455 as fuel efficient as 350 in a GM driving test - anyone heard about this?

Discussion in 'The Bench' started by elagache, Jan 1, 2013.

  1. elagache

    elagache Platinum Level Contributor

    Dear lovers of V-8 Buick engines (da' bigger da' better!) :3gears:

    There was a post on the Station Wagon Forum that ought to be very interesting to us fans of assertive Buick engines. The relevant snippet is:

    I had never heard of this test, but I've made a substantial investment based on an idea like this!!

    Does anybody on this forum know something about this GM driving test? I would be interested to learn more about how GM did this and exactly what were the results.

    Cheers, Edouard :beer

    P.S. Of course there is one small problem in what apparently GM did in their testing. It quite distinctly says: reasonable driving . . . .

    Funny, . . . . did I hear the entire V-8 Buick board scream: Bummer Dude!! :laugh:
  2. John Codman

    John Codman Platinum Level Contributor

    The key in this test would be the rear axle ratio. The 455 can pull a lot higher gear then can the 350.
  3. TurboV6

    TurboV6 Platinum Level Contributor

    Your right, the key word may be "reasonable"

    In theory it sounds good, the smaller 350 is working harder to do the same job as the stronger 455. It also seems like every 350 car I have owned got horrible gas mileage anyway.
    When gas was .20/gallon, did anyone really care
  4. Stampy

    Stampy Well-Known Member

    That was the impression I got from my 340. Not enough motor working too hard to move too much car. I was getting about 9 MPG, driving conservatively. I am sure that with a sharp tune and a carb rebuild I could have gotten 12-14... but I think the 455 is going to provide a similar MPG, but at a significantly higher Fun-Per-Gallon.

  5. urbancowboy0307

    urbancowboy0307 Silver Level contributor

    I would think in a heavy car the 455 would get better gas milage than a small block, but in a lighter car I would bet a SBB would get the best milage. A lot of factors could effect this as well trans set-up, rear end ratio, and what type of driving, and of course your idea of "good" gas milage. :)

    in my 66 I'd get 14 city and 19/20 highway. it's as far as I know a stock '67 340-2 with about 80k miles, ST-300, 2.78 rear and 26.5" tires. I drive pretty conservitively keeping the RPMs under 2000 if I can. it gets the same milage as my SFI truck so I'm happy, I'm sure dropping a 455 in there would give it a little (ok a lot!) more get up and go, but then I'd be putting my foot into it more and of course see worse gas milage. :rolleyes:
  6. nekkidhillbilly

    nekkidhillbilly escaped mental patient

    the 69 papa had would 21 mpg on the highway was stock 350 car. never seen a 455 do that. nailheads will though.
  7. online170

    online170 Well-Known Member

    This is all apples and oranges, but in college (40 km round trip, 50/50 highway city well all highway, but half of it was gridlock), I drove my skylark to and from college every day in the summer because it was the same on gas as my 3.4L 1996 Lumina Van.

    The skylark had a 71 350/2bbl. The 2bbl did ALOT better in city driving, than it did on the highway. Rear gear was 2.73. It had enough torque to get the car moving with very little effort, and city driving in 3rd gear added up to efficiency.

    20L of fuel would last me 4.5 days (round trips). Thats a total 180kms, which is 11.11 L/100km or 21.19 USmpg. (hand calculation based on google distances and litres measured at the pump). It worked like clockwork.

    I found that if I did pure highway driving, that mileage was more like 14mpg. (used 25L to 27L).

