Weight Distribution Performance Benefits
 

I was driving around recently on a full tank of gas and a fully loaded trunk and the car seemed to have more grip overall and the front-end was more eager to turn-in. I'm not sure if it would translate to the track but the perceived benefits were sufficient for me to consider trying to run on a full-tank of gas, keep the spare tire in, and maybe even install a hitch to put more weight on the rear. Would this be counter productive?

For autocross, I usually remove the spare and run about 3 gal of fuel.

For street driving we're not at the limit, so it's quite common to find adding ballast makes the car feel better. However, generally speaking a lighter car is faster even if you have to drive around a balance issue although it may not be as much fun to drive. That's why pretty much all class racing either limits what you can remove, or sets a minimum but not maximum weight. This is also why people put so much time and effort on the suspension, getting the weight transfer to work the way you want it to leads to better lap times than adding weight.

I'm a big critic of this car's abysmal 55F/45R weight distribution. But adding weight to the rear of the car is not going to improve performance. Full tank (mass in front of rear wheels) and full trunk (aft of rear wheels) won't really affect the load on the fronts much, front grip/load will be about the same. Rear grip/load will be reduced a small amount. Acceleration will of course be slightly less.

For my time trialing class, to meet my minimum weight I have to run with full tank and 40 lb. of ballast which I put alongside the spare tire in back (4x 10 lb. bags of steel shot). A couple of years ago I was overweight running a class up so I got a <5 lb. Shorai battery (-30 lb.) , 2-piece front rotors (-12 lb), and a catless header (-10 lb.?). So my current setup has effectively moved ~50-60 lb. rearward vs. stock at same weight. I do feel like there is maybe a couple/few tenths of a second advantage to running at my TT weight of 2920 lb. more rearward weight distribution (~53.5F/46.5R vs. stock 55/45) at the same weight, but nothing earth-shattering...

Improving the F/R weight distribution by messing up the center of mass and polar moment of inertia in not a win in my book. Think how easy it is to swing a hammer left and right with the head of the hammer away from you. Then do the same with the head of the hammer towards you. Then think how that applies to car handling, left right transitions, or recovering a slide.

:Porsche 911 has entered the chat: