I've seen a lot of gas mileage questions lately and everyone is always interested in the subject anyways, so with that said:

1.stock + 2.hypertech = 17.5 (these are all avg mph with city and country driving)

1,2, 3. full synthetic oil + stock size k&n = 17.75

1,2,3, 4. drop base open element = 18 (if not more)

1,2,3,4, 5. cat back = 20

1,2,3,4,5, 6. k&n for open element = 20.2

*with just cat and y pipe I only gained about .3, not even worth the probelms

interested in how I'll do know with no cat and a flat base open element (no spacer ring)

hope this helps everyone




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late model 91 rs, fully loaded t-tops, red leather
paint- gm red and yellow blend (light red)
custom painted 16" Camaro rims
305 tbi 14"x3" O.E, hypertech chip, accel super stock plug wires, only use full synthetic oil and delco filter, 2 1/2" cat delete pipe, Edelbrock 3" cat-back
MTX sub and amp, Bose all around
vic_v8@yahoo.com
street kills: a lot of "family" cars, pickups, New v-6 stang, totally killed '86 SC Camaro, 91 z 28 with 305
next month: rest of ultimate tbi

 

You were only getting about 17 before the mods? I've got the exact same car as you, and I get about 22mpg every time, with city and country driving. I'm getting the K&N drop base open element in the next few months and hopefully a borla cat-back, so maybe my mpg will get even better.

 

Vic / Mrs. LBC,

What rear end ratios are you running? That can make a big difference in highway mileage, but very little difference between stoplights.

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Later,
Vader
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Justice and Freedom will Prevail

 

Great post! I really appreciate it when more of us can post our sussesses and results instead of only the problems

Yeah, if he is running 3.73s, than the mpg will suffer a little...

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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

I have the stock rear for and auto 2.73.

I baby the car and rarely ever get it above 2200rpms. I never could figure out my it only got 17.5. I honestly think it was the chip.