DK7

Hello,
is it really possible to FEEL and LAPTIME the weight advantage of magnesium wheels (-22 lbs) and lightweight battery (-40lbs) on a car like 991 GT3 RS ? Bye

GrantG

Maybe throw in PCCB (or aftermarket carbon-ceramics) as well. Should be able to feel it in the steering and ride quality, but no personal experience before and after. Nobody has claimed they felt a major difference though. And Trakcar did report a laptime improvement at Sebring with ST rotors.

38D

60lbs is with ~0.5 secs on a 2 mins track. Can you feel that? Highly unlikely. Could a pro? Yes.

Drifting

Better odds if you also add in a side muffler delete (40lbs). That makes a full 100lbs after wheels, lithium batter, and side mufflers. Best weight loss for the money with a 991 GT car.

CX_GT3

Giro vs PCCB/ST will give you a much bigger difference in handling than the rims would. I have compared giro vs PCCB vs st as well as OEM rims with FIR. The biggest difference comes in low-speed maneuvering, PCCB and ST is just so much lighter on the wheel and you can feel the road more clearly compared to Giro's.

Ted@dundonmotorsports

Probably not the battery, but we definitely noticed the difference on our 991.2 RS when we switched from stock wheels to the Mags. Steering was lighter, more direct, the car required less static camber to get the tire temps dialed in, etc. It's not just the weight, but the stiffness that makes a big difference in the dynamics of the car. A worthwhile upgrade!

M3the01

This... absolutely true.

Antigravity

As far as feel, and looking at this from the perspective of science as well and the subjective human condition...

The Battery at a roughly 35lbs to 40lbs saving... if your extremely sensitive, potentially your could feel it, but it only a portion of the overall weight of the car. That feeling is subjective to the person. But being objective if you take the mass and energy equation then there is a definite benefit in terms of the mass you are trying to slow down or move or work against, which requires energy to make it move or to slow down. Also if you take into consideration that force of mass goes up exponentially as the speed increases then there is benefit you would see in fractions of second reduced over the course of a track lap.... all things being equal but with a heavier car. That is because the faster an object with mass goes, the harder it is to slow down, or move that mass from a straight line or even speed it up and that is exponential based on its speed. So if you take, for example, a 10lbs weight and toss it to someone at 5 mph... the force off stopping it at 5mph is not so hard.... let say it about 15 lbs of force( this is not accurate number , its just to demonstrate the principal), now take that same 10 lbs with and toss it to some one at double the speed. 10 MPH... well you do not just double that force required to slow it down, it goes up actually a bit more that just doubling it because it exponentially harder to stop as speed increases. Now take that 10 lbs and move it to 60MPH... it going to blow a hole through a house wall easily, and now move it to 100 MPH and you talking something that would probably go through a brick wall easily. So it an exponential increase in energy to slow down mass as speed goes up. So slowing down a 15 lb battery compared to a 55lbs battery from 60MPH is a massive amount of energy saving in terms of the braking the load on the tires and so on. Which can save time around a track, it can also effect the centrifugal forces going around corners at the higher speeds too because there is less mass pulling to the out outside of the turn. Again might not feel it but it is assisting to a degree for sure.

Saving weight on reciprocating mass items like wheels is much more "feel-able" in handling especially on Motorcycles too because it is directly connected to the steering, and wheels that are spinning. With super Lighter wheels the gyro effect and the centrifugal forces is significantly less so as the wheels also rotate faster it less mass having an effect.. so you feel it though the handling more as Dundon said.

I'm not any engineer and, not trying to debate any of this, or the best placement for weight. I'm sure someone else can explain this subject with the real equations and in a better manner than me, I'm just relaying some things I learned from some research and from some old classes but they are factual.

Franko T

F = MA
Force = Mass x Acceleration

If your acceleration is same (100MPH to 50MPH) and Mass is 10lb vs 55lb battery
The force would not be exponential
Or am I missing something here

DR.S

No it's not exponential.

Some example numbers (based on 4RS):
mass 1450 kg, engine torque 450 Nm, gear ratio total 9.92 (2nd), wheel radius 0.35 m
leads to a mathematical acceleration of 8.8 m/s2 (0.90 g).

If you save 50 kg (± 66 l 98 ROZ fuel), this leads to 9.11 m/s2 (0.93 g) or 3.6 % more.
You would have to save further 100 kg to reach 1 g.