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So begins the US RX-8 Aftermarket
Submitted by SuperUser on Tuesday, July 15, 2003 - 1:46pm

Dave Damouth submitted a link to long time rotary tuner Paul Yaw of Yaw Power in Arizona. They have taken delivery of a RENESIS motor and are currently developing a supercharged Renesis engine for competition in the Speed World Challenge GT Class. To reach this goal, Paul has to first understand all the changes in the RENESIS. To this end, he has to Dyno the engine first, and understand and adapt some systems to work.

Paul comments that: "[The intake] is much better than anything Mazda has done on previous motors. All the bends are VERY gradual." "The bell housing bolt pattern is the same as the old motors." Their goal is 450 Horses out of the Supercharged motor.

Stay tuned for more performance news in the future.











The motor as delivered before removing emissions devices.






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.








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.







Look at the size of that alternator. 100 amps!







Here you can see the 4 individual ignition coils.







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







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.







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.








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.







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.








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









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.







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.







Another view of the 3" exhaust.







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.







Same as above.

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subject:
Follow-up
author:
No Rotor
date:
December 31, 1969 - 4:00pm
Mazda trix received their RX-8 today:

http://www.socalrxclub.org/BlueRX8/
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subject:
prince
author:
No Rotor
date:
December 31, 1969 - 4:00pm
this is a highly interesting story to watch, if it continues. great gobs of good luck to paul and his people on development of that car. whos working on the chassis???? can we get the same deal with that too?
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