Gas Mileage

[69stang]

I was looking at Stangnet and saw a member who had a signature reading:

Daily driver
1964 1/2 Mustang
BFR Red
5.0 roller motor 9.5:1 comp
GT-40 Cast iron heads
RPM Performer manifold
Comp 9000 89 Series Dist
mallory hyfire III <-adjustable rev limit on tach
600 CFM Carter AFB carb
dual Flows
13.89 105mph in quarter - I know a trip huh.

How and a daily driver 32-36 on freeway.

This really impressed me, is that kinda mileage realistic and how much horsepower/torque do you think he is making?

Also, is there a reason he used the gt-40 cast iron heads instead of aluminum (minus cost difference)?

I tried to PM him with no response, and I know the 64 1/2s are a good bit lighter than the 69's but it should be able to get similar gas mileage.

Thanks in advance guys.

[Cupid]

32-36 mpg?

*sigh*

That's probably the reason you didn't get a response!

I don't know man...lemme know if you find out that this is a true story. There's only a few 4 bangers that are out there that can register that kind of mpg.

If he's swingin' that then I need to do an engine swap!

[69stang]

Yea, I don't know if its true. I have been told that with a pretty power 302 can get 22-25ish, which i know is a huge difference, but figured i'd ask if its possible.

[Ltnrisk]

Well it says it is has a carb in it which makes that just highly unlikely. I would more likely to believe it if it was fuel injected and a nice setup. But that to would also be a long shot.

[351carlo]

That's possible....

If it were idleing and being towed on the back of a truck. Our cars will rarely see more than 18-22 mpg

[wantahertzdonut]

I could maybe see 22-26, but not 32-36. Mine as it sits gets about 17-18 without overdrive with a lightly built 355W cruising about 65. With OD my hopes are for around 20-25. Of course city driving tends to bring that down since it's not proper to leave an intersection without leaving a mark!

[bnickel]

i was able to get 24-26 on the highway with my old engine. 70 model 357w (.030 351w) flat top pistons with bone stock D0OE heads (around 10.5:1 to 10.75:1 compression) sealed power stock replacement cam advanced 4 degrees, stock dizzy with mallory unilite conversion still running stock advance curve, stock cast iron exhaust manifolds through 2.25" duals, e'brock performer intake and 600 carter carb with stock fuel pump and purolator fuel pressure regulator set at 4psi. trans was stock FMX with shift kit and stock 3.25 geared rearend with 275/50-15 rear tires (26" tall), cruise speed was 65-70 mph. i think the reason it did that good was a combination of the high compression, advanced cam timing and the fuel pressure.


i know of 3.8 turbo buick regals pulling down 30-35 mph on a regular basis but i seriously doubt that a 9.5:1 iron headed 302 is gonna pull that kinda mileage unless his speedomoter is in serious need of calibration.

[Max Power]

He couldn't pull that mileage with an 80mph tailwind.

Albeit a bit heaver, new mustangs with computer controlled, fuel injected V6 engines don't even come close to it.

I would venture to say that it would be impossible to fill that large an engine at that gear ratio and still come close to that mileage, regardless of weight.

[70Mach03]

That sounds a little too good to be true unless he’s running a double overdrive 6-speed and some seriously lazy rear axle ratio. I am running a T-5 five-speed with 3.00 rear gears. My 351C-4V engine combo is fairly stock with the exception of headers, Pertonix ignition, aluminum intake with 670 CFM Holley and I have gotten 26 mpg highway running 55-60 mph. Running 70-75 mph drops me to 22 mpg. Of course around town where fifth gear is never used, I still get 11 to 12 mpg. When my car was new with a FMX auto transmission it usually got 11-16 mpg.