    I later swapped a TA intake, and a holley 750dp carb on there, jetted very close to stoich, and I gained all kinds of power. However, the mileage was now 17 L/100km, (90% highway) or 13.8 USmpg. It didnt matter if I drove aggressively or nicely. I would imagine the 455 would behave more like 15ish MPG, and i dont think you have a hope in hell getting to the 21mpg mark. But its all speculation for me in the big block world.
  8. 75Riv

    75Riv A.K.A. Harry Clamshell

    455, but with lower compression and other gear ratio still needed fuel economy testing in 1975:

  9. LDPosse

    LDPosse Well-Known Member

    My '71 Skylark with 455/TH350/2.56 with 29.5" tires, and speedometer gears to match the combo within 1%, usually will return about 17.8 MPG in "reasonable" highway driving, keeping at the speed limit (65). I never did any better with the old 350/4bbl on the highway, but in short trip and in-town driving, the BBB seems to have a 1-2 MPG penalty.
  10. John Codman

    John Codman Platinum Level Contributor

    Our '72 Cutlass (350 4bbl) would consistently get 21 mpg on the highway. It had 2.73 gears. I had a battle with GM to get that ratio, as the Olds also had the trailer towing package. They wanted me to get 3.23 gears. No way.
  11. 69GS400s

    69GS400s ...my own amusement ride!

    ... just another point of info from Buick's I've owned. all mileage is over a complete tank running on the highway

    1) 69 Sky with 350-2, 350/th350 - 3.23 open rear - 43K miles - weight 3700# - totally stock and tuned very well - best ever mileage 14.3

    2) 68 Buick SportWagon 400-4, 400/th400 3.23 open rear - 29K miles - weight - 4400# - totally stock and tuned well - best mileage 16.8 * With A/C on

    3) 69 GS400 Convert, 400/th400 2.93 open rear - ~93K - weight - 4085# - totally stock and tuned well - best mileage 19.3
    Last edited: Jan 3, 2013
  12. elagache

    elagache Platinum Level Contributor

    Article in "Collectable Automobile Magazine" (Re: 455 as fuel efficient as 350)

    Dear V-8 Buick fans big-block fuel-efficient cars,

    Thanks for all the thoughts on how to squeeze more miles out of a big-block Buick powered car.

    I just got a reply from MikeT1961 on the Station Wagon Forum and he tells me that he read about this GM driving test in an article on 72-76 full-sized Buicks in "Collectable Automobile Magazine". I'll see if I can hunt down the article, it should be interesting.

    As I suspected, this driving test must have been done in the wake of the OPEC oil embargo in 1973. Believe it or not, I remember being in the back seat of my trusty wagon waiting in line to get gas as a kid during that oil crisis. Worst of all, gas stations stopped giving away hot-wheels cars because of that crisis!! :mad:

    Interesting memories . . . . . how times (and I) have changed since 1972 . . . . .

    Cheers, Edouard :beer
  13. BQUICK

    BQUICK Well-Known Member

    In the "gas crisis" of the 70s I ran my 67 Riv 430 between 55 and 60 mph and pulled down 18.5 mpg. That's with 3.42 gears and switch -pitch converter. I'm sure with 2.73 gears I could have topped 20mpg. A fuel pressure regulator I added to control the pressure at a steady 5 psi I'm sure helped since without it the pressure was pulsating between 7 and 9lbs!
  14. SteeveeDee

    SteeveeDee Orange Acres

    When that OPEC-er boy's embargo started, I was in Illinois, leaving Navy A-School, headed back to my new duty station in California. The gas station guys would only let me have 10 gallons. What a joke. I got 23+ MPG with it (327/4 speed/3.08 axle), driving like a banshee. Later, when I was med-evaced out of durance vile, my sister drove my car back from my home port at low speed (55 MPH), and the thing got over 24 MPG.
  15. Nailhead

    Nailhead Gold Level Contributor

    Best gas mileage I remember in any of my Buicks was my 65 Sportwagon with 300 and 2bbl. Don't remember exact numbers, just that it was better than all the nailhead powered full size cars and better than my 65 GS.

    As for the 70's gas crisis, my daily driver was a 68 GTO vert, 400, M21, 3.90 rear. I always tried to gas up where the line ran downhill so I could coast in!

  16. 69GS400s

    69GS400s ...my own amusement ride!

    I was 14 during the embargo ... Dad used to give me his "Old Man hat" and let me drive his '66 Corvair about 1.5 miles and back alone to sit on the gas line.

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