CYGNUS - STELLAR EVOLUTION
Every journey has a story. But this story is one that will likely never end. Every tuning shop has their demonstrator; we are no exception to that. Right from the beginning, Ben (the owner of Rotary Revs) acquired this immaculate, low mileage, ‘Brilliant Black’ RX-8 with the intention of making it the best of the best. Plans in the pipeline were along the lines of a Spirit-R style interior re-trim with the factory Recaro seats as found in the R3 model – with every single factory optional extra, including the illuminated gear knob. A lightened, balanced, clearanced and street ported engine with brand new housings and irons, all powdercoated in black and red to suit the theme of this fine example. A Pettit Racing Supercharger kit with a pulley set allowing it to forcibly pump 10psi of boost into the engine. And in true ‘Ben Dunn fashion’, every single suspension component, polybushed, powdercoated and refreshed. To tie all of that together, MeisterR coilover suspension, a Kaaz 1.5-Way LSD, K-Sport big brakes all round and a set of OZ Ultraleggera forged alloys in 18” in an offset low enough for a wider, properly ‘tuned’ stance. To finish it off, a complete, genuine Mazdaspeed body kit to give the ‘8 the aggressive profile it needed to ward off all challengers on the road. Collectively, all these parts mentioned were just to name a few. There was so much more in store for this fine car. This was the dream. To make the RX-8 the way it should have been from factory – the same practical four door, four seater coupe but with the additional power it so desperately needed out of the box. A chassis so tight, that it would be easy to manoeuvre at great speed with confidence on even the most technical B roads, with pinpoint precision. A car so practical and usable, that it didn’t require having to be sat within a glass container in a museum to admire it. It was meant for the road, and to be a trophy symbolising what ‘we’ as Rotary Revs could achieve with the RX-8.However, due to the constant development and managing of the business, despite accumulating a whole array of parts to make this picture perfect RX-8 a reality, Ben was lacking the time to finish what he started. Work had to continue, and with what little free time he had, he devoted that time to business progression – understandably.The blank canvas was kept under a sheet right in the centre of the workshop for months and months, collecting heaps of workshop dust and other particulates. All of the parts acquired were slowly but surely being sold to customers week after week. In the end, all that was left was the shell. It soon became nothing more than an ornament. In that time, an overly enthusiastic individual was welcomed into the Rotary Revs family......Me. (Josh) I never did ask ‘why is there an RX-8 under a car cover in the middle of the workshop?’. But when I did ask, Ben shared his dream. Everything mentioned above was exactly how he foresaw the making of this car. I was, in a word – inspired. From that point on, his vision was my own vision as well. It became clear through talking to him, that it was still a dream that he would like to see become a reality. After working under his wing for a short while, and seeing how unusually enthusiastic I was about developing on the Renesis engine, despite the general global consensus on the powerplant being that it was ‘a waste of time’, he came to a decision. This clean, low mileage black canvas was to be handed to me. I was over the moon (and as I write this, it has rekindled the excitement I had at the time!), as this was a significant upgrade over the Winning Blue RX-8 I had at the time, even though there were no parts leftover from Ben’s hoarding days to spoil myself with! From this point on, it took less than a month to swap everything over from car to car. I already had a recently rebuilt Half-Bridge engine in the Blue RX-8, so it wasn’t a completely without modifications.
