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

iflyadesk · 07-25-2007, 08:24 PM

Hi, my name is Sam and I asked these same questions over on Rennlist. I enjoyed reading your "Autocross Monster" thread and others on setup, but I wanted to ask some more application-specific questions as well as some clarification questions.

Background
-New to racing 2002 Boxster S, but not new to racing. Have qualified pole in a $7k Spec Miata against national cars (which have $7k engines), so I can at least put down one fast lap.

-Want to build up Boxster S to win in NASA Time Trial class C

-Currently bone stock with street tires

Setup
-Current gripes:
(a) steady state understeer
(b) roll stiffness
(c) ultimate grip
(d) latent turn-in

-What I think will work
(a) bigger front tires & more negative camber (from lowering)
(b) stiffer springs or sway bars
(c) sticky tires
(d) sticky tires

-What I'm hoping you can help me with
--will my ideas work?
--what spring rates are popular?
--can I get away with not upgrading the shocks?
--have you driven the Pilot Sport Cup? --does it really work as a street/track tire?
--would you go with stiffer bars and softer springs, stiffer springs and leave the bars alone, or stiffer both to fix roll stiffness?
--what are the tricks for stuffing more tire in the front? --how big can you go?

-My goal is to modify as little as possible, not for $$ reasons, but simply because less is often better when it comes to tinkering.

-And of course, what am I completely neglecting to think of? (strut bar, blinker fluid, electric supercharger, etc.)

Thanks in advance for your advice, and I look forward to being an active member of the Boxster community.

joyfrog · 07-25-2007, 10:04 PM

I do not know the largest possible application however I know I have 245/35/19 front and 295/30/19 rears with I believe a 10mm spacer for offset. I am not sure how this would work for the track but I know they fit nicely on factory suspension 2002 Boxter S

easyc · 07-26-2007, 10:42 AM

Most of your questions will be answered by searching over at the Boxster Racing board....

But I will give you my 2 cents worth...

I want to eventually make my 01 S into either a stock class Cup racer or NASA car, but its already a pretty formidable DE'er.
Tires... hoosier are what the best are running... you want to be competitive in NASA you have to have them. If not... the MPSC or Toyo RA1 or the new R888.
In the front you will want to run 245 width... depending on wheel height your sidewall number will change obviously. With a 17" stock rim (which is light, strong, and cheap to get used) you would run 245/40-17 in the front... some will run the same size in the rear... now you will need a 17x8.5 boxster rear rim to fit that size tire so you aren't pinching it on a 7". Also others run up to a 275 or so in the rear. The front 245 will need a spacer (5-7mm).
Suspension... GT3 front adjustable sway bar, and either a Tarret or HR rear bar with stronger droplinks... you will have your understeer dialed out with those. Most Boxster racers choose to go with the Bilstein PSS9's... I have them and love them and they work great with the aforementioned sway bars... They are relatively cheap for coilovers too. Last problem you will run into is alignment settings... I will spare you another paragraph about that stuff needless to say if you want full potential you will need control arms in the rear from tarrett and at least camber plates OR GT3 arms in the front. Rear you can get fine camber, but Toe is a problem... in the front stock only gets you around -1.5. Now if you didn't want to get coilovers a ROW 030 setup will be pretty good as well... its the euro factory suspension option, but its almost as coilovers.

As I said the boxster racing board is a wealth of knowledge on the subject... you will find some properly setup 2.7 spec boxsters outrunning GT3s.

racer_d · 07-26-2007, 12:15 PM

I guess the real first step is confirming what improvements are allowed for NASA TTC class (or any other groups you would use the car with) before doing anything.

Sticky tires will help immensly, as will reducing tire stagger front/rear. Not sure MPSCs are the best out there but certainly a safe place to start. I would the worthy tires in the following manner, best to worst: Hoosiers, then Khumo V710s, then Victoracers, then RA1/R888 then MPSCs.

the GT3 front sway bar is a popular upgrade for reducing understeer.

5-7mm spacers up front is also helpful to dial out understeer

Alignment is critical. Using factory components, you will never get "enough" negative front camber for use with the tires mentioned above. Most can get between -1.5 and -1.9 degrees, beyond that you need camber plates and/or GT3 Cup lower control arms. Not sure how legal these would be for your class.

IMHO, PSS9s are too much of a compromise (catering to street and track compliance is not easy. They are a good upgrade, but still a compromise). If rules allow, I would search out something more "race" oriented.

iflyadesk · 07-26-2007, 02:58 PM

If I read you guys correctly, the car needs more tire and camber in the front. So, probably a good first step would be GT3 control arms, 245s, and a strut brace (how much of a factor is the strut brace?). Additionally, I'll get the sways.

