v8 mpg?

[dylanh]

I am looking to pick up an s30, and had my heart set on a turbo inline 6, but with the affordability of nice v8 swapped cars, i was wondering what kind of gas mileage could be expected out of these light weight little cars. include what car and your motor setup to give some kind of idea of what to expect

[zeeboost]

Too many variables to give you an accurate estimate, but my 280zx with a mild 355 (maybe 400 flywheel hp) and t56 would see 25-26mpg on the highway...and that was with afrs in the 15s. I could've leaned out the mixture for 16s to get even better mileage.

[John Scott]

Like zeeboost said, too many variables. One thing for certain is go with an overdrive auto or standard trans. Even my lumpy bumpy 600+ lift solid roller in 383, 750 double pumper and 6 speed, gets mid 20s. Really, if I would drive it at the speed limit, 75 & under and light on the pedal, I'm sure upper 20s. FI can be better yet. MPG is no excuse to convert to V8. Have fun!

Good thing with the old Zs is that if you are really desperate for ultimate mpgs, the floors are usually rusted out providing for great Fred Flintstone kind of propulsion.

Edited April 22, 2012 by John Scott

[Dan Juday]

...Good thing with the old Zs is that if you are really desperate for ultimate mpgs, the floors are usually rusted out providing for great Fred Flintstone kind of propulsion.

 

A hybrid, hybrid!

 

 

Now some helpful information:

When mine was on the road I got about 26 highway. A lot less burning up the tires around town. 240Z, 305tpi, T5, 3.70 rearend (but a 3.36 in going back in).

Edited April 23, 2012 by Dan Juday

[GOTHALOSISM]

I get about 26mpg with my lt1 and t5. My car is pretty gutted so I don't have as much weight as other zeds.

[icewtr]

If you want gas mileage buy a Prius. Pretty sure no one on here built their Z for gas mileage. But to answer the post I have a GM crate motor Zz383 and an 850 cfm carb and 700r4 and 3.54 gears with 25.5 in tall tires and get 24 mpg hwy and about 17 city.

[GOTHALOSISM]

There was a guy that was converting his S30 to all electric, does that count as good mpg?

[SUNNY Z]

I expect 30+ from my LM7 (5.3) and t56. Had my tuner load a lean cruise file, so it should do well.

[Michael]

Good gas mileage is mainly about engine tuning and engine management. I don't wish to start a carburetor vs. fuel-injection debate here, but the preponderance of modern practice gives the nod to the tuning advantages of fuel injection. This, I think, is mainly why the LSx engines are delivering better mileage (in most cases) than the older small-blocks.

 

My own example is atrocious: it gets single-digit mpg, but that's mostly because I am inept at tuning, and the carburetor is mismatched to the engine.

 

The second variable is gear ratios and the rpm at which the engine achieves peak volumetric efficiency. Mismatch those two, or end up with too deep of a top-gear, and mpg will suffer. The worst case is a mild engine forced to rev high because of a deep rear-gear ratio and no overdrive.

 

Boiling this down to a simplistic list:

 

- everything sorted out, excellent tune: high 20s

- modern fuel injection or very good carb tuning skills: low 20s

- mild engine, mediocre tuning skills: high teens

- aggressive engine, and/or tuning mistakes: low teens

- incompetence: single-digits.

[SUNNY Z]

I just documented 29.2 on a 4 hour trip yesterday in my 5.3 /T56 280. Not QUITE the 30 I hoped for, but close!