After rebuilding my 350 TPI and adding flattops and a small cam, everything else stock, I checked mileage twice for two 318 mile trips (going and coming) and got 30mpg. It was a big surprise to me but it is what it is. Went posted speed limit steady on interstate.

The engine (which came out of an89 IROC) is in a bird with 2.77 gears and a 5 speed manual. All emmissions is still on there and AFAIK it all works - at least check engine light does not come on.

Is anyone else here getting that kind of mileage?

EDIT: I am not asking what you think mine should be getting, etc. That is impossible to know. Just is anyone else getting in this ballpark. You are welcome to say I'm wrong if you have some kind of info to back it up. Like no one in the history of TPI 350s EVER got 30 mpg, etc.

 

i get no where near that, wish i did though congrats

 

I get like 9-15 mpg if I'm lucky..haha.

 

There's really no reason you shouldn't get mileage like that on the highway, honestly, as long as all the systems are functioning well. I routinely get "better than expected" mileage out of my cars, primarily because I don't drive like an idiot, and keep up on maintenance. That said, is your odometer accurate? If (like mine) it doesn't read quite right, you could have a skewed view of how many miles you actually went, vs reality. Changing gears, and even tire sizes, can change that reading.

Either way.. Congrats! You have a muscle car that's on par with todays fuel economy from "decent" cars!

 

that is pretty good, the most i could muster out of my bird is 24.

 

i have got as much as 29.4 on my car on the hwy. . i do keep mine fine tuned . LO3 , T.B.I. , T-5 , full M.S.D. ignition , 1.6 roller tips , heddmans , TPI CAI into TBI airfilter , 3.08 rear . 20+ MPG local . it can be done . love your sig. good luck .