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Running the SPB in other series

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Old 07-10-2017, 10:25 AM
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Lemming
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Default Running the SPB in other series

Ace brought this up in another thread and it is something that I've been thinking about as well. I may do some cross-over events with NASA since they come to my home track (Barber). Everyone talks about SPB slotting into GTS2, that may be fine for regional events, but, IMO, the car will not be competitive at Nationals without major modifications. So, why not detune the car to run in GTS1? The car should be more than competitive with the 944s and 325's the rule the class, without having to make too many changes.
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Old 07-10-2017, 11:11 AM
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Or run SCCA in T3 where the car is capable of running up front.
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Old 07-10-2017, 11:52 AM
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Originally Posted by toddlamb View Post
Or run SCCA in T3 where the car is capable of running up front.
I agree that SPB is more competitive in T3, but I've never been fond of the SCCA schedule (at least at Barber), one 9-lap race on Saturday and one 15-lap on Sunday. No practice either day, only 20 min qualifying.
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Old 07-10-2017, 12:19 PM
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Agree - you can thank Barber for that.
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Old 07-10-2017, 04:47 PM
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Thumbs up SPB running in other series

I have run my SPB in HSR and enjoyed it. Raced against other early P cars, BMW, Jags, and Alfas.The Bob Woodman race is alot of fun with all P cars against the Cameros and Mustangs. The class Iis SSB
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Old 07-10-2017, 05:01 PM
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So like 140-150whp or some ballast? Interesting approach. I'm not sure, but I'd like to find it works. I'd bet ballast is better on a lot of tracks as it would give the car more top speed.

I would expect some of the SPB's biggest issues with competitiveness in GTS at the nationals level are the open differential, no underbody aero (which has very little drag / top speed penalty), and better suspension options than the spec suspension are available if you are willing to spend more money. Also the transmission isn't great. Since those are all essentially open in GTS I'd figure the top guys would eliminate all of those weaknesses, and that's too much to swap out for events - it's a dedicated GTS build. Or maybe a once a season swap.

I'd love to hear I'm missing something though!
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Old 07-11-2017, 09:51 AM
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Originally Posted by ace37 View Post
So like 140-150whp or some ballast? Interesting approach. I'm not sure, but I'd like to find it works. I'd bet ballast is better on a lot of tracks as it would give the car more top speed.

I would expect some of the SPB's biggest issues with competitiveness in GTS at the nationals level are the open differential, no underbody aero (which has very little drag / top speed penalty), and better suspension options than the spec suspension are available if you are willing to spend more money. Also the transmission isn't great. Since those are all essentially open in GTS I'd figure the top guys would eliminate all of those weaknesses, and that's too much to swap out for events - it's a dedicated GTS build. Or maybe a once a season swap.

I'd love to hear I'm missing something though!
Agreed. For GTS1 I would add ballast and use an air restrictor to reduce HP while keeping low end torque. It would be easy to achieve the correct wt/hp ratio for different tracks.

To be competitive in GTS2 much would need to be done to an spb as you noted above. Additionally, the spb will be on the low power side for the class.
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Old 07-11-2017, 05:16 PM
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Default NASA time-trail class

I went through the NASA time-trial/performance-touring class calculator (spreadsheet) for Spec Boxster.

For the adjusted weight/HP ratio (tab 2) I came up with 13.720, which would put it below class TTC (14.50). I used 2650 lbs, 196 HP, and +0.3 for tires 250 to 275. This means SPB has to go to the Super Touring classes.

Using the ST calculator, I get an adjusted ratio of 14.120, which put SPB in ST4/TT4 (12.00 and above).

=======

It's irrelevant after the above calculation, but just for fun, I got this for TT/PT points (tab 1):

+7 "asterisk" points just for being a 97-99 Boxster
+5 points for Toyo RR tires.
+4 points for 255 tires
+12 points for 172 lbs underweight (TTE min is 2822)
+1 for replacement pulleys
+3 for replacing the car/muffler
+3 for replacing the shocks
+2 for replacing the spring
+2 for replacing the anti-roll bars
+4 for replacing the control arms
=======
+43 total, means up two classes (from TTE) = TTC.

