Weight Reduction

To improve overall performance there is no better mod than weight reduction. With a lower weight the car will accelerate faster, corner faster, brake shorter, and the transitions between all these, or from corner-to-corner, will be improved. It's just a win win win. Let's use this thread to collect weight reduction ideas. While different people all have different goals and different tolerances for radical mods, I think a 100 lb weight reduction should not be too hard with reasonable mods, and maybe 200 lbs is possible with a determined effort. I'll start with a few well-documented items, and then let's all collaborate to identify the best ideas for reducing the Cayman 's weight.

Lightweight Battery - 35 lb reduction This mod is well-documented with an article in the performance mods category ETX14 Lightweight Battery for the Track . It is inexpensive, easy to do, and reversible. The only downside appears to be that the smaller battery will not maintain its charge if the car is not driven for a long time, especially in the winter. A simple trickle charger solves this problem.

Remove toolkit - 9 lb reduction The "toolkit" in the front boot has little value in the absense of a spare tire. One can either remove it and rely on Porsche Roadside Assistance, or just take it out for track and AX days. In any case, an easy 9 lbs.

Lightweight wheels ~20 lbs reduction Switching to lightweight wheels can provide a significant weight reduction. This particular weight reduction provides a double bonus - it also reduces unsprung weight (improving handling over bumps) and reduces rotational inertia that must be overcome (in addition to the weight) to accelerate or deaccelerate the car. By my estimate the rotational inertia effect doubles the benefit of lightweight wheels, in terms of the increased acceleration. The amount of weight reduction will depend on what wheels one currently has installed, and what lightweight wheels are selected, but 20 lbs is a reasonable expectation. In my case, switching from OEM 18" CS wheels to Champion RS98 1 piece forged wheels should provide about 19 lbs of weight reduction. Edit: the RS98's have come in well over their weight target, and the actual weight reduction was only 14 lb.

Lightweight flywheel - 14 lb reduction The Sharkwerks lightweight flywheel weighs 14 lbs less than the OEM dual mass flywheel http://www.planet-9.com/cayman-modifications/16084-sharkwerks-light-weight-flywheel-kit.html#post191367 . This mod has the bonus that it significantly reduces rotational inertia, especially in the lower gears. There have been a number of estimates of this benefit, but no definitive calculations or measurements. The estimates are typically in the order of a 5-7% reduction in total inertia (weight plus rotational inertia) in 1st gear, dropping to 2-3% in 2nd gear, and diminishing further in higher gears. There are some downsides to this mod in terms of increased noise, and possibly increased gearbox wear http://www.planet-9.com/cayman-modifications/16084-sharkwerks-light-weight-flywheel-kit-2.html#post250752 . But everyone who has a lightweight flywheel seems to love it.

Aftermarket catback exhaust ~5-20 lbs reduction The various aftermarket catback exhausts have different weights, but they are all lighter than the OEM exhaust. To establish a rough range, the Borla catback weighs about 8 lb less than stock http://www.planet-9.com/cayman-modifications/19816-borla-catback-exhaust-pn-12653-a.html#post222065 , and the Supersprint weighs about 16 lbs less than stock http://www.planet-9.com/cayman-modifications/18697-supersprint-headers-cats-muffler-install-test.html#post212150 . I've cited a wider range in the title of this post since I have not done a comprehensive search - perhaps others can help with this data. This mod has the bonus of increasing engine power. Power increases ranging from about 5 HP to about 20 HP have been measured by independent dyno tests posted here. There are downsides to changing the catback. The car will be less neighbor-friendly (louder), and it will no longer comply with EPA and some state regulations, since the aftermarket catback eliminates 2 catalysts.

