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Performance Replacement Brakes for Giulia Models;

11K views 45 replies 7 participants last post by  Alfissimo Int. 
#1 · (Edited)
Group 2 Motorsports and GiroDisc have some VERY exciting news to share with the Giulia community! We are ready to install the first G2 / GiroDisc performance brake setup on a new Giulia road or street-track car!

First, some history for context...

As many here on the forum are aware, Group 2 Motorsports and GiroDisc co-developed some amazing performance brake solutions for various Alfa Romeo models over the years. Product offerings include well-engineered, true bolt-on, tested, high performance front and rear caliper, pad and floating hat rotor solutions for Spider, GTV and other 105 / 115 models, continuing on through complete front and rear caliper, pad and floating hat solutions for 116 Alfetta / GTV6 and Milano / 75 models - and most recently - floating hat, rotor and pad solutions to raise the bar on the 4C model's stopping power as well.

GiroDisc is a first-rate brake design, engineering, manufacturing and distribution company with a-LOT of brake development experience - backed up by decades of racing data feedback from a dedicated community utilizing their products. The quality, performance and cost value of our GiroDisc solutions are well-documented within the Porsche, Ferrari, Nissan GTR, Mitsubishi Evo, Corvette, Lotus and other performance vehicle communities as well. The giant full race AP / GiroDisc floating hat / rotor solution that I run on my own 3.7 litre 24v Milano race car, as well as the lightweight Wilwood / GiroDisc street-track setups running on dozens and dozens of Milanos and GTV6s out there, is first-rate and well-known!

All caliper brackets and floating hats are hard-anodized CNC pieces with branded "AR" part numbers. Floating hardware and fasteners have above industry-standard tensile ratings. Rotors are of a high-quality iron and the final product is zinc-dipped which maintains a nice, rust-free finished rotor edge. Pad selections draw from readily-available performance ranges and OEM part numbers such as Ferrodo, Pagid, Wilwood, Hawk, Brembo, Akebono, as well as GiroDisc's own Magic Pad product offerings.

These brake solutions are designed to reduce un-sprung weight (but also to reduce overall weight), to improve ventilation and cooling capacity, to reduce the potential for fade under performance driving conditions and to decrease stopping distances - all while retaining original dimensions and integrating seamlessly with the vehicle's OEM system! In many cases, solutions require fitment under small OEM wheel sizes for originality or to meet racing regulations and this is accomplished successfully on many models such as the older Alfas where a larger rotor and even a 4-piston pot caliper all still fit under a 15" wheel!

On newer models, the modern wheels are huge anyway and it doesn't matter as much. For vehicles with larger wheels, the performance and cost advantages can increase exponentially.
 

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#2 · (Edited)
One of the greatest advantages to GiroDisc performance brake solutions - especially for performance models equipped with carbon-ceramic brake options - is cold / street performance and cost. Carbon-ceramic brakes are NOT known for their cold street performance (or for their low cost.) :| We hear it frequently - the high cost of replacement and the accelerated wear of carbon-ceramic equipped models is staggering!

On the Giulia Quadrifoglios which are tracked, we also see very uneven "tapered" wear patterns to the pads - eroding their safe and serviceable lifespan very quickly! In the Porsche community for example, for years, Group 2 Motorsports has helped owners of PCCB (Porsche Ceramic Composite Brake) optioned cars such as 996 Turbos for example, by removing the PCCBs, the owners placing them into storage and driving the duration of their ownership on the GiroDisc package. At the end of their ownership, the carbon-ceramic brakes are reinstalled and the vehicle is sold with the OEM brake setup installed - or at least - included with the sale of the vehicle.

During ownership (and while operating on the GiroDisc solution), owners of these models report better cold / street performance, equal or better track performance (especially during early cold laps), lower replacement / operating costs, lower wheel dust levels, noise reduction and other benefits. Most significant perhaps is an increase in cold / street performance and cost! When the floating rotor discs wear out, we simply replace them with new rings and floating hardware at a fraction of the cost and the customer is good to go!

Group 2 Motorsports has made a significant investment in GiroDisc inventory and because they are located here in Washington State as well, most items are available same or next day for local installation and same-day for out-of-state shipping!

