Each sanctioning body will have a minimum suit rating required for competition. The standard for driving suits is 3.2A/X which is typically represented by a patch on the drivers’ left shoulder. The higher the SFI rating the higher the TPP value.
The SFI’s 3.2A spec (3.2A refers to suits specifically), in particular, is a test of a garment’s fire retardant capabilities, with a rating system put in place based on that item’s TPP (Thermal Protective Performance) when subjected to direct flame and radiant heat. This rating is designed to measure and correlate to the length of time one could be exposed to a heat source while wearing the garment before incurring second degree, skin-blistering burns. TPP is a product of exposure heat and exposure time, and is converted into a length of time before the second degree burns occur. The higher the number, the greater protection that a garment provides.
A common misconception is that the TPP ratings are the number of layers a garment has, but that is in fact not the case. Higher-rated garments do, however, generally contain more layers than a lower-rated one, as additional layers insulate and keep the heat source away from the skin by way of air gaps between the layers of fabric. An SFI 3.2A/15 and SFI 3.2A/20 suit are typically at least four or five layers, whereas an SFI 3.2A/5 is typically a two-layer suit.
Grooving is exactly what it sounds like. You trim out a narrow strip of rubber from your tire to channel all the mud and dirt and debris to the outer edge, increasing your contact patch, and thus, your traction. There is most definitely an art to this, however. You can talk to five different people and get ten different patterns that they say are the best to groove into your tires. Horizontal, vertical, diagonal…heck you can even carve diamonds into the tread if it works for the particular track you are running at that point in time. Most tire groovers use V-shaped blades that are heated using electricity to provide a quick, clean and precise cut. Blades typically range from 1/32” to 1/2” wide and can have either a flat bottom or round bottom, depending on the type of groove you want to make.
Tire Siping and Its Importance to Dirt track Racing!!!
Siping is also cutting the surface of the tire, but instead of creating a tread pattern, when you sipe a tire you are only cutting slits in the rubber. The slits may not look like much, but they serve multiple purposes. When the car first hits the track, the sipes help the tire heat up faster. But once the tire is up to temperature, the sipes will “open up” and then keep it from overheating and loosing traction. Sipes generally help improve traction but also will increase tire wear, so how much you choose to sipe any tire will often become a balancing act between traction and durability.
Just So you know you get roughly twice as much fire protection from an SFI-5 rated suit versus an SFI-1 rated suit?
Now let me ask you this. How many square inches of skin graft can you buy for $200???
The difference between surviving a fire in your race car is your firesuit. choose the right one correctly. This is based on budget, sizing and SFI Ratings.
All racers should be wearing at minimum, a double or triple layer fire suit at all times!!!!!