CYGNUS - THE BLACK STAR
Spring, 2017. I had effectively transformed a shell of an RX-8 into a completely working and usable car. Thankfully the full front end of the car had been built up already, so I had the pleasure of feeling the benefits of a fully polybushed front-end. The front subframe powdercoated in red, and treated to brand new genuine Mazda hardware, like camber and castor bolts, amongst other goodies. Ben held onto the MeisterR Zeta-R coilovers too, so I was blessed with those. A rare HKS Legamax cat-back exhaust was withheld and given to me as well. An ill-fitting fibreglass Mazdaspeed front bumper was laying around, so this was installed. My set of Rota GTR alloys gave the reborn ‘8 a bit of presence furthermore. It was all a starting point for what was going to be a well-kept Demonstrator for the business. Because I’m very much one for it, I couldn’t resist but come up with a name for the new Rotary Revs development car. Based on the black hole, ‘Cygnus X-1’, devouring a nearby Blue Star somewhere in the solar system, I thought it would be fitting considering the circumstances. And from this point on, the brilliant black demonstrator would be known as ‘Cygnus’ – the Black Star.Terrible, right? The majority of the year was mainly about enjoying the car, tidying it up, ironing out small issues and observing any changes in compression, power and trying to get the most out of the Half-Bridged engine on the dyno. It was given hell along the way, because what’s the point in development if you don’t at least ‘try’ to kill your hard work and push it to the limits where possible? That’s our belief anyway, and always will be. That way we can recommend products and services with absolute confidence. It was all very enjoyable and gave me a bit more insight as to what the next step was for Cygnus, and the Renesis engine.Throughout the weeks of working at the ‘shop, servicing, porting, rebuilding, as well as reading and researching out of hours. I had a thought about something regarding the ports of the Renesis. “Are we barking up the wrong tree? Are the exhaust ports really a restriction?”In the rotary community all around the world, you always hear the same tune when it comes to the Renesis engine;“The exhaust ports are too restrictive.”Spurring from that, you’ll also hear comments like;“Big power Renesis engines don’t exist.”“The compression is too high for anything more than low boost.”Now, in truth, I am a very stubborn person in certain scenarios. If I strongly believe that something can be achieved, I’ll always believe it regardless of what I’m told. I’ve always believed that big companies threw in the towel way too soon on the RX-8 and the Renesis engine. I didn’t know enough at the time to give a reason why. So during the winter of 2017, I kept digging...If the exhaust ports were really that restrictive, how would I overcome that issue? Well, start by dissecting. With some sort of idea in mind, I got destructive by bringing a grinder to a few irons. I discovered a few things for myself: There was a very small amount of room to advance the exhaust port opening time – documented time and time again in the rotary world. Bridge port openings on the secondaries could be advanced quite a lot – with careful angling. And most importantly, there was a huge amount of material that could be removed around the exhaust port, but only towards the middle of the iron. This sparked an idea, and got me researching even more.Unsurprisingly, there was absolutely no information on this. So it appeared to be an all new idea. How could I put this idea into fruition? The only thing giving me hesitation at this point was the purpose of the outermost ring on the face of the rotor. It was known as the ‘Cut-Off Ring’, but it was apparent that no one wanted to remove it for fear of engine malfunction. Research outside of working hours gave me an insight in regards to that particular ring. From Mazda’s on development papers that I stumbled upon in the SAE directory, during the early development stages of the Renesis, this ring was not present. The side exhaust port engine was running perfectly well without it! It was later on in the development, that the Cut-Off Ring was added to eliminate the remaining intake-exhaust overlap the engineers were experiencing. Their goal was to completely rid of ‘dilution of the intake charge’ (as they called it) to improve emissions and low-load combustion stability.In layman’s terms, they didn’t want braps. ...Young and naive, my thoughts were "we don’t care about that!" Braps are most certainly wanted when it comes to the aftermarket in the rotary community. More specifically, when it comes to motorsport and increasing the performance of any engine, overlap is openly welcomed. It’s actually quite a big benefit when it comes to high revving, high power engines, for reasons that I will spare the complications of explaining. With this newfound knowledge, on a poor set of irons, it was time to cut the exhaust port in the way that had not been done before, coupled with a full-bridge port on the intake side. For now, it was only the front and rear iron that got the new port. Not really knowing what the outcome was going to be from this spur-of-the-moment idea, there wasn’t much care taken during the assembly of this engine. Atkins Apex Seals, and practically everything else second hand. Bearings, seals, springs, even some poorly chattered housings. The Cut-Off Ring was disposed of during the build. It was a case of just seeing how it would work at this point.After a long weekend of not much planning and just generally slinging everything together, swapping engines over, this crazy engine was started for the first time. Albeit, towed up the road with the revs sustained for a good twenty minutes! But Cygnus came