Pelican Technical Article:
Track Preparation / Rollbar extension Wayne R. Dempsey
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986 Boxster (1997-04) 987 Boxster (2005-08)
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This article is one in a series that have been released in conjunction with Wayne's
101 Performance Projects for Your Porsche Boxster. The book
contains 312 pages of full color projects detailing everything
from performance mods to changing your brake pads. With more than 950+ full-color
glossy photos accompanying extensive step-by-step procedures, this book
is required reading in any Boxster owner's collection. The book is currently available and in stock now. See The Official Book Website
for more details.
Check out some other sample projects
from the book:
Any 101 Projects book worth a grain of salt needs to have a section on preparing your car for the track. Increasingly these days, the Boxster is becoming a very popular weapon of choice as a dedicated track car. Its lightweight construction, combined with its mid-engine placement creates an excellent starting point for building the ultimate track car. I could probably write an entire book on the subject of creating the ultimate Boxster track car, but for now I'll just give a brief overview of some of the changes I would make if I were to turn a stock Boxster into a dedicated track car:
Install an aftermarket MOMO wheel with quick release
Remove as much weight as possible (see next section)
A project on track preparation would not be complete without discussing the option of placing your car on a diet. The benefits from weight reductions to rotational components in the engine are twofold—they not only reduce the rotational mass that the engine needs to spin up, but they also reduce the total weight of the car. These rotational components exist all over the car—not just in the engine. All of the rotational drivetrain components (wheels, transmission gears, axles, brake discs, etc.) have a significant effect on your car's overall performance. Using lighter weight wheels for example, will have a similar effect to reducing the weight of your flywheel—the drivetrain will accelerate faster, and the total mass of the car will be reduced as well. Again, the gain is twofold. It is for this reason that most racers try to remove as much mass as possible from drivetrain components when lightening their chassis.
While reducing the mass of drivetrain components can produce the most efficient gains, you can go only so far. This is because the drivetrain is responsible for delivering power to the wheels, and accelerating the car. You can only remove so much weight—you don't want to weaken the drivetrain to the point where it is going to fail. The second best thing to do is to remove weight from the chassis of the car. Theoretically, a 10 percent reduction in weight is equivalent to a 10 percent increase in equivalent horsepower. On a 200 horsepower, 3000-pound car, it may be far more practical to remove 300 pounds than it would be to produce 20 more horsepower from your engine.
So what can you do to reduce weight? There are a couple of rules of thumb. The first place you should remove weight is from “unsprung” components. These are the parts of the car that are not supported by the suspension. Examples include trailing arms, A-arms, brake discs, wheels, etc. The next best place to remove weight is from the highest points on the car (sunroofs, windscreens, etc.). Removing weight here helps to lower the car's center of gravity. Next, you want to target the mid/rear of the car. This is because the Boxster is already slightly tail-heavy due to the rearward mounting bias of the engine and transmission.
If your goal is pure performance, you can lighten your car significantly simply by removing or replacing the following on the car:
Remove the entire heating and air conditioning system
Remove window regulators/support braces in doors
Replace glass with Lexan
Replace decklids and doors with fiberglass
Remove most interior components (carpet, door panels, interior trim)
Remove undercoating on the chassis
Replace the drivers/passenger seat with a lightweight one
Move or replace the battery
with a lighter one (Porsche has a brand new Lithium-ion battery that just
came out for the GT3)
Remove any unnecessary components from the front trunk (spare, jack, etc.)
Remove the DOT bumpers and replace them with fiberglass
Remove stereo system, amplifier and speakers
Remove the convertible top and replace it with a fiberglass hard top
Drill brake rotors
Remove power mirrors
Most of this weight removal can also be done to a street car, but any weight removal must be balanced with the practicalities of daily driving. If you enjoy air conditioning and a good stereo, then you probably won't want to sacrifice these amenities for the improved performance. However, if your mission is to maximize performance, you might be surprised at how much of a difference weight removal can make.
Shown here is the Brey-Krause roll bar extension and padding kit installed into our project Boxster. This kit was specifically designed for use in the Porsche Club of America (PCA) driver's education events. The standard roll bar offers great protection, but only if you're not wearing a helmet. Installation of the roll bar extension is required by many events and offers very good protection against the car accidentally rolling over (yes, there have been Boxsters that have indeed rolled over at local PCA events. At about $750 from PelicanParts.com, the roll bar extension and padding kit is expensive, but it's a necessary safety requirement.
Any dedicated track car requires a welded in roll cage. Be sure to have someone install it who has previously fabricated one for a Boxster. The roll cage should include the appropriate mounting points for a shoulder harness and should also accommodate the Boxster hardtop, either the steel version or a light-weight fiberglass version.
