Inliners International Forums General Discussion Engines How many MPG are you getting?

How many MPG are you getting on your cars and what are your setups. Thought it would be nice for all of us to share some common info.

What gas mileage can I expect from a 79 Caprice 4 door with an inline 250. My plans were to turbocharge that baby, I had all the info, but not the money and still dont. What would be the best mods to increase gas mileage and get a bit more power as well. Right now I am getting 10 MPG tops and the car feels really sluggish. I know its a really heavy car, but what would you consider to be the best gas mileage I could get out of it?

im getting 12-13 with my 76 2 door nova. 250, 390cfm 4 barrel with 55 mains, dual exhaust headers with 2.5" exhaust, stock cam, soon to be .508 lift on both intake and exhaust 223 durationat .050, and a shaved head 60 off and 1.94 intake valves. oh yeah a th350 transmission, soon to be a 700r4.

tatao,

Go with a 200R4 or 700R4. And give the 250 a good major tune up (new plugs, wires, air filter, fuel filter, timing). Then maybe rebuild the carb and make sure the engine runs at a decent temp. The tune up alone will help your gas mileage 5% or more. The overdrive transmission will help much more.

While I cannot say yet because I have not started my truck, I have talked to a few 67-72 owners who get 12-16 mpg. This is in a truck shaped like a brick and probably alot more weight then your car. I would think a well tuned motor in stock form you should get the same or better. Driving habits can also determin alot.

i usually get around 25-30 MPGs when everythings up to par....i use a PCV gas condensator and have periodically used a hydrogen boost which adds hydrogen to the engine but thats not been quite properly built yet...so when thats done i hope for better milage....otherwise the engine is stock and without any emissions control devices of any sort (the gas condensor and the hydrogen to come take care of the emissions end of it as well as better mileage and a much cleaner engine)

this is a '74 250 ci. engine

I've got a 67 C-10 and I'm getting about 12.5 with a webber 2bbl, Stovebolt headers and HEI, and 373's out back. Everything else is stock. Back when I had 307's in it and a tonneau cover, I could get up to 18 on a really good day.

I just got my Clifford 4bbl intake back and plan on putting that combined with a 390 or 600 Holley on along with a bigger cam. I'm also planning on shortening the truck and will put the tonneau cover back on. Once everything is tuned and running well, I expect I'll have about the same mpg, just alot more power.

I have a 63 Nova convertible with a 250, 307 pistons, decked block and milled head with big valves and no bolt boss, solid cam(not sure of specs), HEI, Clifford long tube headers and Offy intake with Holley 390. The rear is a 3.08 with 195-60-14 tires. I am using the Borg Warner T50 5 speed out of a mid-70's V-8 Monza and rpm is 2,400 @ 70 mph. I drove the car about 60 miles a day at 4,500 feet above sea level in all kinds of weather and had overall milage (city/highway) of approximately 21 mpg.

I have a RHD jeep, with a 232 6 cyl engine, stock internals, cyl head work (new valves, guides), no milling , no cam(yet). I do have a Weber 2 BBL 32/36, Clifford dual exit headers(6 into 2, plus Y pipe into one muffler), a MSD distributor(8516) and a MSD 6A ignition module, also 8.5 mm spark cables, and replaced the stock 232 steel one BBL manifold for a later 258's aluminum 2 BBL intake manifold. No smog devices, no PCV system, breathes naturally through 2 breathers, no more gunk into carb/intake manifold/cylinders, runs cooler and efficient. I get around 20MPG.
Before, with the one BBL Carter, stock manifolds and smog devices/pvc in place I got about 10MPG.

Late_________________________

A big ZERO.... I tried starting my truck, no luck there. So I primed it with a gas can. Poof, I end up with 2nd degree burns and alot of damage to the truck. Get a fire exstingisher...

I'm getting around 20-22 mpg on the highway drivi'n in 55 mph. I drive a 1973 malibu 4dr with a stock 250cid and 3 speed manual. My best milage tip is to always keep your engine tuned, and make shure that your airfilter is nice and clean. Here in Norway the fuel costs about 5$ per gallon, so fuel economy is definetly an isue.

Hope you are fine bro, watch out , never stick your head above the carb while no air filter is in place.Flames come out in no time.
Always play it save, you are your own guard.
Late.________________________

I have a 250 in my 37 Chevy sedan. It is 30 over with flat tops, fully clearanced and balanced, major head work including stud boss removal and porting with larger valves and milled to provide 9.75 cr. It runs a Comp 260H cam and Crane gold roller rockers, Offy manifold with 500 Edelbrock carb and Clifford street rod headers, 2 inch duals. Rear axle is 3.36 and the tranny is an M20 Muncie 4 speed. Normal around town driving is between 15.5 and 16.5 and on the highway I get 21 running at 70 - 75 mph. The car is lighter than what some of you are driving and the 3.36 gears help too. Overall after 5300 miles on this combo I can't complain about horsepower or economy. I guess you can have your cake and eat it too.

'33 Willys coupe, built 305 Ford w 2 x 2 intake, C6, 3.50 9": 17 mpg

'23T altered: 1/2 gal/ quarter mile

Right now I'm all stock. 1bbl carb, integrated head/intake, 3 on the tree and a 2.73 rear end and I get about 28 mpg on the highway. It's a great daily driver.

Well I have my truck going now. I am on tank 2 and have calculated 16.4 mpg. Thats almost all stock engine but milled head, rebuilt 1 barrel, and full 2 1/4 exhaust. 3.07 gears, 4 speed and 31 inch tires. Truck is 68 shorty 4x4.

