I have just been noticing that there isnt much difference in milage between the carbed 305's and the TBI 305's, but the TPI 305's seem to get a lot better. am I insane???

 

TBI should be better than carb, and TPI should be better than TBI as far as gas milage goes. Reason being, the injectors spray directly to the cylinder, thus making it more efficient.
I don't believe that the TPI's get THAT much better MPG though. My 305 TBI gets about 22-23mpg highway, and thats after 140k. My buddy has an IROC with a 305 TPI and gets about 25 mpg.
If you have a TBI now, there are a few things you can do to get better gas milage: TBI spacers, MSD ignition, underdrive pullies, a custom chip if you have any major mods, and I believe Jeg's sells something for our computer that allows you to select fuel economy( economy, standard, and performance)

 

That may be true. I was just kinda pointing out what I have noticed... Just to see what people say...

 

I bought my Verte about two weeks ago and drove it from Northern Ohio to Houston Texas. In the hills of Kentucky and Tennessee, I saw 25 mpg - I did the math on each tank. When I hit the flatter parts of Texas, that bumped up to 27 mpg.

Keep in mind a few factors; 15" tires, 2.73 rear end, 93 octane fuel, Lucas Fuel Conditioner, cruising anywhere from 70-75 mph the whole way and that included some small towns stopping and going.

 

I have always avg. about 21-23 MPG during normal driving with my TBI. But I have seen it as high as 31 MPG taking long interstate runs.

 

I'm getting about 17-18 in the city and about 23 on the highway with my Lo3. Does this sound about right? It's been as low as 11 or 13 or something like that but that only happened once, it was a freak occurance I guess.

My GTA (350TPI) averages about 20-21 in the city and 29-30 on the highway.

I've heard that putting a carb on a Lo3 will KILL your gas mileage, but who knows.

 

On my way back from PA this weekend I got over 30MPG on the turnpike. Around town when I'm not giving a darn about milage I get 18-20. Drove 550MI and put 4.9 gal in, and still had 1/8 of a tank when I got home Guess that 2.73 gear isnt all bad.

 

Just got 22mpg with arc at the dissy :-(, since my programmer is fried I just logged a lot with winaldl and adjusted the fuel pressure until it was 128 in the blocks (rpm vs MAP).
I could get 25mpg but I need to be careful not to lean it out too much more. Waiting for my wideband o2 sensor, then I can be a little more daring.
TBI, carb, TPI, all could/should be about the same on the same motor. An engine draws in air and fuel, the ratio is always about the same no matter if you run TPI, TBI, or a carb. I bet with the proper time and software you could program an eprom for a carb to get the same gas milage as a TBI setup. TPI is nice because the fuel distribution SHOULD (key word) be even on both sides of the engine. Wet flow systems have problems with the fuel puddling up on the sides of the intake manifold runners but this only really happens when you slap the throttle open really fast. So long as the pedal is smooth I can't see how any of the systems would be more than 2 or 3 mpg difference. Build a better engine like the Ls1 and it's a completely different story .

 

what mpg stock 305tpi 700r4 2.73 posi gets in city? I dont care GM paper mpg i like know what people gets real life.

 

i have seen it teeter totter back and forth with tpi and tbi. it to me seems to be who is driving them. my tbi has matched tpi time and time again. too many variables. to me if a carb is getting the same mileage they are giving up performance. when i was carbed i did not get as good a gas mileage as my tbi can pull off day in and day out. EVER!!