Do you not know of the universally known physics equation:
KE = 1/2MV^2

Before you respond... talk to someone that is a racer, and engineer, or better, racing engineer. Intuition is not going to cut it here VR. This means, yes, your braking problem could be worse, because at a high level, you get more performance out of your race car if you lighten it. the higher the speed, the worse your braking problem will be (if you have one), even if you are lighter. why? its very simple. the energy goes up with the square of speed.
if you gain 4% more speed for 4% reduction in weight, you have now, 8% more energy to deal with to slow down.
a great example, is what i laid out for you:

3000lb car
120mph top speed down a particular straight getting down to 60mph for turn in.

reduce to 2800lb car, top speed 125mph now, and the problem gets worse because you are going faster even with lighter weight. energy requirements are greater to slow down to the same turn in speed.
(yes, the turn in speed might be a little faster if you are lighter, so that would help, but the help stops there).

Dont be too quick to face palm VR!

 

I am sorry, bro, I have spoken with all of those people about this topic for many, many years. Respectfully, you are incorrect, for several reasons.

I am, however, going to leave it at that...not wanting to reprise any past 50+ page threads arguing about what the definition of "is" is.

Cheers!

 

But if you lightened your car, wouldn't you only need to slow to 65 perhaps for the same corner, not 60, making the formula come out the same?

And possibly with the higher speed there'd be more air flow to cool better?

I don't know, but have enjoyed this discussion.

 

No really, if you have spoken to "those people" and have an interpretation of the situation that can prove i am incorrect, i would LOVE to hear about it. no ego here, just want to hear what is right and what is not. by you saying im incorrect, you should at least follow with a reason (which you really never do)
if you do, i will not follow up with a reprise. I promise.

so, if im "wrong" for "several" reasons, just leave 2 . Ill be happy with that!

 

I mentioned that as a possibility, as certainly a lighter platform could pull a greater g load around the turn. Lets just leave it as the same turn in speed for the sake of argument.

However, I dont think a 200lb change can give a , near 10% ,5mph delta around a 1.6 g turn. But, even if it could, the total load would still be near the same on the brakes, due to the total energy required to slow the 2800 or 3000lb car 60mph from 125 or 120mph in the time needed.
You can see the problem from looking at this intuitively, due to the KE being more heavily weighted by speed.

certainly, the higher speed would add more cooling. how that plays out is a variable for sure.

I would be very curious what VR is thinking or what he has interpreted by other information to the contrary.

 

What temp range should I get? the paint bottle version has a range past 1200degrees or the single paint range has all sorts of 200F temp ranges from low to high.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>




Originally Posted by Jim Devine View Post
Get some of these and use them as directed. Until you do , you won't know your max temps.
Proper brake ducts are a must no matter what, but you have to know your temps before a pad can be properly matched.

https://www.pegasusautoracing.com/pr...p?Product=3161

 

delete duplicate post

 

Yes, the KE varies with the square of the speed. But the speed varies with the square root of (one on) the mass. So they cancel out: alter the mass and the car will have the same energy at the end of the straight, to a first order.

In fact the lighter car will have less KE, for two reasons:

a) Straights are a constant distance, not a constant time. The lighter and faster car spends less time accelerating hence has less KE. Consider 300HP for ten seconds versus 300HP for nine seconds.

b) The lighter car goes faster, hence loses more energy to aero drag.

 

Start high. You'll likely want to start with a range that will get you to 700C. That's smoking hot for most brake systems. Carbon ceramics are usually OK up to this range, but an iron brake system this high will see a big loss in performance.

 

so, you think its best to put it on the edges of the rotors or, inner area of the rotor? what is "smoking hot"? the rotors?
since the problem is really in the pad to rotor friction and not caliper fluid boiling, i would think that would be best to put it on the rotors. but, from the pad specs, i would think the fade would happen beyond 700 degrees. as a note, when i come into the pits the rotors are 450 front and rears 350F, but thats after the cool down lap and 1 min getting to my paddock space. calipers are usually in the 275F range.

im tempted to buy the paint that gives the full range, but its kind of pricey for this experiement.

what do you think?

 

What is your brake bias ratio???

 

I think you are on the same line of though that Garret and i were discussing. the main fact was , not so much that the KE wasnt the same, so no improvemet woud be had. You already indicated this with your example, but see if my example below doesnt show that the KE is actually higher with lighter weight, but not by much. what im saying, is it is near the same, so no real improvement.

to your point (a)
The lighter car spending less time accelerating, doesnt really matter with KE, because by definition, you are stating the unit measure of work...... the HP-second. Your one example is ten hp-seconds, and the other is nine hp-seconds. However, the net result if both cars are braking at the same point, one is going faster than the other, right? (125mph vs 120mph to keep the example constant) So, the car at the #3 marker before the brakes are applied has MORE KE, because its not the HP-seconds, its the NET force that was applied along the way, which is analogous to HP/weight ratio, and would incorporate the aero drag factor as well based on the final speed achieved.

The main point here is that at 125mph for the lighter car, it has slightly more KE due to speed being more of a factor than the weight removed.

The only thing that could change this would be the fact that the lighter car could turn into the turn at a higher speed vs the 200lb heavier car, allowing brake release to occur earlier.

Again: rough KE for 3000lbs car at 120mph vs 2800lbs at 125mph:
1/2 x 3000lbs x 120mph = 1500 x 14,400 = KE= 21,600,000
1/2 x 2800lbs x 125mph = 1400 x 15,625 = KE= 21,875,000

so, yes, they are near the same (within 1%), but this means that going lighter didnt help the KE. its actually a little highter, but certainly close enough to call it the same.

to your point (b). The aero drag, is more of a factor for that 5mph faster speed, but its overall effect would be relatively small. If total drag of the entire car is near 100lbs, at 120mph, then at 125mph, it would be 108lbs of total drag, or 8lbs more drag. a fairly small factor.
That would be near 2ft-lbs of torque at the engine equivalent. There is not much there to effect the KE equations.

 

Ill admit,its pretty weak. this chassis had a little different brake bias regulator. there is a 33bar and an 11bar available for the 928. Anderson in his 928, doesnt even run one. so, his brake force , front to rear is based on the master, and the size difference front to rear i imagine.

 

And on we go.....

 

The first step is try a more reasonable bias ratio.