Building a 986 S for SCCA CS Autocross for National competition
 

I debated long and hard about what class and car to build for a run at SCCA autocross and I settled on the 986 Boxster S as a dark horse for CS. (GRM thread) A search was put forth and I have finally purchased the victim, er "candidate" was located.

https://s3.us-east-2.amazonaws.com/p...44_mmthumb.jpg

It's a 2000 Porsche Boxster S, Finland build, with 2 options: cruise control and the wind deflector. The PO added the correct stand-alone 18" wheels and it's otherwise a stone stock 138K mile example with complete service records including IMS, new clutch, and a 33K mile used transaxle all done at Porsche dealers. I paid less than the PCCB brake option for the 718 Boxster for the whole car.

Cue the intro video:

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I'm going document everything about this build here and on YouTube. It's going to be a dedicated autocross car for C Street in SCCA and may dabble in P03 for PCA as well since there's good overlap. I will be attending the SCCA National Tour and ProSolo in Packwood this season and the end goal is my first trip to Nationals in Lincoln in 2020.

I love this stuff! If you don't know Woody (itsnotanova) yet, follow his six months to live posting. Great stuff there too. Good luck and keep posting!

Welcome to the forum. I've been following on GRM and glad to see you here now too. There's some great guys here who can answer ANY of your 986 specific questions and a whole lot more.
:cheers:

Awesome man! I just bought a 2000 986 base in September for autox and hpde. I will be following your threads and progress!

Congratulations and we look forward to following your progress!

Thank you everyone. It's not my first Porsche autocross rodeo, I campaigned a 944 in PCA Improved for 2 seasons, but I am definitely looking forward to running this car.

I had the complete suspension redone, check out the video here: https://studio.youtube.com/video/9rm0gWH0Vis/edit

Welcome aboard. I have a friend that races SCCA autocross down here in Texas and the key to winning is losing weight. There's only so much you can squeeze out of a M96 but there's a million ways to take some pounds off. Here's a video of him on a practice run.

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The suspension refresh is complete. New OE equivalent control arms front and rear as well as new rear CV axles as well as Koni Sport adjustable dampeners. Watch the video here:

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Alignment did not go exactly the way I wanted. With fresh suspension in place -0.3* of camber was all we could squeeze. We tried every trick in the book, but that's all she wrote for now. We will run a few thousand street miles and maybe 3 events before checking again in case the suspension settles in. (Note - ballast was at 155 pounds in the driver's seat to split the difference between me and my codriver.)****Everything else dialed in nicely. 7.9* of caster, -1/16" toe per side in the front. In the rear we got-2.15* of camber and set toe at exactly 0" for now. I am going to run the front sway bar (thinking of picking up a 996.1 GT3 bar) and 235's on the front (for minimal sidewall flex) and if it starts to plow dial the rotation back in with rear toe changes. (Remember, it's a dedicated autocross car!)

The other really important bit: weight. The car in complete street trim including service records and owner's manual in the car, the radar detector system, the spare/jack/tools, and a box of spares in the trunk scaled at 2953 pounds, or only 98 pounds higher than the lightest factory curb weight. Considering we already have the 18" wheel setup, that's great! 811 pounds on each rear wheel, LF was 695 and RF was 636 for a F/R bias of 54.93% to the rear. (Top up, 1/2 tank of fuel.)

Now that it's home I'll pull all of the extra junk out of the car (and weigh it), clean it up and check for phantom weight (dirt and rocks hiding!), and replace the fluids. On the tire front, thinking of a 235/285 staggered setup on the Bridgestone RE71R's. The goal is the first Bridge City Autosports event of the season, 2/24/19 at Portland International Raceway. Come run with us!

Time for the next episode of Project Porsche Boxster autocrosser.

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This time it's time to put the Porsche on a diet. I pulled the box of spares out of the trunk for 18 pounds and the spare tire out of the nose for 30 pounds, bringing our fighting weight down to 2905 pounds. I still have the floor mats inside, the radar detector, and the phantom weight to get out of it plus taking the gas down more and the changing the muffler we're looking pretty good. The wind deflector is another 2 pounds as well!

Javelin, do you plan to change out your brake hoses? If so, are you going to go with OEM or OEM equivalent?

When I bought my car and got a PPI, I was told that the brake lines look like they are still original, which means at this point they are about 19 years old. I want to change them out, and the cost of SS is not much more then buying an OEM equivalent like ATE and OEM is more expensive then a set of SS lines.

I've tried searching around but there isn't many threads on this topic. I thought yours might be the best to ask this question since you are trying to stay in stock class and I know SS lines will bump you up.

Frederiko is a fast driver, that yellow boxster was beast mode too! He is actually selling a very well prepared S that I’d buy without hesitation. He is jumping ship and buying a Miata :.(

Shawn

Cool to see a Boxster being used for competition, especially in the PNW! I'm in Seattle, and track my 2002 2.7, but haven't done any autocrosses with it yet.

