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Thinking Outside The Triangle - Tech Talk

Goopy Performance shares some innovative ideas about how to improve the Renesis 13B rotary engine.

David Pratte
Aug 2, 2012
Modp 1209 01+thinking outside the triangle+cover Photo 1/4   |   Thinking Outside The Triangle - Tech Talk

In the previous issue we finally got around to building and installing a modified and totally refreshed Renesis rotary engine in our RX-8 project car, and later in this issue you’ll read about its ECU tuning session with MazdaManiac now that we’ve completed the engine and clutch break-in mileage. The new engine sounds amazing and pulls strongly, so we’ll certainly spend some time enjoying our new super-rev-happy Renesis in its current form, but we’re already thinking about ways to further optimize this latest (but hopefully not last) Mazda 13B.

One of our technical partners on the engine side of the RX-8’s ongoing development is Goopy Performance, a small but highly reputable rotary tuner and parts manufacturer from Stony Point, New York (about an hour north of the Big Apple), and based on my conversations with them about how to improve the Renesis, they’re definitely a “think outside the box” company. Or perhaps Goopy’s approach is better described as “thinking outside the triangle,” because we’re talking about rotaries and all the oddball shapes that come with them.

But before we get to Goopy’s creative thinking on ways to extract greater performance and reliability from the Renesis, let’s take a quick look at the company’s history so you have a better sense of its overall rotary tuning philosophy. Goopy opened its doors in 2002 as Goopy Seals (“Goopy” being the nickname of one of the founders). The company’s name evolved into Goopy Performance when they began to develop other components and specialty tools for rotary engines as well as offer refurbishing services for rotor housings and other hard components. Now with more than a decade of experience in the rotary tuning game, Jonathan and Jack at Goopy have made a name for themselves thanks to their focus on cost-effective solutions that deliver equal to or better performance than anything else on the market, all with first class-custom service and a zero-bravado attitude that makes them extremely refreshing to deal with.

Modp 1209 03+thinking outside the triangle+apex seal Photo 2/4   |   The standard Renesis apex seals (bottom) are a fair bit shorter than previous 13B designs (top), but after EDM wire cutting our rotor apex seal slots, they’re ready for the deeper FD-spec Goopy Performance seals and the greater durability they’ll provide.

As Jack from Goopy explained, “Not everyone in the rotary game or those who’d like to be have deep pockets and unlimited budgets. We’ve therefore focused on coming up with innovative approaches to problems that are begging for a solution other than just throwing money at it.” Goopy’s rotor refurbishing service is a great example of this, given that it brings used housings back to like-new condition for a fraction of the cost of new housings. Their rotor repair and cleaning kit is also a good example of their focus on simple, cost-effective approaches to reusing hard components. Goopy’s also taken a slow-and-steady-wins-the-race approach to product development, preferring to methodically perfect their Goopalloy metallic apex and corner seals rather than rushing to produce side seals or other rotary-related products just so they can expand their product line.

As for building an even better Renesis than the one we’ve just installed (which includes Goopy apex and corner seals, Racing Beat–lightened rotors and ported irons, and Mazdaspeed side seals and race bearings), Jack and Jonathan had this to say: “Notwithstanding Mazda’s many significant innovations and best efforts and the fact that many of us love the RX-8, we all know that we wish Mazda had done a few things differently on the Renesis engine, particularly as a high-performance engine. Of course every engine has its shortcomings, but since Goopy Performance is a rotary specialist, we continue to look for solutions to the most significant of the Renesis’ shortcomings.”

The first area the team at Goopy set their sights on when looking for ways to address known weaknesses of the Renesis 13B was the apex seals. As Jack explained, “We provide a custom service where we deepen the standard apex seal slots so as to be able to accommodate a ‘fullsize’ Goopy Performance 13B 2mm apex seal. The results and advantages appear to be an even stronger seal, support for peripheral port exhausting, and further isolation of the apex seal springs from the combustion heat that causes premature apex seal spring failure.” Although we didn’t mention it in last issue’s story about our Renesis build, we did in fact have the seal slots on our rotors EDM wire cut so we could run Goopy’s deeper FD seals and take advantage of the benefits outlined above.

