Pat... your not running a completely OEM motor/electronics are you???
I had EGT & boost guages at the time and EGT never saw 1200 and it was pre turbo. Truck was completely OEM except for guages and exhaust brake.
I have no "ELECTRONICS" per se as the truck in question is a '97 Dodge/Cumins, the last of the 12 valve-no computer plain vanilla Cumins in the Dodges. I have a pyro-EGT, boost gauge, and tranny oil temp.
The engine is stock but came with the HD valve springs which support greater retarding force capability with the exhaust brake.
The performance mods are: 1. replaced stock injectors with injectors having much finer holes, and 2. replaced injector pump with one that has considerably higher injection pressure. This sort of evens out and I spray about the same amount of fuel as stock but in a much finer mist which supports more complete combustion. I get increased HP and Torque AND at the same time a little increased mileage.
How can I get more HP AND better mileage? More efficient, i.e. complete combustion. I'm using the fuel more efficiently not just producing smoke like some "turned up" rigs do. A cost of doing business like this is the need for vigilance in monitoring the EGT as in the heaviest working situations you can force it to overheat. Mind you that if you let up a little bit and only ask the engine to produce a moderate amount of power above stock it will never overheat. Only when you go b---s to the wall for a reasonably extended period will it tend to dangerously overheat as indicated on the EGT. Heavily loaded towing up a steep grade I can drive by the EGT and pull the hill way faster than stock and not overheat.
Before I learned to be more moderate I twisted off the input shaft of Dodge's poor little under engineered 4 speed automagic tranny.
I have a Gear Vendors "Over/Under Drive" an auxiliary overdrive unit mounted to the output of the xfer case. This gives me 8 forward speeds (can't use it in 4wd but don't need it then) This essentially gives me "half steps" between each stock gear. I find that 3rd over is a very useful gear. The big gap in Dodge's transmission between 3rd and 4th is like having a missing gear. If you can't hold the load on a hill using 4th you have to slow way down to run 3rd. This is where 3rd over is so neat.
Lightly loaded and not pulling steep grades you can put it in OD-OD, i.e. 4th gear (Dodges OD) plus OD in the aux unit. Doing this gives about 85 MPH at 2000 RPM. This Cumins is happy at 1700 RPM which gives you just a tad over 70 MPH (about 72) which is a good deal for 70 MPH interstates.
When it comes to a few RPM or a MPG or two versus lugging the engine or straining the tranny, I prefer to opt for what is easiest on the equipment. In the long run harsh treatment of the equipment will result in more cost, less reliable service, and more down time. You'll never be able to pay for decreased MTBF with the fuel savings you might (just might, not a sure thing) get by abusing the hardware.
Pat
It's smart enough to drop into 4th if it needs to. It's also smart enough to kill the A/C compressor if it starts to overheat. But it never has. Worst it has ever done is kick in the thermostatic fan on the long 5% grade at 85°.