To answer one question, the way NASA-TT works is you are assessed points for each mod. So you get to choose your mods, rather than say having springs alone bump you into street prepared, like Solo II. I'm pretty confident I could work in every mod I want and still be within the base class for this car (TTC).

I'm a bit confused on the tires. Are you saying I should run 245s all round, but keep the 7/8.5 wheel staggering? One of the rules for TTC is you are assessed points for the tire width of the widest tire. So, if I had 205/255s, I'd be charged for having 255s. However, if I ran 245s all around, it'd actually be less points than the previous setup.

I was pretty proud of my 1.5 deg neg camber... I guess it needs much more.

Finally is springs. I want more spring, but there are only two available: H&R and Eibach. These are nebulous progressive spring rates, so I have no idea how they compare to a standard racing spring. I noticed the BSR runs 450/500.

I want to avoid the purchase of dedicated coilovers for several reasons. (1) The increased complexity often just causes more headaches than it's worth. Without a true data acquisition system and a shock dyno, trying to tune shocks is a nightmare and best left to the pros. (2) The corner weighting on my car is already close enough to perfect to not warrant fiddling. (3) I have no intention to fiddle with ride height. (4) $2000-$4500 is a lot of races. I think seat time in the new car will be more valuable to me than Motons.

So, the only options I see for getting a lot of spring without buying coilovers is: (1) Some sort of custom fabbed sleeve similar to a ground control sleeve over the stock shock combined with re-valving the stock shock (they are after all Bilsteins) (2) having a custom spring fabricated. (2) is probably not possible, and would probably be more expensive than it's worth.

Has anyone on here ever tried fabbing their own coilover sleeve?

racer_d · 07-26-2007, 03:09 PM

Quote:

Originally Posted by iflyadesk

I'm a bit confused on the tires. Are you saying I should run 245s all round, but keep the 7/8.5 wheel staggering? One of the rules for TTC is you are assessed points for the tire width of the widest tire. So, if I had 205/255s, I'd be charged for having 255s. However, if I ran 245s all around, it'd actually be less points than the previous setup.

I was pretty proud of my 1.5 deg neg camber... I guess it needs much more.

1) I am not sure you can fit a 245 on a 7" rim..

2) Running 245's all around will reduce understeer and make the rear a bit more tossable. I know several folks who ran Carerra Lightweight 18" wheels, I believe 8" (possible 8.5", sorry) wide all around, with 245 hoosiers with great effect.

3) Hoosiers and R comps will wear on the outer edges with less than -2.0 degrees. I think Tirerack has a "care and feeding" section for all the top tires. Seeing neg camber of -2.5-5.0 is really where these tires need to be to maximize potential.

easyc · 07-26-2007, 06:03 PM

You can pinch 245's on the stock boxster front Rim... BP has a good right up on it over at BRB. I think though that 8.5 all around is the best as you can rotate tires to balance wear out. As far as 245's all around... thats a preference... Im trying 245's all around next month, but right now Im at a staggered setup with 245 F and 275 R... Suspension wise the third option are Ruf Springs... they are made by HR but to Ruf's rates. Honestly though... PSS9's can be had for 1900, and their installation is not much more than it would be for the springs... As far as the front strut brace... thats a touchy subject... BUT money is def better spent on sway bars... The guys who cup race a cayman in Canada have been experimenting with adding a brace on the underside of the engine... and their reports are that it makes a difference...

iflyadesk · 07-26-2007, 08:33 PM

You guys have been a ton of help. This is what I love most about racing: consistently high quality people ready and willing to help fellow enthusiasts!

My registration hasn't been approved yet at BSR and BRB, but searching their threads have been very educational.

Here's what I'm planning at this point

H&R or GT3 front sway (still can't find a supplier for the modified endlinks--help)
H&R rear sway
H&R or RUF springs (waiting on RUF to confirm that they're significantly stiffer)
Used Schnell camber plates from "Rob in VA" if I can get a hold of him... registration pending...http://boxcar-racing.com/forum/index.php?topic=491.0

...although this writeup from "bodine" has me second guessing the camber plates:

"If you are building or plan to build a BSX car (that's the one with minimum mods, no cage, full interior) please hold off on buying camber plates or adjustable A-arms. I am going to petition the rules committee to remove these as options for the BSX cars. They will of course remain available for the BSR cars.

The reason is this. Pyrometer readings from the most recent POC Streets of Willow Event have shown that enough neg camber can be dialed into these cars for auto X and STS without them. Temps were linear across the tire with inside being higher by 6-30 degrees. This is a reasonable indication that the tire is not being worked excessively on the outer edge. More runs will be necessary to see a wear pattern and I will update you all on this.

