What is realistic MPG for a daily driven SBC?

I did it this way.

My daily driver that I commute in 60 miles round trip, 4-days a week is a 2003 Accent 2-dr, 5-speed hatch. Without the A/C on and running right at 58 to 62 mph, I average anywhere from 36 to 42 mpg depending on the fuel. We have gasohol around here and my mileage will drop if I get some vs regular unleaded. I have gotten as high as 44, nut only one time??

I also keep my tires pumped up 5 pounds over recommended and this increases my mileage probably 3 to maybe 4 mpg.

I'm worried about our gasohol because the Corn Growers Ass. is pressuring EPA to increase the addition of ethanol from 10 percent up to 15 percent because the farmers can't sell what they are making now!

The problem here is that EPA is thinking hard about only requiring E15 be used in 2006/2007 and newer vehicles because they don't really know how the increase in ethanol will affect the older cars like mine's fuel system??

I got completely away from daily driving an old car when I parked my Strong-Arm 406, '67 SS/RS Camaro M-20 Muncie, 3.31 posi and L-60/14 tires back in 1987. Runing 55 mph, it only got 15 mpg and I was commuting 80 miles round trip back then.

I bought a new '87 Chevy Sprint ER 3-banger, 2-dr, 5-speed hatch el-cheapo car that got 50 mpg running 70 mph down the hwy and only dropped off to 44 mpg 227,000 miles later. Sucker cost me $6300, boy I miss that little corn-popper, drove it everywhere all the time!

And I DON'T take my cars back to ANYBODY except at license inspection time because around here they will F**up your car unknown to you and laugh at doing so!!

pdq67

 

I found a good fun daily driver in a 98 Mustang GT. 4.6 V8, 5 speed. Pretty quick, sounds good with Borla exhaust, and gets around 25 mpg highway. No joke. It has also been the epitome of reliability, and I haven't had to make any major repairs in the 5 years I've owned it.

As far as an old car, I'd stick a 289/302 SBF in something with either a T5 or AOD. Even with a carb you could squeeze 20+ mpg out of them. They really do run great and the smaller displacement than the 350 sbc will save on fuel. Power is more than adequate too

 

Here's a discussion of gear and mileage factors. Dyno values are considered too. http://www.eng-tips.com/viewthread.cfm?qid=203775&page=5

 

anymore older combinations to share?

 

I run a bone stock inline 292 in my daily driver '55 Bel Air. I have a MY6 4 speed O.D. trans with a 3.08 axle gear. On highway road trips at 60 - 65 MPH it runs right at 21 MPG. No idea what happens in city driving.

 

I have a bone stock 305 with a Edelbrock Performer and 600 cfm Carter Comp carb in a 3400 lb car and get 20-23 on the highway. 325 gears and 700r4

 

I have a 1988 Chevy Silverado Ext Cab, longbed, 4x4, that I've gotten low to mid 20's consisantly on the highway. It had a roller block from a Caprice I believe, decent cam, short skirt flat top pistons, a 700r4 with a few upgrades (shift kit, etc), 3.73 gears, no catalytic converter, and a 3" exhaust that turned into a 2.5" glasspack just before the rear axle, and 265/70R16's. If I kept out of it or wasn't hauling anything, it had excellent mileage. Still did decent even if I had a load or was doing city driving.

Now I've done a 1 ton frame swap, ditched the regular bed for a flatbed, Dana 70hd rear axle, and built another engine for it. Non-roller, stock cam, flat top pistons. 4.11 gears, and 285/75r17's now. I don't expect the same mileage I had before, but I'm still hoping it'll do ok with the 700r4, 4:11's, and larger tires.

 

What's it get around town MPG?

 

I had a properly built 350/400 combo in '65 C-10. With a 3.08 gear and 28" tall tires I consistanly pulled down 20-22 on the highway 18-20 around town. My normall cruising speed on the highway was from 70-80 mph.

Keep this in mind do not detune to get mileage. Its not likely you will get any better than what I got and most likely get worse it depends on how well you tune.

 

It has been mentioned, but one of the most overlooked items in the whole combination is rear gearing. If this is a daily that you drive highway mostly, then gear it in conjunction with the O/D trans you pick for effeciency.

Besides a Hamber, I have been doing a lot of research on the modern drivetrains (resto mod builds) as I plan on making my 56 truck a daily with modern drivetrain for reliability and effeciency sake. Although it may be intimidating, endless hours of research have pointed to the 5.3L (327) Chevy LS engine, bone stock pulled out of a modern truck. The EFI is surprisingly easy to have serviced or replaced, there are millions of replacement parts in the junkyards surprisingly cheap. I found locally full setup, wiring harness, computer AND tranny for 1200, with 60k on it! And these things are good for 200k easy, (and if you want to go fast, a cam and headers will get your about 430hp!).

I drive a 5500lb Tahoe with one of these, mostly highway to work and after 5 minutes of tuning the computer with my buddies computer I got 20mpg with the stock setup. Imagine if I put this in a 3000lb truck with high gears? I am hoping for mid 20's. Heck, Gen I Camaro's with 6 speed Tremec's ($$$) and the same engine are seeing 29mph!!!!!

Sorry to get non-traditional, and I don't have any experience with Ford Trucks but might be worth looking into. Again, I am partial to the trucks since there are so many out there in the yards with many years of life left in them for cheap (comparitively)

 

That's awesome MPG!

I had a 388 built in 2008. It's backed by a Richmond 6 speed with a 3.08 rear gear. It has a 236/242 .520 .542 hyd. roller cam,and cnc ported heads with 2.05 valves. I thrashed on this truck for the 2008 Power Tour kickoff in Little Rock,and neither of my carbs would run right. My engine builder let me borrow his 1000 cfm plus Stealth carb for the event. I got 16 mpg driving at 75 plus,and idling in a parade for an hour at least. I was shocked! I was expecting 10 or 12! It gets 10 or 12 in town. The OD and high gears really help the mileage,and it still takes off pretty decently with the 3.27 first gear in the trans.

I bought a 750 Street HP,and ironically the mileage doesn't seem to be as good now!

 

Allen
You have to have everything balanced out to make it work. That's the key, a heavy breather with a large carb will make more torque in the proper RPM range than the same engine with a small carb. If it is making easy torque it will naturally get better fuel mileage than if you have to keep your foot in it all the time with the little carb.

Does that make any sense?

 

Absolutely! I understand,but it's still pretty amazing.