[dmboone25]

Originally Posted by RPM33

I still have an OG M2. Can someone explain what those five buttons do in the M2 CS console (last photo at the bottom)?

Top one it to turn DSC off.

Next one is for throttle sensitivity (comfort, sport, sport +)

Third one is adaptive suspension (comfort, sport, sport +)

Fourth one is steering weight (comfort, sport, sport +)

Last one is for parking sensors.

[RPM33]

Originally Posted by dmboone25

Top one it to turn DSC off.

Next one is for throttle sensitivity (comfort, sport, sport +)

Third one is adaptive suspension (comfort, sport, sport +)

Fourth one is steering weight (comfort, sport, sport +)

Last one is for parking sensors.

Thanks DmBoone. I think the CS is going to be a fun car. The OG M2 is already fun, could only imagine the CS power and handling.

[lax01]

Originally Posted by RPM33

I still have an OG M2. Can someone explain what those five buttons do in the M2 CS console (last photo at the bottom)?

Increase the cost of the car by about 20%!

[Benzima]

MSRP M2CS for Canada 97750$ CAD

[Karmic Man]

Originally Posted by akkando

I think the the redline is more to do with the zf auto transmission?

Engine design

S55 89.6 mm bore, 80.0 mm stroke, 7500 redline
S58 84.0 mm bore, 90.0 mm stroke, 7200 redline
B58 82.0 mm bore, 94.6 mm stroke, 7000 redline

[medphysdave]

Originally Posted by Karmic Man

Engine design

S55 89.6 mm bore, 80.0 mm stroke, 7500 redline
S58 84.0 mm bore, 90.0 mm stroke, 7200 redline
B58 82.0 mm bore, 94.6 mm stroke, 7000 redline

A lot of it is also reciprocating mass and a crankshaft that can tolerate the abuse. Money has to be spent on lighter pistons, rods, and keeping the assembly balanced. Then you get into the cylinder head components. It's cheaper to build a lower revving engine. I'm actually surprised to see a much smaller piston in the B58/S58.

[Conissah]

Originally Posted by Karmic Man

Engine design

S55 89.6 mm bore, 80.0 mm stroke, 7500 redline
S58 84.0 mm bore, 90.0 mm stroke, 7200 redline
B58 82.0 mm bore, 94.6 mm stroke, 7000 redline

A lot of reading (not directed at anyone in particular, just a blanket statement) can be done on oversquare vs undersquare to try and better understand the engine designs here. The longer stroke on the B58 is the obvious reason for the lower redline, and can explain why it makes peak torque (and peak power) sooner than its' shorter stroked siblings. This "instant" torque is the reason most people think that the B58 feels faster.

[medphysdave]

What are the compression ratios of S55 and S58. Sorry, I'm sure there is a thread comparing the two. Up until these posts I wasbt interested in the differences, but now I'm curious. Is the 58 series a lower comp higher boost motor to gain more torque?

[Conissah]

Originally Posted by medphysdave

What are the compression ratios of S55 and S58. Sorry, I'm sure there is a thread comparing the two. Up until these posts I wasbt interested in the differences, but now I'm curious. Is the 58 series a lower comp higher boost motor to gain more torque?

S55 = 10.2:1
S58 = 9.3:1

S58 technical docs can be found HERE!

[medphysdave]

Thanks, please forgive my ignorance as I'm not trying to get into a motor debate. The shift of the power band leads me to believe that the s55 has a better flowing head, but the S58 is using lower compression to maximize the ability to run higher boost.

What are the turbo sizes for S58 and s55. I suspect S58 has a larger turbo. The lower compression will certainly allow a lot of hp/tq gain from increasing boost without running e85 or race fuel. I would assume the block strength is comparable.

[Poochie]

Originally Posted by medphysdave

Thanks, please forgive my ignorance as I'm not trying to get into a motor debate. The shift of the power band leads me to believe that the s55 has a better flowing head, but the S58 is using lower compression to maximize the ability to run higher boost.

What are the turbo sizes for S58 and s55. I suspect S58 has a larger turbo. The lower compression will certainly allow a lot of hp/tq gain from increasing boost without running e85 or race fuel. I would assume the block strength is comparable.

That's true what you said about lower compression can utilize higher boost levels, it's well know in the tuning world.

Also, the S55 has some baby dick turbos but apparently size doesn't matter, 'cause it gets the job done and has bottomless tuning potential, with the exception of its Achilles Heel; the weak crank hub.

I cant find a picture but I'm 100% the S58 turbos are larger.

[medphysdave]

Yes, in the Miata community when getting upwards of 400whp folks would put in 8.5:1 pistons. Kinda makes it a dog when not in boost.

It just struck me as odd when I saw the numbers due to the comments about the S58 being superior to the S55. I automatically assumed it was true because it's the latest and greatest, but something doesn't add up. Unless the internals of the S58 are significantly stronger it would appear it's designed to make power more cheaply. The ideal combo is high comp and high boost to keep response up when out of boost and spool the turbos more quickly, but the safety margin is much smaller due to detonation.

I would expect the S58 to be less zippy, but some of this can be masked with gearing to keep rpms up.

[Conissah]

Originally Posted by medphysdave

It just struck me as odd when I saw the numbers due to the comments about the S58 being superior to the S55. I automatically assumed it was true because it's the latest and greatest, but something doesn't add up. Unless the internals of the S58 are significantly stronger it would appear it's designed to make power more cheaply. The ideal combo is high comp and high boost to keep response up when out of boost and spool the turbos more quickly, but the safety margin is much smaller due to detonation.

