There's more on modifying locomotive diesel engines for biofuels from Steve, the PR man at Cummins in the UK. He says:
It is true, the engines used in the Virgin Voyagers are Cummins QSK19 750hp engines. Their horizontal configuration is designed specifically for use in high speed rail car applications. There were two minor modifications made to the engines to use B20 biodiesel. 1) Additional fuel filtration was added to protect the engine from any contaminents 2) The fuel feed and return hoses were replaced for a compatible spec. The original ones were made from nitrile, which like other natural rubber products can deteriorate with long term contact with biodiesel.
As a former polymer technologist (everyone's got to study something) I should know what the alternative synthetic rubber is.... but it was a long time a go. Steve adds
Cummins has recently announced that our high volume Industrial products are now compatible with B20 biodiesel.
We are currently evaluating biodiesel blends beyond B20 and will communicate more details as they become available.
So keep 'em peeled.