spartan99

"You are correct about the OD. SC dosen't allow you to chance shift points, per say. But, it will give you more power and you'll find that the JK will not drop down into OD as often. You asked about fuel mileage and I can say that I picked up 2-3 mpg as have most other people. If you have an auto, it's worth the $ IMO."

You are not stock, though. Did you install the SC when you had STOCK gears/tires and get the 2-3 mpg's? Or, did you install the SC after you'd already swapped gears/tires. My guess is you experienced the mpg gain WITHOUT stock gears and tires.

spartan99

I'm finding a mileage gain hard to believe if we're dealing stock arrangements and no change in shifting points because if it gives you more power, it could only do so by having you burn more fuel and air which should technically give you a drop in mpg's.

Without changing gears and such, the only way to get better power w/o affecting mileage would be by increasing compression, which SC can't do.

JPop

Turning overdrive off means just that, overdrive off and you won't be downshifting to a lower gear because you are already there.

There is a common misconception that twisting some additional rpms will cause fuel consumption to go up at the same rate as the rpm increase. While you certainly have the extra mass of engine related motor and accessories spinning, your fuel use per stroke is going to be limited by the throttle blade and negative pressure in the manifold.

The case as presented, 60mph at 1900rpm means your making about 60 horsepower at the wheels. Perhaps 65-70 hp with a Flashpaq. To maintain the 60mph you are good up to about a 3 degree grade, if the grade is steeper, you have no place else to go because the throttle blade is open to a point you have manifold pressure nearly equal to the outside air. The only way to increase power is by downshifting, or at minimum, unlocking the converter.

Unlocking the converter will cause a decrease in efficiency, somewhere between 10-15%. Then a shift on a kickdown will also cause efficiency loss, an allotment for some shift smoothness and ultimately a kick down into a lower gear. End result, is that you don't have enough gear, a Flashpaq isn't going to bail you out and you need to gear appropriately or turn overdrive off.

JPop

Advancing timing and giving you more power per stroke raises efficiency. There are 3 separate stokes that are all parasitic, and one that makes power. Increase the power per stroke and you gain efficiency. You may actually burn more fuel per stroke, with more power but it's the ratio between the power stoke and that which is parasitic.

spartan99

Okay jpop that makes sense. So, have you done this? Have you used the SC on a JK with an auto trans and stock tires and gears and experienced an mpg gain? So far I don't have an answer on this perhaps no one's yet bothered with the SC upgrade with a stock set up.

JPop

I don't have an automatic on my JK and it isn't stock. I have had opportunity to do with and without tests as my vehicle is currently configured with the Flashpaq, and in the past did the same with the Hypertech Max Energy. Either programmer provided modest mileage gains. I also have a Flashpaq for my Dodge Ram which does have an automatic and also saw efficiency as well as performance gains. Up shifts are moderately higher and much firmer than stock. Down shifts are also much crisper, I have a better feel for when the converter unlocks and when the engine will kickdown.

So I am not exactly sure what you are looking for, but the principles remain the same. The methods the tuner uses to increase power, what that means for efficiency and better management of the transmission. There are hard and fast rules that we need to work with and physical changes we can make to make those things work to our advantage.

spartan99

"So I am not exactly sure what you are looking for, but the principles remain the same. The methods the tuner uses to increase power, what that means for efficiency and better management of the transmission."

That's exactly what I'm looking for; maximizing the efficiency of the engine and trans. If you said it worked for your auto Ram, that's good news!

JPop

My Dodge Ram is a totally different animal in some respects. It weighs literally a ton more than my JK, has plenty of power and drinks gas like a pig. It's easy to maintain speed because there is plenty of power and despite how large of a vehicle it is, it has relatively the same aero drag as a JK.

If your main objective is getting an mpg increase, the best way to do it just simply slowing down. After 40mph in the JK more of your power is being used to combat aero drag than it is propelling the weight or spinning the tires. From 60 to 70mph it takes 50% more power for a 10mph gain. That's what will show up at the pump more than anything, and why you see so many people with so many different efficiency results.

Jollydodger

Actually, way back when these first came out, and you were first extolling their virtues, the Adjustable Shift Points were supposed to be one of the main features. It was on the Superchips web site, every vender site, on the box, in all the reviews and write ups etc. Then Superchips said it was not technically possible to do the adjustable shift points so they would just "Optimize" the shift points instead.

Flash forward a year and it turns out they are technically able to make the shift points adjustable, it's just and upgrade that costs more.