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Old 08-01-2010, 09:31 PM   #1
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Default GT mods and gas mileage

Im going to be picking up an GT soon (unless something terrible happens) and im going to use it as a daily commuter... probably around 25k miles a year or so :o

Of course i wouldnt mind a bit more power, but i can end up with GXP type fuel economy... and id like to keep 87 oct as well (at least 89?)

What are the options? Im going to keep the stock exhaust (at least cat back) but headers and an electric cut out would work.

how do those with a standard CIA/exhaust/tune etc... for power #s and mileage?

thoughts?
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Old 08-02-2010, 07:40 AM   #2
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With my listed mods I lost 3-4 MPG highway (namely due to the DOD delete) and I get 13-14 and change kicking it around town instead of 15-16 (I never averaged up to 16 mpg non-highway anyway). CAI+headers+tune combined I gained 40-45hp maybe?
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Old 08-02-2010, 07:43 AM   #3
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How do you get rid of DOD? Is that from the tune?
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Old 08-02-2010, 07:51 AM   #4
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From his list of mods I would say yes he tuned it out...

The other route is pulling the top half of the engine off and changing the lifters...but if you go that far most do a cam swap while they have it apart.
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Old 08-02-2010, 08:24 AM   #5
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From his list of mods I would say yes he tuned it out...

The other route is pulling the top half of the engine off and changing the lifters...but if you go that far most do a cam swap while they have it apart.
Im not interested in getting into the motor. I need to keep reliability and gas mileage etc...
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Old 08-02-2010, 03:54 PM   #6
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With my mods in sig. I run 93 octane (cost all of $3 more a tank full) but pull 363WHP and 368WTQ average about 15 City and 26 Hwy on long trips cruising about 70MPH the entire way. Those calculations are done manually not by the car but are usually with in .2 MPG or each other.
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Old 08-02-2010, 07:35 PM   #7
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With my mods in sig. I run 93 octane (cost all of $3 more a tank full) but pull 363WHP and 368WTQ average about 15 City and 26 Hwy on long trip uising about 70MPH the entire way. Those calculations are done manually not by the car but are usually with in .2 MPG or each other.
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I get close to that with my mods (and an easy foot) 14/22-24 421whp 387wtq
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Old 08-03-2010, 10:45 AM   #8
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Im not interested in getting into the motor. I need to keep reliability and gas mileage etc...
I think its more reliable removing the DOD crap since people have had DOD lifters fail. MPG stays within 1-2 and you gain an easy 50-60whp.
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Old 08-03-2010, 11:42 AM   #9
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I get close to that with my mods (and an easy foot) 14/22-24 421whp 387wtq
I would take the extra hit in MPG if I was putting down 420+
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Old 08-03-2010, 04:15 PM   #10
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I guess I'm the odd ball here. I average 18 city and 25-27mpg highway@70 mph. Mods are full exhaust, CAI and street tune (no dyno #'s yet)
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Old 08-03-2010, 04:29 PM   #11
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I guess I'm the odd ball here. I average 18 city and 25-27mpg highway@70 mph. Mods are full exhaust, CAI and street tune (no dyno #'s yet)
I use to get that pre stall and gear change
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Old 08-03-2010, 04:34 PM   #12
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I get 16-19 city and 26-28 highway @70mph. I get 25-27@75mph depending on hills and what not. Thats with CAI, x-pipe, and street tune. I also have DOD turned OFF.
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Old 08-03-2010, 05:14 PM   #13
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I use to get that pre stall and gear change
haha I haven't even looked at mileage since the gears... just figured it was bad.
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Old 08-03-2010, 10:52 PM   #14
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I get 16-19 city and 26-28 highway @70mph. I get 25-27@75mph depending on hills and what not. Thats with CAI, x-pipe, and street tune. I also have DOD turned OFF.
@16-19 city I'm assuming you're barely breaking 1800rpms, ever?
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Old 08-03-2010, 11:51 PM   #15
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@16-19 city I'm assuming you're barely breaking 1800rpms, ever?
I drive it normal, probably harder than most people would call normal but I dont race from light to light either like my wife does, lol. Tuning made the biggest gain in mileage by far, hands down. I have many hours in my tune and tried playing with dod setting and in the end turned it off and was able to get better mileage with it off.
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Old 08-04-2010, 01:39 PM   #16
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i run mine up to about 2400 and let it shift and i get 22 in town and i get 29 on the highway at 75 mph i got a CAI and livernois tune
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Old 08-05-2010, 07:36 AM   #17
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I would probably get better then 15 city, but hell I can't manage to leave a light with out acting like a damn fool or taking a hard say 80-90* turn and kicking the *** end out. So that is my bad, but it's fun none the less. Last night on the way home from the track I was getting 25.8 MPG, that's not to bad.
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Old 08-05-2010, 08:49 AM   #18
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I would probably get better then 15 city, but hell I can't manage to leave a light with out acting like a damn fool or taking a hard say 80-90* turn and kicking the *** end out. So that is my bad, but it's fun none the less. Last night on the way home from the track I was getting 25.8 MPG, that's not to bad.
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lol yea the only thing that helps me is i have my 2 kids with me 95% of the time lol so there is 5% of the time when i get very bad fuel milage lol
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Old 08-06-2010, 11:25 PM   #19
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I get 19.5mpg .. mixed about 1/2 around town and 1/2 on the fwy.. (most of the time I am on the 91fwy.. people in SoCal know what that's like...)
Avg Speed is 35mph... so says my super awesome car computer..
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Old 08-07-2010, 09:40 AM   #20
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Just did a little road trip up to RPM... about 250 miles round trip. Averaged 21-22MPG at 80MPH but went up to 24 once I slowed down to 65-70 due to traffic. So the gears only impacted fuel mileage a little, well worth the loss of MPG! I used to be able to eek out 25-26 cruising at 70 prior to the gears.
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Old 08-07-2010, 09:40 AM
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