back to life, right at the start of 2018! And with some braps for good measure – more prominent than we had ever heard in the Renesis maintaining all of it’s side ports.Admittedly, I didn’t have much faith in this engine initially. But knowing how poorly it was built, I made the choice to get it straight onto the dyno for some abuse. In the capable hands of our in-house tuner, ‘D’, I left him to see how the engine was responding with the ports. A couple of hours later, it was quite conclusive that there was potential in the idea! On such a shoddy engine (I cannot stress this enough), it was making a healthy 195hp at the wheels, which was a slight improvement over my previous half-bridge. It seemed to respond well to the extra ignition timing high up in the rev range. All in all, seemed to be a good contender!So, I took Cygnus away, and certainly enjoyed driving a much brappier RX-8 with a little bit more power. Abused where possible, and logged along the way, all seemed pretty good!...For a mere 330 miles.There was a moment where I came to start him up after a drive, and I noticed a change in the way that the engine started and idled. Very much in tune with how rotaries should sound, I could tell that a Side Seal had broken. A compression test later on had confirmed this. This was a bit disheartening on the onset, but anyway, out the engine came and the teardown happened soon after. Alas, what I found was interesting. The failure occurred on the side of the rotor that faced the centre iron – where the modification of the exhaust port was ‘not’ carried out. That aside, there was not enough damage to render the engine useless either. So, with this in mind I thought it would be wise to port the centre iron’s exhaust ports as well! What could possibly go wrong at this point? Trial and error is part of development unquestionably. This engine was still a test mule for a much better final product, and it always was going to be.The engine was sandwiched together just as quickly as the first time, with a replacement second hand side seal for good measure. And testing began once again. The cause of the failure was still unknown at this point, but could only have been a result of the lack of cleaning and general care of the first assembly. That was a risk I decided to take at the time, so I took a little more care this time. Back onto the dyno with the additional ports!So, did it make any additional power? Well, interestingly enough, power was actually down by a few horsepower this time – 192whp and 118ft-lb. There was such a significant drop in torque. It was quite unusual. We managed to bring it up back to 195whp with a slightly leaner AFR and an extra degree of ignition timing, but ultimately not as good as the first time. Again, when venturing into the realms of the unknown, this is to be expected. I was not discouraged though. I had a whole year to test the longevity of this engine to make sure it was something I could develop on. Throughout the four seasons, this engine was given hell time and time again. Long motorway drives, hard country road drives, and a few dyno revisits to be sure of the consistency. It was consistent over a little more than 10,000 miles. Compression had not changed by much at all, although it had been running about 300ml of premix on every tank, and 500ml if I knew it was going to be sustained at high revs for long periods. This had given me plenty of time to do even more research in my free time. More Mazda SAE development papers, old books, rotary related documents, so on and so forth. With 2018 was coming to a close, and the engine still running healthily, I deemed the experiment a success. Earlier in the year, a name was given to the new port by ‘D’, and it seemed to stick to us really well in the workshop. Race Extension. Has a nice ring to it.During closure of the workshop for the Christmas period that year, I studied porting heavily. We put names to ports, like ‘street port’ or ‘bridge port’, and while we know what that means in terms of how the port looks and the characteristics of the ports, very few of us actually know what it entails, speaking strictly about port timing. There is no definition for port opening and closing times in regards to these ports, if that makes sense. That is what I spent most of my time looking into. Ports are specific to Rotaries and 2-Stroke engines, but the principles of port timing are exactly the same as valve timing. As soon as you get your head around this, you’ll find that getting information is actually a lot easier when developing ports, and to a degree it defines the shape of the port too. Moving on...Out of everything I learnt over that Christmas, the most interesting piece of information I had found on the topic of the Renesis, was ‘why’ Mazda decided to use side exhaust ports over the conventional peripheral exhaust ports. Yeah everyone says ‘for emissions’, but that doesn’t tell us anything at all. Other than the aforementioned anti-overlap, there was a significant benefit for it: being able to retard the exhaust port opening much further than the previous peripheral exhaust ports, thus maximizing the engine’s thermal efficiency. To put it another way; keeping the flame-front of combustion within the combustion chamber for longer, before releasing it.Ultimately, heat is energy. The rotary engine makes power by keeping the rotors spinning in one direction. Heat allows the rotors to keep turning, and by keeping that heat in for longer, you’re actually keeping that momentum going. Release it too early, and you’ll find that some of that energy is wasted. I also suspect that this is actually a reason why the 4-Port (192) engines make more peak torque than the 6-Port (231) engines – the exhaust port opening is retarded even more!I spent a couple of days