What mileage should I be getting?

[The73vetteman]

My L48 seems to drink gas faster than a .... well very fast indeed. It's the original engine with 115k miles on it, a Holley carb, Edelbrock manifold and (make unkown) headers. Most of the driving is around town with just a few longer trips.

I seem to be getting under 10 mpg. Does that sound right to you all?

Any suggestions as to what to look at? (And don't say a Prius!!)

'73

 

[mvftw]

I haven't checked the mpg yet, but isn't good. I have an L82 & 3.70's. I can watch the gas gauge go down.

 

[jclit]

Mine is bad also

I get really bad mileage, less then 10 around town. If on a long trip I might get a little above 15 or so. But I do drive it kind of hard most of the time. I just figure it is part of vet ownership.

Jim

 

[Stallion]

I agree with Jim. Gotta take the bad with the good. If I do get more, then it's not much more over your 10 mpg. But I usually put my foot in her a lot.

 

[Chas]

lucky if i see 10 mpg...Edelbrock Performer series carb , manifold, cam and headers......
Its not miles per gallon that matter here...Its SMILES per gallon!

My L48 seems to drink gas faster than a .... well very fast indeed. It's the original engine with 115k miles on it, a Holley carb, Edelbrock manifold and (make unkown) headers. Most of the driving is around town with just a few longer trips.

I seem to be getting under 10 mpg. Does that sound right to you all?

Any suggestions as to what to look at? (And don't say a Prius!!)

'73

 

[Bob_K]

My '79 L-83 with 3.73 gears got 14 on a good day, usually around 12. Right now all it gets is dust in the garage until my new trailing arms come in, so I'd love to be getting 10 mpg!

 

[Ludigdrums]

That's really funny...because I was just wondering this same thing. I have been averaging around 10 mpg too. I have an Edelbrock Performer intake with a Holley Carb, Unknown headers as well, no emissions, K&N Air Filter w/top filter, true dual exhaust. I also like the gas pedal and the smiles it brings! A few more mpg would be nice though. The new engines seem to do that well in the 20-25 range.

Good to know that I'm not the only one!

 

[steves1980]

Just checked mine, 1980, stock engine, true dual, just tuned it up, all new gm parts, i got 13.3, before that seems to me it got 12 or so, the 13.3 was with the air on and few times, in town, iam thinking it would bring 15 or so on the road.

 

[Vinn]

I've yet to see mine get 10 miles to the gallon. Every time I've checked, it's between 7 and 8. But then again, I do not believe the big block was introduced on Corvettes for economy purposes :L

It seems most any original C3 engine will get no higher then the teens, on the highway, from what I've observed.

But I must agree, the smiles per gallon on the C3 can beat any other make vehicle out there!

Vince

 

[mike weyman]

uh-oh,if i got only 10 before, and i added thousands of dollars worth of go fast parts,....oh man, i'm frigged....lol mike. oh well ,now i know why my 30 year old car has only 30,000 miles on it.

 

[Glensgages]

1982 Cross-Fire/700R4/2.87:1 gears got 23+ @ 75 MPH w/ A/C on, and T-tops off on one 236-mile trip I made. Car ran 15.7/86 with less than 20,000 miles showing on the clock.
Last October, I swapped-out the 2.87s for 3.73s, and my mileage for a 430+ mile trip of mostly back-roads & meandering county-roads was 17+ MPG, and now runs 15-flat @ 91+ @ 21,500 miles.
Stock Cross-Fire sucks for performance, but returns decent mileage...

 

[Vinn]

Wow, I never realized how economical the 82 crossfires are. It has the same horsepower as my 2000 Grand Prix, with just slightly less gas mileage. That says a lot for a 22 year old car!

 

[wishuwerehere82]

Yessiree, I get 23.5 MPG @ 70 MPH on long trips with the windows down. 82's might not be too powerful, but they are cheap to feed. My Japanese freinds ask what my milage is, and when I say 23.5, they say"Oh, you must be very rich man". I guess everthing is relative. For an old Vette, that's pretty good!

 

[GTR1999]

With a crate 350-250 hp slug, edelbrock intake,Q-jet,stock 2" pipes, M-20,336's I got 14-15 around town and 18 @65mph. Normal driving. Changing to headers,2.5' pipes, 373 it dropped to 12 town and 15 highway.

stock 72 350-200 Th400 308's avg 11-12 mpg.

 

[Stallion]

I read this article that a guy and his ZZ4 get 28 mpg. Is that right? :confused

 

[Tom73]

I read this article that a guy and his ZZ4 get 28 mpg. Is that right? :confused

What kind of gearing/transmission? I have a 73 L82 auto that gets 13 mpg on the highway. Also have a 90 L98 auto that gets 27 on the highway. Just that the 90 has about a 2.70 rear compared to the 73s 3.55 and the 90 also has a 4-speed overdrive automatic.

Forget engines, it is the gearing that determins gas milage

tom...

 

[dfw81shark]

repository of carb/engine combos?

Is there a list anywhere of what reasonable gas mileage to expect from certain engine/carb combos? That'll make or break me buying a ZZ4 or LS1 or something else here pretty soon. I've got a stock Q-Jet, mildly tuned L81, TH350, and 2.87:1 gearing (I think), and 255/60/15s, and I get roughly 13mpg. It'd be nice to have a calculator to see what, say a 700R4, new motor, and new carb would get before I plunk the money down. I'd love to get 20mpg, doesn't seem too unreasonable given that a new C5 auto has relatively the same tranny and puts about the same power out as the ZZ4 and LS1 crates and gets 18/25 (I think). I like the sound of the ZZ4, but would get an LS1 crate with the fuel injection and computer if it was going to make a huge difference. I'd daily-drive the vette at 20mpg or better.

An aside question: given the same setup, would a .67:1 final drive tranmission get 1/3 better gas mileage than a 1:1 tranmission's final drive?

Michael

 

[Tom73]

Michael,
It is the overall gearing that makes the difference. On my 90 the engine is turning about 1800 rpm at 70 mph. On the 73 the engine is doing about 3500 rpm at 70 mph. It is all a matter of gearing.

tom...

 

[Glensgages]

Michael,
It is the overall gearing that makes the difference. On my 90 the engine is turning about 1800 rpm at 70 mph. On the 73 the engine is doing about 3500 rpm at 70 mph. It is all a matter of gearing.

tom...

Yup; with the 2.87s, I'd turn 2000 RPM @ 80 MPH; with the 3.73s, I'm looking at 60 MPH @ the identical 2000 RPM.
All readings in the .7:1 OD, with the lock-up converter fully engaged in lock-up.

 

[The73vetteman]

What kind of gearing/transmission?

Tom, how do I find the final drive ratio? Are there any markings on the diff to tell me what's inside?

'73