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SL-C Manual: Performance Options

Oil Cooler

Oil coolers for engine and gearbox can be used to reduce oil temps. The Ricardo box in particular needs an oil cooler if it sees more than 500 HP.
One possible location is either of the side air intakes on the rear. 

If you have a race tail, another area to place the oil coolers is at the front edge of the rear diffuser. This area does not receive as much cold air as the side air intakes, but will also be less prone to over cooling when the weather is cool. The factory 01 race car uses this location for the engine and transaxle oil coolers.
When using a transaxle oil cooler, consider using an inline thermostat. This makes for faster warm-up and smoother shifting as it reduces the time for transaxle oil to get to operating temperature. It also reduces wear in the transaxle as the oil warms up faster than it would if the thermostat were out of the circuit.

Tow Hooks and Loops

Most track day cars and all race cars need tow hooks or loops. This section shows several solutions implemented by different builders. 
The rear tow hook eye bolts in the next picture are bolted through the rear chassis cross brace with a reinforcing plate on the rear of the member.
When required the removable soft tow strap is clipped into each eye and forms a V shape which can be attached with a winch or tow strap for recovery and/or loading. These points can also be used as additional points for securing the vehicle onto a trailer for transportation.

The picture below shows a rear tow hook system made up of a tow strap tied to the rear billet upright. In normal use, it is folded and attached to the chassis with zip ties. When connected to a tow truck, the zip ties break and the strap extends to its full length (in this case, about 6 feet). This proven solution is shown on the factory #01 race car. It is NASA and SCCA legal.

The picture below shows an improperly engineered implementation of front tow hook eye nuts. This is a marginal location, and a good tug will likely pull the front off the car. Avoid this solution unless the tow hooks are only for appearance. Never attach a low loop or eyelets, or any other similar apparatus to the bolt-on parts of the front of the car. Experience has shown that tow loops need to be attached to a part of the chassis itself, not to the radiator supports or radiator floor. The radiator floor, the splitter, and the radiator support panels are not designed to withstand the forces involved with pulling or towing the car.

The next picture also falls into the “Don’t do it this way” category, as the tow loop pictured will come off, or worse, will rip the front end off the car with a hard tug, despite the stout hardware, as it is still attached to the radiator floor, which is only attached with a few small bolts to the chassis. Parenthetically, this picture also shows the splitter supports in a builder-provided solution that is only in single-shear. The factory-provided hardware uses a single rod that ties both radiator support panels together, making the connection much more rigid.

The best solution for a front tow hook on a race car is to weld a ring to the tube in the cage that goes down the front of the windshield as is shown in the picture below. 

This is the preferred method to place a front tow loop on a race car. 

Street cars and track day cars without this bar in the car could make a hook that is bolted to the top and/or front of the chassis and sticks through the bodywork like the green race car picture. Care should be taken to allow for defrost ducts and the wiper motor in this area.
Another solution is to use a receiver for a standard Porsche-style screw-in tow loop. This has the advantage of being able to hide the tow loop when not in use. The hole could be covered with a rubber or plastic plug when not in use.

A stealth approach is to not use tow hooks at all when a tow is needed, but to thread a tow strap through the brake duct openings, wrapping the strap around the suspension lower arm. This location has adequate strength and has the advantage of adding no weight. The angle of the strap must be close to horizontal during the tow, or the bodywork may be harmed, so be careful with this approach. Of course, if you are running brake duct hoses, another solution must be found.


The SL-C has two available splitters. The standard or “Street” splitter is a lightweight, balsa-core fiberglass-covered splitter that is mostly flat.

The street splitter can be seen in the picture above (with the red splitter hardware).
An optional tunnel add-on is available for the street splitter and is shown installed in the picture below.

This tunnel design works to manage airflow under the car and over the front wheels, and reduces front end lift. Contact the factory for prices and availability.

Note the areas of abrasion where the body on this car has fretted on the splitter. This can be reduced by using thin rubber or foam strips under the body where it contacts the splitter, or using carefully trimmed clear helicopter tape on the splitter and body surfaces.

The track splitter is similar, but is all fiberglass, 2” deeper, follows the curve of the fenders where it connects, and has more aggressive tunnels. The picture below is a street car with the track splitter fitted. Note the slightly deeper opening around the radiator intake as well. The track splitter is shown in these pictures:

Because of the location of these body parts, they are subject to wear and damage. You may want to stock a spare in case of damage so it can be replaced quickly.

The use of a lift kit helps reduce the risk of damage from speed bumps and problematic angles of approach.

Normally, the street splitter is supplied with the kit, but it can be replaced by the optional track splitter. Both splitters and the optional tunnels for the street splitter are available from the factory.

Either splitter can be fitted to the car at any time, but if you are planning for a splitter with tunnels, routing of brake cooling hoses and accessories on the rad supports should be carefully planned so that there is plenty of clearance.

Because of their location, splitters tend to be damaged easily. To mitigate the risk of damage from flying debris, consider covering the leading edges with helicopter tape. Use of a lift kit is highly recommended in any case, but especially with the track splitter

Fender Vents

The factory offers an optional fender vent that can be installed in the front fenders for increased downforce in the front. These are the same proven vents the 01 race car used in winning the 2011 NASA Super Unlimited National Championship.

The vents are available in fiberglass or carbon fiber.

They can be installed by cutting a hole in the fender and riveting them in or glassing them in with the necessary bodywork to blend seamlessly. You need to open up the vent openings with a Dremel or similar tool.

This picture shows the carbon fiber version installed on the 01 race car.

These were installed by simply cutting a hole in the fender and attaching the vents from below. The fit isn’t OEM perfect, but is functional for a race car, and was quick to install.

Not shown in this picture is the mesh screen below the fender vent. This keeps most dirt and large objects from exiting the wheelwell through the vents. It also serves the important purpose of protecting the relatively fragile vent from damage from flying objects. 

The next picture shows another variant that one builder used- the opening was cut in the fender, and a lip or shelf was glassed in so that the fender vent could be dropped in and sit flush with the rest of the fender.

Note the use of bonded-in studs invisible from the top of the car. This approach makes for easy removal, and good looks due to the ability to fine-tune the height of the vent to match the fender. These plastic studs are bonded to the vent with epoxy or fiberglass resin.

Another approach is shown in the picture below. This is a track car with custom vents glassed into the fenders.