At the Sports Car Club of America's National Championship Runoffs this weekend, a protest was made that penalized the top six cars in its über-popular Spec Miata class, preventing them from winning the class over a modification to the engine heads. Oops!


Spec racing is supposed to be just that: everyone runs the same car to create an even playing field. In practice, your ability to win also depends on the skill behind your build and setup, but for the most part, the intent of the rules is clear that your driving shouldn't be one-upped by an internal engine mod.

The protest was a blanket protest for the top nine competitors. The engines were marked with paint to "seal" them from tampering for the weekend, so their drivers were still allowed to race. That only seems fair since Laguna Seca was a long haul for a lot of racers. After the race was over, the cars were impounded and inspected by SCCA officials.


Problem is, eight of those cars were found to be in violation of 9.1.7.c.1.f.4. OOF! Thus, seventh place was bumped up to first. This is the lowest position a racer has finished at the SCCA Runoffs who has ultimately won a championship in the entire fifty-one year history of the race.

SCCA Public Relations Manager Reece White had this to say about the abnormal number of non-compliant cars:

Our rules allow mechanical protests within 90 minutes of the final qualifying session (at the Runoffs). If it's for an invasive part, it does require a bond, because if the car is found compliant, someone has to pay to put the motor back together. If you protest correctly, you get that bond back to you at the end of the process. That's the official and general process that the SCCA rules allows. In the case of the Spec Miata, the issue was out of compliance cylinder heads. It's too soon to know what might happen moving forward. The Club Racing Board is always taking input from members on rule changes through the processes there, and examine those on a case by case basis. It will be no different after the Runoffs this year.



Per the Mazda Racers forums, the rule in question was 9.1.7.c.1.f.4:

No aluminum in the bowl area (other than that specified for the plunge cut) or the ports may be removed, added, or manipulated for any reason. It is understood that heads may look slightly different from bowl to bowl due to casting irregularities. No material may be removed or added from the short turn radius in the port.


Shaving and forming cylinder heads into a certain shape encourages better flow through the engine, allowing racers to run with higher compression ratios and more horsepower. The short side radius is frequently listed as the exact location of the offending mod that Spec Miatas tend to quietly modify in the heads of their cars.

Likewise, the preceding rule 9.1.7.c.1.f.3 allows there to be a "plunge cut" made in the heads:

The throat area of the port consists of the 90 degree angle at the very bottom of the cast steel valve seat as it transitions to the aluminum casting below. It is permitted to plunge cut the throats in order to correct for core shift that is commonly found in many cylinder heads. This cut cannot extend further than the specified number below from the bottom of the ferrous valve seat. There can be no tooling or machine marks in the head below this point. The area under the seat where the plunge cut ends and the casting resumes cannot be blended by hand, machined, or chemically processed to create a smooth transition. The 90 degree bend at the bottom of the valve seat and the aluminum directly below it will be measured with a gauge and must conform to the maximum diameters and depths listed below. Maximum Intake Throat Diameter [1.8L engine] - 1.178 in

Maximum Throat Depth [1.8L engine] - 12mm

One penalized competitor, Jim Drago, says that the terms used in these two rules aren't adequately defined and that it's impossible to make a plunge cut without taking material off of the short side radius. In a post on Mazda Racers, explaining his side of the issue:

In rule "3" builders are specifically allowed to plunge cut the heads to allow for the correction of core shift. There is no definition of "plunge" or 'plunge cut" in the [SCCA General Competition Rules]. There is no procedure spelled out in rule "3" or for the plunge cut. The plunge cut is solely defined as a cut that does not extend more than 12 mm below the valve seat and no wider than 1.178", with no tool marks evident below 12 mm. It is VERY important to state that NONE of the competitors protested violated this rule in any way. The rule does not say "how" to do this plunge procedure or what tools may be used. The rule does not specify the "plunge" procedure to be in one step or many, one tool or many. Builders are free to do whatever they wish within the specified dimensions. It does not say you must use cutter "x: with a specified "x" degree radius or no radius at all. Reading "3" and the complete [Spec Miata] ruleset, a competitor will be 100% compliant if they chose to do the entire plunge cut by hand with a porting tool, Dremel or even a pocket knife as long as they stayed within these dimensions. Literally any manner of removing the material would be compliant. The profile of the cut is also unrestricted by the rule, so a multiple step procedure with multiple tools, a radius cut, a straight cut, an elliptical cut and anything else you could think of would be compliant as long as it was within the specified diameter and not to exceed 12 mm in depth. Again, none of the heads violated this rule. Even using the strictest interpretation of "3", If a machinist were to use a straight cutter and machine a cut straight down on the same plane(which is also not specified by the rule) as the factory Mazda plunge cut, material is being removed the short turn radius. By definition, this directly contradicts and violates "4" as "4" CLEARLY states and what we are being found in violation. " No material may be removed or added from the short turn radius in the port" Any larger bored hole definitely removes material from the short side radius, as it is impossible not to do so. This is extremely important to state as this point alone makes EVERY cylinder head ever built for competition SM non-compliant.


Who's right on this issue? It's hard to be sure, and if there's one thing I know about SCCA folks, it's that the exact letter and meaning of the rules will be argued over until everyone's blue in the face.

In a statement published on Racer, SCCA President Lisa Noble said, "What happened this week, with so many cars being non-compliant, is unfortunate. We need to ensure that this moment is a trigger for a positive change in this class."


In the meantime, though, it kind of sucks for the Spec Miata racers. "Is my head still compliant?" is a concern that has rung out across all corners of the Internet, with racers asking for pics of the offending engines to compare with their own.

At the very least, it sounds like a clarification in the rules may be needed for 2015.


Full disclosure: I have no relation to any of the names on the protest sheet, nor am I connected to anyone on either side of the protest. One of those guys coincidentally has a spiffy last name.