The FD RX-7’s factory oil cooler(s) are barely adequate for stock horsepower. To handle our increased power and track use, we completely redesigned the entire oil cooling system with Hayden HD Cool oil coolers, Earl’s UltraPro stainless steel lines, Radium Engineering fittings and catch can, Raceonly oil fill neck and power steering reservoir, and we relocated the oil filter and thermostat with Improved Racing.
The more common “Touring” model of the FD RX-7 only had one oil cooler behind the bumper on the driver’s side of the car. This setup was so insufficient that back in the early 90’s when these cars were new, stock cars would often overheat in the summer and throw oil temperature warnings in stop and go traffic! The performance-oriented “R1” model were slightly better due to having two oil coolers in series for added cooling capacity. Unfortunately, this was not up to the task for much beyond stock power levels on track. Needless to say, we need to upgrade the oil cooling system of our FD RX-7 with our plans to track the car with nearly triple the factory output.
Our FD had the late-model 1999+ front bumper that features larger openings in the bumper for more airflow to the oil coolers, however the previous owner retained the original ducting designed for the smaller, stock bumper. The difference is pretty significant.
After removing the front bumper, we can clearly see the factory ductwork and oil cooler.
The ducting is pretty good as expected for an OEM design. The oil cooler is a plate style heat exchanger that is fed from the bottom of the cooler.
We removed the factory oil cooler to start fitting the new ones.
With the factory oil cooler removed, we were able to inspect it a little closer.
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
10 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.