Hi everyone

[torinodan]

Hi, been looking around for ideas for a new project I have recently acquired. Live in GA and do a lot of driving.... about 128 miles a day for work. This is putting way too many miles on my truck (4X4 F150). I love my job and yes I'm considering moving further south.

The car I plan on making better on gas is a 1984 Corvette I was given. Never say no to a free car (esp a free Corvette) right? It's a slow process of driving it as much and seeing what part is going to need replacing next.
It has the L83 350 Cross-fire fuel injection (twin TBIs) 205-hp V-8 9.0:1 compression ratio, P225/50R-16 tires, and as far as I know it has 3.07:1 gears>>>auto transmission.

Having a background being a mechanic so far I have just under $600 in repairs and parts so I don't think I'm doing bad. Worst part was the car was left in a hanger for 6 years with the windows down and cats living in it. Other than that no problem other than things that just sat up or dry rotted.

Some of you long time experts feel free to shoot me some obvious ideas that I might miss. Thanks all

[oil pan 4]

It may sound backwards but put some kind of tunable fuel induction system on that motor. Even if it's a carb.
Tune it for lean burn.
I did this on 2 carbureted and it boosts fuel economy by about 20%.
Cross fire is kind of all around hated. Low horsepower, laggy throttle response and lack luster fuel economy.

A manual transmission is the way to go. My 1989 firebird has a 350 TPI, 6-speed with 0.6:1 top gear and 3.73 gears and it gets at least 26mpg if I can keep my foot out of it.

I am going to put a T-56 magnum in it with 3:1 first gear and 0.5:1 top gear and a ford 9 inch with a 3:1 or 3.25:1 gears. That should boost the fuel economy up a little.
Then the 350 might not have the torque to turn the wheels going down the highway at 1300rpm so u have a high compression 489 cubic inch engine to put in it.

[torinodan]

I shouldn't have to change over to a carburetor unless I want more performance. The cross fire is a wet manifold design so already kinda like a carburetor system. Installing a better management system from anyone that makes aftermarket EFI would get me better parameters and the ability to lean burn. When I started the car was getting around 16 mpg average. The temp sensor for the coolant was toast as well as the wiring. Bad tps and map sensors replaced and I installed a 3 wire O2 sensor and bumped up the tire pressure a little bit now am around 22 MPG average. I like the TBI system on it cause it's just different and replacement of the ECU should help a lot but just in case I do have 2 tuned port setups setting in the garage.

[ksa8907]

I assume your commute is primarily highway? I have a similar commute, 115 miles round trip averaging 50 to 55 mph each tank.

I would look into sealing body panel gaps.

Do you know what kind of voltage regulator it has? An underdrive pully might help if you're mostly driving highway.

[torinodan]

My commute is mostly highway but through Atlanta 2x a day there is a lot of stop and go. If I'm not stuck in traffic 55 to 65 is a normal speed. The voltage regulator is in the alternator and I just priced a set of underdrive pulleys too. I used them before and it seems to help a little here and there.

[torinodan]

There is a gap between the hood and the front bumper is the source for the engine air. There is a mod I'm doing later that will make a hole in the top of the radiator enclosure to basically provide ram air to the intake. This engine breaths through ducting in the hood and if I go TPI then that will go away when I have to replace the hood or use a filter stuck beside the engine.

The only other large body seam is the top of the windshield and the terga top. It has a bunch of air leaks as it is and I may as well seal it off for the winter.

Short term mods/repairs that may help are:
Replacing the HEI distributer control module (Accel) to deliver more consistent spark to the plugs.
K&N filter
Under drive pulleys
New weather striping
Replace the banged up chin spoiler
LED lights for less pull on the alternator in the dark

The spare tire has been removed (it was full of mud and water so now I have a tire plug kit and 12V pump) Lost about 50 lbs. The AIR pump/plumbing was already removed, not me. That's why I installed the heated O2 sensor for now till I get exhaust back up to par.

And keep my foot out of the gas.

[ThermionicScott]

Welcome!

If FE is your goal, I wouldn't get my hopes up about the "ram air" intake and K&N filter helping that.

[oil pan 4]

Yes if you can make the cross fire play nice with a tunable fuel injection setup definitely go for it. Not very many people have tried making the cross fire tunable, so you will have to build that computer pretty much from scratch. I don't think there is much for moding the stock computer. The cross fire usually gets ripped out and replaced with a carb, tpi or mega squirt.
The accel ignition control modules are not that great, from what I gather the all around best ignition control modules are the ACdelco units.
If you want to make it better add in something like an MSD A6.

I know precisely what kind of voltage regulator the alternator has. There really isn't any reason to mess with it.