Gas milage

[CamaroAdam73]

It's a problem i know we all battle, but i think i've found an expensive solution for my problem.


Edelbrock makes a nice Fuel injection Throttle body system.

The Edelbrock Pro-Flo XT manifold and throttle body's, it would be about a 1000$ install after it's all said and done, but i'm estimating it wold shoot me up into the low low 20's for milage, any opinions?

My setup now is a stock GM manifold, not stock to the car but stock to A car lol, and an edelbrock 750 performer.

 

[kingcolbert83]

If your dont do too much crazy performance on your motor you can do the tbi swap for fairly cheap. I've read and done research that says tbi doesnt run right with trying to make big power. And that is after a custom chip.

 

[dogsht]

While the Edelbrock would not be as fuel efficient as a Q-jet you might find that fuel injection does not provide a lot of mileage over a well tuned carberator. Don't missunderstand me I am all for fuel injection just that most people attribute more mileage to it then they should. For example if you do not have a working lock up converter you might find as much mileage in that as you would a swap from well again a well tuned carb to fuel injection. You already have an overdrive and a mild cam both of which would be a major help. Have you actually checked a few tanks what kind a mileage are you getting now? BTW whats the "mild cam"s at 50 duration?

 

[85 Cutlass Brougham]

Mileage depends on a number of variables the least of which is carb vs EFI. Gearing, torque curve, cam, displacement, etc. all have bigger effects on fuel economy than you think. Also, different carburetors get different fuel economy. This is why so many of us here run well tuned Quadrajets. The tiny primary side (around 200 cfm) allows for better throttle response than the much larger primaries in a square flange carb, which in your case is 375 cfm. The reason is that the velocity through the primaries is much greater, and thus the vacuum signal is stronger, making the booster venturi's much more sensitive to minor input changes. Also, how you drive the car also affects fuel economy. Living in a mountainous region will be far less efficient than living in a flat place like Kansas simply because there is less need for throttle variance. The same also holds true for urban driving vs highway driving.

In closing, I would venture to guess that the difference between EFI and a Quadrajet with both optimized will only be 1-2 MPG. I do not tend to think that it makes the conversion worth it from a cost-benefit analysis perspective. Even someone like me who drives 30-50k a year would find it difficult to justify unless I was getting 10-12mpg. I probably get 15-17 city and 20-25 highway though, so in my case it makes no sense. (I also do not drive the Cutlass that often).

 

[CamaroAdam73]

Yeah i've taken all that into consideration, thats why im staying away from upgrading to a bigger Cam untill i do Roller convrsion.

I am howver going to set out on doing some other sh*t to fix my gas milage, like the lockup wiring in my TC. And getting rid of this Annoying stock intake manifold.

 

[87National]

Throttle Body Injection is old technology, I would at least go TPI, if I were to go through the hassle of swapping to fuel injection.

TPI will get you better mileage and low rpm torque than TBI.

 

[Coveted]

ls1's get 30 mpg in 3400lb maros, so its the obviously mpg choice for the gbody.

 

[85 Cutlass Brougham]

You could also buy a 4 cylinder 5 speed beater for commuting for the same $1,000, and just keep the G for everything else. If I had the money, I would do that in a heartbeat right now. A good 5 speed 1.6 liter Sentra would be tops on my list for it's 32 mpg in the city, and 50+ on the highway. At least that's what mine got.

 

[jrm81bu]

A good 5 speed 1.6 liter Sentra would be tops on my list for it's 32 mpg in the city, and 50+ on the highway. At least that's what mine got.

Mine's getting at best 28mpg on my route. That's kinda like full throttle city driving, so I guess it's not too bad. I'm just glad it's still running(knock on wood), with the quart or two that it spits out of the dipstick hole into the "catch can" I set up for it. Thats after 3 hrs of driving and about 110 miles.

Sorry.

 

[85 Cutlass Brougham]

It all depends on where you drive too. I am in Florida which is mostly flat. The Automatic Sentra I had could only manage 26 mpg city with the A/C on and beat on delivering pizza. The manual one I had before that got 32 mpg in the same conditions. The automatic got 55mpg going from Tampa to Daytona Beach and back with the cruise set at 80mph and the A/C on. Oh, did I mention that my automatic 1.6 liter Sentra also ran mid 12's at the dragstrip on test and tune day? Too bad it was an 1/8th mile...