developing the Race Extension port in terms of shape. I wanted to ensure that it transitioned nicely, and made a bit more of a discovery by doing so. I could actually port match to the ceramic insert within the exhaust port inside the irons, which I thought would help tremendously with forced induction later down the line. This would make exhaust gas flow much more streamlined, or at least that was what I imagined. The end product was a much more presentable port, with no change to the opening timing. Just a bigger area for exhaust gases to rush out of the engine – in theory. On the topic of exhaust gases, based on the findings of the second revision of the experimental engine, I felt it was necessary to divert most of the exhaust gases to the front and rear iron exhaust ports. Why? Because the centre iron shares an exhaust port exit between front and rear rotors. This would interfere with the scavenging effect of the overlap between front and rear, effectively hindering the peak performance. I wanted to keep the exhaust pulses as separate as I could. With this in mind, a 4-port centre iron was used, and the Race Extension porting was carried out exclusively on the front and rear irons only.With the Race Extension well practiced, and with new knowledge about the Renesis engine, 2019 started with a huge bang. A new build was in the works on the basis of the experiment from the year prior to this. Resurfaced housings, Irons with minimal wear ported to my specifications, all new seals, bearings – a much cleaner build on a whole. Significantly more care was taken with this one, needless to say. A long, cold weekend of progress allowed for the all-new engine to replace the experimental piece in Cygnus. When all the necessary fluids filled this block, it was time to start.To no surprise, once the oil system was primed, the engine started effortlessly on the key. The workshop was soon filled with the smoke produced from burning assembly lubricants and Vaseline as always used in our rebuilds. A healthy, brappy idle followed, and I just knew that this was going to be a strong engine. It was not long before Cygnus once again returned to the four walls of the Dyno Cell to be ran-in and tuned in the capable hands of ‘D’ the following weekend. Everyone in the workshop was extremely excited, particularly Ben who was nothing other than proud of the recent developments. Throughout the morning, I am hearing a surplus of exhaust notes from none other than Cygnus. The HKS Legamax Cat-Back is sounding as crisp as ever, whilst the engine works its way through the rev range, all the way up to the notoriously high Renesis rev limit. I was giddy, and at the same time, apprehensive about the results throughout the whole dyno session. A few hours from whence it started, the dyno session had ended. D opened the door with a huge grin, followed by his favourite phrase; “Well who.” I dashed to the display enthusiastically. Lo and behold...224hp, and 150ft-lb at the wheels! Approximately 257hp and 172ft-lb at the flywheel! This was the most power we had ever seen out of a naturally aspirated Renesis, maintaining the side exhaust ports! Also the most torque we had seen as well, which was a great indicator that all the research had paid off. The benefits of the side exhaust ports really shone through – and hypothetically speaking, proves that they certainly were not a restriction in the first place! However, I had to be absolutely sure that this engine was going to work as well as the last one in terms of longevity. 2019 was enjoyed greatly with this new engine. Many hard drives out occurred, long journeys all around the UK, and even a few track days for good measure in the blistering summer heat. All in all, it was just as good as the last year, if not better with the extra power. In summary, both engines performed just as flawlessly over similar mileage for sure. Consistency is all I seem to find with the Race Extension port. Various other RX-8 owners had opted to trial this type of porting in their engines along the way as well. The earliest ones, with extra exhaust port opening advancement did not produce as much power, but still shows to be quite reliable despite that. The later ones were built on the basis of the later discovered information, and all showed results very close to my latest engine. These are engines that still run to this day.Into 2020, with newfound knowledge of the dynamics of port timings and various other quirks of the Renesis, we started to apply the same knowledge into Street Ports as well. I'll never forget one car in particular; a bone stock 231 with zero bolt-ons. It came for a rebuild, nothing fancy at all. Just a customer who only wanted a Street Port before assembly. I assumed the usual - the same port timing changes in the auxiliary and primary ports, and the exhaust ports were only tidied up. Nothing more. This customer opted for a run-in and tune on the dyno, so we actually got to see what power the engine produced before it left the site.We were shocked to see the results: 222whp, 150ft-lb. Almost exactly the same as my own Bridge Port, but the powerband was much smoother, there were zero dips in power on the graph when each intake valve opened,, and torque was more noticeable earlier on. "Is there actually any point of a bridge?" It left us wondering for a while. And I started to question for a while, how come Bridge Ports benefit all rotaries other than the Renesis in particular? And the answer became a bit clearer as time went on.My saga at Rotary Revs ended not too long after that. And while I didn't get to experiment more due to the lack of free access to the dyno, I had lived with this Bridgeport Race Extension engine for quite some time and enjoyed it for what it was. It wasn't quite over at this point though...
