The turbo size depends on the max rpm and volumetric efficiency. Looking at a 223, If you port the head to get closer to 200 cfm and run the engine out to 5000 rpm, you are looking at twin turbochargers with 38 to 40mm compressor inducers. That's with a good intercooler. You could eliminate the intercooler if you run E85 or Methanol. The bonus is you get a built engine to withstand all the torque. Everything helps on and off-boost response, with your variable cam timing achieving part of the goal of a compound system (variable power optimizing in the RPM range.) Or what I'm sure some of the drag racing guys would be thinking, get a looser stall and just get a bigger turbo.
Here's a diagram of what I'm building.. Twin Turbo Rail 5.84 @ 254 Twin Turbo Altered 6.34 @ 224 R32 Skyline 7.28 @ 197. Save Share. A forum community dedicated to drag racing drivers and enthusiasts. Come join the discussion about racing, builds, pro mods, hot rods, events, turbos, nitrous, superchargers, and more!.. The Banks twin-turbo 6.6 liter Duramax diesel road race truck uses a frontal air intake to maximize the cool, dense air from in front of the heat exchangers. Note how the intake tubes are an extremely large 6-inch diameter that only neck down once they're within 12 inches of the compressor inducer. (Courtesy Gale Banks Engineering)