S55 vs. S65

[Ezio]

Originally Posted by basscadet

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.

well first off i came from a 500TQ 540HP n/a LS3 built camaro SS. while daily driving RPMs never needed to go beyond 1.3 RPM. with its tall gears also. wayyy more torque than my M3 and more than the M4. although i never once said i felt i needed more low end power. so i do know what low end power feels like. and honestly to me it gets rather boring having flat power.

i love how the M3 builds the power up high. not to mention revs well past 8k RPM. Most cars today have the flat power. the M3 S65 is just different which some people like.

i do see how some people would want more power down low and would make the statement of the S65 not being well suited for the M3. but for people like me, who wants a engine that is not practical and needs to a mad man behind the wheel to have fun with it on the streets. the the S65 is great

to be honest my M3 sees 8300RPM on a daily basis.

[Boss330]

Originally Posted by 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.

I think nobody expects that the S55 will be on S65 levels of response... We are debating/hoping that the S55 will be extremely good and responsive for a turbo engine. Not even next years F1 engines manage to eliminate lag, even with the electric motor that aids spool up.

[Boss330]

To the OP and everyone else:

There are numerous German tuners that do engine swaps "on a daily basis"

Manhart and others have done 1 and 3-series with the S85, S65 and S63 (twin turbo)engine. Manhart even did, on customers request, an E92 M3 with a tuned N54 and X-drive

So, all of your wishes can come true via aftermarket tuning companies (at least in Germany)

[ersin]

Originally Posted by Powaup

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

Yes, they would. It's not just making it rev higher. It's about extending the torque curve up. If they could just get the torque curve to remain flat more over on the high end then that would be wonderful.

Not saying the S55 is no good. It is lighter (heck, two less cylinders) and more hp. But it will feel different. It may be faster but it will lose the magic of the S65. Now, how much magic of its own will it make? I can't wait to see.


Cheers.

[Falafel Combo]

Originally Posted by Boss330

I think nobody expects that the S55 will be on S65 levels of response... We are debating/hoping that the S55 will be extremely good and responsive for a turbo engine. Not even next years F1 engines manage to eliminate lag, even with the electric motor that aids spool up.

I sincerely feel that the response in my f30 335 (sport mode) was a lot better than my current s65 (power activated). I personally predict the s55 to be much better than the s65 in absolute terms (not just good "for a turbo engine").

[Ezio]

Originally Posted by ersin

Not saying the S55 is no good. It is lighter (heck, two less cylinders) and more hp. But it will feel different. It may be faster but it will lose the magic of the S65. Now, how much magic of its own will it make? I can't wait to see.


Cheers.

i wouldn't say lose the magic of a S65. more so lose the magic of any engine that goes from a high power n/a motor to a turbo motor.

even guys over on the Audi forum are upset about Audi dropping there RS5 high revving n/a V8, and going with a TT V6.

though AMG is probably keeping a V8 for next C63. people will miss the big 6.3L n/a V8. the power and sound of that engine is unreal.

while sure many do welcome the new turbo era.

[catpat8000]

Originally Posted by Boss330

I think nobody expects that the S55 will be on S65 levels of response... We are debating/hoping that the S55 will be extremely good and responsive for a turbo engine. Not even next years F1 engines manage to eliminate lag, even with the electric motor that aids spool up.

See: http://www.f1technical.net/features/19037

It sounds like some teams might be experimenting with electrically spooling the turbos and also using the turbos to generate electricity. It's not crazy to imagine a power control algorithm which uses harvested energy to spool the turbos whenever the driver is not on the throttle and when on the throttle, uses energy to recharge the energy store and also to supply power to the rear wheels.

Pat

[swamp2]

Originally Posted by Boss330

I think nobody expects that the S55 will be on S65 levels of response...

Just as you say it...

Originally Posted by ///M235i

I sincerely feel that the response in my f30 335 (sport mode) was a lot better than my current s65 (power activated). I personally predict the s55 to be much better than the s65 in absolute terms (not just good "for a turbo engine").

It can be a bit tricky to discriminate throttle response and lag when widely varying throttle maps are used. For instance using the aggressive throttle mapping in the S65 M3, I would say the throttle is too sensitive at low throttle openings. This can give an illusion of a "faster" car or better throttle response or it can just make the car downright jumpy and too sensitive (which is my evaluation). However, I find it next to impossible to believe that you find a turbo charged N55 to have a better throttle response than the S65. You really must be confused.

