We replaced the factory oil filler neck with the Raceonly Billet Oil Filler Neck for FD RX7. This beautifully CNC machined piece provides a chamber specifically designed for oil/air separation, making it perfect for the street or track. This filler neck is also offered in many different anodization colors to match your engine bay.
I really like how the Raceonly Billet Oil Filler Neck features two -8AN ORB ports and has a built-in air/oil separator design in the main chamber. This will allow us to cleanly and easily attach the fill neck to a vent tube from the block and to a catch can, while reducing the amount of oil that makes its way to the catch can.
The Raceonly Billet Oil Filler Neck is a bolt-on replacement of the factory plastic filler neck and is compatible with single or twin turbo cars, cast or billet blocks, and high power or mild builds. I must say that it really looks great mounted on top of our blue engine.
The Radium Engineering Universal Single Catch Can is one of the nicest on the market featuring a durable CNC machined construction and an integrated air/oil separator with cleanable and reusable filter media. There are two interchangeable -10AN ORB main ports on the top and side of the can for the inlet and vent. A threaded body and -4AN ORB bottom drain port make for easy draining of the collected oil, and I really like the integrated O-ring sealed dipstick that makes checking the oil level very quick and easy.
These catch cans are designed to effectively prevent “blow-by” oil residue and sludge buildup in the intake, intercooler, and throttle body of the engine which greatly reduces fuel octane, knock resistance, performance, and reliability of an engine. Keeping the inlet clean and ensuring only fuel and air enter the combustion chamber is even more critical in rotary engines that runs hot and are very knock intolerant.
Radium Engineering are constantly evolving and improving their products. These catch cans were completely redesigned internally in 2024 with Radium’s patented Fluid Lock* mechanism that feature a reusable and cleanable stainless-steel media and a new baffled design that greatly increases surface area for the oil, water, and other fluids to condense and drop out of suspension, collecting in the container below.
We 3D printed this bracket to test fit bolting the catch can to the front crossmember in the FD RX-7. I am a big fan of the quality, effectiveness, and the level of details that Radium features in this catch can and highly recommend them, especially for RX-7 owners.
In order to vent crankcase pressure and collect any blow-by in the Radium Catch Can, we ran a -10AN Earls UltraPro stainless steel line from a Radium Engineering -8ORB to -10AN Low Profile Swivel Fitting (PN: 20-1000-0810) mounted on the Raceonly Billet Oil Filler Neck to the catch can. We vented the catch can with a Radium 0.75in ID Breather Filter and -10AN ORB Fitting (PN: 20-0050). We also had the custom catch can bracket machined out of 6061 aluminum for secure mounting to the crossmember in the FD.
Quick Reference:
Page 1 – Stock FD RX-7 Oil Coolers
Page 2 – Hayden HD Cool 778 Oil Coolers
Page 3 – Oil Cooler Ducting
Page 4 – Improved Racing Remote Engine Oil Filter Mount & Thermostat
Page 5 – How to Make Earl’s Performance Stainless Steel Hose
Page 6 – Oil Plumbing Series vs Parallel & Radium Low Profile Swivel Fittings
Page 7 – Raceonly Billet Remote Oil Filter Pedestal & Front Iron Oiling
Page 8 – Raceonly Billet Oil Filler Neck & Improved Racing Catch Can
Page 9 – Crank Venting from Gutted OMP Port & Turbo Drain Fittings
Page 10 – Raceonly Billet Power Steering Reservoir
11 comments
I don’t think I could park this thing on the street knowing the man hours invested.
Good job. Helluva build.
This has been a great build to follow along. I noticed in the radiator articles you were calling it the BJR radiator. Are there plans for some of these parts to go into production?
I called it the Billy Johnson Racing (BJR) Radiator to give it a name because it was a custom build to my specifications for the FD platform. I’ve sold a few to people who reached out to HQ Engineering and ordered one, but this is a high-end motorsports radiator that’s priced in line with similar 50mm motorsports radiators (>$1,000) that should outperform anything on the market from my research based on its dimensions and efficiency (that fits within stock frame rails). The majority of FD owners are street guys who are use to $400-500 drop-in replacement radiators that are only slightly better than stock. If you need a significant improvement in cooling, you’ll have to spend more than double that wherever you go.
Thank you 🙂 It’s far from over…
Wow, beautifully done!
Out of curiosity why did you go with stainless braided lines over nylon braided? I’ve been choosing nylon braided lines since they’re lighter and easier to work with but I don’t have the experience with A/N lines you do.
I’m a big fan of nylon and use it in many applications, especially for those areas that will not see abrasion or impacts. We chose stainless because it was the only option at the time in the PTFE UltraPro -10AN hose, stainless is generally better protected for mission-critical fluids like oil lines that might see debris impacts, and because this new hose is so flexible and light, there really aren’t any downsides other than maybe a few ounces per foot. This -10AN is very light (37% lighter than traditional rubber w.stainless braid) and is extremely flexible with a 1.772″ minimum bend radius (vs 6.0″ minimum bend radius for the all-rubber Super Stock hose and 4.0″ for the rubber-lined stainless steel braided Auto-Flex hose). The UltraPro and new Ultra Flex 660 Stainless & 650 Kevlar Steel & Pro-Lite 390 Nylon hose are a significant improvement in quality than the impression that you or I might have on thinking of Earls as old-school, old-technology ‘hotrod’ hose vs many high-end motorsports hose brands. I’d bet that once you experience UltraPro & UltraFlex hose first hand, you’ll change your impression on Earl’s, like I did.
Thanks for the info Billy. I’m actually working on an oil cooler and catch can setup for Project EF Civic. I was going to use Earl’s nylon braided line but I will definitely take a look at the UltraFlex lines for the cooler itself. It’s a shame this sort of info isn’t easier to find on their website.
Happy to see that parallel flow oil cooler setup. A bit curious to hear that in prior history, others’ experience with the parallel vs series flow didn’t show dramatic differences in performance. I wonder if that was due to airflow restriction of the factory bumpers. Anyway, the reduction in pressure drop is worth the parallel setup alone. But I expect your setup to do well as you’ve properly accounted for the airflow.
Any particular reason you went with the Radium catch can over the Improved Racing one? Or just personal preference.
Love the update. Love all the blue anodized parts. Love the attention to detail.