MPG Fuel Injection vs. Carb-

[dsnyder]

I have a 78 Spider 5 speed that I am running a standard Weber Carb (2 Barrell Electric Choke). I am currently re-doing the interior and I have the dash out and I have a 1982 donor car that has fuel injection.

The car is plenty peppy for me and my purposes but I would like to get better fuel mileage. I get 18 to 20mpg.

While all the wiring is exposed, I am considering putting in the fuel injection from the 1982. Is it worth it? I pretty much have all the parts.

Dave

[narfire]

Going to have to change fuel tanks,fuel pump and filter as well.
Stock 2 liter I was getting around 30 miles per imperial gallon. About 25 miles per US gallon.

[RRoller123]

fwiw: My 80 FI gets about 23-24 average. Not driven toooooo hard....

[redcars]

With my 82 I get 25 most of the time and up to 30 if I drive it easy, which dosn't happen very offen.

[aj81spider]

I have an 81 FI and a 74 carb (DMSA). Like RRoller's FI they both get 23-24 mpg.

[giuliot60]

The gas mileage is a little disappointing on these cars, especially compared to my 4000 lb 190 HP 2002 V6 VW Passat wagon with an auto 5 speed that gets between 20-25 mpg. So much for my argument to my wife about getting a car with a 4 cylinder and a 5 speed manual for better gas mileage. Good thing she doesn't know what it actually gets

But isn't there a way to get better gas mileage performance out of the Spider without sacrificing fun?

[vandor]

>But isn't there a way to get better gas mileage performance out of the Spider without sacrificing fun?

Spiders were not built for mileage. They have poor aerodynamics, low gearing, rwd.

I would think FI would give you 2-3 mpg better in the same kind of driving. I've only broken 30mpg in FI Spiders.

However, HOW one drives will have a huge impact on mileage. It's not just about driving easy. It's about planning ahead so you don't have to brake as much or lose momentum. Don't ever let the engine idle if it does not have to. Shut it off right away when you stop, don't start it until you have your seatbelt on, handbrake down and are ready to go. If you are familiar with the route you can shut it off at long lights. Try and do more acceleration downhill, and less uphill.
An FI car will shut the fuel off if you are coasting in gear over ~1600 rpm, so keep the car in gear when slowing down.
Etc etc etc. There are entire message boards dedicated to high-milers.

[So Cal Mark]

I think it's a worthwhile conversion, not so much for fuel mileage but driveability and power are improved too.

[narfire]

especially compared to my 4000 lb 190 HP 2002 V6 VW Passat wagon with an auto 5 speed that gets between 20-25 mpg.

I have a newer(07) Passat wagon with the 3.6. 280hp and has no problem getting to it's governed speed limit of 130mph. When driving back down from Edmonton I averaged 36 mpg at 100 (62 mph) kms/hr. The 6th speed makes a huge difference in milage. I still get 27mpg around town/to and from work.
The Fiat with the modded engine now has around 28mp imperial gallon about 23 us gallon