Rotary Radness, Mazdatrix’s 13B REW/MSP Hybrid!

Rotary Radness, Mazdatrix's 13B REW/MSP Hybrid!

By Mike Kojima

So far we have not focused too much attention on the Mazda Rotary engine on the pages of MotoIQ.  This is not because we haven't wanted to but because no one on our staff has much expertise on the engine except for Eric and he has been pretty busy lately doing other things in the world of internal combustion besides messing on rotaries.

However rotary experts are around, some right in our back yard.  Mazdatrix in Signal Hill California is just freeway minutes from the palatial MotoIQ HQ. Mazdatrix is a rotary specialist shop owned by Dave Lemon, a long time SCCA, IMSA and NASA racer/champion.  You might have seen Dave's Turbo RX-8 race car before gracing our pages as a MPTCC and Time Attack racer. Mazdatrix is also the employer and sponsor of Formula Drift ace Kyle Mohan, who's RX-8 has been a top 10 contender in the rough world of pro drifting .

Mazdatrix Boss, Dave Lemon can often be found tearing it up in MotoIQ's MPTCC TO class.
Kyle Mohan, Formula D and Time Attack pilot is one of Madzatrix's chief wrenches during the day.

Building Rotaries is pretty tricky, although they are deceivingly simple, there are many tricks to building an engine that will have a good power output and a long service life.  Rotaries are sensitive to tuning and detonation, something every turbo rotary fan needs to be aware of.

This leads us to our feature engine.  The original turbo Rotaries available in the USA are the 13B T and the 13B REW.  These engines used a port configuration of intake ports in the side housings with a peripheral exhaust port in the rotor housing. These engines achieved pretty decent power outputs, with good volumetric efficiency.  However these engines were pretty poor in the emissions department mostly due to the fact that it was difficult to get rid of all the port overlap with peripheral exhaust ports.  This allowed unburned hydrocarbons to blow out the exhaust on overlap.

Basically the rotary is like a two stroke and the “valve” timing is controlled by the shape and location of the ports in the housings.  Port location and size is like camshaft duration and centerline in a conventional piston engine.

In an effort to clean up the Rotaries noxious exhaust, the 13B MSP Renesis or Multiple Side Port engine was introduced in the RX-8.  The Renesis engine did away with the peripheral exhaust ports, instead putting them into the side housings.  This did away with port overlap which cleaned up emissions but also limited the power potential of the Renesis engine.

Well along came Mazdatrix to find a power solution to wake up the 13B MSP.  For their performance build, Mazdatrix keeps the multiported side housings of the Renesis engine and adds the peripheral ported exhaust rotor housings of the REW.  This gives the power producing overlap of the REW with additional exhaust port area and generously sized intake ports from the MSP side housings!

The result is a turbo rotary with better VE due to increased intake and exhaust port area and reasonable port timing for turbocharged use.  A win win situation for everything but emissions.  This is a race motor though and really no dirtier than the 13B REW. 

Check it out as we take a look at how one of Mazdatrix's hybrids are built.

Dave Lemon with his creation, the 13B REW/MSP Hybrid.  The engine requires a pretty elaborate exhaust manifold to accommodate the side and peripheral exhaust ports.  This engine can really breathe and has a wide powerband.  It is sort of like having a high lift but moderate duration camshaft in your naturally aspirated engine.


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