Lightweight tires - 0-20 lb weight reduction Switching to lightweight tires has the same double bonus as switching to lightweight wheels - you also benefit from a reduction in unsprung weight and a reduction in rotational inertia. The rotational inertia benefit is even greater than it is for wheels, since so much of the tire's weight is concentrated in the tread. So the weight reduction might be worth 3 times its nominal value in terms of the benefit to acceleration. The amount of weight reduction depends a lot on what tires one currently has and what tires are selected. Some tires are quite a bit heavier than others. For example, the OEM Bridgestone RE050A tires are heavier than the Continental SportContact 2 OEM tires. The Hoosier A6 and R6 tires are very light.

An easy 100 lbs! Implement all of the above changes, and you can save 100 lbs! That wasn't too bad... The next 100 lbs will be harder! Can someone who has installed lightweight racing seats post the weight of those seats, and the OEM seats as well? I've seen posts that cite a 50 lb weight reduction for this mod...

Change Seats to GT3 (or similar) - 50# FF - good thread! Basing on previous posts and my own lugging out of stock seats (didn't weigh them but they are HEAVY!), changing stock seats to GT3's will net about 50#. Exactly how much would be determined of course by which model of seat you have stock and which ones you are replacing with, of course - so I believe the 50# is a good number to quote in this thread.

Siphon Windshield Washer Fluid - 13# 6 litres at ~ 1 kg/l, or about 13#

10-50 lbs. Go on a diet! Yep, that's right, go on a diet . I bet most people could easily afford to drop 10 lbs. or more and this particular mod has other proven benefits too.

I like this thread! So far we've saved about 90 pounds at a cost of about $11,000. Of course, some of the more costly lighter weight items also add performance other than through weight savings. Don't forget lighter weight aftermarket seats for 40#. To get much beyond 200# savings we might have to go to light weight body panels. Edit: I knew it was a good thread; it gained 5 posts while I typed mine, so my summary is already out of date.

Bose subwoofer - 7.5 lb reduction What a useless piece of junk. The only down side to removing this is the unsightliness its absense creates in the interior.

Removing sprung weight, one pound, is like removing 4 pounds of unsprung weight. Buy magnesium wheels and carbon brakes. Use lightweight racing tires . Enjoying better braking and handling.

Porsche Carbon Composite Brakes (PCCB) - 37 lb reduction These are very expensive - $8K new or $20K+ to retrofit. There are mixed reports on their durability. They are included here for completeness. They have the double bonus of reducing unsprung weight, and reducing rotational inertia, similar to lightweight wheels.

This post just to put the topic out there - what about deleting various options? Auto A/C, Bose , HID's, paint (is it really true that white saves a few pounds?), etc. What about hollow section anti-roll bars? And Sapentia, that recommendation of yours is the cheapest but by far the hardest!

Carbon Fibre Rear Hatch Wasn't Tess Tickle going to work on a Lightweight (CF?) rear hatch w/ Lexan window (if he ever finishes all his other projects )? Don't know how much weight that would save, but probably several pounds. Also, the carpet pad covering the engine cover is pretty heavy, but easy to remove - several pounds there, but a few more decibels too.

djb_rh ran One Lap of America in a Cayman that had a CF rear hatch w/ lexan window. I'll PM him and ask about the weight reduction. Edit: the response was "It's huge...it's got to be 40 pounds, maybe 50."

OEM floor mats - 4 lb reduction Take out the OEM floor mats before your next AX and save 4 lbs.

Well, you're supposed to take those out. How about THE MANUAL in the glove box - that probably weighs a couple of pounds (and nobody reads it anyway ).

Door Panels - 60 lbs Gut the door panels 60 lbs (yes, six-zero!)

Get paid to lose 60 pounds! I lost 60 pounds.....and SAVED money by not eating out twice a day! Therefore its money in my pocket. Now add to that my RAC monolite wheels on the way soon, at 17-18 lbs per corner (not sure total savings but I think its 10 lbs per wheel) and that totals 100 lbs saved!! Now if I just do a few of the above mentioned items....I am well on my way to 200 lbs without getting deep into the car! Of course, to earn my negative 60, I may very well have just been creeping to the same weight many of you are already...so not much of a gain!!

