We are often asked to quote a price for a motor, and find that the customer is surprised at the cost. We hear things like "So and so will rebuild my IT motor for $1,400.00" Our response is that you will not get much of a motor for that price.

Consider this. As of May 2004, a complete 12A rebuild kit from Mazda Competition will set you back $735.00. Add $592.00 dollars for a new set of rotor housings, and you are already at $1,327.00, which leaves a whopping $73.00 for labor. Do you really think anyone is going to build a motor for $73.00? And if they are, what kind of quality can you expect?

The next question is "Do I really need all those new parts?" Need...well, that depends on your priorities. The fact is that you can assemble a pile of floor sweepings, and the engine may run OK. Rotaries are very forgiving in that respect, but notice that I said may run OK.

Everyone will agree that loading the trailer, towing to the race track, paying for a hotel, entry fees, fuel, and food is not cheap! And we have not even considered the night out that your wife is owed for letting you leave town for the weekend.

Having your weekend cut short because your motor dis-assembled itself on the track is going to cost you a bunch.

The point is that there is a lot of work and expense involved in racing, and in the long run, it costs less to do the job right the first time.

So now, about the parts. Many IT/PRO7 cars start life with the motor that came in the car before it was gutted. These motors normally run quite well, and will work fine for a first season while the car is being sorted out. It is not uncommon for a stock motor with 100,000+ miles to run solidly for a season of racing. Rotaries are very durable, but the reason these motors last, is that they started life with all new parts.

These normally end up being a "core" motor when it is time for a rebuild. When you tear down one of these motors, you will find a great deal of wear, but overall they are normally solid. Often you will find that many of the parts are still within factory spec. The issue is, how close to factory spec.

Take the side housings for instance. The side housings are perfectly flat when new, or resurfaced, and the maximum allowable stepped wear is .0039" If you have a motor with stepped wear of .0030", you can say that it is still within spec, but 75% of it useful life is already gone! The motor may have run 75,000 miles already, but it only has 25,000 miles left before it is out of spec. And that is street miles! Racing miles are much harder on an engine.

The same can be said of nearly every part of the motor. If the rotor tips are starting to flare, the apex seal is already compromised, and will only get worse with time. I could go on and on, but I think you get the point. If you start with fresh parts, you will have a strong running motor that will continue to run strong for a long time.

If you start with a handful of worn parts, they will soon turn into worn out parts. That makes about as much sense as starting the race a lap down!

We consider the bare minimum to be all new seals and springs, resurfaced side housings, and new rotor housings. The exception is when we do a freshen up a race motor. Carbon apex seals are much softer than the stock cast iron seals, and so there is little or no wear on the rotor housings. Consequently, they can often be re-used if the motor has not been overheated.

On occasion, we have seen rotor housings that look very good even though the motor has high mileage. If the motor is to be rebuilt with carbon seals, these can be re-used as long as the wear surface is flat, and they show no signs of warpage. If the motor is to be rebuilt with cast iron apex seals, the rotor housings should be replaced.

This brings us to the next question. "What parts can be re-used?"

Eccentric Shaft This normally shows very little wear as long as the oil was kept clean.

Side Housings These can normally be re-used as long as they are resurfaced.

Stationary Gears This is dependant on how the motor was run. An engine that spent most of it's life driving grandma to the grocery store will show surprisingly little wear, and these can normally be re-used. Note: High RPM race motors require hardened stationary gears, and so using a stock gear is not an option.

Rotors Same as above. We have seen high mileage motors with very good rotor tips, and others that are absolutely worn out, allowing the apex seals to rock back and forth. These are fairly expensive, and you will not know if they are useable until the core motor has been dis-assembled and inspected. We suggest that you plan on buying new rotors, and you may get a pleasant surprise.

Bearings Quite often, bearing wear is minimal, and in fact a slightly worn bearing will have less friction than a new one because it "fits" the shaft better. In most cases, if the gears (Which hold the main bearings) and the rotors (Which hold the rotor bearings.) are in good shape, the bearings are also in good shape, and can be re-used.

Oil Pump In most cases, these are in good shape, as long as the oil was kept clean. A pump with scored rotors should be replaced.

Tension bolts Used tension bolts can normally be re-used in low rpm motors. All high rpm motors (GT, Production, etc.) should start life with new bolts to avoid stress cracking.

That pretty much covers it for major parts. Aside from that, all seals, and springs should go in the trash can, as well as most rotor housings. Additionally, we would not even consider putting a motor back together without resurfacing the side housings.

If the core motor came from a nice well maintained car, it probably looks pretty good inside. On the other hand, if it came from a car that looks like it is due for the crusher, you may not get more than a set of side housings from it.

Most of this applies to low rpm race motors, like IT or PRO7 motors which rarely go above 8,500 rpm. The standards get much higher when the motor will spend much of its life at 10,000 rpm, and that description is probably best left for another article.

So now we get to the part that everyone wonders about...Labor.

Building a quality engine requires a great deal of time, and attention to detail. Every single part must be thoroughly cleaned, and inspected, and then the new parts must all be clearanced and carefully prepped.

Doing the job right requires effort, and that means time. And as you all know, time is money! a $2,500 motor that is well built is a better deal than a $1,400 motor that was assembled from floor sweepings...Period!

In our case, we also spend a fair amount of time on cosmetics. Everyone will agree that a pretty motor will not necessarily go faster than an ugly motor, but for us, it is simply a matter of taking pride in our work.

I can not ship a motor that looks like it came out of a junkyard, no mater how fast or reliable it is. A quality piece should look like a quality piece, if for no other reason than to let the customer know that we take our job seriously.

In a nutshell, a good motor is the result of using good parts, and taking the time to do the job right. And that's all there is to it.

Take a look at our engine page to see an example.

Thanks for reading my rant.

Paul Yaw