (NOT that the S65 in a hypothetical F8x chassis would need more power to get the same power to weight ratio...). Thought that was obvious...

And what is wrong about 1655kg for the E9x M3?

Both weights are EU curb weights with 6 MT.

To me, it's very clear that the power to weight ratio is better for the F8x than it is for the E9x. It has 10hp more (on paper) and weighs 80kg less (MT 6 versions). So a 10hp gain from the S55 and a "14hp gain" from less weight...

Meaning that a 1655kg E9x would need 444hp to have the same power to weight ratio as the F8x.

Simple answer(!?) ... because I think THIS was an engine thread and not an car thread !!!

AND when we debate about which engine was better, we must compare an S55 equiped F8x and an hypothetical S65 equiped F8x ... none would/could assert that the E9xM3 would be an better performer than the F8xM3/M4 ... but I think some desperately want make this thread another apples vs. pears thread, by posting things that are absolutly clear and undisputed, to negate the possibility that an S65 equiped F8xM3/M4 could have the same performance as the same car with the S55 !

[Robin_NL]

If only talking about the engine: S65 on its own is a masterpiece, no doubt. Not kidding.


But mated to a too long geared 6MT tranny fitted in a bit too heavy car plus stock brakes which cannot do the job properly at trackdays afer a few laps only; it's that same masterpiece S65 that doesn't shine like it should imo due to issues written above imo. Maybe the S65 engine is 'too sporty' for the whole package, a daily sportssedan/coupe with room for four...?

If I want to have driving fun, the whole package needs to be in order...

Originally Posted by vAnt826

I've owned both an E92 335i and now an E92 M3.

One of the only things I missed from the 335i was the torque down low. I still to this day miss the lovely power available from low revs from a twin turbo engine (I had an N54).

I think the S55 will solve my thirst for torque, as it makes driving the car much more pleasurable and fun. The S65 is brilliant motor, but as I've gotten older, I find myself less likely to rev to the limiter, and more likely to go full throttle to around 6k RPMs for my spirited drives. This type of driving would be much better suited for the S55.

I obviously do not race or track my car, which I believe the S65 would be much more pleasurable to operate under (but if I did, I'd probably choose the S65!).

This. But at the track it needs better brakes


Cheers
Robin

[aajami]

I have three friends that each own a pre-LCI E82 135i. I've had plenty of wheel time behind an N54, and they've all had lots of time behind the wheel of my car. All four of us agree that the throttle response is nowhere near as close on the N54 as it is on the S65.

By the way, my intent is not to start yet another S65 vs. S55 war. I'm just extremely skeptical every time someone talks about a turbo engine that has no noticeable lag. Lag might be minimal, to be sure, but that's not the same as it not being present at all.

Get behind an S65. Drive in third and hold it at 4,000RPMs. Breathe on the gas pedal and see what happens. Very few cars respond as quickly in my (albeit very limited) experience.

[ersin]

I agree with swamp. The S65 is not "peaky". Peaky implies the torque curve is like in inverted "V". The new S55 is the more "peaky" engine.

What you feel in the S65 is like a locomotive: it keeps pulling with the same acceleration (mostly) all the way up to redline. The S55 will give you acceleration until it reaches 5500 rpm at which point it starts to fall off dramatically (IMHO). This will feel noticeably different then the E9x M3. I can see why swamp is afraid that the new engine will not have the same character as the old. It remains to be seen just how bad this will be.


Cheers.

[imserious]

Originally Posted by solstice

I like to see progress when I buy something new. I see progress with the S55 but would absolutely have preferred an upgraded S65 or a new I6 with close to 4l and a 9k rpm redline. Now since we aren't getting either I'll take the S55 with the good and bad for now.

Ooh. Large displacement high RPM 6 cylinder would be awesome. The bean counters and marketing guys wouldn't go for it though. Too expensive, not enough HP. You may just have to get a Porsche to experience that.

I have a feeling this will all become less controversial after the s55 M3/4 crushes the acceleration numbers of the s65 M3. People will be so shocked and awed that they will forget about the magical motorsport engine, the s65.

[Eau Rouge]

Originally Posted by imserious

Ooh. Large displacement high RPM 6 cylinder would be awesome. The bean counters and marketing guys wouldn't go for it though. Too expensive, not enough HP. You may just have to get a Porsche to experience that.

I have a feeling this will all become less controversial after the s55 M3/4 crushes the acceleration numbers of the s65 M3. People will be so shocked and awed that they will forget about the magical motorsport engine, the s65.

Nah. They're two different breeds. Now if the S55 were to obliterate the Nissan GT-R, for sure that would get everyone's attention, but we know that isn't even a remote possibility.

[Powaup]

if the S55 rev'd ~700 rpms more and was louder would people still miss the S65?

At this point I think some people are just resisting change, which is a normal human characteristic so I can not blame them. BUT the S55 is lighter, much more fuel efficient and has a much better torque curve than the S65 (+ a tad bit more HP) it does not sound as good as the S65 but that can be fixed with a new exhaust.

I love the S65 it's an awesome engine and if had an e9x M3 I would try my best to keep it, but geeze can you drive the S55 before you bash it out the window?? getting an engine swap from an older model for sound and RPM is a bit "salty" If im gonna throw out the S55 give me S85 V10 form the e60 M5/M6 then we're talking.

IMO the lighter the better

[basscadet]

Originally Posted by Robin_NL

If only talking about the engine: S65 on its own is a masterpiece, no doubt. Not kidding.


But mated to a too long geared 6MT tranny fitted in a bit too heavy
Cheers
Robin

Robin, you said it perfectly. The S65 IS a good engine but it is the wrong application for the E9x M3. BMW M's division made an uncharacteristically bad decision mating such an engine into such a heavy car that is designed for daily driving - the car required a torquey, fat powerplant and it got an engine better suited to a Lotus Elise. It seems BMW has learned their lesson as that is precisely what they are doing with the S55. The car did not shed enough weight nor gain enough power to make me an interested buyer but BMW is at least heading in the right direction.