I recently ran into a fun issue where my clutch pulley on my supercharger decided to decouple in both directions, leaving me without any boost on the truck. Fortunately, it's fine to drive until I get a new pulley, and as such, I've noticed an interesting change in the driving manners at highway speeds.
Normally, my truck will downshift fairly often when going up hills at highway speeds. It would lug the motor until about 2-4psi of boost, then would downshift. I also noticed that the AFRs would drop into the 11 range if I locked the truck in 8th gear over that boost range. That all makes sense, you don't want to run a bunch of boost while lugging the engine at the stoich ratio. If you want to lug a boosted motor, you have to run rich.
Enter the last couple of days driving around without any boost. The truck has MUCH better manners on the downshifting front. It will lug the motor WAY harder before it goes to 7th gear. Minus being down several hundred horsepower, the chill daily driving I do is actually a little nicer.
This is similar to my 2014 R/T, which is NA. It seldom downshifts on the highway unless I'm pulling a trailer. Yea, it's got less wind resistance and 3.92s with smaller tires, but I always suspected the difference was more about the boost than the gear ratios. That seems to be confirmed now.
I wonder if it's possible to simulate this on the TRX with either a tune adjustment or the smoothboost system. The bypass valve is essentially just open all the time on my truck, so controlling that should produce a similar effect.
Side note, I wonder if my MPGs will go up.
Normally, my truck will downshift fairly often when going up hills at highway speeds. It would lug the motor until about 2-4psi of boost, then would downshift. I also noticed that the AFRs would drop into the 11 range if I locked the truck in 8th gear over that boost range. That all makes sense, you don't want to run a bunch of boost while lugging the engine at the stoich ratio. If you want to lug a boosted motor, you have to run rich.
Enter the last couple of days driving around without any boost. The truck has MUCH better manners on the downshifting front. It will lug the motor WAY harder before it goes to 7th gear. Minus being down several hundred horsepower, the chill daily driving I do is actually a little nicer.
This is similar to my 2014 R/T, which is NA. It seldom downshifts on the highway unless I'm pulling a trailer. Yea, it's got less wind resistance and 3.92s with smaller tires, but I always suspected the difference was more about the boost than the gear ratios. That seems to be confirmed now.
I wonder if it's possible to simulate this on the TRX with either a tune adjustment or the smoothboost system. The bypass valve is essentially just open all the time on my truck, so controlling that should produce a similar effect.
Side note, I wonder if my MPGs will go up.