CYGNUS - EVOLUTION II
From 2021, all developments were pretty much halted, as I transitioned into my new venture; Black Star Motorsport. Into 2022 The Bridgeport Race Extension engine had been thoroughly enjoyed. Repeated limiter bashing, trackdays, hard Sunday morning drives with friends, it received copious amounts of abuse. It got to a point where I decided I needed to see just how a Bridgeport would respond to forced induction. I had previously mentioned turbocharging a Renesis and forming a kit throughout my time working at Rotary Revs. I felt that it was finally time to put the wheels in motion... Starting with Cygnus.
In September 2022, I partnered with a third party fabricator to design a turbo manifold suitable for a low-mount application. Along the way, I had already planned the turbo spec (A Pulsar GTX3076R), and gotten a few other bits and pieces to futureproof the build. Including bigger injectors, a high flow fuel pump, a water methanol injection system and a few other supplements. A boost controller being one of them. A bit of back-and-forth, and some compromises throughout, the fabricator managed to make a turbo manifold and provisions to make the turbo fit (poorly). Nonetheless, I wasn't going to let the effort go to waste at this point in time. It was the stepping stone into the world of boost, I knew there would be some snags along the way, and I was prepared to live with that.
Just before Christmas, December 2022, Cygnus returned to the dyno at what was formerly known as Rotary Revs (Now 'Motorsport And Performance'). Only this time, the same engine, with boost! Felt like some sort of fever dream. 'D' the tuner, made haste with the initial setup on the ECU; bigger injectors accounted for, MAF rescaled to suit the new intake, and the heightened ceiling for the load tables within the ECU were just a few of the changes made to allow the stock ECU to work with boost. Now, there was only a 5psi spring within the wastegate initially. In terms of what I saw on the boost gauge, after the intercooler, what actually went into the engine was about 4psi. I hadn't properly set up the boost controller, and this was pretty useless on such a small wastegate spring with a 3-port boost solenoid. So we ran only with the 5psi spring for the session and called it a day once we were happy with the fuel table. The end result? 246whp and 176ft-lb. That is approximately 283hp and 202ft-lb at the flywheel, and a nice improvement on such a low amount of boost for sure! With plenty more to come in the future as well. It put things in good stead, and meant that testing could begin! I gave it a good shakedown that evening in the cold. But then, the following day...
Commuting to the workshop, all was well. A mix of urban and motorway traffic with newfound useable torque from as low as 3000rpm. It took away the urgency to shift down a couple of gears in order to make quicker progress from the lower half of the rev range. It was such a strange sensation to experience in an RX-8. Later that day though, when I did a standing burnout after a showing a friend the changes, I noticed a slightly laboured idle, and a change in the way it revved - not in a good way. A compression test was carried out there and then, revealing the rear rotor had lost 1.0kgf of compression on all faces. I suspected a bearing related issue even though the engine still started hot. So, not even 24 hours into a boosted Renesis, and an overhaul was already underway!
The teardown brought some interesting findings - finally seeing how the Bridgeport Race Extension had coped after plenty of (ab)use answered a few things for me. Why did the Street Port do almost exactly the same power as the Bridgeport? Were there any drawbacks? Was this suspected failure a result of the porting?
