If regular gas is $3.50 a gallon and I pay an extra dime for a mid-grade, I need to pull a 3% improvement in fuel mileage for it to pay for itself. I haven't done a test for a while, but I was always able to better the cost/value of higher octanes when gas prices were over $3.

 

Thanks, obviously I'm not questioning your math skills, I just found it surprising without doing any leg work myself. So that is good to know, when I hit the pump the next time.

DD

 

I wasn't offended or anything, just know that we sometimes look at the dollars on the pump instead of the mileage we got out of the fuel. While the efficiencies I find with higher octane fuels in the summer are great, in the winter months, staying in open loop longer with richer fuel mixtures as it takes longer to reach operating temperatures, I run regular fuel.

 

JPop. I'm sure if I read every word of this thread I will probably find an answer so I apologize for what I'm sure are a couple of repeated questions. You mentioned at some point that if you had it to do over again, you would not have done the headers and exhaust (Not sure if you included the intake in that statement). At least that was how I took what you said. Anyway why is that? Was the mpg gain just not worth it? I have a 2007 X unlimited 2wd automatic. I bought it as is last year with a 3" +/- lift and 33's. I have no idea if the previous owner re-geared it or superchipped it or really anything beyond the obvious lift and tires. If not, I assume it has the 3.73's. Is that a correct assumption? So with all that said, should I re-gear alone and not spend the money on the exhaust, intake and programmer? If so, to what? 4.10 or 4.88. Maybe even 5.13 as I plan to switch to 35's???? My assumption is that I would save enough on gas with the uncorking that it would pay for itself an a year or two. Again....is that a wrong assumption?? I will be doing most of my driving on flat roads with a mix of city and highway. Autobahn to be exact as I'll be in Germany for 3 years. Obviously I'll be hitting the mountains a little too but without the 4wd it won't bee that much. On a side note....it won't be 2wd forever. But that's another thread all together. Thanks in advance.

 

Headers were a bit of a nightmare out of the gate. I had a different programmer and was running lean. Took me a while to straighten it out and I didn't have the issue after I bought my Flashpaq. I didn't need to upgrade octane a notch and I didn't need to run anything out of the norm on plugs.

Intake and exhaust, I spent more money than I needed with very modest improvements. Could have bought a drop in performance filter, and replaced the muffler and been just as well off. 2.5" pipe is 2.5" pipe, anything bigger doesn't help and it would have cost a third of what I spent to get the same amount of performance.

I agree with most that gears are probably the biggest improvement gain you can make. Doing them first, is a little tougher for me as I really wanted to know where my power was before hand (6 speed). Where I wanted to be rpm wise, what power I needed at certain speeds and such. You also need to have your tire size and speedometer correct to make shift points correct anyway. So I had all that done before I opted to get gears, and I don't look back at the order I did things. Definitely could have done without the exhaust and intake as a precursor for gears, but gears and a programmer kind of go hand in hand because you need to get things calibrated anyway.

Hope that helps.

 

JPop, it's my understanding that calibrating tire size and gear ratio only affects the speedometer in a manual transmission. In your above post, you mention you have a 6 speed, but then later you comment on getting the shift points right. I've been patiently waiting on a tuner for 2 years for my 2011 6 speed, but just recently gave up and ordered the AEV procal just to turn off the tpms sensors and get my speedometer right. Did I also gain some performance improvement that I don't know about? thanks.

 

So if I'm staying with the 33's, are the 3.73's and the programmer okay or would I benefit greatly from 4.88's and a programmer?

 

just received my flashpaq.. trying to update it online - getting "there was a promblem uploading EEprom file: error 5" .. trying to do the TPMS delete (offroad pkg) started it all .. any ideas?

 

So you're running regular fuel on your 91 tune or running that on the 87 tune?

 

Calibrating tires and gears fixes the speedometer in both autos and manual transmissions.

Having the speedometer calibrated will correct your shift points in an automatic as they are throttle position % and mph based.

You didn't gain performance with the procal, but your shift schedule has been restored to a stock level given the changes in tires and gears. This generally results in better shifts than when the speedometer was uncalibrated.