M4 vs Giulia QV - MT BDC Hot Lap

[CanAutM3]

Giulia QV was only able to beat the base M4 by 0.01 seconds around MLSR despite being shod with R-compound tires and having an 80hp advantage:

1:39.68 Giulia QV
1:39.69 2015 M4

[w00tw00t]

All these mag videos are super fun to watch but don't tell me much other than being fun to watch. I'm not Randy at Laguna and I think its more about how easy is a car for me to drive... meaning I want a car that I can drive easily at fast speeds.. for e.g, I bet I'd be much slower in an ACR because its limits are so high.. but a M2/M3 I can more easily drive fast...

Also from a track day perspective, I'd buy a car that has great aftermarket support, is reliable, and I see ton of them on the track ... aka //M ... the Giulia has poor dealer support, has had many reported reliability issues and has no good after market support. In my mind the M4 wins everytime..

[Wills2]

Were both cars on CCB? The M4 was but not sure what difference that would make on a single lap of that track.

[Nikolas]

Originally Posted by Wills2

Were both cars on CCB? The M4 was but not sure what difference that would make on a single lap of that track.

Probably none. Stopping distance has more to do with tires, since Ccb and steel are both hitting abs in hard stops. Ccb will have less fade, but that would be minimal in a test like this. Most track nuts opt for the steel.

[CanAutM3]

Originally Posted by Wills2

Were both cars on CCB? The M4 was but not sure what difference that would make on a single lap of that track.

For a few fast laps, I seriously doubt the CCB will make much difference in lap times.

[Towerworld]

Originally Posted by w00tw00t

All these mag videos are super fun to watch but don't tell me much other than being fun to watch. I'm not Randy at Laguna and I think its more about how easy is a car for me to drive... meaning I want a car that I can drive easily at fast speeds.. for e.g, I bet I'd be much slower in an ACR because its limits are so high.. but a M2/M3 I can more easily drive fast...

Also from a track day perspective, I'd buy a car that has great aftermarket support, is reliable, and I see ton of them on the track ... aka //M ... the Giulia has poor dealer support, has had many reported reliability issues and has no good after market support. In my mind the M4 wins everytime..

Would you not be faster in the ACR because of that reason though? because you can drive as fast or faster than an m3 at its limits but not be anywhere near the point where the ACR begins to lose traction?

[CanAutM3]

Originally Posted by Nikolas

Probably none. Stopping distance has more to do with tires, since Ccb and steel are both hitting abs in hard stops. Ccb will have less fade, but that would be minimal in a test like this. Most track nuts opt for the steel.

It is more complex than this.

It is all about how static and kinetic frictions are balanced between the pad-disc and tire-road interfaces. A less powerful or faded brake system can still have the capability to lock-up or induce ABS, but it will provide much less kinetic friction at the pad-disc interface and will not be able to fully exploit the grip provided by the tires.

And the rotors are not made of steel, but of iron

[ClothSeats]

Carbon ceramic rotors are advertised as being lighter vs cast iron rotors. This weight savings is amplified being an unsprung component (like lightweight wheels). But I haven't seen how much weight exactly.

[Parabolica]

Hard to compare between 2014 and 2017. Different day, conditions, etc. Conditions plays a huge part at Laguna Seca due to the 'dirt' you can get on the track.

[Nikolas]

Originally Posted by CanAutM3

It is more complex than this.

It is all about how static and kinetic frictions are balanced between the pad-disc and tire-road interfaces. A less powerful or faded brake system can still have the capability to lock-up or induce ABS, but it will provide much less kinetic friction at the pad-disc interface and will not be able to fully exploit the grip provided by the tires.

And the rotors are not made of steel, but of iron

Sorry, my bad. I know they're iron, I just always referred to them as "steelies". I got the same ribbing from my P-car buddies!

Regardless, carbon ceramics won't make you stop in a shorter distance. Or induce abs less than iron. Their main advantages are fade resistance and unsprung weight, both of which are negated by price for track use by the unfunded track rat.

In this comparison I doubt the brake type had any major impact. Over multiple laps, possibly.

[CanAutM3]

Originally Posted by Nikolas

Sorry, my bad. I know they're iron, I just always referred to them as "steelies". I got the same ribbing from my P-car buddies!

Originally Posted by Nikolas

Regardless, carbon ceramics won't make you stop in a shorter distance. Or induce abs less than iron. Their main advantages are fade resistance and unsprung weight, both of which are negated by price for track use by the unfunded track rat.

What is the result of brake fade? Answer: longer stopping distances. With enough repeated stops to get the stock iron brake system to fade, CCB will eventually yield shorter stopping distances.

But don't get me wrong, I am fully on the same page as you. Being a track rat myself, I did not opt for the CCB due to their prohibitive cost with track use. Further, I get practically the same overall braking performance (including resistance to fade) with the iron rotors paired with proper track pads.

Originally Posted by Nikolas

In this comparison I doubt the brake type had any major impact. Over multiple laps, possibly.

We are in agreement, I posted the same in post #5 .

[CanAutM3]

Originally Posted by Parabolica

Hard to compare between 2014 and 2017. Different day, conditions, etc. Conditions plays a huge part at Laguna Seca due to the 'dirt' you can get on the track.

Agreed. As with any track comparisons, there are many variables at play. At least here we have the same very skilled driver, particularly on this specific track, as a constant.

To me, this is just one more data point that shows that the Giulia QV, despite it's R-compound tires and significant power advantage, is not able to trounce the M3/4 on a track. So it still leaves me with the same unanswered question, if the Giulia QV has more grip, better acceleration and better overall driving dynamics (according to so many reviews), why is it not any faster around a track?

[CanAutM3]

Originally Posted by ClothSeats

Carbon ceramic rotors are advertised as being lighter vs cast iron rotors. This weight savings is amplified being an unsprung component (like lightweight wheels). But I haven't seen how much weight exactly.

I'll simply quote what I posted a while back:

Originally Posted by CanAutM3

There are quite a few discussions on this exact topic in the "Brake and Chassis" sub-forum, you should have a look there (you even linked one thread and all the info you seek is in there).

The impact of inertia is real and it is not a myth. However there are multiple factors to consider (gearing, rolling radius, shape of the object, etc...) to assess that impact and you cannot take a blanket number like your 1kg to 5kg correlation.

As I posted here, doing rough calculation for the F8X, the equivalent mass ratio of the brake disc is about 1.20. This means that every lb of disc weight is equivalent to 1.2lb of non-rotating mass on the car. A reduction of 27.5lb on the discs equates to 33lb equivalent mass. Add back the 13lb from the heavier callipers (27.5-14.5) and you end up with a 20lb equivalent mass reduction on the total car (~0.5%). Not significant IMO.

Also don't confuse unsprung mass and rotational mass. Rotational mass increases the equivalent weight of the vehicle and impacts the power needed the accelerate or brake the car. Reducing unsprung mass allows the suspension to better react to changes in the shape of the road and helps keep the tire in contact with the tarmac. IMO, the latter is biggest benefit of the CCB from a performance point of view. For reference, the CCB provide about 6.9lb rotational mass reduction and 3.6lb of unsprung mass reduction per corner. If this is worth $8500, that is entirely up to you .

[No Boost]

Originally Posted by CanAutM3

So it still leaves me with the same unanswered question, if the Giulia QV has more grip, better acceleration and better overall driving dynamics (according to so many reviews), why is it not any faster around a track?

My guess....tighter, more rigid chassis.

[M3Tooner]

Originally Posted by CanAutM3

So it still leaves me with the same unanswered question, if the Giulia QV has more grip, better acceleration and better overall driving dynamics (according to so many reviews), why is it not any faster around a track?

My guess is that the driver is never in full control of the Giulia QV, as in the stability program cannot be fully disabled, eventhough in Race Mode. It is always doing something in the background to help the driver. While it may help most beginner to intermediate drivers, it certainly will be more of a hindrance to a pro driver like Randy, thus he couldn't drive it as fast as the stats suggest this car can do.

In the video, Randy did mention that sometimes the car turns in really well but sometimes understeers a lot. Seems like maybe the torque vectoring system is getting overwhelmed by heat or something and is not able to always give the car it's intended dynamic behavior. Our Active M-Differential sure does not seem to have this problem.

I have a few days worth of seat time in this car on the road, not race track. I can tell you for 100% confidence that torque management is always there. Your throttle demands are never fulfilled 100%. Unlike in the M3/4, in Sport Plus engine mapping and with DSC off, whatever you do with the throttle is what you will get, instantly, good or bad. You may crash and burn or you may get the most wonderful feeling of car control, it all depends on your skills. Truly more of a driver's car than the Giulia QV, IMHO.

[OhioRiderAaron]

Originally Posted by M3Tooner

My guess is that the driver is never in full control of the Giulia QV, as in the stability program cannot be fully disabled, eventhough in Race Mode. It is always doing something in the background to help the driver. While it may help most beginner to intermediate drivers, it certainly will be more of a hindrance to a pro driver like Randy, thus he couldn't drive it as fast as the stats suggest this car can do.

In the video, Randy did mention that sometimes the car turns in really well but sometimes understeers a lot. Seems like maybe the torque vectoring system is getting overwhelmed by heat or something and is not able to always give the car it's intended dynamic behavior. Our Active M-Differential sure does not seem to have this problem.

