can anyone shed some light on this?im going to give an example ,it could be a big block or small block.given the same heads,carb and cam would a 454ci bb vs a 496ci bb burn the same or more gas?or if you lighten the rotating mass of the larger stoke motor would that make a difference in gas.my chevelle has a 350ci motor and i live in texas but was born in ohio and would like to drive there 2 times a year in the chevelle.i want to put a big block in it but still want the reliability and mpg of the 350ci.also will a bigger stroke be harder to maintain.can anyone help me decide!

if you want the mileage of a 350 dont run a big block or a stroker . my 540 gets 4 miles per gallon

and my small block 427 with a motown block and a 4.00 inch stroke is almost as bad

what do you think you would get with fuel injection

496 = 8L = 5Honda motors = crap gas mileage.

FIVE Honda motors! Isn't that incredible......

Originally posted by TJC:
496 = 8L = 5Honda motors = crap gas mileage.

FIVE Honda motors! Isn't that incredible...... I like that!

Big blocks are for torque,,,not gas mileage, if you want mileage from a big motor, go diesel :D

Well, you can get decent mileage out of a big-block. My 454 got 20.7 mpg on the highway driving from TX to KY last May. 5-speed with OD and EFI helps.

/Markus

4 MPG huh??? Well the puts the cabbosh to me ever building a huge inch big block.

thanks for the replies?but im still undecided?

maybe 00 camaro ls1 motor?

i know there are some bbc out there getting good gas milage.....where are ya......lol

this summer im planning on building a 454 dually truck and i think i can crack better then 15 mpg out of it using a th400 tranny and some selected gears out back......i'm thinking of a good q-jet or spread bore holley (smallest cfm i can find) headers of course, running a compression of 9 to 9.5 to 1, small rv cam, really working the advance curve, and running synthetic oils in everything.....can it be done.thinking im sure going to give it a shot........most folks i talk to with duallys get about 8-10 mpg....im thinking i can do better....

my bbc z28 runs an honest 15 + mpg with it ran hard and easy......i have gotten close to 18 mpg the one time i really tried hard to stay out of it........i still had a few runs to 120 and 130 mph on that "test" lol......but its 82 ci smaller then what your asking about.......and i really didnt build it for gas mileage it just turned out decent. and the gas tests i did with that one was running most the time on the highway at 65 to 70 mph.....when i was being nice to it.....

Nice post, you got me curious what I'll be getting... I dont like to think about it, but at some point doing the MPG math is a must. Ive chosen a few parts that are somewhat fuel friendly and if I "Stay out of it" ;) maybe I'll be ok, anything over 10mpg I can live with. Still pretty bad though... Its a 461 Im building. Maybe if you build it slowly and carefully choose EVERY part for power and gas, and then theres always master tuning that bad boy which I know takes some skill... I dont know...

There probably is no direct relationship between stroke and fuel economy. Generally, a smaller engine gets better fuel economy than a larger one, but there is a point where it is too small.

One of the problems with a large motor is the amount of vacuum that you are pulling at cruise. Think of your engine as a vacuum pump. The higher the vacuum that you are maintaining, the more power you are losing in pumping losses. That is why a car with variable cam timing, or even a well designed EGR system gets better fuel economy than one without.

There are guys out there who are getting good fuel economy with a big block, but it's very easy to get 16-18 mpg mixed city/highway with a small block and no overdrive. If you go with overdrive and a lock up converter, you should be able to reach the 20 mpg area.

Mike

What kinda mileage do those 496's get in the new pickups? I'm guessing 14-15 mpg.

They get between 8 and 10 mpg. Never driven a big block anything that got more than 10.

my brother 383 with xe274 hyd roller afr headed 67 chevyII, 700r4, 3.36 gears, 13.4 drag strip on street tires gets 21 @ 75 mph. i'd say thats not to shabby. you just have to get the right combo of parts.

I am running a Gen V 454 with a comp 280H cam and an Edelbrock Performer 800 on an airgap manifold in my '66 convertible. I know there is more tuning in the carb and timing that need to be done and I got an honest 12.7 mpg last summer driving it to Frankenmuth and back. That is combined city and highway for a 175 mile test run. I stayed out of the throttle as much as i could restrain myself, but, there were acouple of "hits" in there to be sure.

I also run the 700R4 tranny with a 2000 stall lockup converter. with 3.73 gears out back.