Shown here is a Kinesis K28 wheel, one of the best choices available in high performance wheels. This wheel has a reputation for being one of the lightest and strongest that you can buy for your track car. The wheel centers are forged from 6061-T6 aluminum and are mated to rim sections that are spun by computer controlled machines assuring trueness and consistency throughout the wheel. These wheels not only look cool, but their performance and reliability has been proven time and again at various races like the 24 hours of Daytona.
Here's a shot of two Boxster interiors that have been gutted and prepped for the track. The car on the left has had a replacement dash computer installed in front of the normal Boxster display. This programmable dashboard allows you to monitor all of the systems of the car, while also logging data such as lap times and engine performance. On the car on the left, you can see that a custom box has been fabricated to raise the gearshift lever off of the floor. This allows for less movement from the driver's hand to the lever, resulting in quicker shifts and more time with your hands on the wheel. In addition to having most of the interior gutted and removed, both cars have fire suppression systems installed, as well as lightweight seats, MOMO steering wheels, and five-point racing harnesses.
Here's a photo of an Accusump installed in LN Engineering's test car. The Accusump is a cylinder shaped aluminum storage container that acts as a reservoir of pressurized oil, to be released when there is a drop in the oil pressure. The Accusump is connected to the pressure side of a Boxster's oiling system (typically through an adapter on the oil filter, inset photo) and is charged by the engines own oil pump. Its simple, efficient design revolves around a hydraulic piston separating an air pre-charge side and an oil reservoir side. On the oil side of the Accusump it has an outlet that goes into the engine's oiling system, controlled by a valve. On the air side it's equipped with a pressure gauge and a schrader air valve, which allows you to add a pre-charge of air pressure to the Accusump. Installing one of these on a dedicated track Boxster helps to compensate for the fact that the Boxster does not have a dry sump oiling system.
Nothing says fun quite like driving your Boxster on the track. The car shown here is owned by Mark Foley, driven at California Speedway. I took my wife's 1999 Tiptronic out on the track at the Streets of Willow one day mainly because every other car in my stable was temporarily out of commission. I initially thought the 2.5L engine and automatic transmission would be a slow dog on the track, but I was pleasantly surprised when the Boxster literally outran many of the other cars (mostly early 911s). The mid-engine placement, the balanced suspension and the quick braking combined with the Tiptronic transmission really made the car a secret weapon. I was most surprised at the Tiptronic, which somehow figured out that I was on the track and began to shift exactly where I needed it to.
Big rear wings are a staple of track cars, and no matter how many events you go to, you'll always be able to find a wing that you haven't seen before. I took a whole bunch of fluid and aerodynamics classes when I was at MIT, but even armed with that knowledge, I think it would be difficult to find the optimum wing design and settings without the use of a wind tunnel. It's tough to tell whether the use of a rear wing adds enough benefit to counter the added weight and wind resistance. It's truly trial and error here. An interesting feature of this car (other than the paint scheme) is the addition of center-lock wheels, which are typically found on cars that require quick tire changes in pit lane. Owner: Dr. Chris Murray
Comments: i have a habit of doing more than necessary to do a simple job, only because i've never done it before and "hunt and peck" to do it. i have two simple jobs that look more complicated than i think they are:
Car is 2005 Boxster-S 987, i think
1. The rod or piston that keeps the glove compartment from dropping WAAAAY down when opened.
2. On left door sill is the 2-switch unit to electronically open the front and rear hoods. That unit needs to be removed and replacement installed. I'm sure it is a simple removal, but i don't want to begin prying away at plastic and break something that is done another way that isn't obvious by looking at it.
Where to i find instructions for these two simple projects?
June 5, 2016
Followup from the Pelican Staff: All the Boxster articles are here:
If what you need isn't not there, I suggest getting the Bentley repair manual. - Nick at Pelican Parts
Comments: Looking for info about removing the air conditioning system from track-use only 986-S. What is serpentine belt routing after compressor removed? What belt spec or p/n?
November 12, 2013
Followup from the Pelican Staff: You can run a belt for a model that did not have air conditioning. The belt routing will be the same, minus the compressor. The belt part number from Continental is PK060760. Give our parts specialists a call at 1-888-280-7799. They can confirm I got the number right. This way you get the right part the first time.
- Nick at Pelican Parts
Comments: I know you sell roll bar extensions and padding. Do you sell a harness Bar for Boxster.
September 12, 2013
Followup from the Pelican Staff: We should be able to round one up for you. Give our parts specialists a call at 1-888-280-7799 and they can help you out. - Nick at Pelican Parts
Check out some other sample projects
from the book: