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Good information thanks!
Bought original Porsche front rotors for my 930 (full floating) and found out the holes were actually cast in the rotor when it was made and not drilled.
It allows the molecules to radially align around the holes during casting and prevent most cracking.
Informative - thanks. OEM rotors are drilled so how can that be poser?
Your assumption is that Porsche does not put poser stuff on their cars..... hmm....
Sure, they don't put screaming chickens on their hoods or coooool side vents with sheets of steel blocking even a hint of functionality. But our cars are loaded with Poser stuff that looks/sounds like go fast, form following function.
Without getting into trim or color, try:
1 - Sports exhaust (with a switch!)
2 - Aero kits - I read a quote from a Porsche engineer a while back that the aero kits were for the American market and don't effect performance... I think he used the phrase "bragging rights"
3 - Big wheels and rubberband tires.... bigger wheels actually rob horse power (less leverage), can increase mass, and rubberband tires negate the whole purpose of a pneumatic tire.
4 - Hemholtz resonator https://rennlist.com/forums/997-foru...resonator.html
5. Holes in the rotors.... per this video... which I have read elswhere but I would love to hear from some of you hardened track junkies
I can go on...... aint so "pure" eh?
The issues isn't looks or sound for asthetic reasons, heck if you like it, then fine. I too modified my exhaust with the Sharkwerks pipe. The issue is the performance lie.
Peace
Bruce in Philly
Last edited by Bruce In Philly; 09-13-2016 at 01:08 PM.
Your assumption is that Porsche does not put poser stuff on their cars..... hmm....
Sure, they don't put screaming chickens on their hoods or coooool side vents with sheets of steel blocking even a hint of functionality. But our cars are loaded with Poser stuff that looks/sounds like go fast, form following function.
Without getting into trim or color, try:
1 - Sports exhaust (with a switch!)
2 - Aero kits - I read a quote from a Porsche engineer a while back that the aero kits were for the American market and don't effect performance... I think he used the phrase "bragging rights"
3 - Big wheels and rubberband tires.... bigger wheels actually rob horse power (less leverage), can increase mass, and rubberband tires negate the whole purpose of a pneumatic tire.
4 - Hemholtz resonator https://rennlist.com/forums/997-foru...resonator.html
5. Holes in the rotors.... per this video... which I have read elswhere but I would love to hear from some of you hardened track junkies
I can go on...... aint so "pure" eh?
The issues isn't looks or sound for asthetic reasons, heck if you like it, then fine. I too modified my exhaust with the Sharkwerks pipe. The issue is the performance lie.
Peace
Bruce in Philly
Bruce, it's also about compromise with regards to street/track application. I have used Porsche standard drilled rotors with metallic endurance racing pads on some of the most notorious tracks for brake carnage, such as COTA. They held up fine. Eventually I got spider cracks but to be honest, the rotor was well past due for replacement due to overall thickness anyways. Poser would infer they don't perform; consider the opposite choice: if they came slotted like a race cars, you would be replacing pads much more often. Your stock Street brake pad would get absolutely ground up by a racing slotted rotor. Even a track pad with metallic components would.
thus you would have significant "street" reliability loss as a trade off for a bit more racing braking performance. Or Porsche could leave the rotor plain which would look ugly. So what Porsche did was overengineer the rotors so that drilling holes really wouldn't matter unless you took your carrera and entered it in an endurance race with no race prep, which would be insanity and many other things would fail first.
porsche is known for their brakes for a reason; they spend a lot of time making sure they engineer a really good street and track balance. Sure the holes are for style but they don't affect performance so I don't care.
as for the larger wheels; the cars are faster on the 19s than the 18s. Reason why? New tire technology has stronger sidewalls and new geometry that allows it to be thin and still function well on track. This allows Porsche to fit 1. Larger brakes for more surface area and harder stopping, 2. It allows for less sidewall flex due to thinner rubber, which in turn creates superior turn in.
