Gas Mileage?

Purdy Swoft's comment regarding improved gas mileage with dual updraft B-carbs is intriguing as well as the theory he proposes. I know of a guy that makes his own dual updraft manifolds and put them on all of his A engines with the claim that both power and mileage are improved. Some of us questioned this as it seems counter-intuitive. However, a recent trip showed his dual-updraft Zenith-1 carbs gave him 21 mpg and he left everybody else behind him on the hills. I was impressed.
 
Thank you very much everyone!
Would there be any noticable gain in going with a header as opposed to the stock exhaust manifold.
From what I've read about dry lakes racing before WWII, alot of guys didn't see any improvement when going away from the stock manifold.
I realize when sticking with the updraft carb this may not be an option.
 
I just returned from a 600 mile trip and got 17-18 in city driving and 22.5 in country driving. I made several checks and always filled right to the very top. I have a completely stock 28 Phaeton with a well worn engine with 50 lbs compression in each cylinder and 3.70 rear end. I drove 42-45 MPH and have no side curtains to help the air flow. I have an Aries muffler.

After I rebuild the engine and add counterweights and a higher compression head I hope to get about 24 MPG during country driving.
 
I drove my Vic from Los Angeles to Las Vegas last month, about a 500 mile round trip. Checking the gas mileage I got a consistent 17 MPG. The car has a Snyder head, a Ryan 23% overdrive, and a 378 rear end. We were traveling alone and I was pushing the car the whole trip between 55 and 65 when I could. Lots of steep grades to climb during the trip. Carburetor is stock Zenith and the ignition is stock.
Tom Endy
 
cradlescyth said:
Just a thought. HANG the gas millage and enjoy!!!
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that's always been how I look at it too, but on our French Lick trip Judy calculated our gas mileage.

we did not check every tank, because sometimes we forgot to write down the gallons and some stores do not print quantity on receipts.

worst was 15.6, best was 19.26

'31 slant T/S with Brumfield 5.9 + Mitchell OD. the trunk was filled, the back seat was loaded to the top of the seat backs + 2 sidemounts creating extra drag.

your mileage may vary......
 
Rideing with the lid open in a coupe gives good air circulation in the cab in hot weather especially if you let the windshield all the way out.

I use to drive my 31 coupe as a daily driver. In hot Alabama temps the comfort of the air moving through the cab is more important than the wind resistance or gas mileage.
 
Larry Brumfield said:
"Would a 6:1 cast iron head make an improvement?"

I can't speak for other brands but the Brumfield Heads will definitely help the gas mileage. Even people running heavy fordors loaded with people have reported significant improvement.

This is because the Brumfields Heads generate considerable turbulence by design in addition to the increase in compression. The result is a more uniform mixture that allows the fuel charge to be consumed to a greater extent with less waste than with the stock head and also some other brands of high comp heads as well.

Moreover, the increase in power allows a reduction in the amount of throttle necessary to maintain the same speed and load. (Notice I said "same speed and load." Wide open throttle conditions or generally fast driving are a different story.)

Also, depending on the level of ethanol (pump claims 10% or less in TX.) the gas mileage will be lower than in the past.


Larry B.
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Higher compression ratio results in a higher thermodynamic efficiency (better gas milage) for automobile engines. That is one reason diesel engines(20:1) have higher gas mileage than gasoline engines(10:1). The other is that diesel weighs more per gallon than gasoline.
 
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Mr. Texas,

You know a little something about compression and chemistry but you obviously don't know much about cylinder head design on gasoline engines.

The difference in the amount of turbulence generated in a cylinder head can make a considerable difference in the amount of fuel consumed. Turbulence is the spinning action of the mixture as it is being compressed, and it is created when the air flow follows the shape of the combustion chamber. Turbulence is also influenced by the quench distance and the surface area above the piston.

The proper amount of turbulent air flow allows the maximum amount of the mixture to be vaporized and completely burned. A properly designed cylinder head, such as the Brumfield Head, tends to collect partially vaporized fuel that would otherwise cling to the surfaces of a cylinder head with poor design.

Well vaporized fuel increases fuel economy.


Larry B.
 
On a 300 mile trip last fall I got 21 MPG (avg) on my Town Sedan. It is equipped with a HC (5.5) head, B Cam, B carb and OD.
 
My '30 Tudor with a stock, fairly fresh engine with 160 degree thermostat, Pertronics ignition and Zenith 2 carb with a K&N air filter gets 25 - 26 MPG on the average highway at 45 MPH. Gas adjustment closed most of the time on the highway. When operating properly, the Model A passenger car is supposed to get 20 - 30 MPG, according to Uncle Henry's engineers. You know how engineers are, though.
 
We went on a 180 mile trip yesterday. Drove about 40-42 miles per hour. Engine bored .080 over with Brumsfield head, stainless valves. Otherwise stock. We got 21.92 miles per gallon. Four large adults in a Tudor. I think I'll be satisfied with that.
Jon :)
 
12.5 with mine that is with a lot of 50mph + driving and I dont ***** foot off the line. It get much better gas mileage then my 68 pickup with a 427 big block
 
Zach asks "Have any of you checked what kind of gas mileage you're getting in your model-A's?"

The answers are written in the published road test of several car magizines and those tests are in posts by skip. Gene Creighton states: "Never a bear for performance, averaging 21 mpg..."

Designed top speed and MPG of the 'A'
Read on...

ModelAspecsfromMotorTrend.jpg


ModelAspecsfromMotorTrend1.jpg


ModelAspecsfromMotorTrend2.jpg


ModelAspecsfromMotorTrend3.jpg

skip.

 
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My 28 Sports coupe got 22 miles per gal. This spring on 1200 mile tour. Two other cars got about the same. this was at 45-50 miles per hour. Two were stock except high compression heads. Mine has a 5.5 head, B carb , bored out intake. 1-3/4 intakes valves, counter weighted balanced crank, stock 378 rear gears.

The most imporant thing is get your timing right, get you gas mix set right. I always move the spark lever for conditions. Just think like you were a modern distributor.
 
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