Can someone explain why the GTS lapped 7.7 seconds faster than the standard M4?

[natedog7700]

Is the faster lap mainly because or horsepower? Why is the time so much faster I thought it was pretty much the same except a couple hundred lbs lighter and a little more horsepower with a couple small tweaks. Plus the added aesthetic stuff to make it worthy of being the GTS.

I guess I'm kind of wondering, would it be possible to achieve close to 2:53 with a standard M4 by just adding more hp and better tires (with adaptive suspension) or is there more to it?


Standard 2015 M4 3:00.7
2016 M4 GTS. 2:52.9
https://www.caranddriver.com/feature...storical-data/

[robbo mcs]

Originally Posted by natedog7700

Is the faster lap mainly because or horsepower? Why is the time so much faster I thought it was pretty much the same except a couple hundred lbs lighter and a little more horsepower with a couple small tweaks. Plus the added aesthetic stuff to make it worthy of being the GTS.

I guess I'm kind of wondering, would it be possible to achieve close to 2:53 with a standard M4 by just adding more hp and better tires (with adaptive suspension) or is there more to it?


Standard 2015 M4 3:00.7
2016 M4 GTS. 2:52.9
https://www.caranddriver.com/feature...storical-data/

Its the whole package. Better tyres. Better suspension. Better aero. Better brakes. Lighter. More power. Geometry ie ride height, rake, alignment, Etc etc

[F3IGHTY]

Tires, dampers, tune and you’re there

[CanAutM3]

Originally Posted by robbo mcs

Its the whole package. Better tyres. Better suspension. Better aero. Better brakes. Lighter. More power. Geometry ie ride height, rake, alignment, Etc etc

^ This

It’s the incremental gain of each element and how they work in harmony to provide the total performance gain.

[natedog7700]

Originally Posted by robbo mcs

Its the whole package. Better tyres. Better suspension. Better aero. Better brakes. Lighter. More power. Geometry ie ride height, rake, alignment, Etc etc

Aero cant be 7 seconds thoug, what do you think are the biggest gains from the GTS? Tires and suspension? I see the GTS was running a special tire compared to the standard M4

[CanAutM3]

Originally Posted by natedog7700

Aero cant be 7 seconds thoug, what do you think are the biggest gains from the GTS? Tires and suspension? I see the GTS was running a special tire compared to the standard M4

Have you read your own thread and what I and others have posted?

It's not a single thing that provides the improvement, it's the incremental gain of each improved element and also very importantly, how they all work together.

Regarding tires, PSC2 are worth around 0.5 ~ 1.0 second per minute lap over the PSS on a single flying lap. However, just changing tires, you will not get the most out of them because the suspension will not be able to fully cope with the added grip.

Weight reduction is much more significant than people like to believe. For example, a 100lb weight reduction on an M4 is like adding 12hp across the entire RPM band (not only peak) which is worth a lot more than what the CP tune offers over the base tune. And that's only on acceleration. Weight reduction also contributes to improve handling and puts less strain on braking.

[natedog7700]

Originally Posted by CanAutM3

Have you read your own thread and what I and others have posted?

It's not a single thing that provides the improvement, it's the incremental gain of each improved element and also very importantly, how they all work together.

Regarding tires, PSC2 are worth around 0.5 ~ 1.0 second per minute lap over the PSS on a single flying lap. However, just changing tires, you will not get the most out of them because the suspension will not be able to fully cope with the added grip.

Weight reduction is much more significant than people like to believe. For example, a 100lb weight reduction on an M4 is like adding 12hp across the entire RPM band (not only peak) which is worth a lot more than what the CP tune offers over the base tune. And that's only on acceleration. Weight reduction also contributes to improve handling and puts less strain on braking.

Okay ill dumb it down a bit, i would agree but you're not going to see 25 improvements adding .25 seconds each. My question was, what adds the MOST or which 3, to the better lap time? You could have 5 improvements (example's: carbon fiber roof, suspension tuning, 100lb weight loss, +25hp) pulling a second from the lap time vs one or two things pulling 2 or more seconds.