Feel free to contact us via the shop line at 206.378.0900
By email via Main@G2Motorsports.com
You may also follow us on Instagram here - https://www.instagram.com/group2motorsports/
Or on Facebook here - https://www.facebook.com/group2motorsports/
 

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#3 ·
Why do you that Giulia brakes are not good? Is you replacement brakes better than Brembo? If they are better how can you prove it? Can you for instance post the measurements of 100-0 braking distance 10 times in a row of your brakes and stock brakes? What is the stopping distance from 200 or 250 km/h 10 times in a row?
 
#4 ·
Hi Max, what I typed is still there for you to re-to read, rather than just scan over.

I never said that the "Giulia brakes are not good" - I simply pointed out the excessive leading-edge wear that we are seeing in pads from carbon-ceramic equipped models which are being tracked. I also discussed the known, lower cold / street performance of carbon-ceramic brakes versus well-engineered iron rotors and appropriately-selected pads. My post(s) also discuss the significant cost advantages of replacing the GiroDisc rings as they wear - and storing the carbon brakes until the vehicle is sold.

Unless cost is not a factor for you - in which case you are in a very rare 1% category of Alfa owners.

Am I getting sucked into the classic "Alfa engineers know best" argument, or am I simply bumping up against another "Brembo is the best in the world" perception here...? Besides, we are not replacing the Brembo calipers - only the hats, rotors, pads and floating hardware.

Anyway, based on our past experience with GiroDisc products on many other cars these past 15+ years, it will be easy to improve on the brakes in the base 4-cylinder Giulias. The co-cast "base" rotors on the Q-models are quite amazing though and the cost is significantly lower than the top of the line CCM brakes on the Q models, so we have focused our efforts on a replacement option for the top-top CCM-optioned cars as a first release.
 
#5 ·
I'd be curious John what the weight savings are per complete rotor, hats, pads and floating hardware for 2.0L models.

Front:
Brake rotor on 280Hp model weights in at 20.65lbs
Brake rotors- 5.56lbs
Brake clips- 0.19lbs
adapter bracket-1.39lbs

27.79 Lbs total from info I have gathered. Is there a significant drop in this? If so it would be a very nice upgrade for sure since stock wheels are fairly heavy.

Thx John
 
#7 ·
There's not really convincing evidence that carbon ceramic brakes work well for road cars, even when tracked. If you are also using street tires your tires will give up long before your iron brakes, assuming you fit appropriately harder pads when you are on track.

Evo magazine did an interesting back to back test of otherwise identical supercharged Jaguar F Types fitted respectively with Jaguars standard iron brakes and optional carbon ceramics. The iron brakes stopped better for the first 4-5 stops and then more or less matched the carbon ceramics up to 12 consecutive stops. From 100 mph!!!

That was with street pads on the iron brakes. Admittedly the street pads "caught fire" but they stopped the car anyway.
 
#8 ·
Makes no sense to me both performance-wise and cost-wise. I have seen a few Q owners drop the CC brakes for standard steel brakes. If I were to upgrade my Giulia ti brakes, they would have to be significantly lighter, not drilled, slotted or dimpled. Just a solid face rotor. The drilled look great but do not perform as well. Same with slotted. I am not one to go along with the slots refreshing the pads, more like shaving them down faster than you need. Pads would have to be a good compromise between cold bite to hot and fluid, a high quality fluid with a high temp boil point. I do plan to track it at some point for fun but for daily driving to spirited, stock is fantastic. Next pads are going to be the Tarox Strada unless something else comes out by the time I need them.
 
#11 ·
This is the procedure. Evo magazine, after Harry Metcalfe left it, drop to a garbage level.

Preheating the carbon ceramic material brake discs
The brake discs must be warmed up to make them fully efficient. You are advised to perform the following procedure: brake nine times from 80 mph (130 km/h) to 18 mph (30 km/h) with deceleration equal to 0.7g (the longitudinal acceleration value is shown on the instrument panel display by setting RACE mode and selecting the “Performance” page) with 20 second intervals between brake applications; keep the car at a speed comprised between 36 mph (60 km/h) and 60 mph (100 km/h) and do not brake for 240 seconds to allow the brakes to cool down; then brake three times from 120 mph (200 km/h) to 18 mph (30 km/h) with deceleration equal to 1.1g (ABS operation) with 30 second intervals between brake applications; keep the car at a speed comprised between 36 mph (60 km/h) and 60 mph (100 km/h) and do not brake for 300 seconds to allow the brakes to cool down.

