Birken Vogt
Charter Member
I think the problem was related to the rings crossing the intake ports and chopping the longer oil viscosity improver molecules up.
As for the powerband, it was not due to any intake/exhaust tuning but the simple fact that the standard no-extra-cost fuel injection system was only a min-max governor. No torque rise at all. It simply injected x amount of fuel per stroke no matter what the RPM. Therefore the way to get up the hill fastest was to run at the highest RPM so that you had the most fuel injection events per minute.
Some DD engines had tailored torque, that was an extra option governor with more advance fuel control so that it behaved more like a Cummins to the way I understand it, but I never saw one, however I did drive a DDEC version and it also had good torque rise down to 1400 RPM, not necessary to rev that one out at all.
As for the powerband, it was not due to any intake/exhaust tuning but the simple fact that the standard no-extra-cost fuel injection system was only a min-max governor. No torque rise at all. It simply injected x amount of fuel per stroke no matter what the RPM. Therefore the way to get up the hill fastest was to run at the highest RPM so that you had the most fuel injection events per minute.
Some DD engines had tailored torque, that was an extra option governor with more advance fuel control so that it behaved more like a Cummins to the way I understand it, but I never saw one, however I did drive a DDEC version and it also had good torque rise down to 1400 RPM, not necessary to rev that one out at all.