OK, I went from the 91 tune to the 87 tune last night and I actually feel no performance decrease at all...hummmmmmmmm

I also changed the wheel size to 34.25 from 34.50

 

Just wanted to clarify something that I had a question about earlier. I, too, have 32" stock rubi tires. Like you, I looked into the Flashpaq specs and it stated that my tires were 30.5"'s. Now, I'll be honest, I have not measured them with a yard stick like I know I should, but Is this the "correct" tire size that the Flashpaq should detect?

Earlier I was informed that the Flashpaq, in reading the Jeep's VIN#, determines all the stock specs.

Is 30.5" correct for the stock Rubi tires (255x75x17)?

If not, couldn't this also account for the excessively high mpg's that my dask indicates since installing the Flashpaq as well? (BTW, these dashboard #'s are different than the manual calculations I have done.)

 

The 30.5" will be the same as the factory setting.

 

not sure what the rubi tires are, but if they are in fact 255/75/17, just doing the math that's more like 32", so no, 30.5" would not be correct.

i would think that if you are using a tire larger than what you have programmed (i.e., have 35's on the jeep, but have 32 programmed in the flashpaq) you would get lower mpg numbers on the dash.

even stock, the dash info is questionable. only purpose it serves for me now is the temp and i generally know that before i get to the jeep.

 

Went from the 93 tune to the 91 and I can concur with the others here that there is no difference between 93 and 91.

Will be going back to the 87 tune shortly since the economy is getting better which in turn means that gas prices will begin to rise.

 

When I had the "33" put on I checked my speed against GPS (iPhone) and had to set the calibration to a tire size of 31.5". At that size the speedo was dead on to the GPS at 20mph and 70mph.

In addition everytime I have tried the 93 tune I hear pinging! I am burning 93 octane BP fuel but it knocks (really really it does!!!) so it's 91 tune for me. This worked even at 13K feet and I could never feel a decrease in power!

 

You couldn't feel a decrease in power at 13k'? Mine does fine around town here, but over 9k' its pretty weak.

 

I suppose I could have a defective dynobuttometer but I was recently in Ouray and I just let it idle to pull me over any and all of the local obstacles. Was burning 91 octane out there and highway performance (not at 13K) was better than ever.

I have heard we have some of the cheapest gas in the country right now, maybe that is the reason for the pinging and great performance at altitude.

 

Well, after 2 weeks I am super happy I got the SuperChip!

With the new 35's power is down a little, but not near as much as I expected!

My Gas Mileage has dropped about 1.2 MPG.

On my mixed city/street I was about about 16.7, now I'm at 15.5. Not bad!

I see no need to regear! I think the extra HP helps just enough so I can cruse 70-75 on the freeway without downshifting, and that's with an auto.

Now I am in Phoenix which is low elevation and flat roads, which I'm sure helps.

 

This doesn't surprise me as at altitude and highway speeds the reduction in aero drag in the thin air is greater than what the throttle blade position can compensate for pumping air through the engine. Until your up against WOT at speeds above 60 mph the reduced drag coefficient is going to have a larger role in keeping the vehicle rolling than the lack of air.

It was really hard getting my head around that one but then again never really had to think much about the aero footprint of a barn on wheels. Aero drag at 10,000 feet is about 130lbs and at sea level it would be closer to 200lbs while driving at 70mph. WOT Horsepower at 10,000 feet drops by a third as compared to sea level so you would need to have the overhead available from your throttle blade position to compensate.

The caveat in all of this is that at elevation you generally have a lot of grades to deal with and that's going to do away with any drag advantages of thin air.