Bad just fill when low.468 BBC, TH400 ,3000stl ,9" 3.89 ,31"tire.Car runs 2800rpm at 55mph pretty comfortably...

 

I have a 427, muncie M21, 3.73 posi... Get about 11 mpg cruising. cruises about 2600 at 55 mph. In the city or stop and go, about 6 mpg. If I am going down hill and turn the engine off, it goes up to 15 mpg, with a tail wind...

I built my engine not really worried about mpg, but fpg, fun per gallon...

 

I have never owned anything that gets better than about 14 mpg. Matter of fact my friends think I am weird if I brag about any of my vehicles getting double digit fuel mileage,lol.

 

terrible mileage on my 406
but who cares lol

 

16.8 is my best on a long highway run. Got there from 13 with timing curve tweaks. Still trying to reach 20 mpg.

 

Fairly stout 350 / 4.11 rear - driving on the highway at 55 MPH with the tach around 3200 RPM I got 8 MPG :thumbsup: -- but like Dawg says - who cares!

 

23 mpg highway. Long term average, not just one tank.

EFI 383, tko500, 3.08 rear, 26" tire, 2100 @ 70 mph.

12.87 @ 109, have the time slips to prove it.

 

I only have 800 miles on my 489 w Holley 870 Street Avenger and the 2 tanks I measured I got 7mpg with the carb straight out of the box and tuned using engine vacume/rpm. Im still tuning though, I just installed a O bung and I bought a LM2 to log the data.

 

Im up around 25mpg on interstate cruise now with 350/4 barrel Qjet, 700r overdrive auto tranny, 3.08 posi gears, 26" tall BFG tires.

 

350 w/4.10, TKO600-2066rpm @60mph, heavily modified Q-Jet, 25.5" tall tire: around town: 13mpg, on highway: 20+ depending on what speed I drive. I know I can get 300 miles to a tank on the highway. I think I may be able to get 350 if I baby her. I am going to try for 350 when I install the cruise control. With 350 I will get 23mpg and that is at 15 gallons. When my gauge says "E", I have 3 gallons left.

 

Click, the final drive of a 700 is .75, correct? I ask because is there really that much of a difference between a 26" tire and a 25.5" tire? Oh, wait a minute, you are running a 3.08 where I am running a 4.10. That is where you are really making it up, but I have a .64 final drive where you have a .75 so we should be pretty close. How do you get 25mpg? I also have a Q-Jet. According to the calculators, at 65mph you are turning 1942rpm where I am turning 2280rpm. I guess the rear gear is what makes the most difference. If I had the same rear ratio, I would be turning 1713rpm. That would really make for some MPG, but I have to admit, I love the 4.10's mated to this .64 final drive. In 5th, I can just step on the pedal and the car goes, even up hill. If I had it to do over again, I would have went with the t56. The reason I did the TKO was at the time, I had the stock crappy smog heads installed and it wouldn't have had sufficient power to pull in 6th. I would have had to down shift too much going uphill, but with these new AFR's, the car would love a 6th gear. I will be running a t56 in the 69.

 

lmao... click gets 25mpg because he NEVER goes over 62 mph, never.

 

Jim and Click,

That is really impressive results you are getting. I have another project first gen that in the next year or so I am going to make into a stealthy fuel mizer like both of you have-

 

JimM that was with the old TH350... now I can cruise at 67.335 mph

FYI for the folks trying to get the best mileage, DONT downshift around town or approaching stop signs etc... downshifting sucks more fuel into the engine to do your braking for you... thats wasting gas. Use the brakes earlier and/or slip the tranny into neutral and coast to the stop light/sign.
Old trick I learned from a Chev dealer in Lincoln, Nebraska.

 

No clue on the camaro, but its a very mild 396 m21 and 3.73, my 68 pick up with a 468, roller cam, 950 holley etc t-400 and 3.73 is in the 6 mpg range...

