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Rotary Response and Racing

 Tucson, Arizona USA 85716

Rebuild or New Build?   Motor/Options/Price:  Warranty:

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The rebuilt/reconditioned Rotary Motor

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To Rebuild or Build New?

As of this date Mazda no longer manufactures major engine parts for the 12A-13B 70-95 motors

You are a rotary engine enthusiast because of its unique performance qualities and reliability. Similarly, these engines have very specific rebuild characteristics. If core parts have been cleaned and are within Mazda specifications, they are re-usable. It is relatively easy and inexpensive to build a motor that will last for about one year, but don't expect much more than one year. At Rotary Response and Racing (RRR) the criteria for replacement of used parts allow for less wear than Mazda's specifications. This will guarantee long-term reliability. Success in rebuilding a rotary engine with long term performance and reliability depends on knowing limitations on used core parts. 

Many changes have been made to the rotary engine since the introduction of the R100 in 1968. There were the original twin distributor 12A motors in the early 1970's. In 1974 the single distributor and 13B motors were introduced. These 13Bs have not been imported to the U.S.A. since 1978. In 1979 the Rx7 was first imported. Before 1979 the side housings (front, center, and rear) could  be lapped smooth for all rebuilt engines. They could also be Blanchard ground and lapped a couple of times and still work fine. In 1979 nitride coated steel housings were introduced. This decreased the wear on the side housings from the Side seals, Corner seals, Apex seals and Oil Control Rings. The steel housings before this could be past replacement criteria at only 40,000 miles. Nitriding increased usable life up to 200,000 miles. At this point housings can be lapped or machined but they will only be good for only another 30,000 to 50,000* miles because machining will remove the nitride coating.

A point needs to be made about lapping and Blanchard grinding as it relates to long-term reliability. The nitride coating is very thin and once you have gone past the nitride you are back to pre-1979 housing surfaces. Lapping isn't as aggressive as the Blanchard process. Also, if too much material is taken off the four side surfaces of the housings, a different adjusting spacer needs to be fabricated to be able to set the end play.

Available 1979-85 engines are fourteen to twenty years old and have many miles on them. Very few of the motors that are being disassembled yield many useable housings or internal parts. It may take three or four used motors to come up with anything useable:  pair of rotors, rotor housings and a set of  housings. This added labor due to tear down, cleaning and inspection increases cost. Plus the increasing cost of the core motors. 

There was a major change in the internal design of the water seal groove location in 1986. All the 1985 and older engines had the grooves in the rotor housings.  For all the 1986 and later engines, the water seal grooves are now in the side housings. This prevents them from being lapped more than once, maybe twice before they could no longer be usable. Grinding could pose a problem with the depth of the housing seal groove: seal not compressing properly or failing in the high stress areas. Because of this new seal groove location, finding usable core engines with minimal wear on the side housings is becoming a problem and reasonably priced used motors are less available.

Many of the 2nd Generation motors are very close to replacement criteria at 140K to 160K*. At these mileage's the rotor housings are usually chipped, or have water damage. This is more of a problem in turbo engines which can cause major internal damage when they fail. They usually break apex seals in the rear rotor which will often destroy the rotor, rotor housing, center housing and rear housing.

Because so few of the 3rd Generation were sold in the U.S.A., there is a limited number of salvage motors. New build only is highly recommended for the FD3S. RRR will use only new housings on any modified motors.

Due to the diminishing supply of used engine parts that meet replacement specifications, and low availability of cost effective used parts, RRR has been recommending and selling more new built motors. Also, a few changes can boost performance while maintaining IM240 compliance. RRR encourages the consumer to look at all engine options. This is especially true if you are planning on restoring the vehicle. If the platform is sound and it is a viable builder, the upper grades of rebuilds would in the long run be a more cost effective option.

The introduction of the new Renesis generation rotary engine is the most radical change in design for street application. With it we see Hydrogen as a viable fuel source. Since the rotary  really likes a slow cool burning fuel H2 fits. Granted HP is down now. Wait a few years and we will see a significant increase in performance. 

My belief with the introduction of the Renesis rotary engine, a purpose built dual fuel, petroleum/Hydrogen powerplant, Mazda has discontinued any support for the pre-renesis design to put all engineering efforts into the H2 powered generation of rotary engines.

Warranties on RRR motors range from 12 months/12,000 miles for reconditioned to 36 months/36,000 miles for new built. All are built, assuming adequate maintenance, to remain in service for many years.

