Turbosmart Time Attack FC RX-7

 

Turbosmart Time Attack FC RX-7

by Khiem Dinh

 Khiem Dinh is an engineer for Honeywell Turbo Technologies at the time of this writing.  All statements and opinions expressed by Khiem Dinh are solely those of Khiem Dinh and not reflective of Honeywell Turbo Technologies.

The FC is the middle child in the RX-7 family meaning it doesn’t get quite as much love as the other two.  The 1st generation FB was a pure sports car that really introduced the rotary to North America while the 3rd generation FD was (and still is almost 20 years after its introduction) sex on wheels.  The FC was designed to be a little softer than the FB, but it was still a better performance car all around with an independent rear suspension and rack and pinion steering.  Of course, you could also buy the FC with boost!  For the 2011 World Time Attack Challenge, the boys down under at Turbosmart decided to show that the FC is a highly capable car even with a simple build.

The car originally was owned by a nice older Greek lady and was bought from her with the intent of having a fun street/track car which could also be used for product testing.  Rotaries put out a lot of heat and therefore provided the perfect testbed for pushing components to the extreme.  After competing in various rallys, hill climbs, circuit races, etc, the car was entered into the 2010 Superlap event at Eastern Creek.  The Time Attack bug swooped in and bit the team convincing them to take the car off the street and convert it into a proper track-only vehicle to compete in the 2011 WTAC.  This was the result.

Yes, there is still a rotary under the hood!  This makes Eric happy.  Go-fast boost is provided by a Garrett T04Z which combines a big 63trim, 84mm compressor wheel with a 76trim, 74.2mm turbine wheel.  Rotaries do not like back pressure at all as back pressure can lead to detonation and spitting apex seals out the exhaust ports.  Therefore, a turbo for a rotary typically has a larger turbine wheel matched with a compressor as compared to a typical piston engine turbo.  This 13B FC3S engine was built by Pac Performance specifically for E85.  The build included being dowelled along with a bridge port.  Rotaries make a lot of power per pound of boost compared to typical piston engines; the 13B actually behaves pretty similarly to a Honda F20C in a S2000 which has one the highest volumetric efficiences of any car piston engine in production.  This rotary is putting out a healthy 600hp at 18psi of boost.  

Take note of the intake tube going to a sealed box.  Thermal management under the hood is critical, so pay attention to all the heat shielding and wraps used; heat shields or wrap are used on the turbine housing, between the turbo and engine, around the fluid reservoir on the firewall, on the wastegate dump tube, compressor outlet, and the water line to the turbo just to name a few places.  The exhaust manifold, dump tube and intake manifold are also ceramic coated by Hi Octane Racing to further manage the heat issue.  Also check out all of the sweet Murray clamps!  That’s some more serious race car stuff.

 

Regulating the wastegate flow is a Turbosmart Pro-Gate50 featuring a 50mm valve of course.

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