I've always had a hard time seeing people get high teens to 20 mpg with a 455 or even a 350 with the 3 speed auto. My sister drives our '05 GTO to and from school so 85% highway and she's getting 17.5, Note: fuel injected, computer controlled, overdrive, 366 ci. My 350-2 Skylark got a best of 11.92, my grandpa's GS gets about 9 mpg after he had it professionally tuned (carb, distributor rebuilt etc), our GSX gets 8 mpg if we're lucky, our T-Type gets 17-19 mpg highway, my brother's GS 350-4 that I've been playing with gets about 12 on a good day. I've talked to a bunch of other local people about their mileage and I've never heard anything better than 14, so either we have horrible luck with fuel economy on our cars even after having them tuned, or a lot of people's odometers are off lol :bla: From our personal cars there's a difference of 3-4 mpg between a 350 and 455.
I couldn't agree more. My experience with the 350's is similar, about 10 or 11 around town and 15 hwy, although I've never been known for having a light foot! But I still have a hard time believing 20mpg with either engine. At least not from the early examples.
I've seen both sides of the spectrum with my Riviera. My personal worst is 8 mpg in town, driving hard and fast for the whole tank. My best was 20 mpg highway @ 60 miles mph. As an average I look to about 14-16 mpg as an average, and have hit that every year for the past 7 years. It's a pretty much bone stock 455/TH400 with hei and the stock carb and have a 2.93 rear end. As a small comparison, I have a 1994 Chevy Suburban with the standard 350 in it. It gets the same kind of numbers. Actually, it's more predictable, the low numbers are only about 12 mpg, but the high number is only around 18. ( I have hit 20 on a rare occasion, but that's really trying).
You did not state your purpose for the car. Cruiser, Street/Strip, Always On Kill? 350/2.41 gears/T-400/4000lbs 15/25mpg. Stock jetting. 350/3.42 gears/T-350/4000lbs/13.5 ET 12-16 mpg. Rich jetting. 455/2.41 gears/T-400/5000lbs 12/21mpg. Stock jetting. 462/3.42 gears/200r4/4000lbs/13.2 ET 12-14/21mpg. (4.10 gears/12-15/17mpg) Very rich secondary jetting. 462/3.42 gears/T-400/4200lbs/12.2 ET 8-10/14mpg. Very rich secondary jetting. Just for comparison: 3.8 Turbo/3.42 gears/200r4/3400lbs/11.18 ET 12-16/25 mpg. (stock/12.8 ET 16-19/27-29 mpg) Under boost it will burn 300+lbs of fuel/hour (and I need bigger injectors) of gasoline and 50lbs/hour of alky so you can watch the gauge move. Mikey
Trevor when I had my 71 Riv I got almost the same mileage. Not quite 20 mpg on the high end but close. Bob H.
Mikey, this is for my convertible. To cruise. We have almost every other spectrum covered if you see my car listed below. Just wanted some real examples and that is what I am getting from everyone. Michael, I agree. And I appreciate your numbers. Very helpful. Again everyone, I am not trying to be fuel efficient. I just want to see the real life difference between the 350 and 455 that people have experienced. I get 16 in my 2008 5.3ltr Chevy pickup on the highway. Buick Enclave gets about 17. Those are electronic computers that tell me that, I don't ever check. Tyler said his GN was getting 25, before his changes, and still only 20 after that. I always fill mine up when they get low. After seeing all of this information, I'm going ahead with the 455 plan, if I can afford to build it.
My '66 Toronado with a 425 typically gets about 13MPG. My very best was 15, driving my Mom around through northern Mass (no secondaries) :laugh:
A 455 will use more gas idling and pulling away from stoplights. On the highway, there's barely a difference (it will then depend a lot more on aerodynamics and how steady you keep your speed). -BC
Everything I drive sucks gas! I've started a piggy bank :dollar: for my 53 special 455/400tb as I don't plan on using a strong spring on the go peddle. Im sure its my driving but I've never gotten the mpg others claim to get even cruisng 60 on the interstate. But what can I say I like fat cars with fat motors and I live in the hills of Tennessee and prefer driving the car not riding it.
And just as I posted my comment my wife walks in and says "Gas went up 80 cents today!" My comment: That new SUV has got to go if it gets much higher. Of course I never said a word about the 4000 pound soon to be sucking my gas budget dry that's setting in the garage.
In my opinion if I was building something that was not numbers matching I would go with the 455 and one of the 700-RS. The trans can make it the best of both worlds. A great hole shot and a overdrive for highway use, something around the 2.50 to 2.60 range. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com<o></o> Nelson<o></o>
How are you guys getting such good mpg? My skylark with a 73 455 gets 6.5mpg... Sent from my SM-G900P using Tapatalk
The 1972 BAD LAD XGS 455 gets right around 17 (easy with that foot Eugene!) with a stock 455, headers and a quadrajet. I am guessing about a 3:42 gear. The old mans 225's of the same vintage did the same on cruise control. ws
Ancient thread, but as I have said before, for my non-daily drivers, gasoline is probably the least of my expenses. The one expense that I have found to be scary here in sunny Florida is auto insurance. Nobody has been able to explain to me why agents typically want 50-60% more for the same insurance that I had in Massachusetts. One agent wanted $960 for slightly less coverage then I had paid $564 for in Massachusetts. I did find another agent, but the price was still $740 for the same slightly lesser coverage. In Massachusetts I lived 30 miles from Boston, the city that insurance companys say has the highest claim rate in the USA. WTF?
I think you all are missing one vital piece of information: Ethanol in the gas, makes the fuel have less power. My mild, warm 462 (in my sig) gets about 8-13MPG around town, light highway driving. I am not easy on it and I like the sound of the quad moaning, second gear barking. My stock 350 (also in the sig) manages 15-16MPG in town & light highway driving. None of it is scientific, just fill the tank, note the mileage and record it for later. My very first Buick GS 350 got 18MPG on numerous occasions back in the 78-80 when gas had no ethanol in it.
if you guys can't even get 10 with your 455s then you must have severe tuning issues. unless you're pounding the hell out of it. I get about 12 with my stage 2 motor city driving, 15 country driving and it'll just touch 13.5 on the highway. it absolutely flys too
My bad! You oughta see what the $4.95 chinaman key board gets! That wallyworld keyboard is yellow with BIG letters for us old blind guys to see, but even tho I read and re-read my stuff first, one gets by once in a while ou: 17 is much more like it! ws
Massachusetts has significantly less fraud compared to FL as well as fewer uninsured drivers. Both of which are impacting the rate you are seeing. The study showing Boston to be the worst city(I think it was actually second behind Worcester) that I am aware of was done by Allstate. Their market share in Massachusetts is so small as to make that data nearly unusable. "Corrections" can be made to it but again not useful. Others of us working in the indutry raise an eyebrow at that study, Allstate does it to get into the headlines. Don't get me wrong, traffic around Boston is chaotic and it didn't take me long in my 3 years there to figure out why people talk about massholes...