[CanAutM3]

Originally Posted by natedog7700

Okay ill dumb it down a bit, i would agree but you're not going to see 25 improvements adding .25 seconds each. My question was, what adds the MOST or which 3, to the better lap time? You could have 5 improvements (example's: carbon fiber roof, suspension tuning, 100lb weight loss, +25hp) pulling a second from the lap time vs one or two things pulling 2 or more seconds.

Your question in the OP was specific about what makes the GTS faster than a base M4 around a track and you got the appropriate responses.

If you really meant what is the single mod that will make the biggest improvement in lap times on a base M4, the answer is simple: driver skill . The next best thing is R-compound tires . But it will not turn a base M4 into a GTS.

[RichBunch2]

This might help explain some things for you...
https://f80.bimmerpost.com/forums/at...8;d=1463413166

[M3SQRD]

The speed thru the climbing esses at VIR definitely increases with functional aero so I wouldn’t be surprised if a large portion of the 7 sec delta at VIR did not primarily come from the aero + PSC2 tires on the GTS.

[MasterP]

MPSC2's from MPSS is likely a 2-3 second gap. Aero on a 2:30 plus minute track is another 2-3 seconds. Suspension gets more out of the whole setup. Suspension, power, weight, faster DCT shifts. It all adds up on a track that big. I think that the standard car being only 7 or so seconds behind says more about the abilities of the base car than it does about the GTS.

[dvas]

Tires? SC2 is around 2 - 3 seconds a lap faster than PSS around Limerock, which is a 1-minute track. Extrapolate that that to a 3-minute track and you have a 6 - 9 second gap.

[OhioRiderAaron]

Originally Posted by MasterP

MPSC2's from MPSS is likely a 2-3 second gap. Aero on a 2:30 plus minute track is another 2-3 seconds. Suspension gets more out of the whole setup. Suspension, power, weight, faster DCT shifts. It all adds up on a track that big. I think that the standard car being only 7 or so seconds behind says more about the abilities of the base car than it does about the GTS.

Originally Posted by dvas

Tires? SC2 is around 2 - 3 seconds a lap faster than PSS around Limerock, which is a 1-minute track. Extrapolate that that to a 3-minute track and you have a 6 - 9 second gap.

I think most of the delta is tires and suspension. It would be nice to know what the suspension setup/alignment was on the GTS.

I think it would be interesting to see them run a stock, off the showroom floor model, vs say...a car equipped with extreme performance tires or camber plates so we could really use the effectiveness of such mods. They could write a separate 1/2 page article about it too.

[CanAutM3]

Originally Posted by dvas

Tires? SC2 is around 2 - 3 seconds a lap faster than PSS around Limerock, which is a 1-minute track. Extrapolate that that to a 3-minute track and you have a 6 - 9 second gap.

That's not quite my experience with the PSC2. I'd say they are worth between 0.5 to 1.0 second per minute lap over the PSS on a flying lap. 2-3 seconds over a one minute lap seems overly optimistic.

The PSC2 will however remain more consistent over an entire session compared to the PSS, where the PSS will overheat and start to fall off after being pushed for multiple laps.

[dvas]

Originally Posted by CanAutM3

That's not quite my experience with the PSC2. I'd say they are worth between 0.5 to 1.0 second per minute lap over the PSS on a flying lap. 2-3 seconds over a one minute lap seems overly optimistic.

The PSC2 will however remain more consistent over an entire session compared to the PSS, where the PSS will overheat and start to fall off after being pushed for multiple laps.

Mileage may vary, especially depending on suspension setup? 3 seconds may be optimistic, but around 2 seconds was my experience. Agree on your second point that they are more heat tolerant, longer.

[The HACK]

I'm about to drop some RICER math on you.

Weight makes a HUGE difference. You wouldn't think it does, but it DOES. It slows you down coming out of corners, on a track with LONG straights, you're looking at seconds worth per hundred pounds. I took my Corvette C7 Grand sport to a local track last October, went out one session with no passengers, and one more session with a 200 lbs passenger. It being late October the weather conditions didn't change much between the two sessions, but my AVERAGE LAP TIME on the 2.8 mile track was a whopping 4 second difference.

On a track I've driven a thousand times.

Granted, I usually drive with an extra 10th of caution when I'm responsible for SOMEONE else's life on track, but at most that accounts for maybe 1 second of average difference on this particular track. And believe you me. It was a fellow instructor so I was out to impress and wasn't pussy-footing it.

Nothing changed between the first session (SOLO) and the second (w/ Passenger) except maybe about 1/4 tank of gas. So maybe 170 lbs instead of 200 lbs difference between the two sessions.

So a 150 lbs difference in weight can easily account for 3 seconds of lap time at a track like VIR. With a more accomplished driver that delta may even be bigger.

Tires makes another HUGE difference. Let's just use a conservative figure of 0.5 second per 1 mile, although I suspect the difference between MPSS and MPSCup2 is probably significantly larger than that. Heck on the same 2.8 mile track, I was told the difference between similar R-comps can be as much as 2 seconds. My lap time between Maxxis RC-1 and Nitto NT-01 of the SAME SIZE shows that there's about a 1-1.5 second per lap difference in, again, same track, same car. And that's between two R-comps RUMORED to share the same rubber compound. Cup2 and Super Sport? Again, let's just be conservative and say 2 seconds for VIR. We're already at 5 seconds of difference just from weight and tires ALONE.

And we haven't even touched BRAKES yet.

Here I don't have any empirical data, except, MY personal experience with CCM brakes and upgraded, 2 piece rotor, fixed caliper BBKs on my own car running track pads seems to suggest that CCM brakes are far superior at handling heat. Bone stock I can brake harder, later, in a shorter span and slow down significantly quicker with the CCM on the Corvette than I ever could in my BMW with iron 2 piece rotors in fixed calipers running Hawk DTC-60 pads. It is not unreasonable to say I can push my braking point back and compress it by about 1/10th of a second for every single braking zone and gain that much time per application on a decent lap. I mean, again, that's pure conservatism speaking here. The CCMs are THAT good from a pure performance perspective (dollar per stop though, that's another story). Assuming a complicated track like VIR has 7-10 braking zones, you're looking at at least another second for the advantages CCMs would get you.

We're already at 6 seconds per lap. And we haven't even touched aero and suspension yet.

Bear with me. I'm in full bench racing mode here.

Aerodynamic advantages are REAL. Especially if you're coming up on a fast sweeping turn that follows with a moderate or long straight, a 2-5 mph faster speed through the turns is a 2-5 mph faster speed down the straight (assuming the drag negates the advantage coming out of the turn). that same 2-5 mph faster speed all throughout a say, .5 mile long straight, means a quarter second advantage per straight. Just aero advantage along can net you another second if there are 4 long straights that are preceded by a high speed corner. There isn't at VIR so I'll go über conservative again and say the aero gives you at least 1/2 second.

We're at 6.5 second per lap. Without mentioning better dampers, better springs, and better lateral grip that results from all this working as a system.

So if you ask me? I'm surprise the advantage is only 7 seconds and change. It should really be larger. For a 3.xx mile long course? Just the 150 or so lbs weight reduction is probably worth about 4-5 seconds. And the Cup 2 tires another 2-3.

[CanAutM3]

Originally Posted by The HACK

I'm about to drop some RICER math on you.

Weight makes a HUGE difference. You wouldn't think it does, but it DOES. It slows you down coming out of corners, on a track with LONG straights, you're looking at seconds worth per hundred pounds. I took my Corvette C7 Grand sport to a local track last October, went out one session with no passengers, and one more session with a 200 lbs passenger. It being late October the weather conditions didn't change much between the two sessions, but my AVERAGE LAP TIME on the 2.8 mile track was a whopping 4 second difference.

On a track I've driven a thousand times.

Granted, I usually drive with an extra 10th of caution when I'm responsible for SOMEONE else's life on track, but at most that accounts for maybe 1 second of average difference on this particular track. And believe you me. It was a fellow instructor so I was out to impress and wasn't pussy-footing it.

