About Our RX-7 12A & 13B Engine Rebuilding

When it comes to rebuilding rotary engines, it's a unique process. We carefully inspect and measure many parts, some can be cleaned and reused while others need to be replaced because they're too worn out.

While it might seem cheaper to use lots of used parts, it doesn't guarantee great results. An engine's performance depends on the quality of its parts. That's why we focus on using new parts to ensure longer-lasting and more efficient engines.

At Known Motors, we build engines that are meant to last for years with proper maintenance. That's why we replace essential components like apex seals, corner seals, side seals, and more. We use only new seals, gaskets, and other parts to ensure top performance and durability

NEW PARTS & SERVICES INCLUDED IN THE BASE PRICE BELOW (this list represents approx. $1800 retail cost in parts):

  • Oem mazda 2mm 2 piece apex seals (except where 3mm apex seals are required or requested, price variable depending on seal selection available). IF you desire some other brand of apex seal in your build, you can supply the seals for installation and I will discount the build cost.
  • OEM mazda apex short & long springs
  • Oem mazda 2mm corner seals w/ rubber plugs
  • Oem mazda rx8 corner springs (for NA applications) or 93-95 FD corner springs (turbo applications)
  • Oem mazda side seals cut to length
  • Oem mazda side springs
  • Atkins rotary viton oil oring inserts
  • Oem mazda inner and outer coolant seals
  • Dowel pin orings, tension bolt seals, rear stationary gear o-ring, front/rear main oil seal
  • Front cover gasket (paper w/ oring(s), for 91 and earlier models, metal version for 93-95 models)
  • Atkins rotary thermal pellet replacement for front of e-shaft
  • Main bearings
  • Rotor bearings
  • Spark plug holes threads are cleaned and retapped. OMP injector holes are drilled to remove clogged carbon.
  • Oil Pressure regulators are replaced with 93-95 High Pressure Regulators


  • 2) rotor housings
  • 2) rotors
  • Eccentric shaft
  • 2) stationary gears
  • Front cover
  • 3) iron housings/plates
  • Oil pump, chain, sprockets, various small hardware
  • Rotor metal oil control scraper rings (8)

Please Note: $1200 deposit is required before the project can be put on the books

Short Block Engine Rebuilds Estimate Pricing

79-85 12A Non-Turbo     $2800+ core

•86-88 Non-Turbo             $2800+ core

•89-91 Non-Turbo             $2800+ core

•89-91 Turbo            $3,100.00+ core

•93-95 Twin Turbo     $3,200.00+ core

 ​Engine Rebuild with Installation

•79-85 12A                   $3,850.00+ Tax

•86-88 Non-Turbo        $4000+ Tax

•89-91 Non-Turbo        $4000+ Tax

•87-88 Turbo                $4200+ Tax

•89-91 Turbo                $4200+ Tax

•93-95 Twin Turbo       Call for Quote*

Prices are based on your having a rebuildable core. Please call for pricing if you do not have a core. 

If required or desired, additional parts/services are available:

  • Streetporting or Bridgeporting for all intake and exhaust ports priced at $750. (For 86-91 NA models, this includes labor to switch exhaust port sleeves to smooth-style turbo sleeves if you can provide them.)
  • If you send your complete engine with external accessories still attached (such as intake manifold, water pump housing, wiring, sensors, oil pan, etc.), I will remove those accessories to expose the short block for rebuilding. Later, I will reinstall those accessories correctly to address vacuum leaks and any previous installation issues. Additional labor charges of $200 apply, plus the costs of gaskets and o-rings (usually $50-200), hoses, and potentially other maintenance parts depending on the year/model and specifications.
  • New rotor housings are available at prevailing current prices, approximately $1700 per pair for FC or $1900 for FD models.
  • New iron housings are available at prevailing current prices, approximately $2000 for a set of three.
  • New apex short/long springs are priced at $60 each.
  • New metal oil control scraper rings with springs are available for $450.
  • A new oil pump is available for $200-275 depending on year/model, at current prevailing prices.


  • Shop rate is $100 per hour
  • Turnaround time for engine rebuilds is typically 2-4 weeks, depending on current workload.
  • You're encouraged to bring all engine cores or parts thereof. After inspection, leftover parts can be traded in for credit.
  • Located in McPherson Kansas, visits are by appointment only. Shipping via truck freight is available, with assistance provided upon request.
  • Upon receiving your engine, work begins after pending jobs are completed. Detailed photo documentation is provided throughout the process.
  • Payment is accepted in various forms, with a deposit potentially required upfront. A signed service contract is necessary prior to work commencement.