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The RX8 is a great performance car out of the box. The car is a direct competitor in its class of nimble and balanced track ready street cars. This class includes the likes of the Lotus Exige, the Honda S2000, and the Mazda Miata.

These cars typically boast there nimble handling, great engine response, balanced front to rear 50/50 weight distribution, and great driving feel.
The RX8 adds to that list of specs with some unique parts such as a factory equipped carbon fiber driveshaft, and a torque sensing limited slip differential to increase the utilization of and transmittance of crank horsepower into the pavement.
With this kind of approach, you’d think that the car is originally underpowered and that Mazda is trying to milk every ounce of hp out of it’s drive-train but that’s far from true. 232hp @ 8500 rpms with a 9000 rpm redline and a wide powerband of 3000 rpms between peak torque and peak power. The engine is also an internationally acclaimed motor of the year as far back as year 2003 when it first came on the scene.
However, as the nature of this car is ‘track ready’, the car will inevitably be taken to a track where it may find itself outclassed by purpose built 500+ Hp carerra’s, Z06′s, and cobras… leaving the enthusiast thirsty for more power to keep the car in the pack on the high speed straights in the track (as we all know this car is no slouch around the corners).
So what would a basic 350hp RX8 build include ?
By loading up the numbers into the power calculator we get the following results
Volumetric Efficiency 193%
Boost required to reach our power goal 6psi
Intake Cold Side 100mm (3.9″)
Intake Hot Side 85mm (3.4″)
Header Primary Diameter 1.58″ (using 3 cylinders for calculation)
Header collector Diameter 2.92″
Catback Diamter 2.82″
Spark plugs 1 step colder
Compatible superchargers Lysholm 1200AX, Eaton MP62, Rotrex C30-94, Vortech V5 F-trim
First thing that jumps out at us from these numbers is the almost 200% volumetric efficiency.
This is really simple to explain, the Renesis is a rotary engine that has 1 combustion event per rotation of the crank. This makes the engine very similar in power output to a 2-stroke engine (which is twice as power efficient from the same displacement engine as a 4-stroke).
What results here is that any resonance tuning figures that come out of the power calculator are irrelevant (because the calculator was designed for 4 stroke engines with 1 pressure pulse per 2 crank rotations and so all the intake and exhaust manifold tuned pipe lengths are not applicable here).
What I have posted above are the flow based results based on our target power figure of 350hp, and our boost level of 6psi.
Furthermore, figures like ‘camshaft’ duration don’t apply here either as intake and exhaust process of the renesis is controlled by the location of the engine ports (and the control of the intake system stages) and has nothing to do with traditional camshaft timing.
Now let’s look at some parts for this build up:
Petit Racing Supercharger Kit

The Pettit racing supercharger kit is a complete solution for supercharging the RX8 including:

K&N Air filter & completely new intake system including an oversized MAF housing
Lysholm twin screw supercharger set
Hi efficiency water to air intercooler
Two possible boost levels of 6 or 8 psi depending on your requirement
A matching FI tune for your choice of boost level.
Racing Beat Header
The racing beat header is a result of many months of R&D on the RX8 including multiple dyno sessions. The header provides a reasonable gain of 4hp on a naturally aspirated renesis, but comes with generously sized 1.75″ primary piping and a 3″ Collector outlet.
This generously sized header makes it ideal for a supercharged car , especially in comparison to some of the other headers on the market such as the OBX with the 2.72″ outlet.
Exhaust System
Racing beat also offers a high flow midpipe & catalytic converter with a 3inch inner diameter, which can be followed by the racing Beat 3inch cat-back exhaust system for a complete 3inch system from the header back. This setup will be ideal as it matches the figures we get from the power calculator of 2.92″ for that horsepower level.

Results:

Typical results with the Pettit Racing supercharger stage 2 kit (8psi) and a high flow cat with matching tune are 308 wheel horsepower. Considering the car dynos stock in the range of 175 to 181 whp, this means the car is now producing at least 359 hp which is very close to our calculated target of 350hp.
Don’t believe these numbers?
Here’s a great video of a Stage 2 Pettit Supercharged RX8, with the Pettit SC IV pulley, ExoticSpeed header and matching tune putting down 327 wheel horsepower.
httpv://www.youtube.com/watch?v=sx5QQ6V7hMM