Well let's start with the failure: The rear rotor had a cracked bearing journal, and the rotor bearing was almost floating. Absolutely new type of failure, I have never seen anything like it. However, given how this engine was used and the fact that it wasn't balanced. It could have happened at any point. I think it broke just because of the extra power made, no matter how small it may seem. Continuing on..:
- The failure was completely random
- The Bridgeport adds power*
- The additional wear found was related to frequent high RPM operation
- Additional chatter marks in the housings were from the Apex Seal metallurgy (These were aftermarket seals)
- Strange blowby was found on the sides of the rotors
Other than the above details, I saw the usual wear that I would see from an engine with higher mileage. But getting back to that initial point:
*The Bridgeport adds the power for sure. and the Race Extension contributes to exhaust gas flow. HOWEVER, because of the port arrangement on the Renesis, there is some form of dilution carried over repeatedly on the side of the rotors. Any gains from the Bridgeport are simply negated by this. And the Race Extension has a similar issue - the gains in exhaust extraction are also cancelled out by the fact that it induces even more side contamination, and it's almost a similar story to the whole porting argument in regards to other people who have built the Renesis - they port the intake ports for longer duration, and port the exhaust to open earlier to extract exhaust gas for a longer period. But in porting the exhaust, reducing the thermal efficiency, they negate the benefits of the extra intake port duration. So in summary the benefits of these new ports are pointless when you factor in the drawbacks too. This is the reason why Mazda cancelled out all overlap in the design with the cutoff ring mentioned in the previous chapter. In side exhaust applications, it offers no benefits to that port arrangement, only drawbacks. And I suspect this will be more apparent with boost. My take on it is: A street port is the only viable improvement to make inside the engine, provided the exhaust port is left well and truly alone. That is dyno proven.
Moving on now, I would like to prove that theory in the long term. So I have taken the liberty to continue using the Bridgeport Race Extension just to prove a theory. This engine was rebuilt with a dynamically balanced rotating assembly courtesy of GarageREG, and all parts (apart from the one damaged rotor) were reused for testing purposes. In the Spring, Cygnus was back up and running, and for the sake of fun, he had a 7psi spring put in. At this point, I decided to do a bit of road tuning myself to suit the extra boost, not truly knowing what the extra power was.
2023 saw Cygnus on many drives, and the stiffer 7psi spring brought more aggression to the boost during spool up. Not forgetting the extra power that came with it, that's for sure! And while I never found out what the extra boost made at that point in time, I would consider it a good benchmark for a boosted RX-8. Assuming it was about 260whp (300hp), I'd personally say that it's the amount of power that the RX-8 should have come with in the first place. The chassis can manage it well, even as far as DSC's limitless capacity is concerned. And it makes it an excellent contender for the modern world of sports cars too (and hatchbacks). A few Sunday morning sends, a track session at Silverstone Circuit, and a good tour around Wales amongst friends proved to be very enjoyable (and competitive!) with boosted Cygnus. There was just one caveat though. And this was apparent mainly at warmer ambient temperatures: the engine was getting HOT. To the point where the almost useless temperature gauge was regularly sweeping to the hotter end after extended pulls on the road. I put this down to a couple of things;
- The small 2.5" intercooler (I knew the risks)
- My old A/C Condenser
- Zero heat management around the turbo
- Ineffective oil coolers (around 80% bent fins)
This ultimately led to the engine's demise right as the summer ended when I pushed it too hard. When I finally got around to removing the engine in the Autumn that year, distortion around the compression area of the rotor housings told me everything I needed to know. I had to upgrade my cooling at some point! One other thing I noticed - the Apex Seals were starting to wear away at the Apex Seal Slots within the rotors, widening the slot, knurling the edges over as if the seals had been rocking back and forth constantly with the extra stress introduced from boost. My immediate thought with regard to the seals was that I had to opt for the deeper 2mm seals, as found in earlier engines like the 13B-REW used in the RX-7 FDs. So, for the rest of the year, while I continued to manage my business workload, Cygnus was off the road until 2024.