[Ezio]

Originally Posted by ///M235i

I sincerely feel that the response in my f30 335 (sport mode) was a lot better than my current s65 (power activated). I personally predict the s55 to be much better than the s65 in absolute terms (not just good "for a turbo engine").

mathematically the chances are there is something wrong with your S65 for it to give less throttle response. even BOSS agrees that he doesnt expect the S55 to be as good as the S65. (in that sense).

and you even went as far to say "a lot better"

the S65 is known for throttle response.

[swamp2]

Originally Posted by Powaup

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

Those alone would help significantly for me.

Originally Posted by Powaup

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.

Indeed, change is hard.

Lighter - that's good, not by much.

Fuel efficient, that's great, but surely it is a relatively low priority for a sports car? Perhaps engine character might come above carbon footprint for such a car?

Torque curves are almost if not entirely meaningless for the performance of a sports car. Wheel torque is slightly more meaningful but peak power tells us almost everything.

Originally Posted by Powaup

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??

The power of science, engineering and experience allows one to form very resonable conclusions without direct experiential knowledge. Exactly my point is how the S55 will and does run out of steam at high rpm and will almost for sure need to be short shifted to achieve maximum performance (at least in the latter gears). How sporty is that...

[Robin_NL]

Cheers
Robin

[Robin_NL]

Originally Posted by swamp2

However, I find it next to impossible to believe that you find a turbo charged N55 to have a better throttle response than the S65. You really must be confused.

I think he meant power delivery....


Cheers
Robin

[catpat8000]

Originally Posted by Ezio

mathematically the chances are there is something wrong with your S65 for it to give less throttle response. even BOSS agrees that he doesnt expect the S55 to be as good as the S65. (in that sense).

and you even went as far to say "a lot better"

the S65 is known for throttle response.

I've heard lots of people confuse flooring it in D3, then waiting for all the shifting and ECU activity to settle down, with the notion of throttle response.

I've also heard people talk about the poor throttle response of the S65 at low rpm in higher gears.

Personally I prefer the term throttle modulation because it seems more precise. And to be pedantic, the response to the throttle at low rpm in higher gears is poor when compared to a turbo motor

Pat

[BMW M3 CRT]

Originally Posted by ersin

Yes, they would. It's not just making it rev higher. It's about extending the torque curve up. If they could just get the torque curve to remain flat more over on the high end then that would be wonderful.

Not saying the S55 is no good. It is lighter (heck, two less cylinders) and more hp. But it will feel different. It may be faster but it will lose the magic of the S65. Now, how much magic of its own will it make? I can't wait to see.


Cheers.

Good post !!!

But lighter ... I don´t beleave that the gross weight of the S55 is lower than the gross weight of the S65 -> I heard numbers of 205kg (S55) vs. 202kg (S65), that is pretty much the same weight class.

[435iaffair]

Originally Posted by Powaup

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 agree partially - people always resist change. But so far the S55 sounds like pure a** IMHO in all the vids I've watched Hopefully it's an easy fix, or maybe the audio just wasn't good in those BMW promo videos.

Originally Posted by Ezio

well first off i came from a 500TQ 540HP n/a LS3 built camaro SS. while daily driving RPMs never needed to go beyond 1.3 RPM. with its tall gears also. wayyy more torque than my M3 and more than the M4. although i never once said i felt i needed more low end power. so i do know what low end power feels like. and honestly to me it gets rather boring having flat power.

i love how the M3 builds the power up high. not to mention revs well past 8k RPM. Most cars today have the flat power. the M3 S65 is just different which some people like.

i do see how some people would want more power down low and would make the statement of the S65 not being well suited for the M3. but for people like me, who wants a engine that is not practical and needs to a mad man behind the wheel to have fun with it on the streets. the the S65 is great

to be honest my M3 sees 8300RPM on a daily basis.

It's hard to beat the exhilaration of being above 5000rpm from corner to corner in my z4m, as well as the e92 M3 I get to drive from time to time. I'm all about low end torque but like you said that does get old - but I guess what doesn't? I had an LS3 Corvette and the S65 is just starting to really "wake up" when the Vette is hitting its redline lol. Damn I feel like going out for a drive right now (4am here in socal)

Originally Posted by Ezio

though AMG is probably keeping a V8 for next C63. people will miss the big 6.3L n/a V8.

Sorry to nitpick but the M156 was a 6.2L as I'm sure you are well aware. Stupid Mercs and their 6.3 badges. And you are right - that engine will be dearly missed, but I'm sure the M177 will be freaking awesome as well.

[435iaffair]

Originally Posted by Robin_NL

I think he meant power delivery....


Cheers
Robin

+1 I read it as the N55 in his F30 providing much better low end torque delivery, though the wording was confusing. Throttle response-wise the S65 obliterates any N5x engines IMO.

