450st isx

[Daytripper]

I own 2 prostars...both cm871....one is a 450st and one is a 450....the "st" is noticeably louder and seems to have more bottom end torque. What does the "st" stand for and what are the differences between the 2 engines?

[Magard]

ST=Smart torque. Should be a 450-1550/1750 or something like that. Don’t know why one is loader than the next. Shouldn’t have anything to do with that.

[hhow55]

original post: http://rawze.com/forums/showthread.php?t...5#pid50145

CM871, CM2250 ... Considered Smart Torque 1
It is controlled by gearing when above a 1:1 ratio (top gear only for most trucks), or can be on all the time on other trucks (where gearing does not matter). It kicks in for 30 seconds than falls back to lower torque.

CM2350...
Same Smart torque 1 as on the CM871,CM2250 (old style). Smart torque 2 is also applied on some 2350 trucks though, and is on the X15.

Smart Torque 2 == applied by estimated weight of vehicle and its load (determined by how hard it is to climb hill, how hard its driven, etc.). It effects load based speed control (that thing everyone hates where their truck feels like it pulls good when heavy, but feels like it can't get out of its own way when light), driver reward system, and fuel economy control system.

Load based speed control effects not only torque, but injection timing, and a lot of other sub-systems.


This from Mr Rawze