Sent from my Z957 using Tapatalk
 
#13 ·
Considering that most people use their Giulia as an everyday car, with occasional track days at most, I think this confirms that the CC brakes are a useless upgrade for 99.99% of owners out there.

I do not know of anywhere outside a race track where I could brake nine times from 80 to 18 without causing an accident and break multiple laws. So, on the street, the CC brakes will nearly always be sub-optimal.
 
#12 · (Edited)
harry metcalfe, you mean that prehistoric fella that does youtubes vids now? just kidding i luv that guy.

dont buy a jag... lol i used to work there in Coventry. the procedure you mention is not too different from what i do when i swap out street pads for track pads on iron disc. am i the only one here that does this these days to bed in pads properly?

some of these disc and caliper packages housed in these supercar large wheels are ginormous. at over 16inch or more, the disc themselves have become bigger in diameter than a 105 wheel and more than twice as heavy if they were conventional cast iron. the weight savings and inertia reduction are substantial. not so much on a pokerchip size 105 disc.
 
#14 ·
Brakes are heat generators, that's all they do. Kinetic energy is converted to heat.

Drilling brakes (or casting them with holes) reduces the capability of the disc to absorb heat, so they get hotter, faster.

Hotter brakes are more efficient at dissipating heat. That's not always a good thing. For road driving it's a very bad thing.

The issue is with achieving the optimal operating range for the pad material.

Pick your pads to match your driving requirement. Your discs don't matter very much. What matters is using pads that will brake effectively over the temperature range you expect the car to experience. Same for tires.

Carbon ceramics brakes on any road car are just a fashion statement. Like very large wheels, almost all spoilers and often those very expensive tires.
 
#17 ·
So the Alfa is nearly all fashion! Typical Italians! Must have been designed by Dolce and Gabbana or Versace.

I beg to differ on the rear spoilers on the giulia and tires comment. Wheels comment, depends on what you are doing really. 19" is slightly excessive but not overly. Adds a lot more weight. 18" is a better setup. If I can ever find a good looking 18" wheel for this car, I'd move to those. These 19" are heavy. 18" is the norm in DTM these days. in 1993, the 155 V6Ti DTM car used both 19 and 18" wheels. I know this is not a daily driver but it gives some idea that 19" wheels are not necessarily USELESS or Fashion statements especially with proper sized tires. I dumped the 225 tires that wrapped the wheels from the factory and went with a larger tire, larger sidewalls. I prefer this over the stretched tire.

Spoilers...

"The vast majority of spoilers out there don't do anything – you don't get any bang for your money," says Dr. Martin Agelin-Chaab, assistant professor in automotive engineering at the University of Ontario Institute of Technology (UOIT) in Oshawa, Ont. "They only work if they're properly installed, and even then, they only work at speeds of at least 100 km/h or more."

Spoilers are supposed to spoil aerodynamic lift: the force that wants to pull your car off the ground. They're supposed to push your car onto the road.

"Usually, spoilers are intended to increase downforce – they deflect air upward, which creates a downward force on the car," says Dr. Ron Miller, an engineering professor at Carleton University who has worked on race-car design. "This helps stick the tires to the road to give the car better grip and therefore better handling in cornering."

Spoilers can also reduce drag, Agelin-Chaab says. And the less air resistance your car has, the less gas you'll have to burn. But you probably won't notice the difference driving the kids to soccer, unless you're taking the highway.

"At 120 km/h or more, 50 per cent of fuel goes to combat drag," he says. "So, at high speeds, reducing the drag even slightly can have a huge impact on fuel economy."

But a spoiler only works if it's cutting through the air at the correct angle, Agelin-Chaab adds.

"Factory-installed spoilers on higher-end sports cars are very effective. Many others out there probably aren't so effective – and some car manufacturers even say their spoilers are for looks only." I'd argue these are higher end vehicles especially the Q and the design of the rear deck spoiler

Properly installing a spoiler requires at least three hours in a wind tunnel (UOIT's costs $700 an hour), Agelin-Chaab says. If you're installing one yourself, you can measure the drag on your vehicle doing a coastdown test.


