IMO, there are a few factors:

• older cars are heavier than newer cars
• carburetors cannot be as "finely tuned" as fuel injection systems
• old cylinder heads/intakes probably don't "flow" as well as new ones
• old ignition systems are not as efficient as new ones - especially the new LS1 design with individual coils per cylinder - big improvement!
• ultimately, nobody wants a "fuel efficient" old car --- all old cars are just meant to be loud and fast!!!

Well, those are a few thoughts anyway!

 

My 69 Firebird 400/400, 9 MPG city 12-13 freeway, 13 if I was a good boy.

 

72 camaro 502 800 edelbrock 4spd. 11 mpg if I baby it..but that only happened once
(I did't like it)

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72 ss 502 4 speed hugger orange

 

with my new engine, I'm hoping for 8...with the old 400 engine, I got 13 when I BABIED it, and about 9-10 normal(well as normal as I ever drove it!) driving.

 

Don't forget air drag, today's bubble cars are great.

 

I have to dissagree with one statement, older cars weighing more than newer ones. I have had a 67 camaro and a 72 rs camaro and now we race a 67 rs Camaro that weighs 3000lbs, and none of them weigh more than my 87 Formula (~3600lbs). I agree with the rest, fuel injection, computer monitoring and the better ignition systems all lead to better gas milage(mostly enforced by the government).

As for my gas milage, my first 67 had a 250 6 cyl with a 4-speed (not stock) and it got 19-20 mpg on the highway. The 72 had a 350 with holey 600 vac secondarys, and it got 16-18 mpg and it ran a best of 15.00 in the quarter. The car we race now is better measured in gallons per mile We make about 4 passes before we have to fill up the 5 gallon fuel cell.

------------------
Wayne Best
Best Racing
67 rs Camaro

• 355 cu in Chevy
• 12.5:1 compression
• 10.90s @ 120 mph

87 Formula 350 w/388cu.in. motor

www.geocities.com/best_racing

 

13.5 in town and 15.5 highway

------------------
Eric
69 Glacier Blue Camaro with 1977 350 TH350
B&M shift kit- Stage 2
B&M Megashifter
10 bolt open 2.73
Speed Demon 650dp
MSD Distributor & MSD6a
Flowmaster Delta Flow 40 series mufflers
manual disk brakes
Harwood fiberglass 4" cowl

[This message has been edited by Murfys_Law (edited August 12, 2002).]

 

Well, maybe Dr. Mudge's theory is right about the increased air-drag? I guess cause old cars look bigger, they look heavier, but I'm sure that they do have more square-footage on the front, and more squared shapes, so they probably do push more air. All the theories sorta make sense, don't they?!

 

SOME old cars are heavier. A Olds Delta 88, or vintage Impala, etc... Actually, if you watch the new-car mags, the trend is towards heavier cars as engines get better. Sound deadener, crash bracing, computer-controlled suspensions, etc all weigh something.

second gen camaros weigh about the same (a little more some years) than 4th gen cars. and the 4th gen cars come from the factory with alot of fiberglass parts - second gens are ALL metal!

I think the biggest influence is US. When was the last time you thought "for my next Camaro engine, I'd like to build for the best fuel economy I can!" Everybody will tell you to stroke it to 383 instead, it only costs a few hundred more - and a few more MPG
Modern cars are built be the OEM's to meet strict federal fuel economy standards, thus the good economy numbers that a '02 'vette or Camaro turn out...
HP/Torque takes gas - plain and simple. The more you have, the more gas you'll use. Of course, EFI, hyd roller cams, CNC heads, overdrive trannies, etc all help, but those can be retrofitted as well.
As long as my camaro turns something in the double-digits then I'll be happy (it'll be a 350, 235/245 solid cam, Q-jet, TH350)
It'd be interesting to post on one of the 'newer' forums and see what economy some of the guys with built (and stroked/bored) LT1/4 or LS1/6 motors get!

 

Yea, our 67 isn't very aerodynamic and when you have a big head wind it shows in the time slips at the track.

What struck me as funny, looking at the early 90's cutlass and compairing it to the firebirds you would think that the firebird was more aerodynamic but according to Warren Johnson, he said the cutlass was more aerodynamic because it had a smaller frontal area than the firebird which means less air drag on the body. Anyway, yes the newer cars have a bigger advantage with aerodynamics also.

 

I asked open road racers how much HP it took to make a first gen fast, and they all agreed that it takes "significantly" more to get a first gen going fast on Highway 318 than it takes a 4th gen. FWIW the 4th is also much natural to duct tape the front up to smooth it even more.

The first gen is my dream car (soon soon!!!), but yes its got more drag than the 4th gens for sure, windsheild, nose, hood angle (downforce advantage for the 4th gen), and from what I remember of the trunk downward angle I'd say the 4th gen has advantage there as far as sticking to the pavement. ~25 years engineering makes a difference.

 

Oh, my 4th gen "pumped" out about 12 city 15 freeway, 3.42 rear gears 6 speed.

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94 M6 Koni DA, 600#/140-160#
Shorties, Cutout, K&N
Stock bottom 411.91 SAE RWHP@5900 RPM (dying rotor, fixed)

 

My 67 SS stock 350 w/3.42 gears and a powerglide averaged 15 and a best of 18. Now I have a 2004R in it and it gets in the 20's, and a high of 24 on the highway.


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67 RS/SS 350 2004R (owned since 81)
97 V6 5-speed Coupe (work car ordered new)
My Camaro

 

When talking about air resistence I have heard that to double your speed you have to increase the power by a factor of eight, just to over come the air. That is why frontal area is so important. You know how forceful the air can be if you hold your hand flat out in the air when you are on the highway. Compare that force with driving in the city.

And about milage, when driving a Musclecar no one really cares.

Jan




------------------
Jan Suhr
Stockholm, Sweden
-----------------
1969 Camaro Z-28 Cortez Silver with 396 BigBlock

My homepage

 

Well, not sure about that but it shouldn't be too far off the mark.

100 HP will get some cars to 100 MPH, but takes around 500 HP to get many 'sporty' cars to 200 MPH, I belieev thats what it took the ZR1 to hit 202, around 515 HP or so.