[Boss330]

Originally Posted by catpat8000

See: http://www.f1technical.net/features/19037

It sounds like some teams might be experimenting with electrically spooling the turbos and also using the turbos to generate electricity. It's not crazy to imagine a power control algorithm which uses harvested energy to spool the turbos whenever the driver is not on the throttle and when on the throttle, uses energy to recharge the energy store and also to supply power to the rear wheels.

Pat

The F1 tech of regenerating electricity from the turbo and also aiding spool up time was discussed in a few other threads a while ago.

To quote myself again

Originally Posted by Boss330

Of particular interest is the MGU-H (Motor Generator Unit - Heat) that is attached to the turbo:

This is a brilliant piece of engineering, possibly a game changer of power delivery characteristics on a turbocharged engine

Any rumours of a electric turbocharger on the next M3/M4 might be a similar device as shown here, to spool up the turbos, or slow it down instead of using a wastegate to dump excess exhaust.

Source: http://www.renaultsport.com/Nouvelle...Energy-F1.html

Here is MagnetiMarelli's version of a "electric/hybrid" turbo. TThey have chosen a slightly different solution with the generator/motor unit between the compressor and turbine units of the turbo. Seems like Mercedes is using a variant of this solution as well.





BTW, this is what next years F1 engine will sound like:

And a little bit on lag and response, since that has been brought up again...

Originally Posted by Boss330

The single turbo is there by regulation, not by engineering choices... The previous gen F1 Turbo V6 engines used twin turbos, as that was (is) the preferred choice on a V engine layout. Nowhere in the Renault F1 statement is boost treshold mentioned, even though the MGU-H might be used for that purpose as well. The MGU-H unit is there to "reduce turbo-lag to near zero" (and regenerate energy from the turbo when used to slow down the turbo). They have even defined the delay in torque delivery on a turbo engine as being caused by the turbochargers need to vary it's speed to match the requirement of the engine, which means that the turbo might be spooling down when you start accelerating. The turbo then first needs to stop decelerating (spooling down) before it can start accelerating (spooling up) and create the needed boost. It doesn't take long on a moder engine, but it's not instant. If your argument is that the torque delivery on a turbo engine is just as constant as on a NA engine you are arguing against what is the accepted knowledge (and Renault's F1 engine department...). Even in a situation where you are accelerating (making boost) and then giving the engine full throttle, the turbo will have a short delay before it has reached it's full rpm and boost level for that engine rpm. It's shorter than in the previous scenario, but it's not instant as in a NA engine. Yes, a turbo engine will give you more torque than a similar size NA engine, but it doesn't give 100% of the available torque instantly when depressing the throttle. BTW, I love the torque of a turbo'd engine and have had several turbo'd cars


Not sure why you call a twin turbo "in-efficient"? Are you saying that the BMW M5/M6 engine uses in-efficient turbo design? A smaller turbo has lower inertia, quicker spool up etc. It's also easier to keep exhaust gas speed higher with smaller diameter tubing and inlet (can be done on a big turbo as well with advanced interior design of exhaust tubing).

Regardless, a F1 engine that operates between 10-15000rpm during a lap (might not go as low as 10 grand either) does not need the same low rev driveability characteristics as a street car engine.

And I feel that this quote from Renault's F1 department sums up the difference between a traditionally turbo'd engine and a NA engine:



So, even with the new technology, the turbo lag is "only" reduced to near zero. Not the instant torque delivery that todays NA engine deliver.

By definition a turbo engine must have turbo lag under certain conditions, because "the turbocharger speed must vary to match the requirement of the engine". That's why rally cars have anti-lag devices and Renault's new F1 engine has the electric generator/motor unit to decrease lag to "near zero". Even with this tech, it won't be instantaneous. I guess there is a limit to how fast the system can react and spool up the turbo

Originally Posted by Boss330

Lag and "torque wave" are two very different things. A NA engine will, for all intents and purposes, have instant torque delivery. When opening the throttle there will be, within milliseconds, a delivery of 100% of the available torque at that rpm and throttle opening.

A turbo engine will have the same, millisecond, delay before it delivers the unboosted maximum torque. When the first combustions at that level have taken place, the extra amount of exhaust will come into the exhaust manifold and start the process of spooling up the turbo. Depending on the operating stage of the turbo, this spooling up process might have to include first stopping the process of spooling down (turbo is loosing rpm's), then starting to accelerate the turbo up to it's maximum rpm and boost for that engine rapm and throttle opening. The turbo's compressor side also has to start the process of compressing the air, routing it through the intercooler and the necessarily longer intake tubing before the compressed air reaches the intake manifold and then enters the engine. Just the extra volume and length of the intake side of a turbo engine MUST produce a delay between throttle input and power delivery. Hence why even on a F1 engine with a motor to spool up and down the turbo, the manufacturer states that they cannot get as rapid response as a NA engine. By design, a turbo'd engine can't have as fast response as a NA engine.