While a spoiler might not help your car's handling or fuel economy, it can't hurt, right? Sorry to be a spoilsport, but a badly installed spoiler could mess with the airflow around your car. "Since it was not part of the aerodynamic design of the car, a spoiler may or may not interact correctly with the flow around the vehicle to improve things," Miller says. "It can even make things worse."

A badly installed spoiler can give the rear wheels too much grip, causing understeer.

"It can make the car more reluctant to turn as the straight rear wheels tend to overrule the turned, less gripping, front ones," he says.
 
#19 · (Edited)
Just a reminder that stopping distances are determined by the tires, not the brakes. As long as the brakes can lock all of the wheels, or activate the ABS fully on all four wheels, then they are sufficient.

Otherwise, upgrading of brakes is an exercise in heat management.

https://www.apcautotech.com/getmedi..._Whitepaper_B1-Warped-Brake-Disc-8-2018_1.pdf


Road car spoilers are largely decorative primarily because effective speeds for downforce generation are very high indeed. Two important functions for road car spoilers: front chin spoilers reduce front end lift at high speeds, 160 km/hr plus as long as the ride height is not too high so the air gap under the spoiler is only a few inches, and rear lip spoilers reduce drag by quite a bit improving fuel economy through the Kamm effect.
 
#20 · (Edited)
Just a reminder that stopping distances are determined by the tires, not the brakes. As long as the brakes can lock all of the wheels, or activate the ABS fully on all four wheels, then they are sufficient.

Otherwise, upgrading of brakes is an exercise in heat management.

Road car spoilers are largely decorative primarily because effective speeds for downforce generation are very high indeed. Two important functions for road car spoilers: front chin spoilers reduce front end lift at high speeds, 160 km/hr plus as long as the ride height is not too high so the air gap under the spoiler is only a few inches, and rear lip spoilers reduce drag by quite a bit improving fuel economy through the Kamm effect.
What do you think of the rear diffuser on the Q? Decorative as well?

Those fins help take advantage of Bernoullis principle and draw the car towards the ground. It shortens the space available for the air to pass through thus accelerating the airflow reducing pressure, resulting in downforce gains.

Also I am referring to the OEM carbon fiber Quad re-spoiler, not anything else and you are referring to "road" spoilers. I suppose this is similar to Toyota building the 4runner for off-roading when most don't off-road. But for the TRD engineers, they build the car for the 10% who do. If you don't, it's just another SUV.

I was on the fence with the rear spoiler as I preferred the built in spoiler off the trunk lid. It is a nice built in one. From what I know and from what I have read this OEM spoiler.aerodynamics, this one is fairly functional both in the aspect of spoiling the air/creating downforce as well as reducing drag.

I opted for the carbon fiber version seen below. I felt the front aerodynamics were as good as they get for a street vehicle.

Of course I realize the spoiler is for looks as well but this one serves a function. With the way this car can get up to high speeds (and for the most part even at 50mph the spoiler functions) it can help with stability at higher.

"Just a reminder that stopping distances are determined by the tires, not the brakes. As long as the brakes can lock all of the wheels, or activate the ABS fully on all four wheels, then they are sufficient. "

No reminder needed. I feel this is a contradiction in what you have posted prior. Stating high performance tires are a waste of money. "Carbon ceramics brakes on any road car are just a fashion statement. Like very large wheels, almost all spoilers and often those very expensive tires."

So if stopping distances are determined by tires but expensive tires are a fashion statement why do those fashion statements always typically stop better? I am running those expensive fashionable dolce & gabbana tires.

"The MICHELIN Pilot Sport 4 S takes only 33.66m to brake from 100 km / h to a complete stop. Even the best of its direct competitors takes nearly a meter more (+0,83m). On a wet track, 27.73 m is all the distance needed for the Michelin Pilot Sport 4 S to brake from 80 km / h to 0. This shows it once again as the best at almost 2.5m (+2,41m) shorter than the worst performer.

Wear tests conducted by the Dekra Test Center demonstrated that the new Michelin Pilot Sport 4 S has the best longevity in its class. It is also one of the first tires in its category to get an A rating on the European labelling scale (19 inch tire) in braking distance on wet surfaces. This label is meant to inform customers of the performance of the tires and also gives them information on the energy efficiency of the tire and its road noise level. The Michelin Pilot Sport 4 S also set a new milestone when it comes to the rolling resistance as two-thirds of the range are graded C.
 

