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Well considering STR was hugely popular at nationals with 64 cars entered and it is also very popular in most regions I really doubt they are worried about having enough options for the class and they probably wont want to mess with turn out success.

NJ-GT

Plus Porsche has SS, AS, ASP, BSP, FP and XP to dominate.

kjchristopher

Write a letter describing in detail the pros/cons of the Boxster taking into account all of the STR allowances. Any information on potential weight (using all the allowances) and power (using all the allowances. If you have direct evidence (event results), that would be helpful too. Make useful comparisons with existing cars.

Go to www.sebscca.com to submit your letter.

Edited to add that I'd be one of the blokes reading your letter if you send it in.

Autocrosser#73

Stephen, Are you not racing an S2000 now rather than your (past?) Boxster S? I have been watching you on YouTube.

I race a stock 986S in SCCA (Houston) and get clobbered by S2000s. As mentioned before, they are lighter, with closer gearing spacing, have an LSD, and have more neg camber.

PedalFaster

Yup, I now run an S2000 CR. In retrospect, I neither set up nor drove my Boxster correctly, but nonetheless, I think the CR's a better car for B Stock.

kjchristopher

I'm doing a little more research on potential classing in the ST category. Does anyone have the following handy for the 2.5 and 2.7 versions?

2nd gear ratio
final drive
hp (see below)
torque
curb weight

Wiki is showing the hp at:
2.5 - 201
2.7 - 217 (2003 - 225)
Accurate? How much gain using ST allowable mods?

Thanks,
KJ

PedalFaster

Renntech.org is a good forum for researching Porsche car stats. You have to register to see its contents, but registration's free.

From the 2000 Boxster manual posted on the site, the second gear ratio's 2.12, and the final drive is 3.56. The earlier 2.5 L cars had shorter gearing, but I don't know the exact numbers -- going by memory, Stock-prepped 2.5 cars run out of second gear in the low 60 mph range, whereas the 2.7s go to the high 60s.

Autos.msn.com (<-- click that link) is a good place to get and compare official weight, power, and size stats, although the comparison page I linked to seems to have the wrong weight for the 2.5 car. Weight as well as power went up in each midcycle refresh (in 2000, and again in 2003). Boxsters tend to come in heavier than their published curb weights would indicate -- Stock-prepped cars have weighed as much or more as Porsche's official weights on SCCA scales even with lightweight wheels and exhausts.

I think the base Boxster would be very competitive in STR; conceivably even a class leader.

ToSi

Gearing info (click me)

2.5's use a 3.89FDR & have a lower RPM limit. Wheel TQ is a wash, 2.7 nets more usable RPM for fast courses.

kjchristopher

Thanks for the replies. After 1.5 hours of googling this am, I found the info. I was under the impression that the transmission gearing had changed, but ultimately discovered it was only the final drive.

NJ-GT

KJ,

Boxsters have become affordable. A 1997 can be found for $5k.

I agree, people interested should send letters (via email to seb@scca.com) requesting the Boxster in STR, with supporting technical documentation. I think the car is a nice entry in STR, and as long as the super powered cars are exclude, such as the Boxster S, and 2009 or newer standard Boxster and Boxster S (they come with the 9A1 engine).

The base Cayman 2.7 should be included as well.

The 2.5 and 2.7 up to year 2008 would be good for this class. With all the top preparation, they could reach 2,750 lbs (light muffler, light seats, light battery, light wheels, add weight for LSD).

I still prefer the S2000 for STR, but a 2008 CR is more expensive than a Boxster 2.7.

kjchristopher

Thanks Rad. We're looking over the specs. What is magic about the 2008 cut-off?

When are you moving back out to the left coast! I miss the sound of that Fiat!

NJ-GT

If business was any better, I would have a small place in L.A., another in NYC and the main house in Miami. Then live at the 3 places at my choice. Business is not great yet.

2008 was the last year of the old engine. In 2009 Porsche switched to a brand new engine called 9A1, less moving parts and lighter, so the base Boxster and Cayman went to 2.9L and the S remained at 3.4. With this new engine the car gained torque and power (265Hp) which is even more power than the old Boxster S.

Now if the Boxster S is to be included, I don't see a problem including the 2009+ 2.9 cars. The problem is that the S and the 2009+ base cars have good torque compared to the rest of the STR class, and torque wins autocrosses. I think these cars are too fast for the class.

If case the 2008 and earlier Boxster 2.5 and 2.7 prove they are not competitive, then the inclusion of the Boxster/Cayman S can be considered.

In my opinion, the base Boxster and Cayman up to 2008 are competitive in STR.

ToSi

not sure what the point of the diff rule in STR is - both leading cars come standard with a helical LSD that works well under auto-x conditions. Other than adding initial cost & significant development expense to fully exploit, what does allowing alternate diffs accomplish?

Re: Boxster - Contrary to what the camber-junkies preach, a stock Box has enough range of adjustment to make the inner shoulders of its tires (F & R) run hotter than the outsides (on 140 t/w tires). I suppose the 8 degrees of caster has something to do with it..

with ~150 lb*ft of torque, 255 tires, & a rear biased weight distribution, inside rear tire spin-up isn't really an issue.

IMHO, the Boxster's most significant short coming is a lack of front grip in low speed / steady state corners. Haven't figured out a good way to fix that yet. I suspect much of it is intentional via geometry & some of it is just inherent to the M-R layout. Based on the tire temps, I don't think the STR allowances are going to fix this without compromising stability in faster transitions.

I don't have enough experience w/ tuning 2-way diff's to know if the push can reduced while maintaining the wonderful high speed transitional balance these cars have (the GT3 I drove seemed to be even worse in this regard though). Again, see paragraph 1.

As others have suggested, the 2.5L cars should be a good fit for STR & it is unfortunate that they were excluded.

PedalFaster

My experience didn't corroborate this -- I was only able to get about 0.8 degrees of camber in the front of my Boxster, and as a result I wore the outside shoulders of my fronts more quickly than the inside.

Wheelspin was an issue (albeit not a huge one) on my R-compound-shod Boxster S. I'm not sure how much street tires and the base car's lesser torque would reduce this, though.

I agree with your suspicion that this behavior is endemic to mid-engined cars; both my Boxster and my codriver's Elise offered a choice of low speed push or back end instability in transitions.

We disagree on whether the Boxster would benefit from more front camber. I think it would; if true, increasing front camber would increase its front-end grip and thus its overall speed potential, even if you had to increase rear camber as well to preserve the car's overall handling balance.

MechanicalEng

I thought that the 986 Boxter non S was allowed in STR already...