Fastforward to 2024, it was another Spring of action, following the move into the current workshop and tying up a few loose ends. The engine received some love once more. This time, we had the rotors machined to take taller Apex Seals, courtesy of GarageREG again! I took a chance with the distortion in the irons but replaced the housings because they were blatantly distorted. Buttoned up with new 10mm studs, the engine was reinstalled in Cygnus, and away we went, carrying on with the testing... Which was once again, short lived. Maybe 300 miles into this engine, following a hard drive in the Peak District, it cut out on me and refused to start willingly. Another fastforward, the irons were well and truly distorted, particularly at the back half of the engine, which I half expected in all fairness. SO, spare irons that I had around were Bridgeported and used in this build. This time, the engine was better. Ready for a year of action!
Spring saw even more drives, particularly around Wales again. A cheeky track session at 3-Sisters Circuit, and plenty of local driving in the summer amongst friends. I was racking the mileage up, and turning the boost up along the way. Temperatures seemed to be managed better with the Water Injection System implemented into the intake at the expense of a bit of power. 12psi was definitely the point where it really started to come alive. And it made Cygnus very competitive on the street for sure. Modern hatchbacks that would usually leave the RX-8 for dust from a roll, such as the Audi S3 (8V) no longer showed the usual dominance on a straight run. Boost finally started to make sense! In the back end of summer, just after fitting a much larger and ill-fitting universal 4" Intercooler, I arranged to bring Cygnus back for some dyno action at Motorsport And Performance, to see just how much power we were making, and how much we could extract from the mighty Renesis.
We were making 315whp, 230ft-lb at 12psi, which tallies up with what I experienced on the road against other cars. But just when things were getting exciting with about 18psi, we noticed something happen mid-pull. The official number we made before aborting the power run at 7,500rpm, was 355whp, 264ft-lb. Had we finished the run at the 8,500rpm, and finalised boost control to hold 18psi all the way up there, we would have likely seen at least 400whp. Which would be mind-blowing in an RX-8. Alas, we did some damage... a cracked front iron. Right where the top dowel is, which feeds the front rotor bearing. Losing oil pressure is not a good thing AT ALL. Naturally, we had to abort mission and call it a day.
We finally found the physical limit of the standard Renesis block at around 400 crank horsepower. Something that no one has openly talked about. Something that the average Joe would not have experienced at all.
So what now?
Well, I drove Cygnus back to the workshop despite that. WOW is all I have to say. Holy f*** if only the block could hold all that power! It was just as good, if not BETTER than most FDs I had driven at similar power. The powerband, the high revs, the off-boost response, hell even the AZ6 6-Speed Gearbox worked SO WELL and helped keep that momentum going. It was sensational, and made me eager to find a solution for the weakness in the block. I was determined after experiencing that!
I had a roadtrip in Scotland due not long after that. My thought process was 'I reaaaaally don't want to miss out on that with Cygnus...' so with a few days to spare, I got to work. One of the tricks from the early days to reduce the chances of an iron cracking (and this is definitely just a band-aid) was to put a one-piece solid dowel into the engine. I knew this wasn't a fix by any means. But if it allowed me to run that kind of boost for the trip, it would make me a happy man.
Naturally, the top dowel hole on a rotary acts as an oil passage (with the S2/R3 Renesis engine being the only exception). So by putting a solid dowel in place of the hollow ones, you effectively need to redirect the oil feed externally. This is known as an 'external oil feed mod', which consists of using a special adapter plate on the Rear Iron, in place of the oil filter pedestal. You have to run a Remote Oil Filter Housing plumbed in before the oil line goes from the Oil Cooler back to the engine. You also have to drill the brass plug out from the top of the Front Iron, ironically just above where the iron cracks. (Previously used as a turbo oil feed on the older 13Bs). This allows for a direct feed to the Front Rotor and Stationary Gear bearings.