Nothing changed between the first session (SOLO) and the second (w/ Passenger) except maybe about 1/4 tank of gas. So maybe 170 lbs instead of 200 lbs difference between the two sessions.

So a 150 lbs difference in weight can easily account for 3 seconds of lap time at a track like VIR. With a more accomplished driver that delta may even be bigger.

Tires makes another HUGE difference. Let's just use a conservative figure of 0.5 second per 1 mile, although I suspect the difference between MPSS and MPSCup2 is probably significantly larger than that. Heck on the same 2.8 mile track, I was told the difference between similar R-comps can be as much as 2 seconds. My lap time between Maxxis RC-1 and Nitto NT-01 of the SAME SIZE shows that there's about a 1-1.5 second per lap difference in, again, same track, same car. And that's between two R-comps RUMORED to share the same rubber compound. Cup2 and Super Sport? Again, let's just be conservative and say 2 seconds for VIR. We're already at 5 seconds of difference just from weight and tires ALONE.

And we haven't even touched BRAKES yet.

Here I don't have any empirical data, except, MY personal experience with CCM brakes and upgraded, 2 piece rotor, fixed caliper BBKs on my own car running track pads seems to suggest that CCM brakes are far superior at handling heat. Bone stock I can brake harder, later, in a shorter span and slow down significantly quicker with the CCM on the Corvette than I ever could in my BMW with iron 2 piece rotors in fixed calipers running Hawk DTC-60 pads. It is not unreasonable to say I can push my braking point back and compress it by about 1/10th of a second for every single braking zone and gain that much time per application on a decent lap. I mean, again, that's pure conservatism speaking here. The CCMs are THAT good from a pure performance perspective (dollar per stop though, that's another story). Assuming a complicated track like VIR has 7-10 braking zones, you're looking at at least another second for the advantages CCMs would get you.

We're already at 6 seconds per lap. And we haven't even touched aero and suspension yet.

Bear with me. I'm in full bench racing mode here.

Aerodynamic advantages are REAL. Especially if you're coming up on a fast sweeping turn that follows with a moderate or long straight, a 2-5 mph faster speed through the turns is a 2-5 mph faster speed down the straight (assuming the drag negates the advantage coming out of the turn). that same 2-5 mph faster speed all throughout a say, .5 mile long straight, means a quarter second advantage per straight. Just aero advantage along can net you another second if there are 4 long straights that are preceded by a high speed corner. There isn't at VIR so I'll go über conservative again and say the aero gives you at least 1/2 second.

We're at 6.5 second per lap. Without mentioning better dampers, better springs, and better lateral grip that results from all this working as a system.

So if you ask me? I'm surprise the advantage is only 7 seconds and change. It should really be larger. For a 3.xx mile long course? Just the 150 or so lbs weight reduction is probably worth about 4-5 seconds. And the Cup 2 tires another 2-3.

A few counterpoints:

A US spec M4GTS is not 150lb lighter than a base M4. While the GTS does have some weight reduction elements, some of it is offset by the rollcage and heavy ass 0.5" wider 666M wheels. The US spec GTS does not have the EU lightweight bucket seats. I reckon a US spec GTS is close to an M4cs in weight, maybe 50lb lighter than a base M4.

The PSC2 are relatively mild R-comp tire. They are quite less aggressive than the NT01 I normally use, which aren't the grippiest R-comp out there to start with. I'd say 0.7 seconds per mile is the most difference you'd get between a fresh sets of PSC2 and PSS on a flying lap.

I reckon the difference provided by CCM rotors is marginal at best. Even if the CCM were indeed capable of providing better braking (which has been demonstrated not being the case) over the course of a full lap, you spend very little time braking, so there isn't much time to be gained. Further, for the sake of the C&D Lightning Lap comparution on which this thread is based, it’s a moot point because the base 2015 M4 was also equipped with CCB.

It is also a common misconception to believe that if one exits a corner at a higher speed that one will maintain that speed advantage throughout the straight. In reality, the speed advantage diminishes as you travel down the straight. That being said, exiting a corner faster makes a big difference on lap time because the average speed through the straight is higher.