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#21 · (Edited)
Street cars are nowhere near low enough for a diffuser to work. Bernoulli's principle is the explanation for the Venturi effect the diffuser is supposed to create. It doesn't.

The only trunk lid spoiler that can work on a street car is the lip type. Wings with supposedly effective slots are purely cosmetic. The trunk lid lip type spoiler is a variety of Gurney flap. It reduces drag by using turbulent air to mimic a teardrop body shape. Turbulent drag is higher than the form drag of the theoretical teardrop shape but skin friction is eliminated. The net result is a reduction of total drag. You also get a taller trunk and a much shorter car.

High performance tires are a waste of money on most North American roads because they never get hot enough to deliver the grip you're paying extra for. Ultra high performance all seasons are now the way to go unless you drive frequently on very twisty roads or track the car. I'd be interested to see the first cold stop performance of the Pilot Sport 4S against the A/S 3+.

Road cars rarely experience the second hard consecutive stop, let alone the 20th you really need to get your money's worth out of the top performing tires and brakes.
 
#25 · (Edited)
Street cars are nowhere near low enough for a diffuser to work. Bernoulli's principle is the explanation for the Venturi effect the diffuser is supposed to create. It doesn't.

The only trunk lid spoiler that can work on a street car is the lip type. Wings with supposedly effective slots are purely cosmetic.

High performance tires are a waste of money on most North American roads because they never get hot enough to deliver the grip you're paying extra for. Ultra high performance all seasons are now the way to go unless you drive frequently on very twisty roads or track the car. I'd be interested to see the first cold stop performance of the Pilot Sport 4S against the A/S 3+.

Road cars rarely experience the second hard consecutive stop, let alone the 20th you really need to get your money's worth out of the top performing tires and brakes.
I am only speaking of the lip spoiler. Not wings.

Tires. Cost is not the only factor to look at. Stating "high Performance" tires are a waste of money is a very generalized statement. Yes, some expensive tires do just as well as lower priced tires or sometimes even worse. This is where research comes in. I do my research on tires and sometimes that research can fail. One thing for sure is I never let my tires get too worn. I am one for safety as well not just performance.

The Michelin PS4's that I purchased were no more expensive than a good all-season. I paid $947.00 for all 4 tires including shipping of around $65

If I went with: Michelin Pilot Sport A/S 3+ in the sizes I have, I would have paid $789.00 with shipping. A savings of $178.00
I have used the A/S 3 before. Fantastic tire. Any better than the 4S? Can't say yet.

I will try to find stopping distances for both cold stopping. I'd be interested too.

Again as mentioned. The tires, the rear lip spoiler, diffusers etc is all for the 10% of the time. On the track or at high speeds or on curvy roads etc... Don't worry, we won't go into lowering springs...that is clearly a waste of money and destroys cars suspension systems especially these giulias.


I like this guy, he does his research. There are more factors involved than just cost.
Why Expensive Tires Aren't Always Worth The Money - Digg
 
#24 · (Edited)
Fangio's probably apocryphal quip to his team mate when asked about the secret to faster lap times, in the very same car on the very same day.: less brakes, more accelerator.

There is no doubt the less heat you generate in your brakes and tires to deliver a given lap time the faster you are able to go. Not to mention overall race time if tire or brake wear or fade are relevant as they still are in racing.

For a road car a great deal of driving pleasure is available by seeking to drive as quickly as possible down a given road (including in "possible" the legal restrictions) while generating the lowest g forces when braking or cornering. Speed available to the usual road car on a public road is almost always limited by regulation, not the capability of the car. It's as well to remember that when deciding which car to buy and what performance options are really worthwhile. Counterintuitively, the less capable the car the more fun it can be to drive.

I am unable to resist generating maximum g forces when accelerating, however.
 
#26 · (Edited)
Quick search.

Michelin A/S 3

113.9 feet to stop Dry/Cold, 60-0 (I believe) Source: https://www.motortrend.com/news/michelin-pilot-sport-as-3-tire-test-307753/

Michelin 4S
Averaged: 110.4 (62-0) Source: https://on-sitetires.com/blog/view/...helin-raises-the-bar-outdoes-themselves-again
60-0 might be less.

In this case maybe not a huge difference.

