ISX 2350 485

[Rawze]

You guys can keep spewing your ideas all you want to but someone has to be pretty dumb to think a fixed turbo is across the board going to be more efficient than one that is programmable and adjustable (variable geometry) on any engine that has to adjust to a wide variance of torque, speed, and RPM ranges on a constant basis.

First of all, those engines still have heavy emissions controls through the combustion process, VG, EGR valve, external EGR piping or not.

No one has considered that with no need for external EGR piping, it is simply cheaper and more profitable to stick a non-vg on the engine when they sell it. More profit for the engine maker and slightly higher reliability would easily be my first conclusion. Has nothing much whatsoever to do with making the engine "more efficient" by not staying with a VG. - It is simply a matter of cost difference vs how close they maintain efficiency in its same class.

YOUR PARTICULAR APPLICATION is what comes into play most of all on how an engine (and truck) should spec'd and what will be the most efficient combination of components will be for you. It is as simple as that. For most trucks here in the states, there is too much variance in what they do for a non-vg to even come close in most applications. For the few that have a constant high-torque application it still does not really "beat" a VG by any stretch of measurable means to make up for the costs of conversion from one to the other. They never get their money back on the investment made because the long term gains are just not there.