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Bad mpg with 2.73's???

This is a discussion on Bad mpg with 2.73's??? within the General Help forums, part of the LSx Technical Help Section category; I have a 98 Z28 and was wondering why I'm only getting 12mpg or maybe 13mpg, city driving? Is this ...

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    candy red
    98 Camaro Z28

    Bad mpg with 2.73's???

    I have a 98 Z28 and was wondering why I'm only getting 12mpg or maybe 13mpg, city driving? Is this normal when I got a tr224, vig3200, headers, ls6 intake, and 2.73's? I really need to know how to improve my mpg?

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    Member jag42420's Avatar
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    Quote Originally Posted by CandyRedZ28 View Post
    I have a 98 Z28 and was wondering why I'm only getting 12mpg or maybe 13mpg, city driving? Is this normal when I got a tr224, vig3200, headers, ls6 intake, and 2.73's? I really need to know how to improve my mpg?
    Depends on your style of driving, your tuning, and your mileage. If you drive it fairly hard, it will use a lot more gas. If it isn't tuned well, it will use more gas. And as your mileage increases, the engine becomes less efficient naturally.

    I'm not cammed yet, but with the mods in my signature, a tune and 3.23s I get 29mpg on the highway and average around 17 in town.

    To improve your mileage, you could get a CAI and possibly a better tune (depending on what you have now). Not sure about your current mileage, but you may need fresh o2 sensors if they have a lot of miles on them. A good tune up is always worthwile too (plugs, wires, air filter, oil & filter, etc...). Besides engine efficiency, you can change driving habits to improve your fuel economy by letting off the gas earlier instead of braking as much, taking off slower at lighter throttle, etc...

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    candy red
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    I have had came to 3 theories 1. theory is that when I got my stall install that, I also put a big tranny cooler just under my air lid and obstructing air flow.
    2. theory is that my car still had a bad alignment.
    3.I have my cut-out open
    So would any of these cause bad gas milage and if they do how much?

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    Member 02WS6dream's Avatar
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    stall will decrease gas mileage in city. and don't know what you were expecting, mpg sounds acceptable to me with those mods, but in my nearly stock 02 ws6 (borla cat back and lid/filter) I see about 15 city treating it *about* nice. i'm curious to see what others are getting with similar mods. jag--i can't see your signature. hell--mpg is part of the reason i don't have a stall converter...well that, and i've never had it at the track...

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    Member jag42420's Avatar
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    Here's my sig...
    2002 WS6 Trans Am, A4, SLP lid, P&P TB, 3500 stall, 24K GVW tranny cooler, HPTuners, Pacesetter LTs, Bassani dual exhaust with 'x' crossover, coolant bypass, sealed airbox to hood.

    http://www.cardomain.com/id/jag42420

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    Member Since 1998 Mecinoid's Avatar
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    Quote Originally Posted by 02WS6dream View Post
    stall will decrease gas mileage in city. and don't know what you were expecting, mpg sounds acceptable to me with those mods, but in my nearly stock 02 ws6 (borla cat back and lid/filter) I see about 15 city treating it *about* nice. i'm curious to see what others are getting with similar mods. jag--i can't see your signature. hell--mpg is part of the reason i don't have a stall converter...well that, and i've never had it at the track...

    Seems about right to me. If your getting 30mpg on the freeway using cruise control and in straight line. Then you are getting 12mpg around town with a high stall converter. I'd say that's just about what you should expect.

    I have a manual and do the 1-4 skip shift in town and treat it nicely on the freeways these days. I'm getting 17city/29fwy with 3.73's.

    When the new gas became standard in Kali I dropped about 1-2mpg over the higher CO2 formula. That was on all my cars ... Doh !!!
    Last edited by Mecinoid; 11-06-2007 at 10:29 PM.

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    Member jag42420's Avatar
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    Where you live (weather and terrain), the gas type you use, your driving habits, your tune, your mods, vehicle mileage, your tires, and your gears all factor in to your mileage. I use 93 octane, live in a flat area, am well tuned with intake and exhaust mods, have 17k miles, and drive pretty easy most of the time which improves mileage too...

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    Senior Member slims00ls1z28's Avatar
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    Change those 2.73's and I'll bet you get better mileage. It takes more pedal to get moving with the 2.73's than a deeper gear. I noticed that off the bat changed stall one day then changed gears the next. With the 2.73's it takes longer to pull up so you are pressing the gas longer. I didn't get that bad with a MS3 and 4.11's.

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    Quote Originally Posted by slims00ls1z28 View Post
    Change those 2.73's and I'll bet you get better mileage. It takes more pedal to get moving with the 2.73's than a deeper gear. I noticed that off the bat changed stall one day then changed gears the next. With the 2.73's it takes longer to pull up so you are pressing the gas longer. I didn't get that bad with a MS3 and 4.11's.
    You know, I've been thinking the same thing myself lately. I have 2.73's in my Formy, and the thing seems to constantly be out of it's powerband. Most of my commute to work has a 55mph (or lower) speedlimit, and the car seems to always want to be in OD. It seems like I'm always lugging the motor at 1500rpm or less.

    I have some hills in my commute, and while it never downshifts out of OD to tackle them, I figure the motor has to be working a bit harder than it needs to. I wonder if 3.23's would put it in a better rpm range to get better economy?

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