 

I can get around 21 cruising on the freeway...really bad when your foot is in it . 427 small block , comander 950 MPFI TKO-600 3:73 rear gear .
Mark.

 

Fairly mild 468 w 3:73 gears and a TKO600 aprox 10 mpg around town but in 5th gear cruisin on the highway with the wind in my favor about 17-18 mpg. 1850-1900 rpm doing 60-63 mph. Thats driving with a super light foot. Once I get into it around town I can just watch the guage move like a second hand on my watch.

 

I have what is a "stock" 68 Z28. M21, 3.73, rally wheels w/radials. I have a cc modern grind and fairly hot cam in it. Other than that, it's what the factory put on it. I get around 10 mpg on the hwy and less around town. With 110 race gas and premium mix at $80 a tank, I figure it cost me .50 a mile to drive. It would be a bargain at twice that.

 

I get between 14.8 and 16.8 fairly consitanly cruising around town and up to 18 to 21 on the highway.

 

Never really calculated but it seems to be somewhere around an hour and a half. LOL
406 / 750 mechanical 3:73 rear with T350/3000 converter. Not an economy car by any definition.

 

I got a 383 / 10.25 CR, 3.08 rear, TH350, Holley Spread Bore 4165 on an eddy airgap, the cam is a voodoo 60103 hyd FT.
The best I got was just under 16 mpg. I was pretty easy on it only cruising 70-75 on the freeway keeping my foot out of it, I think if I slowed down to 60-65 I might get another 1 or 2 mpg's.
Sometime in the future when I get done payin' college tuition I will upgrade the drive train to an OD.
Don

 

13 mpg here in light stop and go traffic.Wot blasts between the lights..and she drinks fuel like a Boeing 747.
8-71 roots blown 461 bbc.Dual 850 dp,s.700r4/3.73 rear with 28" m/t drag radials.3500 lbs w/driver.A/f ratio at cruise 14.5/1.-11.8/1 with the loud pedal buried in the oil pan.

 

My Fuel Consumption Is Measured in Gallons Per Mile

My fuel consumption is measured in GPM......Gallons Per Mile . I am easily spotted on the highway......just look for the fuel tanker following me as I cruise the streets in my '69.

David F.

 

I havent actually measured the mileage with any of my hot rods,but years ago I had an iteresting obvservation with my firebird.

Back when I first built it I drove it to the street race spot about 30 miles from my house as part of the stipulations of a race.I left my shop in Bayonne New Jersey and had to drive to Mt Vernon New York.I had a 3 gallon fuel cell in the car and brought a 5 gallon can of race gas with me and had my friend follow me with my truck.I figured I was going to use a lot of gas.I jumped in the NJ turnpike and drove about 17 miles to the George Washington Bridge,all highway doing about 70 mph.I would run it up to about 80,throw it in nuetral and coast.When we got to the bridge I jumped out and popped the trunk while waiting at the toll booth and was surprised to see that I only used less then a 1/2 tank of gas.I toppd it off with a little over a gallon of gas,and made the rest of the night on what I had in the gas can.I was getting more then 10mpg,I think I figured about 14 mph average that night,but we didnt actually race the car though,we collected the "dp" when the other guy walked away because he was told it was a steel head 350 on motor in a Firebird and figured it was a Pontiac engine.The Chevy engine I had would blow your pants legs against your shins as you walked by it when it idled,and sounded like WJ's pro stock engine with mufflers.

At the time it was a 3400# 73 firebird,4.10 gears with 30 inch tall slicks{lol} th350 with a loose 3500 stall convertor,355 smallblock 11:1 compression,very heavily welded and ported camel hump heads,solid flat tappet cam with 260 at .050",ported strip dominator,worked 750 double pumper,1 7/8 headers and 3.5" race flowmasters in front of the axle.

This may not sound like good mileage,but my HD2500 chevy with 4.10's never get more then about 12 MPG and thats with an O.D. trans,fuel injection and only 300 hp.

 

I'm getting between 20-23 mpg with the LS9 in my 69.