Just wanted to be sure, the 1/16" toe figure is toe-out, correct?

Looking forward to following your progress, Javelin.

I am not planning on replacing the brake hoses at this time, but if I do have to I will have to use the OEM style rubber/PTFE versions. I have used SS lines on other projects, including track day cars, and never needed them nor got any actual measurable performance advantage from them. That said, can't hurt either.

Awesome! Maybe I'll see you at an event this season. Yes, the toe is toe OUT.

cool project.
you've obviously got a lot of experience, but 235/285 seems to be a huge difference in stagger. why not closer to a square setup and dial the handling with suspension tweaks? are you limited by class rules?

In SCCA C Street rules you have to run the stock wheel width, and I have the staggered 18x7.5/18x9 optional wheels. With the lack of spring force and front camber I will be lacking in the mechanical grip and tunability needed to run a square setup and really will need to just maximize tire contact patch at the detriment to everything else. Really good autocross setups are terrible on a road course and visa versa.

I did some testing last season in my CAM class Cobra with staggered wheels (17x9/17x10.5) and found that it performed better with a staggered 245/275 setup than with a square 275 setup (or a staggered 275/305 setup for that matter). Sidewall deflection started to make itself known. That's why I'm leaning towards the 235/265 over the 265/285 for now.

gotcha, very cool

Nice

You may want to consider going to 17" wheels
A little lighter and tires are much less $$

It would be interesting to see which would improve the lap times. Slightly lighter wheels vs a wider contact patch.

Are you running commensurately larger / diameter tires? Or are you adjusting profile to maintain diameter?
I'd be interested in how that impacts autox. I'd think the smaller diameter might aid in accelerating from point to point in those lower gears. On the other hand, sidewall flex is probably a big deal too?

Sent from my SM-G930T using Tapatalk

Chiming in because I've wanted to do this for a while. Are you on the standard suspension or the M030? I have all the US M030 part numbers saved somewhere if you need them.

Can you get to the adjusters on all 4 Konis while installed?

How's the gearing? I think my biggest concern with the 986 (or Porsches in general) is 2nd gear digs.

I think things got a lot tougher with the 2019 ND2, but still a fun project. STR 986S or 987 base is also on my list of things I'd like to try.

I too think I would try 17" 245s square first, but that's pure speculation.

Do you have the part number for the US m030 springs? Are those even still available for sale? I've only found ROW at suncoast.

Here's a dump of my notes, which appear to be incomplete unfortunately.

All that data is copied / pasta'd from forum searches, so double check. I'd bet people on this forum actually could correct any errors on this.

I appear to be missing the p/n for the red/white springs, which is M030 front 00-03.
Of course you'd have to get all 4 correct springs and one of the swaybars to be legal.

Not sure if it's worth all the effort, but if you put some of those part numbers into Google you might hit a website that's selling the springs you'd need for $150/pair used. New is about double that.

Do you think this would be that part number?

Do you think this would be that part number?

https://www.****************************.com/products/porsche-coil-spring-front-boxster-por-98634353116504

I have done quite a bit of testing on this on my CAM Cobra and there is a high margin of diminishing returns on wheel weight, and a bell curve on contact patch. Let me expand on that. If you run an exaggeratedly heavy wheel, say a 35 pound steel wheel, and then a regular alloy of say 25 pounds, you will not only see a difference in the lap times, but actually physically feel the momentum difference. Dropping again to say a 20 pound wheel will net more improvement, but maybe only 35-40% of the previous as opposed to the expected 50%. Every pound more you take off (at increasingly higher expense) takes off less and less repeatable time. When it comes to diameter, there isn't really a strong correlation in just 1-2" steps. In other words, if you go from a 17" wheel and 24" tire to a 19" wheel and a 24" tire (thus no overall size difference, but a 1" shorter sidewall) you will gain about as much from the sidewall height reduction as you lost from the increased weight, but it might not even make a measurable difference (in autocross!).

Way way back in the day we experimented with 13", 14", 15" and 17" rims all with nearly identical height tires on my FB RX7 autocross car and saw a bell curve of grip. The 13's were slowest, the 14's went faster, the 15's went fastest, and the 17's went about like the 14's. That's when I started figuring out that tire width to rim width was an issue. All of the tires were 205 mm but the 13's were 6" wide, the 14's 6.5", the 15's were 7", and the 17's were 6.5". You want the closest to square wheel width to tire width cross section that you can get, erring on the side of wider wheels/narrower tires, assuming good suspension travel/camber gain. (With camber issues like my 086 S has, it's better to run a much wider wheel and narrower tire to try and counteract that force trying to push the sidewall over on the outside edge).

