All SR20s run hot, but this goes double for 280-whp, turbocharged SR20DETs in flat black cars on the racetrack in 100-degree weather. The problem, I'm convinced, is a bad water pump design, but since nobody seems to have made a better water pump, the solution has to be a bunch of bandages.
We've already applied the biggest, most effective bandage, a Koyo aluminum radiator. Coupled with the 160-degree thermostat that came with our junkyard engine, the car runs alarmingly cool most of the time. But in the searing heat of a California summer, there are a few more steps that can be taken to help the SR shed some BTUs.
Airflow
We've made two inexpensive changes to improve cooling. The first is simply to let more air hit the radiator and intercooler. The stock Silvia nose has a clear plastic panel between the headlights. Air doesn't go through clear plastic. Recognizing this, the Japanese aftermarket offered countless grilles to replace this panel. We got one-don't know what kind-from Spriso Motorsports. They got it from a junkyard in Japan. Next came the cutting. The Silvia front bumper includes an ungainly license plate mount. Since our front plate mounts solidly under the carpet in the trunk somewhere, we cut out the mount and made it into a vent.
Air tools will come in very handy here. To cut the bumper, we marked the rectangle, used a 1/2-inch drill bit to drill the corners of the rectangular hole, and then connected the dots with an air-powered body saw. The saw uses miniature hacksaw blades and cuts through the plastic more easily than any knife has ever gone through butter. The saw is a little hard to steer, though, so we cut slightly inside the rectangle, leaving a drunken, weaving cut. The edge can then be cleaned up with an air-powered die grinder.
Once you're through the plastic, you have to cut the styrofoam bumper. Here's a tip: you'll still be able to see some styrofoam when you look in the new vent, so hit it with some black spray paint.
Cooling isn't the SR20DET's strong point, so every bit of airflow helps. The upper grille is a common aftermarket bit in Japan. We got it from Spriso Motorsports. The lower grille used to be the license plate mount. We like cutting holes in things.
Next, you'll hit metal. Japanese bumpers are thin, single-layer deals, so it's relatively easy to cut through. If you have a plasma cutter, you don't need me to tell you what to do next. We don't, so we used an air-powered cut-off wheel and some patience. The body saw probably would have worked too, but making sparks is fun. This will, of course, weaken the bumper, but it wasn't exactly a battering ram before anyway.
The final touch was a wire mesh grille. Go to www.mcmaster.com and you'll find every kind of wire mesh you can imagine, and they even tell you what percentage of the mesh is air. Hint: more airspace means better cooling. We used a woven mesh because it looks cool and is mostly air. To mount it, we simply bent it 90 degrees and bolted the horizontal part to the underside of the bumper. The vertical part just stands there looking grille-like.