On ApexSpeed.com I've been conducting a survey of operational costs for each class.
Here I'm only looking at the predictable costs that vary between the classes.
Some costs are more or less the same between classes, such as towing, hotel, food, entry fee, and so on. I am ignoring those costs.
Some costs are personal choice, and not inherent in the class, such as how much you choose to spend on your tow vehicle or RV, or paying people to support you. I am ignoring those too.
Some costs, while having some correlation to the class, are unpredictable and so difficult to quantify, such as crash repairs or engine failures. I am ignoring those too.
That leaves me with:
- engine rebuild (by a professional)
- gearbox rebuild
- brake pads
- other, depending on the class
I guess there are other smaller but predictable maintenance costs, such as oil changes, brake rotors, brake fluid, etc. If you think Spec Miata has above or below average expenses in these areas, let me know, and I will include them.
Drivers from many of the classes have responded with data for their class, and the result is:
a spreadsheet in Google docs.
Here's what I have for Spec Miata. If you have changes, please reply below, and I will update the spreadsheet.
Class name: SM
Engine make: Mazda
Engine model: BP
Power at crank, HP: 126
Torque at crank, ft-lbs: 122
Weight with driver, lbs: 2,400
Purchase new, $: 35,000 professional build, SCCA Run-offs competitive
Purchase used, $: 25,000 professional build, SCCA Run-offs competitive
Tires set, $: 836 Hoosier SM7
Tire competitive heat cycles: 12
Engine rebuild, $: 5,000
Engine competitive hours: 27
Fuel $/gallon: 3.00
Fuel gallons/hour: 8
Brake pads set, $: 264
Brake pads hours: 10
Gearbox rebuild: ?
Gearbox hours: ?
Other operational costs per weekend or per hour, $: