In the weight loss thread there is good math on how lowering the weight of a car translates to better hp/lb and better acceleration, but I have plenty of horsepower and am thinking that I would appreciate the enhanced stopping power of my car with 400 less pounds traveling down the track at high speeds. Is there any math anywhere that translates how much losing 400 pounds would improve stopping distances?

I know our cars out brake lots of other cars, but at 3,400 lbs they are heavy and at 560 AWHP they are fast, which leads to lots of brake requirements and brake pad/rotor consumption.

Any track enthusiasts with real world experience on taking 400 lbs out of our cars and seeing significant improvements in braking?

 

Joe,

Porka, and myself have been in a GT3 completely stripped out. His car weighted 2750 lbs with fuel and him in the car.
At turn 2 at laguna seca, I would be about 1.5 car lengths ahead of him (prior to some more weight loss) prior to hitting the brakes. As hard as i tried hitting the brakes later, he would always out brake me, and get back those 1.5 car advantage i had, and put about 1.5 cars on me ( and i'm not someone that is afraid to brake late etchead and porka have been in my car with me and can attest to that) . Our acceleration coming out of turn 2 was dead even. With me and someone else in the car. Under braking he would gain on me at turn 5 again. My car at laguna seca, i have a flash only for power gains. He has a 996 gt3 with 380 bhp, i have 100 hp and tons of tq more then him yet, acceleration is dead even.

Long story short what i'm saying here, his car being so much lighter helped.

I then got a ride in his car, and omg, even as a passenger i could feel the difference on how much lighter his car was. Then my quest to lighten my car started about 5-6 years ago.

What i have noticed over the years in driving a lighter car, not only is my car easier on the tires ( they last longer), easier on the brakes ( i spend less time on the brakes ) , it is more nimble, much better turn in. lighter steering, weight transfer is much more manageable etc.

My last mod, with 2 pc rotors i made, i noticed that under very low load, when i'm in second gear, and coming to a near stop, my lwfw does not chatter as much, and my throttle response is much more responsive.

that said, that is why i breach people whom want better handling to do weight loss and get a proper alignment.


As a reference, i weight my car in a few weeks back. It now weights 3200 lbs with over 1/2 of fuel. The interior looks oem, outside it looks oem.


joe, if any people whom have credibility for being track junkers here on 6spo, its Dez, tom, gunther, and myself ( that i can think out of the top of my head) .

 

what kind of 2 pc rotors you made ???

i just bought ebwerks 2 pc rotors will save 16lb from the front only ..
still did not get them , but hope they worth the cash


btw .. how is the oz wheels ? with light weight rotors ???

 

The oz wheels are fantastic for the money.
They are very light. The oz's are my street wheels, i have TR wheels
which are forged alum that my track wheels, they are super light, wrapped with some light tires too

their is a reason why all the light cars on top gear score the best lap times, even though they do not have the power. Their is a reason besides N/A why the gt3 is fast, ( due to weight )

 

Nice job Enrique. 16lbs per rotor is super light for an iron 2 pc rotor considering that a 350mm PCCB rotor assembly weighs a little over 12 lbs. Both 350mm Brembos and Giros are right at 20 lbs each. How did you get them so light Enrique while still retaining full strength? I know my narrow annulus 380mm floating rotor assembly weighs just a touch over 20lbs, so basically the same as a normal annulus 350mm floating rotor. Porsche cup rotors are over 20lbs as well. The aluminum hat is probably only a pound or two with 90% of the weight in the iron ring. The only way I can see the iron rotor being so light is with fewer internal cooling vanes making the rotor less "dense", if you will. How many vanes are on your rotors? Brembos for example have 64 vanes, so very dense. I know Coleman for example uses very few in comparison.

Weight, or lack there of, at the track is everything. My car weighs 3280lbs now with a half tank of gas so I'm about 80 lbs heavier than you but I have a roll bar, dual mass flywheel, 380mm brakes, transmission cooler and a Guard LSD all of which add some weight. I recently ran with a 997TT with the Evoms 775 package and I still had him by over 5-7 seconds per lap on a 2.5 mile twisty circuit. Even on a straightaway I pulled on him which surprised me. I also rode in a friends 996 cup car and it was amazing to see how much more speed a light car like that could carry through the corners. I was almost 20 mph faster on the straight away but almost 10 seconds slower per lap!!!! Granted, his skills far surpassed mine, but still.... I'll take a light car with great brakes over a high HP pig any day.

 

Thanks guys. I was starting to think about a tuned 3.8 X51 Cayman (480 crank HP) as my next track car, knowing I can get it down to 2,700 lbs, but if I could get my turbo down to say 3,000 pounds stripped, I think it would be a whole different animal and that's what I hear you both confirming. Lots to ponder.

