In Part 1, you met our adopted FD RX-7 and its new billet-wheeled Turbonetics turbocharger. This turbocharger is capable of producing a lot of boost and a lot of heat as a result. For cooling purposes, oil from the motor is sent to the turbocharger and then returned to the oil pan as part of this setup’s circle of life. Although a bone-stock FD comes with twin oil coolers from the factory, with our Turbonetics GT-K 700 not being water-cooled like the stock turbochargers, we’re asking a lot of the engine oil to not only lubricate the built 13B-REW but also cool this big twin-scroll snail.
So to upgrade the oil cooling capacity on Project Single Turbo, we got in touch with Earl’s Performance Plumbing. Earl’s has been in the game a long time, having specialized in fluid transfer and cooling for more than 50 years, and currently offers an extensive line of products ranging from AN fittings, hoses, and fluid coolers, just to name a few. The company sent us its big daddy oil coolers, dual 34-row to be precise, along with Perform-O-Flex hoses and the AN fittings needed to finish the job. Despite what your girlfriend might think, bigger isn’t always better, but if you’re concerned we’re over-cooling the oil, don’t worry. We’ve got a 180-degree thermostat onboard to ensure the oil quickly gets up to optimum operating temperature.
We didn’t choose these Earl’s 34-row oil coolers just based on their size or aircraft-spec aluminum alloy construction. We also like the fact that they utilize corrugated screen internal “Turblator plates” that increase thermal efficiency as well as mechanical strength compared with other aftermarket coolers. The internal design of the oil tubes and large collection tanks also ensure the largest possible surface area while maintaining minimum pressure drop. Using Earl’s new oil cooler mounts, which include rubber isolators to protect the coolers from vibration stress, we fabbed up some chassis-side brackets and plumbed the coolers in series, meaning the hot oil from the engine enters the first cooler and from there travels to the second cooler before heading back to the engine.
For plumbing we chose Earl’s -10 AN fittings and hose for a slight increase in internal diameter compared to stock, but not so large as to cause pressure drop or to strain the factory oil pump. The Perform-O-Flex hose is a premium stainless steel braided hose that can withstand 1,500 psi of pressure. The outer stainless steel wire braid also provides extra protection for the inner rubber hose against abrasion or track debris, and we do plan to throw around a lot of track debris with this car! To complement the hoses, we used Earl’s Ano-Tuff Swivel-Seal hose ends. The Swivel-Seal ends allow for easy orientation of the hoses while keeping a tight seal. They also feature a nice black anodized finish and military-spec hard-anodized construction that complements any engine bay.
As much as we love the durability of stainless braided lines, anyone who’s assembled their own lines with this type of hose knows all about the unique fingertip torture that comes with it. No matter how cleanly you try to cut the hose, there are always rogue strands that stab your fingertips as you try to mate hose to fitting (under the fingersnails is the best!). Mercifully, we came across a tool aptly named the Koul Tool, a device that makes assembling braided hose and fittings painless. (See next page for how it works).
Mounting our dual Earl’s 34-row oil coolers was made easier thanks to Earl’s new mounting kit and Ano-Tuff Swivel-Seal hose ends. We also installed a thermostat between the coolers and the engine to ensure the oil warms up fully before being allowed to flow to the cooler.
With oil temperature sorted, the next thing to address is the direct and radiant heat in our FD’s engine bay. With the turbo system in such tight proximity to the intake side of the motor, we have a high-tech shielding to show you in an upcoming issue, but for starters we’ve heat-wrapped the downpipe with a little help from our friends at Design Engineering Inc. (DEI), using their new titanium exhaust wrap with LR technology.
LR stands for Lava Rock, which DEI pulverizes into a fine powder and then combines with the fiber strands to create a weave tighter and more durable than Oprah’s. To put it a little more scientifically, LR wrap can withstand direct heat up to 1,800 degrees F and 2,500 degrees F of radiant heat, significantly higher on both counts than a standard wrap material can survive. Installation couldn’t get much simpler and does not require pre-wetting or high-temperature silicone spray. It’s just a matter of wrapping it tightly and securing it with the supplied locking metal zip ties. We also used some safety wire to play a supporting role to the zip ties, just to be on the safe side.
Both the 4-inch downpipe and unique wastegate “screamer” tubes have been wrapped in DEI’s titanium exhaust wrap featuring LR Technology, where pulverized lava rock is stranded into a proprietary weave that can withstand direct heat as high as 1,800 degrees. Thanks to its pliability, we found it easy to wrap tightly and then secured it with the supplied stainless steel locking ties.
With the giant Earl’s oil coolers in place, the freshly built 13B and single turbo should both be happy, and the DEI LR wrapped downpipe is our first step in decreasing engine bay temperature and reducing heat soak. Once we complete our heat shielding, we should have a single turbo rotary that runs cooler and more reliably, allowing us to lap longer, not to mention faster.
But before we turn any hot laps, we still need to tackle a few more areas of the build, including a serious upgrade to the engine management system. So stayed tuned as we continue to sort our Project Single Turbo in search of that elusive combination of boosted rotary horsepower and reliability.
Koul Tools AN Hose Assembly Tool
Manufactured from a high-tech composite that’s extremely rugged, just insert the AN fitting into the appropriate sized tool, clamp it down in a bench vice, and twist the hose into the funnel-like opening that guides the hose into the fitting. No more pricking your fingertips with the ends of the braided hose, no more swearing like a drunken sailor while assembling custom lines. Better yet, you can repeat this several times without re-cutting the hose end, so you won’t waste valuable hose re-cutting it in an attempt to clean up the end. Both a time saver and a fingertip saver, this is one tool that definitely lives up to its name.