Wow! That's amazing!

Seat swap The seats my car came with were the full leather, all electric adjust with heater models - 55 pounds. Leather 996 GT3 seats (from Suncoast), 28 pounds. Base savings, 27# each side, for a 54# savings.... BUT - if going beyond the cosmetic - need to add back weight of 6 point harness ( 4# x 2), anti-sub brace (2.5# x 2) and harness bar( 8#). So race-ready with GT3 seats is 33# savings. :cheers:

Change to a Titanium exhaust system. Will be very expensive however.

I would say there is only so much you can do to a street car and leave it so it is still worth driving on the street. I mean you can strip out all the carpets, gut the stereo and speakers, remove panels, headliner insulation, put on aluminum or carbon fiber hood, mirrors, body panels, remove heater and A/C, passenger seat, etc. Then it would be a full fledged race car and not really drivable on the street. I guess what you are getting at is what are practical things you can do. The list of remaing things must be really short.

I'm just trying to compile a list of possibilities, ranging from the mild to the wild. Each owner can decide for himself what they choose to do, if anything. The responses so far have been great, and very much in that spirit. Keep 'em coming!

Don't date and carry "large" women in your car (or men).

Someone mentioned lighter tires - be careful what you sacrifice, poorer tires will not make you faster just because you're lighter.

Carbon fiber bonnet?

Dont fill up your tank with fuel. Remove all the redundant stuff under the front bonnet. - carpet, covers, repair kit, air compressor etc. CD player? - you dont see it anyway. Heres a big one...How about all the under body paneling which is used to lower the Coefficient of Drag? I mean its unlikely most of us are going to be trying to drive at the same speed of a Jet.

Been discussed before, I think the consensus is very little saving over what is already a very light weight bonnet.

Uhhhhh.... isn't that backwards?? Unsprung weight is stuff like wheels and brakes (not riding on the springs). Unsprung weight reduction has the extra benefit, not sprung weight.

Porsche Carbon Composite Brakes (PCCB) - 37 lb reduction Great thread! Note that PCCB only save 37lbs over "full size" GT3 rotors. The calipers, etc., are bigger/heavier. There is barely any weight savings over stock S brakes.

Re: An easy 100 lbs! I have the MaxSpeed Motorsports GT3 Carbon Fiber (replica) seats installed. Porsche GT3 Carbon Fiber Seats The weight savings over OEM are: Driver: 21 lbs Passenger: 29.5 lbs The difference in weight savings between the passenger and driver seats is due to my re-use of the OEM seat bracket for the driver seat. Another thing to note is that my OEM seats include the heated seats option, which I'm sure adds a little weight over non-option stock seats.

I lightened my 996 C2 Techart Widebody Cab in 2000. If you want to see the rollcage, brakes and carbon seats check out "My Vehicles" on my page. I have no idea which ones are applicable to the 981 . 1. Took out factory power seats and put in Sparco Carbon seats (400$ per seat and very comfortable) saved well over 50lbs for both sides. 2. Stripped out the rollover protection system (saved well over 100lbs) 3. Added a lightweight FVD Roll Bar but removed back seats. (+20lbs or slightly more if you incorporate the seat removal) 4. Went into a larger Brembo Package and Saved (no sure how much, but it was sizable) 5. Dropped from a 19" 335 HRE 3-Piece (I was having a lot of trouble with clearance issues with the huge wheels) to a 18" Techart Daytona 285 (saved A LOT, but not sure how much) I had the ECU Dyno Tuned, had Techart headers , sport cats, exhaust ... It was supposed to net 30hp more, but when I removed all the weight, which was done in one fall swoop I noticed much better performance gains.. The characteristics of the car had changed for the better, all around. It's not as easy to get that much weight of of the 981 . Someone was mentioning a lightened flywheel. I've driven a couple Boxsters and 996s with them and it really screws with the driveability.