I do know that the A/S 3 that is slightly worn does not perform well in light snow or wet. Again there are other factors to tires besides just stopping distance and cost. I mean looks are at the top of the list!!! ;)

Anyway, back to the giro brakes or brakes in general. Don't want to side track John's original post.
 
#33 ·
And if you do bear in mind that European versions of the same model of tire can be built differently for North America. Also, Goodyear are built by two different manufacturers for Europe and for North America due to brand name ownership being different in those two markets.
 
#31 ·
Very cool. My dad put up all the Atlas, Gemini, Titan rockets, worked on cruise missile, aircraft and space shuttle stuff. Worked for aerospace Corp in El segundo as well as Lockheed Martin, Martin and Airforce.

Guy in glasses was my pops, about 1962 here.
 

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#37 ·
Anyone have Drag (cd) for the Giulia ti?

Alfa only shows Drag Coefficient (cd) for Quad at 0.32

I find it interesting they only show that model.

I did find the Giulia AE (diesel coming next year to EU) which is lowered by 5mm compared to veloce models has a Drag Coefficient of 0.23.

So the question is, does the base models have better Drag than the Q with all the useless spoilers, diffusers, large wheels with wide tires, active front splitter and overall height lower than other models?? This could be telling...
 
#39 ·
#41 · (Edited)
I think it can be said that front spoilers and rear wings dont influence downforce much at 80 kph, which is the speed from where aerodynamic aid is starting to work. So not much to expect in everyday traffic. However in countries where there is no speed limit like in Germany, where you can go over 200kph, the spoilers and wings can make some difference. Then also in racing at higher speeds.
The size of the difference is hard to say without comparing a car body without the aerodynamic aids with the same car with the aids. A help comes form a German Magazine Sport Auto which in their Super Test on Nürburgring also measures the downforces on the test cars in windtunnel and lists up these values at 200kph. Its interesting to see what values we can expect from sport and sporty cars for the market.

Some examples.

Audi RS 3 Sportback......F/R...21kg up/1 kg down
Opel Astra OPC.....................7Kg up/ 1 kg up
BMW M135i..........................7kg up/ 13kg up
BMW 1 M Coupe...................5 kg down/ 37kg up
VW Golf R............................17kg up/ 29kg up
Subaru WRX STI...................64 kg up/ 14 kg down
Mercedes A45 AMG...............43kg up/ 15 kg up
Ferrari 458 Italia..................32kg up / 31 kg down

This should give an idea of size of aerodynamic forces on cars at 200 kph. At normal road speeds it will be much lower of course.
One could also notice the Subaru cannot be so much fun with 64 kg lift at the front at 200kph, while the BMWM1 Coupe actually generates a small downforce and should be quite stable at 200kph in comparison.

Have not seen figures for the Alfa Giulia Q, which would be interesting.
 
#42 ·
Lowering the front ride height only delivers the aerodynamic effect noted on the BMW 1M. This isn't an effect of aerodynamic bodywork. Any road car will decrease front lift relative to rear lift if it is raked downwards towards the front axle, spoilers or no.

The Subaru numbers result from the ridiculous wing which clearly doesn't work properly at any speed. At least you'd be leaving the road understeering safely into the trees.

At 200 km/hr aerodynamic stability becomes a very important safety consideration but you don't see downforce , that particular BMW excepted. That car demostrates pretty scary handling at any speeds, I would definitely avoid very high speed cornering given the published numbers, exactly opposite to what you require for safe handling on the road.
 
#45 · (Edited)
Drag coefficient is used for marketing, and it is pretty much a useless number for consumers. Example was the big change in the Chevy Caprice from angular to bulbous body. The drag coefficient improved but I'd bet the drag losses were not reduced at all. GM just increased the frontal area cross section number by making the car body fatter all over. By making it organically rounded it looked "smoother" and more aerodynamic but it wasn't.

For different models of the same car body, however, the difference in coefficient is meaningful in that the lower coefficient version definitely produces less total drag. The efficiency difference however is not indicated by the delta in the coefficient. Only the fact that it is better for the version with the lower number. This results from the formula: higher cross sectional frontal area with no increase in drag will produce a lower coefficient but no savings in fuel economy. In the case of the Giulia it is clear the QV version develops significantly more drag than the normale. The TI will develop more drag than a version with smaller tires. The QV will develop more drag if only due to its wider tires. Various aero appendages will make that worse. I very much doubt the QV version generates any true downforce. Any reduction in lift is likely irrelevant to actual performance except at very high speeds. Even then back to back comparisons between the QV and the TI if fitted with the same power would be needed to establish that reduction in lift compensated for reduction in top speed. Maybe the aero effects just make the QV easier to drive at very high speeds rather than actually improving performance.

