Renegade_Brad

What sort of mpg should a stock 86 trans am get with an automatic 305 tpi get.

FruityOne

I get about 20-22mpg with my 350TPI. So, I dunno around there if its in good shape?

Dante93GTZ

iTrader: (5)

26mpg highway for my 305tpi IROC

Renegade_Brad

Something must be really wrong with my car then because i only get 13-15 mpg. What should I do to whats causing this.

DauntlessZ28

I get about 15 city. Not sure highway. Granted I have a compucarb, there's not much of a difference between TPI and compucarb. Without knowing how many miles are on your car, I'm just gonna say that your engine is old dude. Wear and tear.

There's lots of things that could affect gas mileage. Tire pressure/allignment, dirty air filter/fuel injectors, blowby, throttle-happy driver.

RebelTillDeath3

I get 10mpg on a 305TBI with an automatic tranny.

pvt num 11

TEN?!? Goodnight, have you considered throwing a tune-up at it? If my car got mileage that bad, I'd be filling the tank every two days, and my commute to work is only forty miles round-trip... Now, if you had a 454 BB with a Flintstone-era carb in between your fenders, I'd understand... The LO3 should be getting close to twenty, if it's in tune, and I know you can do some mods to bring that up, too.

RebelTillDeath3

Brand new wires, brand new plugs, brand new cap, brand new air filter, fresh oil and filter.


It's probably so bad because of where I live and where/how I have to drive. Four lane highway with a speed limit of 60mph, but it has lots of stoplights. So I do a lot of stopping, going back up to 60, stopping, etc. etc.

Actually, if I figure correctly on this tank, I got 14mpg.

steven90GTA

With my CrossFire 305 I get about 15mpg pedal to the floor, but with the 350 TPI in my GTA I get about 13mpg city with a light foot and 14-15mpg highway also with a light foot

Fast305

Ouch 10 mpg. I get 15-16 mpg with my foot heavily on the gas and 17-18 if the cruise is set at 70 mph. That is a Flinstone era carbed 305 and 700r4 in a 4,500 lbs brick.

RB83L69

I have a L69 car, T-5 & 3.73 gears; the motor has been worked on enough to put out somewhere around 290 crank HP according to a chassis dyno, but is still stock enough to pass CA emissions; it gets a little over 20 mpg on the highway, like a couple of weeks ago between Cinci and Cleveland, or last weekend to and from the dyno in Dayton.

I'd think your LG4 car, with its highway gears, should do a bit better than that; maybe 23 or 24.

Swigbeast

I've gotten 33mpg in my 5 speed 305 driving about 68 w/o cruise. Bet I cold get 35mpg+ driving about 60 maybe more with a cruise control. Call me crazy, but I did it.

apie2546

Exact same car, without AC right now I get 12 in the city and about 22 on the hwy. I do like to show the throttle some love

Ghettobird52

12/25 here on my mildly built 350 TBI (LO5)

dmccain

iTrader: (2)

21-22 in my 3.73 geared 305 TBI. Was getting 25 with the 2.73s.

Orr89RocZ

iTrader: (20)

Just tested mine. 16-17 mostly highspeed cruise but one section of the drive was mountain climb so it was rich for a few minutes goin up hill

Gonna have to play around with it as my L98 used to get 20-23 highway.

Hoping 305 would do same

rusty vango

my 86 IROC 305 TPI is bone stock . and with the cruise on on the freeway i have got as much as 23 MPGs. around town it gets 18 MPGs