*Note: Quoted mileage's reflect over 20 years of experience with rotaries operating in the temperature extremes of the Southwest desert and 30 years overall rotary experience. .

 rotors.jpg (7132 bytes)     Engine Price List

Last Updated 09-06-2014

**Please Note That Due to Market Fluctuations**

**Prices are Subject to Change Without Notice**

Rebuild or New Build?   Motor/Options/Price:  Warranty:

As it stands right now all motors are done as the come in on a one to one basis. Motor estimates are now hard because of the lack of parts. Rotor housings in particular. There is a company now that claims they can rechrome housings, We wait to see back on that. If you are looking into doing a motor properly then now is the time to bite the bullet and get any new parts that you still can. None of the motor parts will ever show up in the aftermarket. In the world market we are still a very small percentage compared to piston pushers. Hydrogen will change that. The Rotary is the perfect power plant for this fuel which burns cool and slow. Just what the round motor likes. Sure performance isn't there right now, but put these into public domain and with the advancements coming so quickly now it will not be long before we are racing with hydrogen as fuel. 

Base RRR* rotary engine prices at one time use to range from $2175 (rebuildable core) to $6900 (GT3). Unfortunately with the shrinking supply of good used parts, replacing all the housings is becoming standard. Rotary motors with highest reliability include all new housings, soft and hard seal replacement, oil pump, chain, bearings, water pump and thermostat. Go to descriptions to see the complete listing. All engines require core or core charge.

At this point in time the range of  a properly done recondition or build new  project is  $8500/12,000.  Most need rotor housings, many all 5 housings. Other items which usually need attention now are having to replace at least the main wire harness. Original turbos are now wearing out. Radiators, hoses.  All rotaries built here now are on a one to one basis, essentially each is a custom job. Everyone is different due to previous maintenance, service and use.  

A proper estimate of a specific job can not really be done without seeing the patient also. So please do not expect to have anything truly accurate unless I can see the vehicle or engine. 

Please Email for more information.

*Rotary Response and Racing

Reconditioned and New Built Motors

Most Pre-Renesis motor parts NLA
Performance enhancements for the street 



Modified motor price range-

$3000 - $5200

-cost determined by new components and

amount of porting involved-

Base Pre-Renesis engine labor
Motor labor only  $1250

Porting $100 per hole

Standard no bridge $600
J-Bridge $1000
- Full Bridge  $1500
Base-Renesis engine labor   Renesis porting labor higher because there are 4 exhaust ports
Standard no bridge $800
J-Bridge $1200
- Full Bridge  $1700

Race and Turbo Motors

Improved Touring  Inquire

All motors custom built, Prices based on Time and Material

Base start labor $1250

Spec 7  Inquire
E Production  Inquire
GT - 


Turbo/Twin turbo  


Special Applications Inquire
Dyno Testing Inquire

If you are a member of Mazda Motorsport you can purchase the parts from Motorsport and have them drop shipped to Rotary Response and Racing to have the work done.


Standard Reconditioning:

Performance 'enhancements'


*For Racing Purposes Only - Not legal for public street use on pollution controlled vehicles

rtrbutton1a.gif (914 bytes) For FD3S Extreme Temp Improvements

Core or core charge required with all build levels. Core charge $1250.00 US.  Core includes: assembled rotary engine with front pulley, water pump and thermostat housings, oil pan and flywheel.

Engine Warranty Information  rotors.jpg (7132 bytes)

Rebuild or New Build?   Motor/Options/Price:  Warranty:

RRR - Rotary Response and Racing

Rotary Response and Racing and Rx for your 7 warrant to the original purchaser that each reconditioned or new built engine shall be free, under normal use and with required periodic maintenance as set forth by the original manufacturer (RRR), from defect in material and workmanship subject to the following terms and conditions:

  1. Term:  This warranty shall exist for 12 months/12,000 miles (for reconditioned) or 36 months/36,000 miles (for new built) whichever occurs first. This shall commence from date and mileage of installation by Rx for your 7, or seven days from the date of shipment for mail order.

  2. Standards: Subject to the provisions of Limitations hereof. RRR, after inspection and approval, shall repair, or replace said engine within the term set forth without charge to the owner user.

  3. Limited Liability: The liability of RRR under this warranty is limited solely to the repair or replacement of defective parts or workmanship. RRR shall not be liable for any incidental, special consequential or exemplary damages, or for any service not expressly provided for herein relating to or arising from the RRR engine.

  4. Limited Warranty: This warranty is given in lieu of all other warranties, express or implied, including any warranty of merchantability or fitness for a particular purpose on the part of RRR. No dealer, nor any agent or employee thereof, is authorized to extend or enlarge this warranty.

  5. Limitations: This warranty applies only to the basic engine block and internal parts replaced in the reconditioned or new built engine. This warranty shall not apply to, or include any of the following:   

  6. Required Maintenance:

  7. Required Repairs/Parts at time of engine installation:

Rebuild or New Build?   Motor/Options/Price:  Warranty:

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Tucson, Arizona 85716


22 May 2010 00:18 -0400

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