Returning to the brake upgrade issue it is critical for safety that you look for a brake upgrade package from a supplier who is competent to design one. Brakes are a system and any changes must be effected as a system even if you upgrade only one part. Buying brake upgrade parts you choose yourself is a very bad idea and potentially dangerous. You can very easily make the brake system worse.

For example, fitting bigger front brakes changes the brake bias. That changes weight transfer which can actually increase stopping distances (before the sceptic experts leap in you should recall that tire grip is related to load but not in linear fashion and, no, ABS cannot compensate for all brake imbalances). Changing just the rotor size without matching the compound to the heat requirements can result in a brake that develops less brake torque than stock because the temperature rise in the pad is insufficient. Counterintuitively, bigger brakes on the same car benefit from softer pads, or, looking at it the other way fitting more heat resistant rotors means your stock pads will likely work better than a set of harder pads. Just changing the pads to more heat resistant pads is the most common and worst amateur error because on the street you can substantially increase stopping distances when the brakes are cold, which they almost always are. If you can touch your wheels after a spirited drive your brakes are fine as they are.

The most egregious effect of fitting unnecessarily large brakes is unsprung weight. Car makers now fit the thinnest brake discs they can get away with for reasons of weight. Many modern cars wear out their discs as fast as their pads.

Holes and slots reduce weight a little but also reduce heat absorption capacity. There are zero proved benefits to holes or slotting in brake discs for road use, btw. This unsprung weight issue also arises if you fit bigger calipers, not just if you increase rotor size. Those four piston calipers you lust after can be heavier than the supposedly inferior sliding calipers your car maker fitted.

Like wheels and tires, brakes should be the smallest and lightest components you can find that perform to requirements. Going larger than you need is purely an aesthetic choice and one that I do not understand, frankly. Brakes become ugly after the first very hard stop.....
 
#46 ·
Time for a new thread me thinks!

Yeah, I think there is partial truth to your claims but I am not sure you are 100% correct as there is information supporting both. It's difficult to fully believe your claims without evidence.

I do not believe the Giulia's roofline is too high for a spoiler on the trunk lid. The spoiler I speak of is the OEM spoiler nothing else. I am not speaking of anything aftermarket.

"Spoilers are used primarily on sedan-type race cars. They act like barriers to air flow, in order to build up higher air pressure in front of the spoiler. This is useful, because as mentioned previously, a sedan car tends to become "Light" in the rear end as the low pressure area above the trunk lifts the rear end of the car."

"Where most road cars (using your terminology here.. ;) ) get into trouble is the fact that there is a large surface area on top of the car's roof. As the higher pressure air in front of the wind screen travels over the windscreen, it accelerates, causing the pressure to drop. This lower pressure literally lifts on the car's roof as the air passes over it. Worse still, once the air makes it's way to the rear window, the notch created by the window dropping down to the trunk leaves a vacuum, or low pressure space that the air is not able to fill properly. The flow is said to detach and the resulting lower pressure creates lift that then acts upon the surface area of the trunk. This can be seen in old 1950's racing sedans, where the driver would feel the car becoming "light" in the rear when traveling at high speeds. See the diagram below."


"Not to be forgotten, the underside of the car is also responsible for creating lift or down force. If a car's front end is lower than the rear end, then the widening gap between the underside and the road creates a vacuum, or low pressure area, and therefore "suction" that equates to down force. The lower front of the car effectively restricts the air flow under the car. See the diagram below."



"What all these "ideal" attributes stack up to is called the Drag coefficient (Cd). The best road cars today manage a Cd of about 0.28. Formula 1 cars, with their wings and open wheels (a massive drag component) manage a minimum of about 0.75.

If we consider that a flat plate has a Cd of about 1.0, an F1 car really seems inefficient, but what an F1 car lacks in aerodynamic drag efficiency, it makes up for in down force and horsepower."

Aerodynamics


Anyway, might want to start a new thread and see if you can get some folks in the field to respond!
 
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