Less,

Real world compression ratio went down when you blew off the 1/8" of carbon covering the piston tops.
Hemifever tune caused you to gun it more often, 12.8mph.

Probably accelerated just a hair better.

 

Ill throw in a guesstimate of 16 mpg

 

I was going to less, but for the only reason that he'd be in the throttle more, with all the new found power.

 

So first day of driving with the 87 tune, HUGE difference. I thought I noticed a huge difference with the headers and plenum fixed, well damn. i have to touch the gas pedal half as much now going slowly through parking lots, and the throttle response I would say overall a 30% increase. First time ever i almost fishtailed my truck accelerating hard out of a turn (new tires too). Can't wait to see the 91 tune. Oh and the reason why I said I was going to test the MPG with 300 miles under each tune is that the first 40-50 I figured Id go nuts testing and the last 250 will be 65 mph highway. This way I can drain my gas tank of all the inferior gas to get a better estimate of mpg. Seafoam produced a decent amount of smoke but not as much as I had anticipated. Ill post a pic maybe tomorrow.

 

I'm curious as well to how much it goes up. But damn you were getting 14 mpg before? I hope that's mainly hwy lol

 

ill bet his mileage wont go down very much until the higher octane tunes. i know with my superchip on 91 i burn gas at maybe 7 mpgs, but thats also due to having a really heavy right foot

 

Ok, Ok, I know its been foooorreeevver since I posted, and I do feel like an a$$ so dont make me feel any worse peoples :P I'm about to get married, went on a huge vacation and lot of stuff happening in my life. Anyway the best part is that I'm back, hopefully with a vengeance. So heres my results:

Stock 300 miles driven - 14mpg
Comments Mostly all regular driving 65mph nothing crazy

87 Tune: 297.7 miles driven 21.880 gallons used 13.6 mpg
Comments: Driving like a bat out of hell! Loving this new found power.

87 Tune driving normal : 16-18 mpg

89 Tune: 285.4 miles driven 22.085 gallons used 12.92 mpg
Comments: Considerable increase from 87 as far as initial acceleration, Slight higher RPMS at 65mph driving like crazy still :P

89 Tune driving normal 13.8 mpg

91 Tune: 292.4 miles driven 22.607 gallons used 12.93 mpg
Comments: Considerable increase in all over performance I would say 30-40% more response then stock, 25% more response then 87 and about 10-15% more response then 89. Definitely super fun to drive on!!! So much that I dont care about the price of gas, I leave it on 91 tune. In about 10 full tanks ive reached as high at 14.5 mpg driving very moderately on this tune, and about 11.5 if I do all city driving and drive like a bat outta hell. My last fill up was 304 miles driven 21.94 gallons used which is 13.85mpg.

SCT TUNE DEFINITELY WORTH IT! I wouldn't hesitate twice to go with this product through hemi-fever.

Hope all is well with all you fellow D-F'er. Good to be back.

Next upgrades: 90 to 120amp alternator and fixing a vacuum leak somewhere ( stuck on defrost)

 

Wow. Really busy! Congrats on getting married, and hope vacation went well.

Good to see your results form SCT tune. 2 to 4 mpg over stock is a pretty good increase, and will pay for tune easily, depending on how many miles you drive!

 

Well that all depends on how you drive. Plus once you put the 91 octane tune on, you wont go back unless your broke. If your broke you wouldn't of bought the SCT in the first place. However getting 14mpg stock, and 14mpg on 91 octane driven very moderately is good imho, because when you need the power you got it and screw the mpg. Thanks for the nice thoughts gd Really love the DF people, such a wonderful group of people!