All of that is completely useless unless you have the grippiest compound possible though. I did a lot of testing on tire compounds and sizes last season. A 305 Nitto NT05 is slower than a 275 Falken Rt615K+ is slower than a 255 Bridgestone RE71R, all on the same wheel on the rear (so no camber issues) and they are all 200TW. Compound is everything in autocross, that's why the schizoid guys are buying pallets of tires, shaving, heat-cycling, and keeping temperatures in check with warmers and/or sprayers. Getting the grippiest compound to it's absolute traction sweetspot is the majority of the game and you have to be willing to do that if you want to e on the trophies end of the stick (but at least it's not Hoosier's anymore!).

Standard. I can't get a complete breakdown on Porsche letterhead of the M030 package and my car doesn't have it equipped already, so it's not worth risking right now. I can change the struts and one sway bar anyway, so it's basically just the springs and other swaybar if I ever do get my hands on the info.

Gearing is super favorable for Nationals-levels courses. Second fuel cuts at a GPS and data-logged verified 73 MPH, which is higher than the 67ish of the ND, and the 986 S makes more torque and from a lower RPM than the ND so grunt out of the hole should not be an issue. I'm going to dyno the car after finalizing the new exhaust to get good torque vrs RPM graphs to estimate acceleration G's.

I am running the staggered 18's and tires, I am theorizing that absolute peak grip is going to be more important than the superior transitioning of the square setup. I ran square setups on the RX7, Miata, 944, and 914 and staggered on the P71, Javelin, and Cobra, so I have experience with both.

Oh, and here's the next installment:

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Apologies in advance for the terrible audio. I am not a video editor, I'm an amateur autocross car builder! The next one is better, promise.

What year Javelin did you autocross?

1973 Trans Am Championship Edition with a 360/727TF combo. I did a Grand Cherokee quick-ratio box on it, the biggest front factory sway bar, all graphite bushings, modern raised ball joints, and swapped the rear differential for an Explorer 8.8 with a 3.73 Track-Loc. I ran 17x9/17x10.5 wheels with Dunlops and it did well for the big old beast it was (which is terrible by any other standard).

Did you catch the latest episode" I got some seat time in on the Boxster: https://www.youtube.com/watch?v=fI4zMBu2bxY

Cool stuff. I agree that the M030 likely isn't worth the cost and effort at this point since you've already swapped the shocks. If you end up consistently within a tenth or two of the top NDs, then maybe it's worth tearing back in there.

According to thrust charts, I have the ND1 out-accelerating the 986S in 2nd up until about 50mph. I haven't run a chart on an ND2, but I'd wager it pulls on the 986 in 2nd all the way to 60. The 986 does have a tall 1st though, so any time you can use 1st you'll have an advantage over them. I doubt either car runs into issues putting their power down very often.

I waded into that GRM thread a bit, and looks like you have all of the mis-information covered already, but just to note anyone else wandering into this thread that:

- ROW M030 is not CS legal
- 18x7.5/18x9 are the widest legal factory wheel, which means you can run 17s or 19s in those widths as well

I've never driven a 986S but from what I hear you'll want to do everything possible to get more front grip. On a top-tier build I would consider experimenting with front bumpstops. They're open in street as long as they don't engage any sooner than the factory ones. That means you can shorten the long OEM ones, which would have the effect of softening the front end in most situations.

Good luck and I'll enjoy following this thread. Hell maybe I'll see you in Lincoln in CS.

I did some very preliminary and unscientific skid pad testing:

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Yeah, if I actually start getting close to the top of the field, I'll look a lot closer at the US M030 setup, especially for the springs and other swaybar. Shortening the front bumpstops is also a more advanced tweak that is an option as we go on.

Next step is the tires, then the swaybar. We are still on basics now.

I also worked on changing the headlights out:

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Winter storm Maya meant that annual tech got postponed, so we changed the first event the car will be at, it will now be the ORSCCA AX #1 and #2 March 2nd and 3rd at PIR in Portland. More updates in the new episode:

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Today was Annual Tech day for both the Oregon Region SCCA and PCA clubs, so I took the Boxster to both and passed both. It now has Annual Tech stickers for both clubs for the season, saving us time at every event to better spend preparing the car and ourselves for the runs.

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I also got a really close look at the only other 986 S in the Northwest to run CS at the National Tour since it was moved into that class. Chuck is a long time Nationals participant and is an inspiration to this build. It was pretty cool to get up close and personal with his car.

I finally got the tires put on. Bridgestone Potenza RE71R in 235/40/18 F and 275/35/18 R. My new numbers and class letters also came in. I'm pretty well set for the first two autocross events, which are this Saturday and Sunday March 2nd and 3rd at Portland International Raceway in Portland, OR with the Oregon Region SCCA.

https://youtu.be/pXwxCQLW8VM

Good luck, have fun!

And it's not supposed to rain!