Modp 1209 04+thinking outside the triangle+installing seal Photo 3/4   |   The standard Renesis apex seals are a fair bit shorter than previous 13B designs (top), but after EDM wire cutting our rotor apex seal slots, they’re ready for the deeper FD-spec Goopy Performance seals and the greater durability they’ll provide.

Goopy Performance has also done preliminary work on another Renesis problem area: the front cover/water pump housing. As Jack put it, “Sometimes cost reduction becomes the overriding objective when developing a component for a new engine, and as a result, other goals [like performance and reliability] suffer. This may have been the case with the timing cover/water pump housing on the Renesis engine. It appears that Mazda’s goal may have been to reduce the number of parts from three to one by incorporating the CAS (crank angle sensor), the water pump housing, and the timing cover into a single cast part. They got their part count down and reduced their cost but did it by introducing what we suspect may have been some unintended consequences.”

As any RX-8 owner who takes it to the track can tell, the Renesis runs extremely hot. Add a forced-induction setup and the result is often a car that can’t turn more than a couple of laps before it overheats. According to Goopy, “The first source of the Renesis’ overheating problem may be in part due to the reconfiguration of the water pump. This has been done in such a way that the engine may not be getting adequate coolant flow to handle the additional heat generated in a high-performance environment. To solve this, we’ve been replacing the stock Renesis cover with an FC Turbo II front cover and water pump to improve coolant flow.” This isn’t a straight bolt-on solution, however, as some custom machining by Goopy Performance is required to make the Turbo II housing fit the Renesis.

The other source of overheating in the case of the Renesis is the routing of exhaust gases through the irons rather than through the housings (as was the case with previous 13Bs). As Jack from Goopy explained, “Exhausting through the irons creates a zone of excessively high heat on the quadrant of the iron adjacent to the exhaust port. This area creates a significant problem for the water gaskets, side seals, and side seal springs. Long-term exposure to these elevated temperatures leads, we believe, to premature underperformance [loss of compression] and engine failure. A visible example of the effect of excessive heat on these parts is seeing water gaskets that are burned into the seal grove on the housings, and the rubber appears to be impregnated right into the aluminum slot.”

Modp 1209 05+thinking outside the triangle+housing Photo 4/4   |   Goopy Performance isn’t afraid to think outside the triangle; their rotor housing peripheral exhaust port inserts are a great example of their creativity in addressing the heat problem the Renesis suffers from.

To address the exhaust gas routing issue, Goopy Performance has really gone “outside the triangle” in their thinking by creating a process for adding a peripheral exhaust port to Renesis rotor housings. As Jack and Jonathan explained, “We believe this will allow for better flow of exhaust from this area and therefore less concentration of heat in this zone. This requires a special ‘peripheral port insert’ from Goopy Performance and custom machine work to install it. A select few Goopy Performance dealers are providing these specialized services as well.” This idea is particularly intriguing given its potential to reduce internal engine temperature, improve exhaust gas flow, and allow for the addition of forced induction without the usual loss of track-friendliness.

Not that adding Goopy’s peripheral port inserts isn’t without its challenges, one of which is the fabrication and routing of a custom header that exhausts six ports instead of the usual three. Adding a turbocharger to the equation would further complicate header fabrication and routing of the exhaust runners and downpipe, but these are not insurmountable challenges compared with the potential heat-reduction benefits that come with it.

Who knows? Maybe we’ll put Goopy’s Renesis heat solutions to the test on Project RX-8, but first we’re going to enjoy zinging our lightened, ported, and refreshed Renesis up to its stratospheric redline and see how the temperatures look after a day or two at the track.

Send your feedback to dpratte@modified.com

By David Pratte
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