> Turbo cars are that way in general. The trouble is that the engine, as it > slows down with the throttle closed, can no longer accept all the air >that the turbo is blowing. Then pressure builds up and the turbo, >fighting against it, slows down. > This is why blow-off valves exist; when the throttle is released the valve > opens and allows the turbo to blow into the atmosphere. That way no > pressure builds up and the turbos spin freely. Unfortunately the > currently available Island turbo kit (which is the only one I know about) > does not have a blow off valve, to the best of my knowledge. This statement isn't quite right and needs to be clarified. Actually a blow off valve is something used in the CART racing series cars. It limits turbo boost to the CART rules by opening, or blowing off, when a CART driver dials his boost higher than allowed by the CART rules. When that happens he must return to the pits to have the blow off valve reset. Our DeLorean turbos have what's called wastegates. These divert the exhaust gases that drive the turbo around the impellers when the pre-determined level of boost is reached. They use spring loaded or linkage activated valves that open at pre-determined boost levels. The single turbos use a remote wastegate installed down stream of the turbo and the twins, Islands offering, have interrogated wastegate, built in to the turbos, to accomplish this. When the exhaust spins the turbo's impeller to the speed that produces the desired boost level, the excess exhaust is diverted around the impellers to maintain the level of boost that the system was designed to produce. None of this process involves anything that happens when the throttle is closed. Driving with a turbo requires some practice whereby the driver learns what it takes to get into the boost area and staying there during the up shift process. Bruce Benson