A turbo engine will, a few milliseconds after throttle opening, only deliver a certain percentage of it's maximum power delivery for that rpm and throttle opening. That percentage depends on how much of it's power is made under boost. The higher the boost, the higher the percentage of power is made under boost. A engine that has a boost pressure of 0,5BAR (low boost) will typically make around say 40-50% more power under boost than it does without boost.

So, a turbo engine that boosts at 0,5BAR will only deliver 2/3rds (66%) of it's maximum power (at that rpm) a few milliseconds after the throttle has been opened fully. It then takes the added time of completing the combustions which creates the exhaust gases needed for spooling up the turbo(s). Then the turbo starts generating boost, delivering the air through the intercooler and intake plumbing before entering the intake manifold and finally the engine. That is turbo-lag my friend and is not remotely comparable to a NA engine.

Yes, a turbo engine will deliver more torque than a similarly sized NA engine. But where the NA engine delivers 100% of it's available power just a few milliseconds after throttle input, a turbo engine will only deliver maybe 50-60% of the available power in that same time frame, and then you have a delay before the turbo has reached max boost and you have 100%. It's kind of like a two stage power delivery. As explained above, it takes added time to reach 100%. There is currently no way around this, not even the clever F1 engineers have been able to eradicate it completely...

A NA engine cannot have lag from idle to redline, it constantly delivers 100% of available power at any given rpm and throttle opening. A turbo engine cannot, and does not, replicate this quality. Not even next years F1 engines!

And, just to reiterate, I love the torque wave a turbo engine delivers. It's addictive and much more useable in daily driving than a high revving NA engine that needs high rpms to deliver the goods.

And BTW, the beauty of the MGU-H unit is that it can start spooling up the turbo at the instant the throttle is opened. The turbo doesn't have to wait for the exhaust gases to start the spooling up process. This saves some time and boost production starts allmost immediately. Obviously not instantly as the compressor side has to compress the air and then flow it through the intercooler etc. But at least the turbo can respond immediately to throttle input The delay (lag) on the exhaust side of the turbo has been eliminated/minimized, it's now the compressor side of the turbo that is the cause of delay (as the turbo's compressor side cannot go from 0BAR boost pressure to 3,5BAR immediately. Air is compressible (unlike most fluids) and it therefor takes time to build pressure as more volume of air is needed to fill up all tubing/intercoolers etc before the desired pressure can be reached. The turbo has to pump air to build pressure, which takes time).

[Swancoat]

My S65 has such quick throttle response that if I'm at a low speed and low gear (moderate rpm level) and have the power button on, If I hit the throttle sometimes the car 'bucks' as it jumps ahead, pushes my foot off the throttle, slows, and my light pressure on the throttle is enough to push it down again -- repeat a few times for a weird 'jerking'.

Doesn't happen very often, and it has to be the weird specific set of above circumstances, but in that case (and that case only ) maybe a decreased throttle response wouldn't be a bad thing, lol.

[mPlasticDesign]

You also have to consider/include the extra cooling in the S55 that the S65 does not have.

[catpat8000]

Originally Posted by Boss330

The F1 tech of regenerating electricity from the turbo and also aiding spool up time was discussed in a few other threads a while ago.

To quote myself again

And a little bit on lag and response, since that has been brought up again...

Too many threads on bimmerpost - can't keep up!

Pat

[Sedan_Clan]

I'm going to laugh my ass off if this S55 engine becomes adored. People were fairly resistant to BMW going to the V8 too, and people were writing it off long before they were able to drive it because it wasn't an I6.

[aus]

Originally Posted by 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

An extra 700 RPM doesnt matter if it's not making power up there.
There is also NO WAY an I6 will sound as good as a V8, no matter what exhaust you put on it.
As for efficiency, the new Porsches get excellent mileage, make great power and don't have a blower. The S55 is all abou saving money.
If you don't track the car, you'll never really appreciate what it's like to rev out a high rev motor that lets you reach the next turn without needing to shift.

Originally Posted by swamp2

Just as you say it...



It can be a bit tricky to discriminate throttle response and lag when widely varying throttle maps are used. For instance using the aggressive throttle mapping in the S65 M3, I would say the throttle is too sensitive at low throttle openings. This can give an illusion of a "faster" car or better throttle response or it can just make the car downright jumpy and too sensitive (which is my evaluation). However, I find it next to impossible to believe that you find a turbo charged N55 to have a better throttle response than the S65. You really must be confused.

Agree completely.