if you want to test it yourself, see how much more you understeer and have issues with turn in when you swap to a fat tire on 18 inch wheel to keep the ratio of wheel to tire the same. On track, if I don't align my car properly for new geometry established by my 18 inch track wheels and fat r888 rubber, despite having more grip (a lot more grip with r888) I have marginally better lap times because my turn in is noticeably sluggish. If I were to modify my suspension geometry and alignment to accommodate 18 inch wheels with fatter tires, I will also experience a very "twitchy" car. I'm used to it but when I let others try it, it terrifys them. The car feels much lighter at 100mph+. It turns much easier with a track alignment, but is also much more sensitive to "cya later" oversteer and other dangerous moments. I can control this but your average no track experience person wouldnt want to drive my car on the autobahn at 150mph and would probably deem it unsafe/a much worse car than say a Ferrari,Bmw,merc,Audi,etc that doesn't bounce around on the autobahn. It's about performance balance. With less agressive alignment, a thinner tire and bigger wheel offer a better track time, and more road stability.
this was proven by some professional racers on our car specifically.
there is a reason many race cars are running bigger wheels nowadays. There are advantages and disadvantages.
also as for aero kits, they add enough downforce to be noticed according to some pro drivers. Is it as much as the massive wings on the gt3rs? No, but it will stabilize the car at speed and induce some drag. If it didn't work then the guys racing pwc and continental sps would be running without because it induces needless drag on straights. But they use the stock carrera aerokit with some gts aero as well. Not gt3 aero.
the thing is, in any sporty street car, there are just going to be compromises. The Porsche just makes the best balance in my opinion.
Last edited by Alexandrius; 09-13-2016 at 03:06 PM.
drilled rotors are a faint whimper in the "poseur" dept. tacked on aero,excessive venting etc., loud colors-there's an audible shout.
if I truly had a car for track (I do not) some of this makes sense, but we have all seen cars, Porsche et al, wayyy too tarted up, and with no intent to thrash to the limits where these added kit would be pertinent.
Gemballa is an extreme example. maybe some of their outlandish kit was functional, but it seems they sold a product to rich folk who craved attention.
like the 100k Range Rovers fitted out with bull bars driven by peeps only getting groceries and lattes.
For the most part Porsches I see just look functionally sound. I know some use dd for track at times, and will have aero kit. ok.
I myself don't want to call attention in my direction. I did mod my exhaust, but for my pleasure, not to show boat.
as for the larger wheels; the cars are faster on the 19s than the 18s. Reason why? New tire technology has stronger sidewalls and new geometry that allows it to be thin and still function well on track. This allows Porsche to fit 1. Larger brakes for more surface area and harder stopping, 2. It allows for less sidewall flex due to thinner rubber, which in turn creates superior turn in.
Cross drilled rotors are pure junk for track applications. Why Porsche continues to put them on cars is beyond me. They are good enough for the street but will fail quickly on prolonged track applications.
The GT4 and 991 GT3 have rotors that appear to be cross drilled but are actually cast with the holes in them. These rotors are lasting longer but still fail
after prolonged track applications.
I raced a 968 for 5 years. For reasons I can't explain I used crossed drilled rotors. At best they may have lasted 2-3 track weekends before the cracks elongated to the point I was uncomfortable. When I sold my house up north I had a stack of junk cross drilled rotors in my garage maybe 3' high. In the end I went back to just the flat rotor....and guess what they lasted.
We sell replacement slotted 2 piece rotors into Porsches by manufacturers AP, Giro Disc and PFC.
For any prolonged track application the 2 piece rotor is the most economical way to go.
The provenance with cross-drilled rotors traces back to when older materials in brake pads would gas under extreme heat. The holes allowed degassing, nothing more, nothing less. With modern brake pad material no longer gassing, cross-drilled rotors are nothing more than cosmetic.
Why would you guys want slotted rotors on street car Porsches ? Shorter pad life ?
The holes are for looks; I have tracked my 997s hard, gone through a few sets of rotors. If you are that into tracking, you will be replacing rotors so often who cares what they come with stock? most people that track, by the time they see any cracks, have already worn the rotor past it's useful life anyways. It has lost enough material to not adequately cool/heat up anymore to the demands needed by a track application. Might as well prolong the life of soft street pads by not using slotted and allow the end user to decide if they want to track, put on some slotted rotors and steel compound pads.
When i I buy a Porsche stock I personally am ok with the rotors not being built for a 24 hour endurance race, since the rest of the car isn't either. It's a street car, people.
09-13-2016, 11:46 AM