Some people might have to add +3 for a front splitter, or +2 for side skirts, bringing the total to 48. In fact, you can go up to 59 points and still be in TTC.

However, as I said, that's irrelevant since the adjusted weight/HP ratio puts SPB into Super Touring.

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Old 07-11-2017, 05:34 PM
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Default SCCA T3 and Hoosier R7 tires

The Spec Line for Spec Boxster in the SCCA rules say you can either run tires as spec'd in the PCA rules (255 Toyo RR) or you can run any 225 DOT tire.

I saw a video from a Spec E46
(2001 BMW 330i) running in T3 at Thunderhill, and noticed that it was running about 2:03 and the fastest in the class was 2:01. Track record for T3 is 1:59.7. Spec Boxster track record is about 2:04 and typical times are 2:06. There's no way a SPB could do 2:01.

However, the driver of the BMW said he runs about the same with the RR's, but competes in T3 using the 225 Hoosier R7 (giving him 2:03). He thinks that Spec Boxster would be competitive in T3 with these tires.

Todd Lamb, do you run the 225 Hoosier R7 when you compete in SCCA T3? Is it faster than the 255 Toyo RR?

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Old 07-11-2017, 10:07 PM
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Default NASA GTS

I happen to have dyno data (a spreadsheet, not just a chart) on my Spec Boxster from an approved NASA dyno operator. I entered the data into the GTS calculator. HP=192, torque=176. You can see the result in the attached PDF.

The results are, that for GTS2, minimum weight would be 2658 lbs. Average horsepower: 183.3. Class multiplier: 14.5.

Your car might do a bit better--I still have the cat on my car. Worth maybe 5 HP. That would result in a minimum weight of 2668 lbs.
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SPB GTS Calc.pdf (54.6 KB, 28 views)

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Old 07-12-2017, 12:34 PM
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I missed the SCCA rule that allows you to run Hoosiers. It would be interesting to know how the car does on 225's compared to the RR's at 255. Where the car is competitive likely depends on track. I did a quick search of SCCA records and SPB records. For a number of tracks they were close, but at some SCCA was significantly better. Not sure I saw any track where SPB was faster than SCCA T3.
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Old 07-12-2017, 12:35 PM
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Has anyone run an SPB in PBOC? If so what class (although PBOC just about lets you self select)? PBOC comes to Barber every November, the weather is usually great and it's been my favorite race weekend of the year for many years.
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Old 07-12-2017, 07:00 PM
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I think the 225 is a typo. It should be any 255 (I was the one they called to clarify that any DOT tire would be adequate since I got the car classified in T3).

But the car is competitive in T3 with the Toyo's. 2:11 at VIR is competitive against the 350Z and E46's.
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Old 07-13-2017, 06:42 PM
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I've run mine with NASA in Spec 986, but I was the only one in class.
I've also run in BMW CCA, and just trundled around mid pack.
ProIT would also accept the car, but I doubt it would be competitive. I've enjoyed ProIT with my SP3 in the past though.
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Old 07-14-2017, 06:57 PM
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Originally Posted by toddlamb View Post
I think the 225 is a typo. It should be any 255 (I was the one they called to clarify that any DOT tire would be adequate since I got the car classified in T3).
It's not a typo. The Hoosier R7 sizes for a 17" rim are 225/40, 225/45, 245/40, 245/45, 275/35, 275/40. No 255.

225 is also the size for the SpecE46. The SpecZ (350Z) runs the 245.

I suppose you could petition the SCCA to bump the Spec Boxster up to 245. Of course, the SpecE46 is a 2950-lb car, and the SpecZ is a 3350-lb car, so it might be hard to make the case that the Boxster needs a wider tire at 2650 lbs.

Read the comments on youtube for the video I posted above. The driver of the E46 says that he's tried both, and the Hoosier's are good for several seconds a lap over the Toyo's. Even though they're not as wide.
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