 

That sounds very fun.

 

Mine have a little more then Brembo's. My 2 pc actually weight 17.6 lbs all assembled. I was using the Cayenne S rotors prior which weight 28lbs, so i felt instantly the 10.5lbs off each wheel.

Our cars weight very similar, that is the nice thing about this forum, we all take different road maps to get to where we want.

I modeled my hats/rotors very similar to the AP Racing. If i'm going to engineer some, mine as well take clues from some of the best. Your car with no sunroof is to drool for...i need to do that mod sometime soon i hope..



joe... this is where it gets tricky for me. i cant get myself to strip down my porsche. I want a VERY capable track car but I also want it to be very capable and presentable as it was my dd.

My opinion is , set a goal what you want...if you want full track car, why not get an old 3 series bmw ? they look beautiful, cheap and reliable fast track cars... that is what i'm looking for...

 

You mean like a 1996 E36 M3 with 75k miles on it? Like the one I sold for a song five years agobefore I ever thought about tracking a car because it had been next to a housefire that tarnished that paint on the driver's side? Oh that hurts. As theysay, timing is everything, and that would have been a cheap starter platformfor a dedicated track car.

My problem now, and I share only because I believe others are likely in asimilar place, is that I have grown very addicted to 563 AWHP and my butt dynowould certainly be unhappy moving to something with significantly less get upand go like hell acceleration. That's why I am considering the 3.8 X51 Cayman as the HP to weight would be close if I got it down to 2700 lbs, and the braking and wear and tear would be less.

The other option is just to get a 997.2 GT3 with some suspension and leave it stock otherwise, but that doesn't feel like the right path given me use as either exclusively or almost exclusively a track car.

 

Bummer on the M3... i was thinking e30 3 series but the e36 is a much more capable platform.

Yes the power is addicting, and their isn't anything that can make up for it... tough decision, i never said these decisions make any common sense, because if they were... we would not be tracking Its a drug.

 

Enrique, what do you think about gt3 Lower Control Arms ?
do you have them on your car ?

 

Honestly, if you are not trying to get more then 1.5 negative camber in the front, or more then 2.5 in the rear, their is no need. The only thing they provide is adjustability.

If you want the back in to stop wigging when you brake from 130mph to 60mph, you need rear toe links. If you want a better steering feel when turning in, and feel the road ore, you have a 997t right ? solid top hats is a must for the suspension you are using.

If you hate how it is hard to get form 1st to 2nd and 2nd to 3rd and so on... get some semi solid or solid motor mounts. My solid motor mounts fixed that. Makes the car feel like go kart.

 

I have the adjustable GT3 LCAs on my car. You don't need them in the back but in the front they are very nice. Like Enrique said, with the stock arms you will max out about -1 to -1.4 degrees of camber depending on your ride height. With the 7mm of shims that come stock on the GT3 arms you will easily get -2 to -2.5 and obviously more as you add shims. They are definitely nice to have especially is you have stock adjusters at the top which will limit the amount of camber adjustment you have in your shock towers.

 

In my experience Enrique, the one thing that eliminated the tail wiggle under braking more than anything is an LSD with a moderate preload, say 50-60 lbs. I have all the solid arms in the rear but was still getting the back end moving around under braking, kind of a scary feeling actually. Once I installed a Guard Club LSD, voila, car tracked solid as an arrow under braking. Matt set mine up with a 60 lb preload IIRC. With a moderate preload in the LSD, the rear wheels are effectively "tied" together and really stabilize the car as the back end unloads during hard braking. If you have an open diff, there is nothing to tie the back wheel together as they are basically freewheeling. The "wiggle" is generally also a way to tell if your LSD is getting worn out, your car becomes unstable under braking. Most GT3 guys run into this problem after only a few track days with the stock Porsche LSD as it is set up with a preload of only about 7 lbs and quickly wears out. It still locks under acceleration but is useless under braking. What type of diff are you running on your car btw?

 

Joe, I've driven both the Cayman and obviously the TT and to me a properly set up TT (meaning RWD, LSD, No PSM, around 3200#) will be a more challenging but ultimately more rewarding car to track. If you strip the TT and get it down to 3000 lbs, you will have a beast that few cars can touch. I also know the Cayman guys are constantly battling cooling issues on those cars, at least they are in Colorado at the hot and high altitudes of our tracks. I've never had any cooling issues on the TT besides the gearbox which I supplemented with a cooler. I think you would be hard pressed to find a more durable motor than the Mezger we have. The beauty of the TT is the fact that you can get it around 3200# and still have it look like a road car with a presentable interior, and when properly set up you will be able to drive to the track on some R compounds, spank 95% of the cars out there, and drive home while the rest of the crowd is loading their track toys back on the trailer. Best of luck..