Re: twin sequencial turbos
That engine is an older mechanical injection 12v Cummins B-series. They didn't generate nearly the power the ISB 24v's do today, however, with some easy tuning of the injection pump and more airflow, they can make power. As mentioned, detonation simply isnt a factor in diesel engine, whereas in a gasoline engine its life or death. Unless you have a tremendous lag problem or are making zero power on the top end, a single turbo set up will make life easier, not to mention reduce underhood temperatures.
Sequential turbochargers are used to broaden the powerband so there are no dead spots (lack of low end torque or high-end horsepower), and are primaraliy used on large diesels which require a flat torque curve since maximum operating speed for a small bore is 3K and a large bore is 2200.
Caterpillar uses a sequential turbo system on thier engines for emissions purposes. The C15 has two turbochargers, an internal water heat exchanger and an external charge air cooler. It also uses ACERT varible valve timing to eliminate the need for EGR.
Back on track: these systems are becoming obsolete with the newest advancements in varible vane and varible nozzle turbos, which are far faster and more precise than a wastegated turbocharger.
