1988 Porsche 928S4 Twin Turbo

Purchased in the summer of 2005, this 1988 Porsche 928S4 is the development platform for the late model 5 liter, 32V Porsche V8 engine.  While many had previously been implementing belt driven centrifugal superchargers on the 928S4 engine platform, there were few turbocharged examples, and certainly none done to our standards.  Even with a sea of negativity spread across well know Porsche online forums, this build was promised to outpower anything else built on a stock 928S4 platform.

The development on this platform representes well in excess of 1,500 hours of engineering and fabrication time, but that's what it took to do it properly.  The twin turbo system consists of:

  • Twin Garrett GT2871R ball bearing turbochargers
  • Twin high-energy hybrid exhaust manifolds, ceramic coated
  • Twin side mount, bar and plate, air-to-air intercoolers
  • Dual 3" exhaust with Borla XR1 mufflers
  • JDS Porsche SuperMAF and Shark Tuner massaged EPROMS (fuel and ignition)
  • 42 lb./hr Bosch fuel injectors
  • Turbocharger oil scavenging system
  • Turbocharger water cooling system with post-shut-down circulation pump
  • Bosch recirculation valves
  • Intake piping system
  • Greddy Profec B spec manifold pressure control, cockpit adjustable

The system was completed in the spring of 2007 and the results speak for themselves.  With less than 9 psig of manifold pressure, the system put out nearly 500 wheel horsepower on a completely stock 928S4 engine with over 170,000 original miles.  Turned up to 12 psig, the same system produced in excess of 570 wheel horsepower, again on a stock 928S4 engine.  These peak power numbers are also backed up with a very wide torque curve which has not been matched by any other forced induction system on a stock 928S4 engine.

Our build standards show through on this car, even though it is the original prototype and is still driven daily at present.

 

© 2011 Kuhn Performance Technologies.