New SCCA National Time Trials Category Proposed

New SCCA National Time Trials Category Proposed

In order to close the gap between Tuner and Max while protecting category philosophies, the Time Trials Board (TTB) is proposing a category between Tuner and Max and is looking for feedback on the proposed category.

Vehicles in this category are expected to be able to be street driven and will still be required to run a minimum of 200-treadwear tires.

The major item in the proposed class is a set of “either-or” engine allowances. Vehicles may have ONE of the following done, but not multiple.

  1. Aftermarket Forced Induction added.
  2. A non-OE camshaft installed.
  3. Same-manufacturer engine swap.

There are some restrictions here, such as single-unit forced induction only, no twin turbos or twincharged cars, and a forced-induction engine may not modify or replace its OE forced-induction system. (E.g., you can add a turbo to a naturally-aspirated Subaru Impreza 2.5RS or swap an STI engine with the OE forced induction into to a 2.5RS, but may not change the turbo on a Subaru WRX or STI.)

Other than those allowances, engines may not be modified further than Sport or Tuner. (Meaning, no modified internals or engine work is allowed.)

Other drivetrain parts – transfer cases, rear ends, transmissions – may either come from the original vehicle or the donor car. Further combinations from different vehicles are prohibited. 

Additionally – in order to prevent nearly impossible to attain engines as the “need to have” for any allowed swaps, the TTB has set the minimum production number for donor vehicle engines at 10,000 units during any production year in any one market. This is the first shot at a number to limit this and we recognize this might not be the right spot. We recognize that this will allow an Integra Type R to compete, but it will not allow a Civic with the Type-R engine to compete. Eliminating rare swaps at this level is our goal.

ECUs and throttle bodies are also open, and the intake manifold may be replaced with some restrictions. The replacement intake manifold may either be an OE unit from the same manufacturer which bolts directly to the engine without adaptors or, if it’s an aftermarket intake manifold it must be the same style as OE. For instance – if the car didn’t come with individual throttle bodies, they may not be installed, and a custom-slab-built intake manifold may not be used in place of a cast piece. The intention of this allowance is to enable things like common cast intake manifolds which are easily sourced.

In order to accommodate swaps, replacement or or modification of the existing wiring harness is allowed and subframes may be modified the minimum amount to perform allowed modifications in this category. (This should not be construed to allow suspension mounting point changes.)

The proposed category will also open body and aero allowances, and vehicles here may replace hoods, decklids and convertible hard-tops with replicas of alternate material. These items will need to use factory hinges and use the same design shape, so as to avoid super-thin, single-layer, ultra-lightweight parts. The proposed category also allows over-fender flares and non-domestic OE bumpers and bumper-covers, and they may be cut or trimmed for parts fitment or aerodynamics. (E.g., those holes you see cut in many bumpers.)

Aerodynamic aids such as spoilers, splitters and a rear wing are now allowed – but each of these are limited in size. Splitters are limited to 3” forward and no wider than front bodywork or 3” – whichever is less. The rear wing and spoilers are about 80% of the allowed area in Max Category.

Wheels and tire-widths are open, but the contact patch must not be visible when viewed from above. (Cover them with those flares!) Under the wheels, big brake kits are allowed, and the proposed class allows adjustable brake-bias.

Vehicles will also be allowed to adjust camber with more than one part. (E.g., Upper and lower control arms may be replaced) and we will allow bump-steer correction which bolts to the OE tie rods and tie-rod ends. (E.g., ball-joint extenders.) Leaf-spring cars are also allowed to convert to a coilover design in the proposed category.

For the exhaust, test pipes in place of catalytic converters are allowed here, but as usual – competitors are cautioned to watch federal laws when driving these vehicles on the street. Federally-approved fuel for use on highways is still the rule here, but the use of E85 is not restricted.

For the proposed category classing, there will be four classes, all displacement-based with minimum weights for each class to avoid ultra-light production cars being dominant. The upper limit of displacement is fairly well set at the Class 1, as is the Class 4 limit of displacement, but we are looking for feedback on where to draw the line for Classes 2 and 3 to include the most reasonable vehicles for each class.

Class 1:
Eligible vehicles with a real or corrected engine displacement of more than 4.7L, but not more than 6.5L, weighing no less than 3,000 lbs. and some combination of underweight vehicles from classes below.

Class 2:
Eligible vehicles with a real or corrected displacement of no more than 4.7L, weighing no less than 2,750 lbs. and some combination of underweight vehicles from classes below.

Class 3:
Eligible vehicles with a corrected displacement no more than 3.2 Liters, not weighing less than 2,250 lbs. and some combination of underweight vehicles from classes below.

Class 4:
Vehicles with a corrected displacement of less than 2.21 Liters, not weighing less than 1,750 lbs.

As with Max and Unlimited Categories the displacement correction factors are as follows:

  1. Rotary: Actual displacement X 2.0
  2. 2-Cycle Engines: Actual displacement X 2.0
  3. Forced induction: Actual or corrected displacement X 1.5
  4. For each additional forced induction unit 0.5 should be added to the forced induction displacement modifier (e.g., twin charged, twin turbo: Actual corrected displacement X 2. Quad turbo: Actual displacement X 3).

So, there you have it – proposed class. The full proposed rules and the feedback page are linked below, and the TTB will be accepting feedback on the proposed category until February 20, 2019 and the category rules will be submitted for official approval at the SCCA BOD meeting the following week.

SCCA Time Trials Feedback Page

SCCA Proposed Category Rules

Matthew Huffman

okay, i guess... but at least regionally we are already struggling to get reasonable class sizes so we're not racing in classes of ones or twos...  Seems like we already had a decent number of classes.  For example, I've seen 3g MR2 with a K24 Honda swap... they went from 140HP to probably 240+ HP at 2200ish pounds.  That's tough for other folks to compete with if they have an OEM engine.  Seems like making swaps play in Max isn't unreasonable.

Dave Deborde

How about really old cars like my 1971 240Z Datsun. Car has a 280Z engine, headers triple Weber carbs and an R200 differential swapped from a 280Z.  Can a car like this with after market carbs run in the - proposed class, or does it have to go into Max or U?

What if I swap back to the L24 engine with triple Webers and engine internal mods. Cam, forged pistons, reworked cylinder head etc.  Would this be eligible for Max class depending on tires?

Just looking at different options to see if I can get something ready for the April 13-14 Thunderhill TTNT. 

Dave Deborde

Looks good to me. Have you decided what the name of this class will be?

Brandon Ryan

Love it!!  Finally a place I can feel at home with my engine swap!