I have a few days worth of seat time in this car on the road, not race track. I can tell you for 100% confidence that torque management is always there. Your throttle demands are never fulfilled 100%. Unlike in the M3/4, in Sport Plus engine mapping and with DSC off, whatever you do with the throttle is what you will get, instantly, good or bad. You may crash and burn or you may get the most wonderful feeling of car control, it all depends on your skills. Truly more of a driver's car than the Giulia QV, IMHO.

+1.


I wish they would have taken a M3 ZCP with them this year to see how it would compare, same day/week? however they decide to run these laps. Wouldn't be surprised if the ZCP was a bit quicker.

[Powerslide]

Don't worry guys - I'm sure mcc3456 has an explanation for this!!!

[kitesurfer]

Originally Posted by CanAutM3

Agreed. As with any track comparisons, there are many variables at play. At least here we have the same very skilled driver, particularly on this specific track, as a constant.

To me, this is just one more data point that shows that the Giulia QV, despite it's R-compound tires and significant power advantage, is not able to trounce the M3/4 on a track. So it still leaves me with the same unanswered question, if the Giulia QV has more grip, better acceleration and better overall driving dynamics (according to so many reviews), why is it not any faster around a track?

Because the M4's power is underrated from the factory...the prof is in the laptimes.... But lets not debate it again cause we already know your opinion on that

[CanAutM3]

Originally Posted by kitesurfer

Because the M4's power is underrated from the factory...the prof is in the laptimes.... But lets not debate it again cause we already know your opinion on that

Look at the acceleration numbers in any review. The Giulia QV out accelerates the M/4 by a significant margin. By your logic, it implies that the Giulia QV is just as underrated as the M3/4

... which still does not explain the lap time difference.

[Rambler]

Also for reference, the M4 GTS was about 2 seconds faster, even with the wrong aero setup and all.

[dkhm3]

Originally Posted by kitesurfer

Because the M4's power is underrated from the factory...the prof is in the laptimes.... But lets not debate it again cause we already know your opinion on that

when you actually do the math and compare the m3/m4 hp per lb, vs the competition, you'll find that underrated crap to be completely false. The M3 just weighs less and has less hp. Some people love to believe internet bullshit and never actually look at the math.

per car and driver:
M3 comp 8.2 hp/lbs------> 12.2 @ 120 mph
ATS-V 8.3 hp/lbs ----->12.2 @ 117 mph
C63S 7.9 hp/lbs-------> 11.9 @ 123 mph
GUILIA 7.6 hp/lbs -------> 11.9 @ 121 mph

accounting for the better efficiency of the dct vs the autoboxes you can see all cars perform acceleration tests pretty in line with their hp/lb ratios.

http://www.caranddriver.com/comparis...e-specs-page-6

but it's more convenient to believe in a lie. BMW has magical horses!

[Absurdium]

Originally Posted by dkhm3

when you actually do the math and compare the m3/m4 hp per lb, vs the competition, you'll find that underrated crap to be completely false. The M3 just weighs less and has less hp. Some people love to believe internet bullshit and never actually look at the math.

per car and driver:
M3 comp 8.2 hp/lbs------> 12.2 @ 120 mph
ATS-V 8.3 hp/lbs ----->12.2 @ 117 mph
C63S 7.9 hp/lbs-------> 11.9 @ 123 mph
GUILIA 7.6 hp/lbs -------> 11.9 @ 121 mph

accounting for the better efficiency of the dct vs the autoboxes you can see all cars perform acceleration tests pretty in line with their hp/lb ratios.

http://www.caranddriver.com/comparis...e-specs-page-6

but it's more convenient to believe in a lie. BMW has magical horses!

Actually I believe you've interpreted the data wrong. They listed the units as lb per hp, not hp per lb as you've described, which means a higher number is actually worse. With that definition, the M3 has pretty much the second worst weight to power ratio. The ATS-V with roughly the same power to weight, but 20 extra hp posted a trap speed that's 3 mph lower; that is a pretty big difference. Furthermore, the M3 trapped nearly the same speed to the Giulia while being down in power by more than 10% when the Giulia has a much better weight to power ratio 7.6 vs 8.2 (lower is better). Given all this data, it actually supports the theory that BMW has underrated the S55 motor.

I do believe however, that a big part of the M3/M4's good performance numbers is from the efficiency of their turbos, not just because they're underrated. The high midrange torque means that versus an NA car of similar peak power, you're making a significant amount of power higher everywhere else other than the peak. This really matters a lot because as much as peak power is great, you gotta get through the midrange to get there