With the modifications made, and the replacement Front Iron Bridgeported, the engine was pieced together for the third time that year, and put back into Cygnus, the evening before the departure to Scotland. That morning, still very much drained from all the rushing around, I drove in convoy with my group of friends up to the Scottish border. Along the way, my friend with a lightly tuned BMW M2 (OG) with an N55 making roughly 430hp, lined up with me, and had a couple of sprints. To my surprise, we were neck and neck! The only deciding factor was whether I missed my shift or not! (excuses, excuses) Nonetheless, I was so impressed, especially up against a fast car with a dual clutch transmission. That was all I needed to see to monitor my progress, to see just how far Cygnus has come over the years of development. But in summary, the trip was enjoyable - despite the snags like boost pipes popping off, cracking another front iron after one hell of a wheel hop experience, and piercing the sump on a rock that definitely didn't exist to anyone else! Cygnus drove from England, to Scotland and back on his own power. And that was the year 2024 wrapped up.
The year 2025; it did not bring the same amount of action as '24. After the engine inspection, I had noticed some unusual wear brought about from the added stress of higher boost. This was directed predominantly to the rear rotor. Now, the rotor itself was actually fine. The apex seals were doing their thing, but there was a noticeable sharpness to the Sideseals. Call it a 'burr', like a knurled edge. Upon closer inspection of the Irons, there appeared to be some sagging or distortion right around the exhaust ports. It didn't appear to be directly related to heat as such, and there were no signs of detonation or pre-ignition on the rotors, so the tune appeared to be fine. However, the only common denominator in that regard, was the turbo manifold design. There is a very obscure bend leading into the T3 flange that acts almost like a brick wall before going into the turbine housing on the turbo, creating some very much unwanted backpressure and elevated EMAP. Admittedly, the runners on the manifold in general I would deem as too small as well. Unfortunately I had a feeling this would be a problem later down the line, but I wanted to get into the boosted realm with what I had at the time. I also knew that space was always going to be an issue when attempting to package a low-mount turbo configuration effectively, ticking all the boxes along the way. Trying to get ahead of the curve, I had lined up another fabricator with greater understanding of the demands of high-revving engines in a motorsport environment, to design a whole new manifold and create a completely different setup. Many many setbacks have been experienced during the creative part of this process, and even as I write this at the start of 2026, it is not yet completed. I soldiered on with the existing setup I had, replaced the second cracked Front Iron, and continued to drive Cygnus at leisure, back at the 12psi he used to have. The engine finally met it's demise for good while queueing up to a Cars & Coffee event locally. Ambient temperatures climbed too high while creeping in event traffic for well over an hour in 30 degrees. I refused to turn the engine on and off at the expense of trying to keep coolant flowing, all while the coolant gauge was pinned fully right. The engine was never the same after that - hot and cold starts were very tedious, so I am under the assumption that most of the engine is practically scrap at this point.
The good news is, I have a brand new setup waiting to go into Cygnus for 2026, comprising of:
- New Irons
- New Housings
- New Dynamically Balanced Rotating Assembly w/ GarageREG FD Seals
- GarageREG 1/2" Stud Kit (Engine machined to accommodate)
- New Turbo (Pulsar G30-660 Reverse Rotation, 1.01A/R)
- Green Brothers Racing Billet Water Pump
- Twin 25-Row Oil Coolers
- Haltech PnP ECU
And all of this, combined with a Street Port should see Cygnus making the desired target of 500 crank horsepower, approximately 435whp. I believe all these changes will address all of the issues I have experienced up to this point. The new manifold should bring EMAP to much better levels. The extra cooling measures will keep heat at bay, and having the Standalone ECU adds much more flexibility to the safety and tunability of the powertrain. The turbo is technically a size down from what it was, but if my previous theory about porting is correct, this should still offset the size difference, and I have a sneaky suspicion that it will actually yield more gains than the Bridgeport Race Extension, pound for pound of boost.
2026 is going to be the most exciting year yet, and marks the third Evolution for Cygnus. There will be a number of other mechanical changes to prepare him for hard usage on the track, and upon the success of the turbo kit, he will be put up against some much faster, expensive modern cars. All in the pursuit of showing you just how capable the Mazda RX-8 can be with the right setup. Fingers crossed, we will enjoy the fruits of our hard labour. We will continue to pave the way for our humble UK RX-8 community.
