powdrhound

I figured I would start a build thread here that some of the track guys here might find interesting. About a year ago at the end of the ‘20 season I parked the car and took it to CTS for a complete down to the tub teardown and rebuild. There was nothing wrong per se with the car and it performed beautifully all year easily winning the NASA Rocky Mountain Region TTU championship. What makes this notable is that the car did it in essentially street legal form still wearing a license plate on the back. The reason for the full teardown was to install a full weld in cage so the car would be legal to race wheel to wheel. My plan for ’22 is to race it in both NASA and HSR, the latter being a fantastic series based an all accounts. The main benefit of having a full cage is naturally the vastly improved safety this will bring. I had been lucky up to this point running the car with just the OEM IMV 997Clubsport rear cage but it was time to put safety first because all it takes is a blown tire at speed which can quickly make for a very ugly result.

I just got my car back from the shop after having a new roll cage installed. The finished product turned out fantastic. This cage is replacing the above mentioned OEM IVM 997 Clubsport bolt in roll bar that was in the car. While the OEM Clubsport roll bar was a great product for a dual street/track use car, it was totally inadequate for the use that the car was operated under. The new cage will bring an amazing amount of additional stiffness to the chassis and above all, vastly improved safety to the driver.

The new cage is built to the latest FIA regulations utilizing the newest techniques to distribute impact forces throughout the chassis and away from the driver This is evident with the additional rear bracing which ties the cage into the tub. The whole cage is constructed from T45 Seamless Steel Tube FIA / MSA Motorsport grade material and welded to the body at 18 points.

Numerous gusseting and reinforcements are welded in throughout the chassis including both front and rear strut towers. The rear strut towers are encased with a full steel "dome" which is welded to the existing strut towers thus drastically increasing the strength in an area which is highly stressed especially on applications using stiff spring rates, in our case, 2100 lbs per corner in the rear. This technique to beef up the rear strut towers is used on all the later generation Cup cars. Additionally, a full weld in strut bar is used to tie the rear strut towers together with the tub.

The front strut towers are reinforced via additional gussets added between the towers and the frunk firewall. In addition, the thin front OEM bolt in diagonal strut braces are replaced with a full bolt in transverse strut bar which ties both strut towers together and at the same time triangulates with the main firewall for a significant improvement in stiffness even over that in a 996/997Cup. Two quick disconnects were added to the strut bar allowing for quick removal of the center cross bar for easy access to the fuel tank lid/pump underneath where the battery would normally be located. In our case the battery is in the main cabin..

The door bars are made of continuous one piece tubing along with a diagonal A pillar bar which is a change in the latest FIA mandate. This is employed on the all 991 and later Cup cars. All 996 and 997 Cups used 3 bar door segment which were gusseted in the center, a design which is naturally much weaker. Two additional transverse bars run underneath the dash from side to side for increased side impact protection. Finally a door sill bar is used on each side to significantly improve cockpit intrusion in a low side impact. Neither 996 nor 997Cups have the dash or door sill bars. As part of the cage install, all the various brackets that are present in the street car tubs were removed including the heavy transverse floating crash tube which runs from one side of the car to the other enclosed in the rear seating area. This is only installed in the street car tubs and weighs about 20lbs. With a weld in cage, this bar is totally unnecessary and as such, the removal of it results in a significant weight saving.

When it was all said and done with, the full installed cage as seen here weighs just 90 lbs. thanks to the light weight and high strength of the T45 FIA motorsport grade tubing . This is amazingly light. My previous OEM 997 Clubsport rollbar weighed 40lbs and that was just the rear section. The front Clubsport section which I did not install weighed 21 lbs. Considering that 20lbs was removed from the tub during the install of the new cage, we only added a net of an additional 30 lbs. With a full weld in cage, we are changing out the OEM solid steel roof panel with a Manthey Racing carbon fibre roof which if I recall nets a 15 lb weight saving from the top of the roof. The Manthey carbon roof is a gorgeous product but for safety reasons I would only recommend it on a car with a full weld in cage with roof bars.

I must tip my hat to both Brian and Sam at DS Autosport who installed this cage for me. These guys are absolutely top notch fabricators and the go to place for anything having to do with a roll cage. Brian and his shop built the cage for David Donohue's highly modified Pikes Peak 991Cup and they have vast experience with all the required certification paperwork from the various governing bodies including SFI and FIA. I don't get impressed very easily, but the quality of their work simply blew me away. Their attention to detail is really impressive with the main hoops built very tight to within a few millimeters of the body. I never actually realized how much skill goes into building a full roll cage and it is absolutely mind boggling how they manage to weld every joint a full 360º even in the tightest spaces. Welding a cage like this properly is akin to building a ship in a bottle and is a definite skillset. Brian told me this is probably one of the most complex cages they have done as it involved over 100 weld joints. I was told that on a typical cage they will use about 3/4 of a full bottle of Argon. They used 3.5 on this one and spend over 120 hrs welding the cage. Thanks for an amazing job guys! Later on this week he car goes into the shop to get the whole cage and interior painted body color. Then in goes back to CTS for the reinstallation of all the components. Essentially everything in the car is being addressed including completely new aero, Cup doors, Cup windows, LED RSR lights, carbon clutch, Motec ECU, etc. etc. The engine, gearbox, and suspension will be largely unchanged for the time being. The end goal is to have the car at 2750 lbs ready to run with 800hp at the wheels and 1000+ lbs of downforce at speed. Target for testing and initial set up will be March when the weather improves.

Indiana Jones

I was expecting much more than 90lbs…fantastic!

gorgeous work, and safer makes it a win win.

Tuned in, keep the pics coming.

zbomb

Big cage with a lot of detail often overlooked.

Thanks for sharing.

racingfan

Nice work! Impressive attention to detail.

pranqster

You should be safe at Daytona with that cage.
Damn impressive.

Cemoto

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Amazing skills!

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ScottArizona

And here it is folks,,,when completed, the best 996 ever!

rodneyr

Looks great and the work is impressive! 120 hours welding the cage, wow! That would to $20K in labor in area. Why not just buy a 996 Cup car? They are inexpensive at this point.

spiller

Unbelievable work John! Can’t wait to see it progress further. That interior is going to look amazing when painted blue.

powdrhound

I enjoy the performance of this car which even in its previous “street legal” form was far greater than that of a 996Cup which is sedate in comparison. I enjoy the development aspect of it and don’t care much for the newer video game paddle shifters cars.

lf a super clean 6Cup ever came along I wouldn’t be opposed to getting one as a few of my friends have one but I will always keep the blue car which is just way too much fun.

powdrhound

Thanks! Yeah, I think a color matched blue interior will be nice.

DHI

Thank-you for sharing!!
Very impressive work and car.
Cant wait to see it all buttoned up again !

zbomb

@powdrhound What are you planning for aero with your build - with all that HP you could certainly push through some aero drag for the benny's the DF would provide.

I have been waiting ( and kind of planning ) for someone to put some modern big aero on their car, looks like yours would be a good candidate. If you want the contact for someone I've talked to who can make some cool custom carbon aero stuff, hit me up. He mentioned he's been wanting to get some stuff developed for the chassis.

powdrhound

Yes, we are doing full aero on the car. We actually already have it made. We worked with a company which specializes in Motorsport aero consulting using advanced modeling software, testing, and analysis. They do a lot of work across all levels of motorsport from NASA, Pikes Peak, IMSA, etc. The aero that was designed for my car consists of a full front splitter which is bolted to the front subframes and attaches in the front with hidden support rods behind the bumper cover tying into the aluminum bumper beam. The front splitter sticks out approximately 6" all the way around the bumper. It is constructed from 1" thick carbon fiber with embedded aluminum plates which are used to bolt the assembly to the subframes. The whole set up is super strong and several people can stand and jump up and down on the splitter lip. The outer edges have small strakes which will tie in to the wheel arch flaps. Attached is a pic of the top of the splitter.

The rear carbon wing is 72" wide with a 13" chord and uses an advanced airfoil which has been proven to be far superior to the standard Porsche Motorsport wing used on the 996 and 997Cup. The max width of my car is 72" at the rear wheel arches and that is why we went with a 72" wide wing as you have stay within the footprint of the body of the car to be legal. We discussed using a swan neck wing which offers slightly better aerodynamics but I've always been partial to the uprights on the 997RSR and asked them to model something similar which they did. I'll post up pics once all the aero is on the car but based on what I've seen it will look great and I was told will provide right at 1000 lbs of combined front and rear downforce at speed based on their modeling software.

Front CF splitter

997RSR wing/upright inspiration

996CTSR upright / wing pylon mount

powdrhound

Few more misc pics...

Motec engine harness getting finished up....





The Motec harness and wiring for the whole car using the Motec PDM will weight about 10 lbs compared to the 62 lbs of OEM wiring removed from the car..


The OEM dash in the car is replaced with the Motec C1812 Motorsport dash display data logger which will tie in with the M150 ECU. The Display Creator will allow for total custom dash graphics display and configuration. Motec PDM eliminates the need for all but 2 or 3 fuses in the car.





Tilton 5.5" carbon clutch replaces the 996Cup clutch that was in the car before. The Tilton complete clutch package weighs in at 13.8 lbs compared to the 25.8 lbs of the 996Cup clutch. The MOI of the Tilton is a fraction of that of the Cup clutch.