Introduction: Mini Cooper "S" with Jet-turbine engine
Mini Jet roof construction:
Our clients request for a custom top on the Mini-jet project car was very straight forward. He wanted an electrically operated front roof mounted air intake scoop for the turbine engine, which could remain closed when driving when the turbine engine was not in use. This would avoid ingesting water if the vehicles was driven in the rain. At the rear of the roof would be a sliding exhaust roof exit for the twin 10" exhaust stacks. Both must work simultaneously and be controlled from within the passenger compartment of the vehicle. And the entire package needed to have a factory like appearance or as original as a Mini Cooper with a turbine engine could possibly look.
Concept and design:
Designing and fabricating the custom roof was not so easy. The front air intake scoop needed to pick up air approximately 10 inched behind the windshield. At this point is where wind tunnel test indicated the highest air velocity. Since the electric motor drives and sliding roof mechanism requires at least 2.5 inches, the vehicles roof would need to be raised approximately 3 inches.
The electric roof actuators included 2 electric drive motors to operate the roof exhaust sliding roof, which is attached to a linkage system which opens the front air inlet allowing the engine to get an ample intake air supply. All this is required to be water tights, with a service cover in the event the system needed repair, adjustment or maintenance.
The actual top shell:
The top shell design started out as a series of simple hand sketches that were emailed back and forth to the owner, who lives in Florida, until we were all satisfied with the final look.
For those of you that are not familiar with fiberglass construction. This type of project will consist of making the "Plug". Which in this case is a foam cap which is temporarily glued directly to the roof of the vehicle. Once the foam pieces are adhered to the vehicle's the foam is then carved to the desired rough shape. The foam plug is then covered with fiberglass and resin to give it a hard surface. Using masking tape and several sheets of plastic cloth, care is taken to not allow any resin to get onto the painted surfaces of the Mini Cooper. Many layers of body filler are then applied. During this phase we can use body filler to add any special curved lines, intake duct detail and a small rear lip spoiler. At the point that everyone involved is happy with the look. We block sand, and apply a high gloss quality paint job. At this point one would think the job is almost complete, however in reality we are only at the half way point.
Making the roof mold:
With the Foam core plug still firmly attached to the vehicle, we apply 2 coats of a special mold release agent. Once dried we then apply a layer of tooling gel coat, along with many layers of fiberglass cloth and resin. We continue layering the product until we achieve a thickness of approximately 1/2 inch. When the resin has cured we carefully separate the final mold from the plug, which should separate at the layer of the release agent. The part we have now removed is the final mold which will be used to make the new fiberglass top. The foam "Plug" can now be removed from the roof of the vehicle and can be discarded.
The roof mold:
The part that we have removed is the mold of the final roof cap. This mold will now be cleaned up, wet sanded and polished. All edges will be smoothed in order to allow for a clean and accurate final part. The mold is coated with mold release, and 2 coats of common automotive wax. We then apply one coat of black gel coat resin, and 3 layers of fiberglass cloth to the smooth inside surface of the mold. Once all is cured we remove this piece from the mold. Finally we now have a new fiberglass roof for our custom turbine powered Mini Cooper.
Installing the new top:
The new top is now carefully trimmed and fitted around the entire outside perimeter of the vehicles existing top. Once the fit is perfect, we apply a liberal amount of 3M permanent urethane adhesive. Once we install the top we clamp the top in place for approximately 2 days. After the glue has cured we begin the process of block sanding, priming, and painting. End result we have one mini Cooper "S" with a factory looking roof extension, and a mold for any future customers that may want to do a similar project.