I get low 20's in my '64 Valiant with 225 slant six and the Carter BBD 'Super Six'. I think can get better than this.

Here's a recent update on my mpg's:
After finally getting all the bugs worked out of my drivetrain for the most part, using the 250/T-5 combo I'm getting about 17mpg @ 65mph. My engine has about 140,000 miles on it and I think it might be .30 over, but can't remember. These L6's aren't known for their high compression and I suspect with a good solid rebuild and 9.5:1 comp ratio, I could get kick @$$ mileage from this. Most likely in the spring I'll experiment with a Q-Jet and try to get better mileage since they have smaller primaries.

Since I know I'm getting 17 @ 65mph, I should be getting higher mpg's at 55mph. That's on a tired, old engine and a 4100lb rolling brick! My eventual goal is 21-22 mph highway!

I used a GPS since my speedo is just slightly off. I notice that when it says 75- I'm actually doing 70. 55 is about 54, etc. That's why I don't really trust many of the numbers thrown around this board and others, regarding mileage- even what people tell me in person until I can really question how they came to their conclusion.

Here's my combo: Rebuilt 250 w/possible .30 over pistons, stock cam as far as I know, 500 cfm 1403 w/stock jetting and rods, HEI which probably needs a rebuild, Clifford intake and shorty headers, dual exhaust with H pipe, Camaro T-5, 3.73's in the rear, tonneau cover on bed, 275x15x10" tires in back 245x15x8" tires up front. If I were to put thinner tires on it that would help mileage due to less rolling resistance.

hello all,
I have made a few recent changes to my 67 Valiant,225 slant.it always (to me) had 2 barrel Carter,perry headers and 2 and a half exhaust.
that gave 20 - 21 mpg.
now with electronic distributor,GT 40 coil (@ full 12 V) and NGK -ZFR 5 N extended reach plugs.new leads too.

last weekend ,a 500 mile excursion,cruised @65 mph,and about 40 miles of twisty steep country,
got a smidge over 25 mpg.
I am more than happy with this.the old slant is smother at idle and much crisper engine note.
VERY happy.

regards,Rod

I'm really surprised that MPG's are that important to all you Inliners. Most of us that have inlines, use them as secondary transportation. I know there are some that use them for daily use and I applaude them!
I guess if my ride got the mileage my neighbor's '67 435hp vette got, I'd be concerned about mileage too. He hardly every drives it which is a shame. But Premium fuel at 8 mpg is hard to do.
My 292 gets decent mileage on the freeway but poor in town. I get betwwen 18-20 on the freeway and about 12-14 in town. If I would keep my foot out of the secondary's, it would do much better. How can anyone not want to hear a big block, six pack inline growl through chambered pipes?

RapRap
1940 ChoppedChevyCoupe

Crude oil prices are now over $90 per barrel....and climbing!!! A new all-time record!

I'm getting 18-20 mpg on the freeway with my 235 2x1 carbs and 3.55 rear in a 4200 lbs. truck with the tailgate down.

Will be interesting to get the milage on my new 261 2x1 carbs and 3.55 rear in a 3000 lbs. coupe with much less wind resistance.

It's actually a 269 after boring and also has a mild cam grind.
I wonder how the additional fuel consumption and power but lighter weight and less wind drag will affect milage.

my 1971 lwb c-10 with a 250, 3 on the tree and 3.73 gears get 11-14 mpg if i drive it nice, thats below 65 mph. i,am thinkin 3.08,s and a sm 465 might help.

I'm at the point where I can't afford to drive my Nova every day. I alternate a week between it and my 4 cyl Toyota (I almost mistakenly sold). It's still an inline though.

Ford 300 van with 4 barrel and 4 speed averaged 22 MPG over 520 K miles before rusting out the third time from the salt and cinders (thanks Modot), and being retired.

Replaced with a V-6 "computer on wheels". Now looking for another older van, tired of replacing electronics!

Jon.

Last March I made a 4,000+ mile trip to the Lone Star Roundup In Austin from Nevada. We drove my '53 Chevy pick-up & hauled my son's Triumph. We drove 65 to 75 mph all day and averaged a little better than 16 mpg. The pick-up runs a 270 that I built in '78. It's bored .030." the head is shaved .010" with some port work.(small ports) 500cfm Edlebrock, Pertronics Ign.,Fenton headers that go into one 3" Flowmaster.It sounds cool but not a wise choice.It run a lot stronger with Clifford tube headers and smaller pipe. I can't remember the cam grind but its a lumpy-rumpy Clifford. The trans is a T-5, rear gears are 3.55 Dana 44 posi. This engine has hundreds of thousands of hard miles on it and needs to be freshened,but it is the most dependable car I own. How sad! With some tweeking and holding It to 55-60 it would beat 20 mpg. That would be about 2200 rpm. This cam loves 3000rpm and I ran it there with a Saganaw and 411s. It was quicker then. I run regular and the engine doesn't care. It's a fun rde at sea level!

235, fentons, HEI, O.D., radials, 3:90 rear. I get 16-18 at 70mph. When the truck was ALL stock with the tube-types on split rims, I was getting about 12 at 55-60mph.

I have been running 292's with the old
Borg Warner 3-speed overdrives for over
20 years now. My 1964 Belair Wagon with
that setup (rochester monojet, electric fan)
used to get 24mpg in the 55 mph interstate days.
It has a 3.36 rear end ratio (car was converted
from automatic).

I built a '73 Dodge Clubcab 3/4 ton pickup with
the same setup, and I get 20mpg on the highway, and
18 driving to work and back (about half open road,
half city driving). Can't remember off hand
what the rear end ratio is, but it cruises 55
at 1800rpm in overdrive.


-Brian