951and944S

Point taken on your personaly preference.
50% of 951's make "more rwhp thasn a regular 951", alot of them see track time but you're still limited to the size wheel/tire combo which ultimately slows the car's mass.
My question remains, what purpose does it serve to enlarge rotor size and caliper efficiency on a 944 if properly maintained and cooled S4 brakes can lock race tires at the end of a 50 mile heat...?

TS

Laust Pedersen

I can assure you that I have gone beyond the limits of the OEM brakes on “Streets of Willow” after 4 laps. An almost impossible pedal pressure just before the fluid was boiling and on the next lap the pedal to the floor was not fun, scary actually.

Although I have not been on that track since, I think it my car can handle it now, by a combination of good maintenance practice and upgrades such as, new high temp fluid, almost new pads (thermal distance from heat source to fluid), drilled rotors, venting rims (as opposed to the Design-90 rims I had), good brake ducting (modified OG-Racing), etc.
See more here1, here2 and here3 for details.

Laust

Guns951

Heat dissapation...some of us will be seeing over 190 mph in our cars regularly. Show me one car capable of over 200mph at around 3000lbs that has smaller discs than the 993 twin turbo. These are now considered small by 90% of the high end tuners.

I was very tempted to go with PCCBs until talking with Bob and seeing what he had to say on the subject, now I'm sticking with the 993 tt route. My car will be VERY LIGHT however the braking capacity needed far exceeds stock with the amount of power I'll be putting down and the ability to stop hard repeatedly is something I would rather be slightly overboard on than not. (tires 17x10, 13 respectively)

I want to go over to Ceramic eventually as prices drop to a reasonable level (reasonable for some) due to the fact that fade free braking under pretty much all conditions is something that is very desireable to me. And if they provide no better performance than steel (equal or greater than that is) then the sheer exclusivity of them is appealing.

BTW what's your experience with 951s?

951and944S

That's a nice setup Laust. I think the last post I made to you was arueing semantics so I apologize in advance but notice in the text you pasted from my reply that I said "properly maintained and cooled".
For someone even contemplating the ramped expense and maint. of big reds, I'd have thought it understood that they'd be willing to invest a few bucks in simple ducting.

Your heat sink setup goes beyond that, nice work.

If you don't mind making a rough guess...., other than replenishables, i.e. pads/rotors, just for the record, what do you have invested in the upgrades....?

TS

951and944S

Regularly.....?

Where are you going to "regularly" go 190mph in your 951 guns...?
With 30 seconds full throttle from the bustop to turn 1 at Daytona, the PCA lap record holding RS spec GT3 may not have even hit 190mph, that's roughly what (?), 1 + 1/4 mile at WOT....?

I've been around.

TS

Guns951

I wasn't referring to the track. When this car goes out for a drive, there will be much top end testing/tweeking done as well as spirited sprints up to the 170-190 region. There are places to do this at and I will be doing a lot of it when I'm stateside.

Was the GT3 geared for top end? Probably not. By the given time, most highly tuned street vettes or vipers capable of 200 hit 150 within 15 seconds, so my guess is the GT3 (being on a track) was not setup for high numbers but rather the configuration of the track considering a 30 second burst would yield maybe 190.

Guns951

BTW the Kokeln Orca reguarly sees 180 at willow springs, just talk to Dave

turbo8

i dint see anyone mention that the ceramic rotors are half the waight of steel rotors ;-)

Guns951

This is well known, and also why I want them eventually. There's another thread about the processes the use to make them, they're currently looking for a way to make them in a continual process rather than in batches which would make costs plumet if they could come up with an "assembly line" style of manufacturing.

The article said something to the effect that the target would be $465/rotor

951and944S

Hey....would you quit makin' me reply?

I'm trying to cram in season 1 of the X-files from that 'TV Links' site you posted....



TS

Guns951

http://www.alluc.org/

Well there's another one for you then.

Back on subject, you seem to have a bunch of track related experience - do you race in Louisiana?

951and944S

Ok...while I'm buffering the "Ghost in the Machine' episode.....

I travel around for tech/mechanical support most everywhere with a few guys from the Mardi Gras region. One won the Saturday sprint and the other, the Sunday Enduro in SP2 at the big PCA Octoberfast at Daytona.
I'm currently building my own GT3 951, also own a moderately modded street 951 and an S2, formerly an 87S also, now my son's.
Transmission tech by trade, work on a few customer's 951s/944s/928s.
As a matter of fact, currently refreshing my son's 16V engine since it's out of the car while we section in a new frame apron and new wheel housing (wreck).
It's probably due, having put 300K street and track miles on it over the past 15 years after having assembled the engine personally from a bare block and boxes of parts on a dare (salvage purchase in 1991) while never owning a shop manual at the time nor having internet resources.

I get around.....

TS

BTW - pm me if you're interested in track car project pics...

Back to regularly scheduled Mulder and Scully....

Laust Pedersen

Ducting comes in many configurations and not so humbly I think the sealed air to the center of the rotors is one of the best solutions.
Unfortunately it appears that OG-Racing no longer sells the brake cooling kit.

Brake upgrade cost? Fluid, pads, Zimmerman rotors, OG-Racing ducts (+ fiber glass for sealing) and heat sinks probably amounts to about $500 not counting better venting wheels (half that for the non-consumables) + a lot of time in planning, procurement and implementation.
I do like the challenge of getting optimum results for minimum expense.

Laust

951and944S

I have a feeling you and I would get along just fine....

TS

Bob Rouleau

Lower weight is the big plus for ceramics. At today's prices the bang for the buck factor is poor. If ceramic rotors cost $1,000 each more of us would be using them. At current prices which are around $6-8K per rotor (12K on a Ferrari), the benefits are not cost effective. As yields improve prices will go down, how long that will take is a guess. When I saw that GT3 Supercup teams switched back to cast iron rotors from ceramics, it underlined the bang for the buck factor. In Europe Supercup is big time racing with equally big budgets. The price of rotors is negligible compared to the cost of a single race. There is a message there for all of us.

With respect to an earlier comment, any brakes will invoke lock-up or abs if equipped. Good brakes can do it consistently lap after lap with a pedal that is firm and easy to modulate. This takes a system with large rotors, pads and cooling ducts for heat dissipation.

Any racer can fry the brakes on any car irrespective of how exotic the system is. Good racers manage their brakes just like they manage their tires. Big pads, rotors and calipers tolerate the additional heat better than small ones. It's physics pure and simple.

Best,