Boxster in NASA-TTC - 986 Forum - The Community for Porsche Boxster & Cayman Owners

iflyadesk · 07-30-2007, 08:58 PM

After prolonged pontification, this is where I have arrived

Since I really only have one shot at this, and just 6 weeks to prepare, I've searched every Boxster racing thread I can find to get the best mod list. The rules are I can only spend 19pts.

These items have already been purchased:
-Four 17 x 8.5 stock wheels (0pts)
-Schnell camber plates (0pts)

These will be purchased momentarily:
-Four 245/40/17 Khumo V710s or BFG R1s or Hoosier R6s or A6s (all choices are 9pts) (opinions welcome... my only experience is with V700s and RA-1s)
-H&R sway bars F&R (2pts) (The GT3 sounds like too much work to get right with having to match end links to my specific setup, etc.)
-Fabricate rear chassis support (3pts)

This will get me to 14pts. If I were still racing Miatas, I'd revalve the stock Bilsteins (3pts) and add Ground Control coilover sleeves (2pts), probably copying the BSR's 450/500 spring setup and bringing the total to 19. Unfortunately, there don't seem to be any coilover sleeve options (or any other option for mounting a race spring on the stock shocks). This leaves me with just the H&R springs (which don't seem to be much stiffer than stock, so no need to revalve the shocks). Would the car be competitive with soft springs and stiff bars? Rather than rebuilding, I could just buy the Bilstein HDs, but I'm still left with no stiff spring choices.

Alternatively, I could use DA coilovers valued at <$3000 for 5pts making the total 19. I'm a bit hesitant to purchase what seems to be the Boxster owner's favorite: PSS-9s. I've dyno'd shocks while interning at Ohlins, and DG explains my reasoning the best. The Ohlins at $2500 looks like the better choice, but no one in the Boxster community seems to use them... why is that? Ohlins makes just about the best shocks money can buy, so why no love? All of the other mods are relatively inexpensive, so I don't mind taking a chance on them, but $2500 for coilovers is a lot of money to spend when I'm not even certain the car can win and it might be back to stock a week after Nationals. And if Ohlins aren't respected in the Boxster community, I'll loose my shirt selling them.

My required weight is 2855 with driver, and I'm certain I weigh more than 3055 w/o me right now. I'm 150lbs, so that makes 350lbs I need to lose without doing anything irreversible. Where can I find that much weight?

If you have (or know of anyone who has) any of these parts listed that would like to sell them used, I will purchase them immediately... time is running out!

Please shower me with your (doubtlessly) infinite wisdom on getting a Boxster to put down one excruciatingly fast lap.

Pat · 07-31-2007, 05:33 AM

Great thread guys. Thanks.

racer_d · 07-31-2007, 11:55 AM

Define "irreversible" mods

1) Seats. Stock seats weigh 50 or so pounds. Get a nice lightweight race seat. Figure they weigh about 20lbs ea, so there is 60 lbs saved, maybe more.

2) Muffler. I am told the stock system oi very heavy. Likely save another 30 or so pounds with aftermarket units... I am sure a search here would help you out.

3) Remove spare, toolkit etc - another 20 or so lbs my guess

4) Lightweight battery - maybe shave another 10lbs there

So.. there is the first 100lbs.. the rest, well, now it gets harder... If you went with lightweight "carerra" rims, you could shave off maybe 5-10lb/corner (20-40lbs)... Also, check wieghts of your proposed tires. Some are heavier than others. This could add up, plus it reduces unsprung weight which improves performance

What can you remove without penalty? Side airbags? Front airbags? How about removing the soft top and its weight with a factory hard top? Do you really need heat and airconditioning? if not.. rip them out! Do you "need" to have side windows (and all that electric hardware?)

Loose the windstopper (light, but still, a pound is a pound) Remove cupholders, lower center console (I put in the GT3 console more for the looks and increased legroom, but it is lighter than the stock one.

Check to make sure you account for any required safety gear that needs to be in the car to meet regulations.

Just some ideas.

iflyadesk · 07-31-2007, 04:13 PM

At the race, I plan on running just one aluminum seat, pulling the spare tire, the passenger door panel, all the speakers and head unit, and running on fumes. I can't change the exhaust without being assessed points based on power gains, and I can't spend any more points in this class. I don't think there is anything else I can do without going off the deep end.

