We received this motor at the same time that we received our new dyno. Since our new dyno uses a driveshaft, instead of a flywheel adapter like the old dyno, there was a fair amount of work to be done building adapters, mounts, etc.

As it turns out, the motor is quite different, and also required that some custom parts be built. I took several pictures during the process, and they are posted below for those of you who are interested in this sort of thing.

The first order of business is to run the motor in naturally aspirated form to gain an understanding of the effects of the side exhaust ports, and the larger intake ports. The data that we collect will guide us in choosing the correct supercharger, and also give us a thorough understanding of the motor so that we have a strong knowledge base when we begin development of our performance parts.

The dyno is the latest offering from Stuska, and includes a complete data acquisition system. In addition to torque and horsepower, this system will measure air fuel ratio, fuel flow, brake specific fuel consumption, airflow, brake specific air consumption, and volumetric efficiency. The interpretaion of this data tells a very complete story about the engine, and allows us to make improvements based on a thorough understanding rather than making a guess.

To give you an example, let's say that the horsepower drops off rapidly above 8,000 rpm, and the air fuel ratio and ignition timing have been optimized. If there is a corresponding drop in volumetric efficiency, it is clear that the motor is limited by intake airflow. If the volumetric efficiency carries well above 8,000 rpm, but the brake specific air consumption rises steeply at high rpm, we can be quite sure that the horsepower is being reduced by pumping losses during the exhaust stroke.

This is just one example of the importance of proper data acquisition. As we make progress on the motor, we will document what we find, and post it to the website. As a result, you will be able to see what the motor is capable of, and how we achieved those numbers. Some of you might find the information boring, but for those of you who want a clear understanding of the Renesis engine, check back often for updates.

We will be working with Motec USA on this project for one simple reason. Motec builds the best engine management system on the market! They have gone to a great deal of trouble to make sure that their system can handle the complexity of the Renesis engine, and their system, will even be able to run the fly by wire throttle body.

Note: We have 36-2 trigger wheels that will bolt in place of the stock unit and supply Motec engine management systems with the correct pulses. This is a simple bolt on piece, and it utilizes the stock pickup so no modifications are necessary.

Check back soon for engine updates, and remember to hit the reload button on your browser so that you can see the latest content.

The motor as delivered before removing emissions devices.

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Good view of the exhaust ports. You can see the divider in the middle of the intermediate housing port. It's bad for flow, but required to keep one rotor from blasting hot exhaust gasses on to the side of the other rotor.

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Here is a good shot of the intake manifold. Internally, it is much better than anything Mazda has done on previous motors. All the bends are VERY gradual.

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Look at the size of that alternator. 100 amps!

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Here you can see the 4 individual ignition coils.

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This shot shows the motor on the docking cart being test fitted to the brake.

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This is a better view showing the mounts. The stock motor mount is a 3 point arrangement on the passengers side, and the exhaust manifold fits through it. We built the cross mount underneath to make sure we cleared the manifold/headers. This required building new adjuster pods for the stand because the mount was so low that the pieces supplied with the dyno would not drop low enough.

Luckily, the bell housing bolt pattern is the same as the old motors. (All the way back to 1974.) We made the mount by cutting a 1974 bell housing in half, and then welding aluminum vertical supports to it to make the rear mount.

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Here is a picture of the dyno room as seen through the viewing window. The 6" vertical pipes in the rear corner of the room route exhaust gasses out through the roof, and then into 2 large straight through diesel mufflers.

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The new dyno uses a driveshaft arrangement to drive the brake. As you may have guessed, they make driveshaft adapters for everything EXCEPT a rotary. We made this from a 6061-T6 aluminum billet.

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We wanted to run the motor just as it would be in the production car. Instead of adapting a different throttle body, (This is a "fly by wire" unit) we modified this for cable pull operation. This ended up being one of the more difficult fabrication jobs. We removed the motor drive assembly, and welded a shaft from an old RX-7 carburetor in its place. We built a bracket that takes a stock first gen. RX-7 throttle cable, and a second gen throttle position sensor. We also included an idle speed adjustment screw which is on the bottom bracket and not very visible in this picture.

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This engine uses a returnless fuel system. Fuel comes directly from the pump with no regulator, and no fuel return line. The fuel pressure is controlled by the computer which runs a pulse width modulated control circuit for the fuel pump. We converted this to a conventional return style system by welding two steel AN fittings to each of the two fuel rails. We then had the rails replated so they would not rust. This allows us to run a standard adjustable fuel pressure regulator.

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It's hard to tell from this picture, but there are four separate lines going to the rails.

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Rather than looping the two fuel rails together, we built a small manifold, and ran 4 separate dash 6 lines directly to them. The fuel pump, and regulator will feed through single -8 lines. This is overkill for a naturally aspirated motor, but it takes a lot of fuel to make 450 horsepower which is what it will take to be competitive in the Speed World Challenge GT Class.

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Because the engine is so narrow, we could not run a straight pipe off the back of the exhaust manifold without hitting the brake. We built a flange to mate to the manifold, and brought the pipe out to the side for clearance. From here, we can add a muffler, and a straight section of pipe to roughly equal the length of the stock system. This should give us a good indication of what the motor can do in a "mostly stock" racing class, or a street application.

We will build headers after testing with this piece.

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Another view of the 3" exhaust.

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This engine uses a banjo style fitting for oil inlet and outlet. We built this small distribution block so we can feed the motor with a dash 10 line, and pickup oil temperature and pressure from the side of the block.

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Same as above.

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We built these headers for testing. They are shown here on display at Sevenstock, 2003. That's me to the left trying to look cool. Someone suggested that I would look cooler if my face wasn't visible, so we cropped the picture.

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