I'd like to do something to get a little more power out of my 08 Rubicon Unlimited. I have to almost redline the beast to maintain 60-70 over mountain passes, and it will bog down, even in low range, when heading up a snowmobile trail. I see that Superchips offers some improvement; however, it seems that the performance boost may be tied to Octane rating. Now, I run 87.5 regular and never experience a knock, even here at high altitude. I'm wondering whether I'll have to buy super premium gas to make a Superchips unit deliver, or whether I can expect even modest improvement with the 87.5. Regardless, it my be worth the price of the Superchips to simply be able to lock the front and rear diffs in high range. Thanks for any feedback.

you will definitely notice modest improvements with just the 87 octane tune, the 93 tune is a blast but your gas mileage suffers because you tend be more aggressive with throttle. I run the 87 octane tune but I use 89 octane fuel and it seems to be a happy medium.

Thanks very much. My gas choices are 85.5, 87, and 91. I've used 85.5, too, without problems.

no problem, I didnt know they even made 85.

so did you pick one up jimmy? like to hear what your thoughts are on buying one as well. i plan on getting one prolly this spring.

Not yet. One thing that concerned me a little was that you can't lock both diffs in high range. Only front or rear.

I thought you could only lock in low range and below 10 mph. Here is a quote from the 08 Rubicon owner's manual:

There is a modification that can be made to override the setting of lock in 4 low only. It appeared on this forum once in a thread that talked about the circuit. I don't know anybody who has tried it yet. As far as memory serves me, nobody had posted in the thread that they had tried it.

As for the lower octane, at higher altitudes, you don't need as high of an octane to achieve the same results, as the air is less dense up there.

As for the superchips, it sounds like you're needing more gear more than more power. The programmer WILL help with SOME power boost, but at altitude, it will again be limited by the denser air. Your best bet is to either re-gear, or get a supercharger. Really. A supercharger forces air in, regardless of altitude ("boost"), so your power loss won't be nearly an issue. The tuners almost solely focus on timing, so they'll help SOME, but only a very small amount- Mark W.

and trans shift points if its an automatic. from what i hear thats where they really shine in the "power gain"

I put a chip in my computer and it didn't do a thing!!!



And it was even a Sour Cream and Onion one too!

^Har har

Just thought of something- go for the Superchips. You'll need it when you re-gear anyway. Try it first, but my previous post is still my $.02 on it Mark W.

Thanks, partner. The high altitude may just be why running 85.5 works fine. Although any power gain I could get with a Superchips would be welcome, I also was interested in being able to lock the axles in 4-Hi. Alas, I can lock only one at a time. Still, that's better than the stock setup. The expense of re-gearing is not something that I'd consider, though your point is valid. At the moment, I plan to shell out more than a few bucks on a set of tire chains. There's always the option of trading for a Power Wagon with a Hemi