Updated Proposed Category Rules Released

Updated Proposed Category Rules Released

Following a month of feedback and discussion by the Time Trials Board (TTB) an updated set of rules for the proposed category between Tuner and Max Categories has been released.

Because of overwhelming support for most of the category allowances, much of what was changed was fine-tuning of wording, but there were some areas with more adjustment.

Tire tread no longer must be hidden by fenders and there were minor wording changes for fender flares in order to create space for cosmetic additions or modification while limiting aero effectiveness.

For suspension, the wording for control arms and camber adjustment reflect the allowance of aftermarket arms and the restrictions on them, while mirroring the Tuner-category rule of only allowing camber adjustment at a single arm, or a camber plate, but not through both or by using multiple adjustable control arms.

The major changes to the proposed category come with the dropping of the allowance for diffusers, further solidifying the engine allowances and adjusting the class boundaries within the category.  

Diffusers are no longer allowed because the TTB did not desire effective diffusers in the class, and the ineffective cosmetic diffusers should be easy for a competitor to uninstall.  

The largest allowance of the category – the  “Either-Or” engine modifications have been further refined and each option formally named.

  • Option 1: The OE engine may be swapped for another engine (including OE forced induction engines) from the same make, and the swapped engine must stay OEM from the exhaust port to throttle body or turbo or supercharger inlet and may not take advantage of any other engine option allowances.
  • Option 2: An OE naturally aspirated engine may replace the camshaft(s) and anything from the “Ports out” meaning intake manifolds and throttle bodies are unrestricted. An OE forced induction engine must keep its intake manifold, throttle body and forced induction unit (super or turbo charger) but can change the piping and intercooler. Swapped engines or engines with aftermarket forced induction may not take advantage of these allowances.
  • Option 3: An OE naturally aspirated engine may add forced induction but may not perform any of the items from the other options.

Ultimately, these allowances focus on the most common ways to majorly improve a vehicles engine performance. Those with already-potent naturally aspirated engines tend to pick up gains through the intake manifold and camshaft, while those with less potent naturally aspirated vehicles tend to swap in an engine or add forced induction. Those with forced induction tend to focus on maximizing the performance of their OE turbo or supercharger by increasing airflow through piping and intercoolers. The TTB feels that changes beyond those put a vehicle in “Max” category.

The class boundaries have been adjusted with different weights and displacement for three of the four classes within the proposed category.

Class 1 still has a displacement limit of 6.5 Liters, and a minimum weight of 3,000 lbs., but Class 2 has moved to a displacement limit of 3.9 Liters and a minimum weight of 2,600 lbs. Class 3 now has a displacement limit of 2.995 Liters and a minimum weight of 2,200 lbs. The Class 4 displacement limit has been dropped to 1.995 Liters and a minimum weight of 1,900 lbs. As with Max and Unlimited weights are with driver and there are displacement correction factors for Forced Induction, Rotary and 2-cycle engines.

Because of the lack of allowance for weight reduction in the proposed category, the minimum weights are focused at keeping each class from being dominated by ultra-light cars on the market.

The link to the proposed rules can be found by clicking on the link below. In the document new wording or rules are in red, and old wording or deleted rules are struck out.

2019 Proposed Category Update

Jason C.

A diffuser is easy enough to remove. 

Erik Vandermey

Engine Option 1, engine swap must include the OEM intake manifold from which engine? The original OEM intake or the intake that is OEM to the swapped engine? Example: NC Miata, keep 2.0 intake manifold or use the 2.5 intake manifold? Or am I reading too much into this and whatever intake it is must be an OEM bit not an aftermarket bit?

Jon Raymond Krolewicz

Intake manifold would need to be from the engine going in the car. 

Tony Machi

It seems there are no changes to the prep rules for Sport Classes.

Chris Robbins

Tony, I read that the Sport, Tuner, Max, and Unlimited class rules are frozen for two years.