Maybe next year... One trick I would do with the miata is remove the soft top, drive to the event with the hard top, and then remove that too. Of course, after a while I figured out the increased stiffness of the hardtop about countered the weight, and the aerodynamic advantage at speed outweighed them both. I'm not thoroughly convinced a little bit of weight matters, as I once qualified in Spec Miata only to find out I was 65lbs under weight. I added two 25lb bricks and 3 gals of fuel and lost 0.003 seconds in the next qualifying session.

Does anyone have a set of PSS9s with the 450/500 BSR springs they'd like to sell me? What about a used set of PSS9s? Don't let them collect dust in your closet! Help a Boxster win Nationals!

easyc · 07-31-2007, 04:58 PM

My attempt to answer some...

I have never seen any 996 or 986 Porsche use Ohlins coilovers... Motons are the external reservoir of choice... The HR springs are not matched to your struts... you will have improved handling because of the lower CG, but I just don't know how much. You can get brand new PSS9's for 1900... why not go for that? The PSS9's are so widely used in the Porsche world... I love mine and except for an upgrade to Moton's I wouldn't go any other way. And with the upgraded springs I am sure they are even better. You will most likely be able to get away with your stock Droplinks for a weekend or two, but after that they will break. I wish I had a picture to show you the difference between the stockers and the Tarret ones... OEM look like a pencil... Tarrets are just huge... There are post after post over on rennlist about failing stock droplinks with aftermarket sways. I think its essential. Also... the GT3 bar offers more adjustability than the HR front... I believe its cheaper as well (call sunset porsche).
Ive never run nasa, but from what I have heard Hoosiers R6's are the only way to play... a good 1-2 seconds a head of the RA-1s. As for your wheels... if you have OEM 17"x8.5's then I am sure they are great... they will actually weigh just as little as the carrera lightweights... no need to go different there. Biggest weight loss past removing carpet, radio, spare tire/tools, seats, and etc is the Covertible top... chunk it... I believe that is something like 150lbs... mechanism and all... you can put it back in, shouldnt be too hard. Also you shouldn't get any HP increase by chunking the exhaust... so you shouldnt get any dyno points from that, just a hefty loss of weight... Hopefully I didin't miss anything.

iflyadesk · 08-01-2007, 06:00 AM

Then I guess the question is does anyone have a Lapis Blue hard top they'd like to sell? That way, I could remove the soft top and mechanisim, then put on the hard top on the way to Ohio, then remove it for the race.

Motons would bump me into a higher class.

If the drop links are the same length as stock, I can just use those as a template and fabricate some heim joints.

easyc · 08-01-2007, 11:26 AM

I have a lapis blue hardtop on my kitchen wall... but its not for sale... haha. You should get a fiberglass one and race with it on... larry at Gtmotorsports.net is a place to start.

iflyadesk · 09-02-2007, 04:55 PM

Quote:

Originally Posted by easyc

the Covertible top... chunk it... I believe that is something like 150lbs... mechanism and all... you can put it back in, shouldnt be too hard.

My convertible top weighed 37.6 lbs and my motors, trannys, and hardware weighed 17 lbs. So 54.6 total loss to pull the top, FYI.

The sound system: head unit, door speakers and enclosures, dash speakers, subwoofer, amp, and CD changer weighed 38 lbs.

The spare tire and jack were 29 lbs.

Seats were 46 lbs a piece. I took them both out and put in an Ultrashield with custom bracket totalling 20lbs. So that was a net loss of 72 lbs...but that makes me very suspicious of the supposed 60lbs of weight loss from going to GT3 seats. Unless they are 16 lbs a piece with the hardware, there's no way.

A shocker was the interior carpet panels on the front of the engine (7 lbs) and on top of the engine (8 lbs). 15lbs from removing two pieces of carpet. If I have time this week, I might try to pull the center console and all the carpet from the bottom.

easyc · 09-02-2007, 07:09 PM

Nice info... good to get real numbers! Nationals are in a few weeks if Im not mistaken, so good luck! Last year's TTB nat'l champ has instructed me before, he's hella fast in his M3...

And I would want to say with OEM rails the GT3 seats would be over that 16lbs... but the way I have my driver GT3 seat, with BK floor mount hardware... Im under that number.