Highest MPG V8?

[Mr. Pig]

My last car was an '04 GTO with the LS1 V8 and a six speed. It would regularly get 27-28 mpg highway, but it was geared a little different than the 'Vettes and F-bodies with the LS1. What a fun car. Unfortunately it was too much fun.

[Jay2TheRescue]

I used to regularly approach 30 MPG in my old 74 Chevy C-10

300,000 miles, a/c, cruise, 350 V8, 4bbl carb, TH350 automatic tranny.

FE mods:

Electronic ignition out of a 75 Chevy van, platinum plugs, flipped air cleaner lid upside down, and aftermarket cruise installed.

Then in 75 they started putting emissions crap on light duty trucks and FE dropped quickly.

-Jay

[itjstagame]

Originally Posted by Jay2TheRescue

I used to regularly approach 30 MPG in my old 74 Chevy C-10

300,000 miles, a/c, cruise, 350 V8, 4bbl carb, TH350 automatic tranny.

FE mods:

Electronic ignition out of a 75 Chevy van, platinum plugs, flipped air cleaner lid upside down, and aftermarket cruise installed.

Then in 75 they started putting emissions crap on light duty trucks and FE dropped quickly.

-Jay

That's rediculous. I can't really believe that our milage has dropped so bad. Although I guess 55MPH limits helped and it was probably 100% gasoline (10% ethanol drops our energy content a bit and I think effeciency of the burn too).

I guess gasoline was cheap enough too that using more to cool the charge and power the catalytic wasn't too bad in their eyes, but that's still rediculous.

[Jay2TheRescue]

At the time I owned it E10 was not mandated here, but "oxygenated" fuel was required in the winter. The mileage didn't drop as much with E10 because it was a carb with no o2 sensor.- The truck didn't know it was burning leaner. It was even designed to run on leaded fuel. I usually ran midgrade with lead additive added to each tank. I never really drove it hard because then it got under 10 MPG. (Then again I was only paying $1.079 for midgrade - those were the good old days... ) I realize that not all 74 Chevys got that mileage, I made small mods that helped like the electronic ignition, widened the plug gap, and switched to platinum plugs. I also drove it respectably, I think I could do even better if I still had that truck.

I initially bought it as a toy. A beater to drive once in a while and have fun. Back then the BWH was a beautiful car and was waxed weekly. The truck ran so well that it quickly became my daily driver, and the Buick became the toy. The truck got better mileage, and I had better visibility in the truck so I ended up driving it a lot. After driving it for a few years I started thinking that I loved the truck so much that I looked into getting the rust taken care of. It had the typical early 70's Chevy Cancer - rust holes in the fenders so large I could stick my arm through them, and it had rust holes in the floor of the bed. I remember when I bought it the guy jokingly said "Don't haul any sand in it" I figured that by the time I replaced the bed, doors, fenders, and put a quality paint job on it that I'd be spending at least $5,000 and I'd still be driving a 20+ y/o truck with over 300,000 miles. I was afraid that it would be just my luck to spend that kind of money on the truck, and have something serious happen with the engine not long afterwards. I figured I'd look at newer trucks.

When I bought Rusty he had 95,000 miles and was 10 years old, garage kept, and looked fantastic. The truck was even optioned just as I would have ordered it from the factory, right down to the paint colors. $5,000 and it was mine. I sold the 74 to my sister who had it as her DD for about 2 years, and her beater for another 3 or 4 years.

[thisisntjared]

Originally Posted by Jay2TheRescue

The mileage didn't drop as much with E10 because it was a carb with no o2 sensor.- The truck didn't know it was burning leaner.

ethanol just has less btus....

[sk6strng]

My commuter car for work is an 86 Honda Civic si hatchback (1.5 w 5-speed manual trans, 200,000 miles on the odometer). I drive this car light and dont wind up the revs, also have plans to swap out my 5th gear to the 85-88 crx hf 5th gear (taller) to drop the overdrive rpms for better fuel economy.

Going for high efficiency in this car is to compensate for my 56 Belair 9 passenger wagon.

The wagon is a brick. It runs a 1970 vintage Corvette 5.7 litre v8 and 700 r4 overdrive trans into a 2.73 rear gear. (Headers and dual exhaust)
I am running Michelin Primacy x 245 series tires meticulously kept at 35 psi.
I guess that this 57 year old car gets quite poor fuel economy...dont know for sure since the speedometer is inoperative. The engine turns just under 2000 at 70 mph.
But check this out...The car is generally used with three or more occupants in it, often upwards of 6 people with my two 9 year olds and their friends.

It does merit mentioning that if this car did not have three rows of seating many of my weekend car trips would require two vehicles and two drivers.

Any tips for saving fuel on the wagon are always welcome (comedy appreciated)..
Thanks and have a great day!

[Jay2TheRescue]

Originally Posted by sk6strng

My commuter car for work is an 86 Honda Civic si hatchback (1.5 w 5-speed manual trans, 200,000 miles on the odometer). I drive this car light and dont wind up the revs, also have plans to swap out my 5th gear to the 85-88 crx hf 5th gear (taller) to drop the overdrive rpms for better fuel economy.

Going for high efficiency in this car is to compensate for my 56 Belair 9 passenger wagon.

The wagon is a brick. It runs a 1970 vintage Corvette 5.7 litre v8 and 700 r4 overdrive trans into a 2.73 rear gear. (Headers and dual exhaust)
I am running Michelin Primacy x 245 series tires meticulously kept at 35 psi.
I guess that this 57 year old car gets quite poor fuel economy...dont know for sure since the speedometer is inoperative. The engine turns just under 2000 at 70 mph.
But check this out...The car is generally used with three or more occupants in it, often upwards of 6 people with my two 9 year olds and their friends.

It does merit mentioning that if this car did not have three rows of seating many of my weekend car trips would require two vehicles and two drivers.

Any tips for saving fuel on the wagon are always welcome (comedy appreciated)..
Thanks and have a great day!

Welcome! I'd say if you have a 350 V8 that's turning 2,000 RPM @ 70 you're probably doing 18-20 MPG. Considering what the car is, I'd say that's pretty good.