I reckon (bench racing gross estimates):

• Tires (PSS to PSC2) = 2.0 seconds
• Power (70hp) 1.5 seconds
• Aero (250lb added downforce @ 125mph) = 1.5 seconds
• Coilover suspension = 1.0 seconds
• Weight (50lb) = 0.7 seconds
• CCB = 0.0 seconds
• All elements working in unison = 1.0 seconds

[robbo mcs]

Also, it is worth remembering that all the gains are not additive on top of one another they work together.

For example, say for argument that tires as the only change made a 3 second improvement. Also for arguments sake, suspension as the only change made a 3 second improvement. If you then did tires + suspension, you would not get a 6 second gain. Probably, something more like a 4 - 4.5 second gain.

The faster you go, the harder it is to make more gains. So for people saying that individual components themselves are worth a large percentage of the gain, and they are surprised the total delta is not bigger, that is your answer.

The fact that individual components on the GTS are designed to work together is very important, and helps maximise the total gains of components together

[mfurse]

I was once told "Tyres, Talent and Testing" in that order make the biggest track time improvements.

[CanAutM3]

Originally Posted by robbo mcs

Also, it is worth remembering that all the gains are not additive on top of one another they work together.

For example, say for argument that tires as the only change made a 3 second improvement. Also for arguments sake, suspension as the only change made a 3 second improvement. If you then did tires + suspension, you would not get a 6 second gain. Probably, something more like a 4 - 4.5 second gain.

The faster you go, the harder it is to make more gains. So for people saying that individual components themselves are worth a large percentage of the gain, and they are surprised the total delta is not bigger, that is your answer.

The fact that individual components on the GTS are designed to work together is very important, and helps maximise the total gains of components together

I agree with the point that "gains work together" as I've said the same myself in previous posts in this thread. I however disagree with your math.

You are contradicting yourself in your argumentation. If the sum of the total gains is less than the sum of the individual gains, it means that the modifications are working AGAINST each other. I believe it should be the other way around. For example, if the modifications are properly tuned to "work together", the total time gained by the combined modifications needs to be greater then the sum if the individual gains. For example, if doing tires only gets you 2 seconds and doing suspension only gets you 1 second, doing both and tuning them to "work together" would get you 3.5 seconds.

Most amateur drivers/tuners are not able to achieve these "total gains" because of general lack of skill in both driving and tuning. Driving at the limit to exploit the full performance envelop of the equipment and chassis tuning are both very complex and fine arts that very few master.

[DJM4]

Maybe the GTS driver was better

[SD ///M4]

In August 2016, during the BMW CCA Annual Oktoberfest which was held in Monterey that year, I had a chance to take a few Charity Hot Laps at Laguna Seca in an M4 GTS driven by Tom Plucinzky, one of BMW's drivers. The Charity rides took placed near the end of the event and I had already done two days of lap sessions prior to this, so the comparison was fresh. My M4 has Ground Control camber plates, Dinan HAS, Nitto NT01 tires on Apex wheels (275/35-18x10 front, 305/35-18x11 rear), and the M Performance Exhaust but is stock otherwise. My only aero is the M Performance CF rear spoiler and CF rear diffuser, so basically nothing.

The first thing I noticed is that the acceleration was noticeably faster than my 2016 M4. Surprisingly similar, but definitely faster. The really big thing I noticed was the first time we came to a corner at speed. Tom drove really deep into the corner and slammed on the brakes. It just about popped out my eyeballs with the deceleration g-force and I strained against the harness. I apparently looked really surprised and Tom explained that with the combination of the carbon ceramic brakes and the massive aero wing and front splitter, that to be most effective, braking had to be extreme. If you bled off speed before hitting the brakes hard, either by lifting the throttle or by easing into the braking, that you were losing the aero effect on the braking. So every corner was dive deep, slam on the brakes, point the car, and then accelerate out. Once I knew that, the rest of the ride was exhilarating and I looked forward to the extreme braking at every corner.

So the GTS accelerates much faster, no doubt corners much better, but definitely brakes much more quickly. Overall, I was surprised how similar it felt and sounded to my M4 but just more extreme. A fun ride to be sure!