We want these cars to be usable as daily drivers so if we can avoid excessive neg camber, we might hope for more than 800 mi to a set of street tires!

The delete of camber plates or A-arms will make this entry class even more affordable.

If you have already made this investment for your BSX car contact me for names of people who need these parts for their BSR cars at a no-loss buy-back.

bb"

I'm going to wait for the article this month from GRM on race tire testing, but I think I'm going to run 245s all around (maybe 245/18s with some new wheels based on some things I've read).

Any additional thoughts before I start swiping my card?

easyc · 07-27-2007, 05:25 AM

I got my droplinks from Tarett Engineering. They are a work of art and as strong as I will ever need. You can also get them from The Racer's Group, or I believe someone is know selling some custom one over at BRB.
The only other thing is... do only changing out the springs cost you less points than say struts and springs? Reason I ask is that changing out the springs is going to lower your car significantly and your stock OEM struts are not paired for such springs... thus at some point they will give away much sooner... many people will pair their aftermarket springs with Bilstein Sport Struts or ROW struts... Also I still think you should think about the PSS9's, you will be almost spending the same amount on installation for the springs as the coilovers will be... and the difference between the two is night and day.

Lastly have you thought about safety at all? Brey Krause Roll Bar extension is pretty much essential in our cars....

racer_d · 07-27-2007, 11:43 AM

Double check the safety component needs.. Some tracks/clubs require a BK bar ($350 or so used, $700 new), and/or the hardtop ($800-$1500 used) to be installed, and others still, a roll cage for what are technically "open" cars.

iflyadesk · 07-27-2007, 03:28 PM

I've tracked my Miatas for years and never had a club require anything more than the broomstick test. Have you actually been turned away by a club?

I won't be paying anything in labor. That's what a garage and air tools are for.

The BK bar doesn't appear to add any additional impact protection... it just raises the level of the bar, and I pass the broomstick test just fine already.

I love those GT3 seats, but in all honesty, the stock seats hold me really well. They are 100% better than any stock seat I've ever seen. I still use the "lock" trick where I slide the seat back, lock the belt, and then push the seat into the locked belt. However, in one session, I forgot to lock the belts and it wasn't until I pulled in that I even noticed. Genuine lateral support rocks! Worst case scenario, I have an Ultrashield from one of my race cars that I could throw in there.

The stock shocks performed flawlessly this weekend. If they don't handle the stiffer springs very well, I could always rebuild them. They are after all, bilsteins.

racer_d · 07-27-2007, 04:26 PM

The Boxster enjoys unequal enforcement among PCA regions. I went through some of this recently where I live.

1) VIR (Virginia International Raceway) requires the use of a BK bar, regardless of passing a broomstick test with the stock rollhoops

2) Potomac PCA allows you to run with a hardtop, even if you don't pass a broomstick test.

** Potomac PCA also judges your safety equipment by considering your equivalant PCA Club Race class. So. If you had a 2.5 boxster, but stuffed in a 996 motor, which would put you in a GT class for Club Race, it would be expected you have full cage and fire suppression. Yikes eh!

3) NNJR PCA only says you must pass the broomstick, hard top or not. If you need a BK bar to dos, then you must do so.

I my 914 days, I tried to run with the roof off at Watkins Glen. I was told I could do so, but that I must run with Arm Restraints. So. The roof went back on.

Things may be different where you plan to run, but consider looking at the rules for any/all groups you plan to run with, especially since the Boxster is an open car.

easyc · 07-27-2007, 04:31 PM

And just to add to the PCA region's differences... the Kentucky Region won't even broomstick you, just require you run top up or hard top on.

But with that being said... the Boxster Spec BSX class require the BK bar... On another cage note, Bruinbro over at BRB has a nice full cage that he can take in and out of his care... worth a look IMHO.

iflyadesk · 07-27-2007, 08:47 PM

Does anyone know how long it takes to get admin approval at BRB? ...or alternatively how to get in touch with "Rob in VA" so that I can buy his camber plates?

Thanks!

racer_d · 07-28-2007, 10:35 AM

Quote:

Originally Posted by iflyadesk

Does anyone know how long it takes to get admin approval at BRB? ...or alternatively how to get in touch with "Rob in VA" so that I can buy his camber plates?

Thanks!

I know Rob posts on a DC area board called www.dorkiphus.com so youy might try there...

iflyadesk · 07-28-2007, 09:11 PM

Thank you. I got a hold of him there.

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!