swapping to FI

[85 Cutlass Brougham]

Well, I will start by saying what do you get now, and what do you expect to get post-swap? Also, what performance do you want? Even with EFI, the car will never be too stellar on fuel economy. I get in the 15-17 MPG range with my 350 running a carb, but everything is set up right to work together and maximize the efficiency of the combo. I had an Edelbrock 600 on it when I measured 15-16 MPG, but did not have the TCC hooked up. Now, I have a Quadrajet on it that I have not fully finished tuning yet, and will have the TCC working soon. I expect 16-18mpg city and 22-25 hwy when it is done. TBI fuel injection will not be much better, nor would a TPI setup. If you want to maximize the fuel efficiency with fuel injection, there is no substitute for a full sequential multi port setup. Batch fire systems just do not have the accuracy to get the most out of it. You also need proper gearing--not too low, but not too high. You could theoretically spend thousands on a proper fuel injection system. On the other hand, you could take the money you would have spent on EFI and just get an efficient beater like a 1.5 or 1.6 liter Sentra or Civic with a 5 speed trans. They get 30+ city and can even see over 50 on the highway. The money saved on gas could offset the money spent on insurance. In fact, I am trying to do that myself right now, as I drive 30-50k a year and it would save me a substantial amount of money. I would kill for a serviceable cheap CRX!!!

 

[79LT1Monte]

In my opinion swapping to a newer vortec setup would be well worth the extra time. We swapped one into my buddies truck and it was a breeze, we didn't have to hook up more than 5 wires and it purred like a kitten. They have a smooth idle and a ton of low end torque. If you are upgrading to an overdrive at the same time with this swap you will get even better milage. I swapped my carb and three speed for an LT1 and 4L60 out of a 1996 Caprice and it was an easy swap and cruising to Kansas City last year for the Super Chevy Show I got 24-26 mpg with several wide open runs. That mpg suffered greatly with the 3:73's I run now but it was worth it for the 60 ft times. Like I said this is just my opinion but the reliability in all four seasons is why I swapped to FI from a carb, and If you are mechanically inclined enought to go this route over a kit I think you will be happier. Once you buy a kit you will be somewhat dependant on that company for replacement parts or help. If you pull everything from another truck or car you know what to buy replacement parts for or what forum to get help from.

 

[Tony_SS]

In my opinion swapping to a newer vortec setup would be well worth the extra time. We swapped one into my buddies truck and it was a breeze, we didn't have to hook up more than 5 wires and it purred like a kitten. They have a smooth idle and a ton of low end torque. If you are upgrading to an overdrive at the same time with this swap you will get even better milage. I swapped my carb and three speed for an LT1 and 4L60 out of a 1996 Caprice and it was an easy swap and cruising to Kansas City last year for the Super Chevy Show I got 24-26 mpg with several wide open runs. That mpg suffered greatly with the 3:73's I run now but it was worth it for the 60 ft times. Like I said this is just my opinion but the reliability in all four seasons is why I swapped to FI from a carb, and If you are mechanically inclined enought to go this route over a kit I think you will be happier. Once you buy a kit you will be somewhat dependant on that company for replacement parts or help. If you pull everything from another truck or car you know what to buy replacement parts for or what forum to get help from.

What did you do as far as a fuel pump, etc?

 

[1988montess]

im not sure what the MPG is since im in canada its a little different. but i get about 350 km to a full tank at about $80 to fill. so whatever that is,.

 

[pontiacgp]

When you checking your fuel milage (or here in Canada i guess it's fuel kilometerage) keep in mind that if you have changed your diff gears or even just your tires your odometer won't be correctly registering your distance if you havn't changed your speedo gears to match your set up. I'm was running 26.5" high tires and my speedo was 20% off so I was traveling 20% more than the odometer registered. I measured it with my gps navigational unit. I'm running 26" tires now and I'm about 17% off.

I don't know what motor the op has but if you switched it out to a 5.7 vortec you'll have better performance and better fuel economy....

 

[megaladon6]

i've got 217mi with an 18gal tank it's 12mpg. if you have a 3 speed it's agout what i'd expect. an OD unit may get you to 20 if you do a lot of highway.
worst case with the 350 vortec motor;more power, better performance and the same mileage. most likely slightly better mpg, definately better with a 3-4spd swap.

 

[1988montess]

i have the original 305 for the SS. it seems that i am unusually low for gas mileage. tomorrow i will be getting an entirely new exhaust from the y-pipe back because i have almost no back pressure with blown out mufflers. im hoping this might help, what do you guys think?

 

[1988montess]

also, i do have the OD on the SS.....

 

[megaladon6]

low or zero back pressure is a good thing, high back pressure from a bad cat. converter or crushed pipe would choke the engine and kill efficiency. i'd check the basics first--plugs, air filter, PCV, valve lash, carb tune, timing, etc. you may want to try some seafoam to clean out the carb and intake too.
does the trans go into 4th gear? if you get on the highway and it goes into 4th, look for a 200rpm (or so) drop soon after, just to make sure it's going into lockup.

 

[1988montess]

it is going in there perfectly fine. ive done all the tune up about a month ago. my car started running really crappy when the end of the muffler blew out and i figured that might be part of the problem.