Weight Reduction (MantisSport)

Stan And Ernie, I really enjoyed the article on your website on the build of your Cayman racecar. Here's the part on your "strip down": "The car was still on the alignment rack and the interior bits filled the area behind it. All the way to the back door! Before we began to clean up and store the parts (Mantis had to open for business on Monday), we weighed the car, 2600 lbs, there was over 400 lbs of interior parts spread across the floor of the Mantis shop." Can you tell us which parts accounted for the majority of that 400 lbs and which are mission-critical (I'm assuming the engine cover is not an item you can leave removed!) At some point I may want to make mine a full track car and just rape its soul to get a better weight/hp (I'm not a racer but appreciate the value of any weight reduction). Would've just PM'd you but thought this might be of general interest. Congrats on all yout success out there! Anyone plse share your experience on this too. So far I have GT3 seats that take off about 50 lbs total and apparently the Milltek system is 10-20 lbs lighter than OEM.

I've had my interior apart (see articles) and I find it hard to believe that there is 400lbs in the interior that can be shed. Most of that would be in the seats, so replacing with GT3 seats is probably the single biggest improvement. The entire rear area plastic and headliner and center console and engine cover 'maybe' weigh 50 lbs cumulative. Take off door panels some other dash parts, and carpet and maybe you get another 50lbs, but I find 400 very hard to believe. Stan and Ernie's car weighs in at what 3104 with driver, assume 200lb driver that's still 2900lbs My car with GT3 seats and no driver is 3024, so it would appear that their car is maybe 100lbs lighter than mine, 125 tops.

I agree the seats are the biggest improvement. Stan and Ernie probably included the seats in that 400lbs they reference in their article. AC and NAV system another 30 lbs you think? For reference, my alignment and roll cage guy (extremely knowledgeable on all things Porsche ) thought he could probably get 150-200 lbs total if did a full strip (interior trim, undercarriage etc). But would be a noisy ride! So all in with GT3 seats (50lbs net), a race battery (30lbs net), interior strip (150lbs net), Millek header/exhaust (15lbs net), race wheels (20lbs net), PCCBs (30 lbs net?) prob looking at 2954 - 295 = 2659lbs for a barebones killer Cayman . Reason I ask is I was checking out the PCA club racing - the Cayman S would be in the GTS 3 (non-stock and up to 3.4l) series. Most of those cars seem to be under 2500lbs.

AC and NAV weigh 2 maybe 3 lbs, AC unit in dash weighs nothing pratically.

What about the sound system - good speakers can weigh a ton (assuming they are good). What about Bose with the multitude of speakers?

Total HVAC system in car (including HVAC module, Compressor, Condenser, Control, Lines etc) is about 50 lbs.

Oh yeah the total HVAC yes, I think he was just talking about the control unit in the dash. I don't think they removed the total HVAC system but I'm not sure, maybe Stan will chime in.

cayman will be killed in GTS3 for sure. the only class it has a chance is in D, where mantis is racing in.

Ken - does that include full fuel, oil, etc?

Another weight data point: My '07 CS with 5/8 tank of gas, all other fluids full, 19" carerra sport wheels, TPMS, stock interior, fire extinguisher, DMC harness bar, unheated manual sport seats, no PCM/NAV, no BOSE, no PCCB, no rear wiper... ...weighed 3,100 exactly. So, if you figure gas weighs 6.3lbs/gallon (it's quite a bit lighter than water), and 5/8 of a tank of gas is around 9 or 10 gallons, then with zero gas my car weighs around 3,040lbs. With GT3 seats I could get down to 2,990 perhaps. Of course, if I syphon out the 1.58 gallons of windshield washer fluid (at 8.3 lbs per gallon), I could cut down to 2,976 lbs. Yee..... hah. BTW: The owner's manual says "empty weight" for manual tranny '06 CS will vary from 2,954lbs to 3,153lbs depending on optional equipment. I have a feeling that only a car with ZERO options (and with the cheapest audio system that's not even offered in the USA) would be 2,954 lbs. Q

I've lost 10lbs of weight. Boxing, running does wonders for the abs.

bose ... good speakers... two phrases that don't belong together in the audiophile world they're just treated paper cones and most of them are small enough that the magnets aren't very large. And the nd woofers in the door are a "patented lightweight design." Supposedly the magnets used contain 10 times the "energy density" of conventional speaker magnets, thus they are made 10 times lighter. And that amplifier cluster in the front trunk sure as heck doesn't weigh much. - Suneet

Interior Weight Bob; Good guess, the seats weight a ton. In the 400 lbs we had removed every thing from inside the car except the window glass and dash. Besides the seats the carpeting, with sound insulation weighed a lot. The speaker magnets made good dumb-bells. Surprisingly the airbags weren't light either, there were four of these in addition to the seats. Now, we had to re-install most of this after we fabricated the roll cage to meet PCA stock class rules. Some of the bits got a bit lighter prior to re-installation. We kept the door panels and centre consule intact. (We have since removed the drivers door panel to make room for the NASCAR bars). The real advantage to reducing weight came from weight reductions at the extreme ends of the car. These were very difficult but just moving something a foot or so inboard can contribute a lot to balance. The battery, for instance, when replaced with the tiny racing unit saved almost 30 lbs of weight that is considerably higher than the roll centre. Besides the obvious, there was nothing major, just a whole lot of little bits that add up. Stan