I would expect the S58 to be less zippy, but some of this can be masked with gearing to keep rpms up.

Perhaps the S58 will be near its limit, pushing a butt ton of boost stock to hit its power figures? The S55, as we know it, has plenty of head room for tuning, and it's no dog from the factory. I guess the only real way to know is to wait until people start modding the S58, and we can all see how it responds.

I was unaware of the comp ratios until I posted it, and now thinking on it, it could prove to be a let down. BMW engineers surely know more than me, but if they are relying purely on boost to make power, wouldn't that end up becoming a flaw? Idk, really just talking aloud here.

NOTE: In that technical document, it only references the S58 in the current SUV chassis. Perhaps the SUV S58 has a lower comp ratio since it will ONLY be paired to the ZF8, and it's a big SUV that won't really benefit from more low end? If, for some reason, they make an S58 with higher compression, and throw that in the new M2/3/4, then that would potentially make sense. Just wanted to point out that in the document I linked above, the chassis designation for the X3M and X4M are the only ones listed. Just made me think.

[medphysdave]

Very interesting indeed. It runs out of gas at a lower rpm, which could be the choice in hot and cold side to aid spooling large impellars more quickly. I can't imagine they would create a head that flows less air so it may just be the turbos running out of gas. All in all it seems that BMW builds a stout base block, crank, etc. So turbos and headwork can create big power.

You may be on to something that a change in turbos for M cars could unleash the beast.

[Hegge]

Speaking of the S58, new X3 M owners have been reporting turbo lag. Also in the M driving events last summer comparing X3 M, M4, M2, there was a lot of turbo lag reported with the X3 M.

[Conissah]

Originally Posted by Hegge

Speaking of the S58, new X3 M owners have been reporting turbo lag. Also in the M driving events last summer comparing X3 M, M4, M2, there was a lot of turbo lag reported with the X3 M.

The M2C has lag in Efficient mode, but in Sport or Sport+ it essentially vanishes. The higher, pretty much NA, levels of compression ratio also could be helping the S55 to not feel like crap at low RPM. Sure, it doesn't have an insane amount of torque compared to when it's in boost, but based off the comp ratio alone, the S55 "could" actually make a decent NA i6. The same cannot be said for S58, a 9.3:1 ratio is low, and in NA form (which obviously isn't the point of the motor) would feel like ass. This also explains why some are complaining about the lag in the 58, since it literally has no balls out of boost. If BMW is relying purely on boost, then, as I previously mentioned, I personally think this could be a downfall to it. Sure, it makes 475+ hp, but if it's getting that from 30 psi stock, idk how much more we could expect the stock motor/turbos to handle.

Just listing my personal reference points here, the VQ35DE in my other car has a 10.3:1 ratio stock, for an NA V6 (almost the same as the boosted S55).

[medphysdave]

M2 CS listed in the 2020 technical guide.

https://www.press.bmwgroup.com/canad...EN?language=en

CS looks to be about 55lbs lighter than the C.

[Karmic Man]

As a comparison with two Porsche engines just for fun

911 Carrera series (2,981 cc)
Bore/Stroke - 91.0 mm/76.4 mm
Compression ratio - 10.0:1
Redline - 7500 rpm

911 Turbo/S (3,800 cc)
Bore/Stroke - 102.0 mm/77.5 mm
Compression ratio - 9.8:1, 9.0:1 (GT2 RS)
Redline - 7200 rpm

[Karmic Man]

Originally Posted by medphysdave

M2 CS listed in the 2020 technical guide.

https://www.press.bmwgroup.com/canad...EN?language=en

CS looks to be about 55lbs lighter than the C.

CS weight is listed as 1,550 kg (DIN) there which is the same as the M2C

[medphysdave]

Originally Posted by Karmic Man

CS weight is listed as 1,550 kg (DIN) there which is the same as the M2C

Under the US weight it looks to be 55lbs lighter in both empty car and with fluids. That's odd.

Payload increases by 30lbs so I'm guessing stiffer springs.

No charge for gold wheels and cup 2s, but you gotta pay for paint colors. Killin me BMW just price it so you can pick whatever color you want.

[AlpsRider]

Originally Posted by medphysdave

Under the US weight it looks to be 55lbs lighter in both empty car and with fluids. That's odd.

Payload increases by 30lbs so I'm guessing stiffer springs.

No charge for gold wheels and cup 2s, but you gotta pay for paint colors. Killin me BMW just price it so you can pick whatever come you want.

The BMW adaptive suspension has soft springs so that the suspension can be soft in comfort mode. They use the dampers to make the suspension stiffer.

[dmboone25]

Well guys, I have officially let my allocation for the M2CS go. I have been going back and forth on whether or not the car was for me for a few months now, and I decided to go in a different direction.

I was lucky enough to score a one owner, 2016 CPO 981 BGTS that only has 3K miles on the odometer. This was a local guy's 4th car or something and he only drove it on really nice days apparently.

I had a 981 CS a couple of years ago, and I lamented letting it go after the fact, so this is a way for me to try something new (never had a convertible before) while enjoying some naturally aspirated goodness. And since we already have an OG M2 in the garage, I can still get my ///M fix when I need it.

On that note, the M2CS is going to be a great car, and I am really looking forward to getting to see how they're received (and hopefully one in person at some point).