VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 1940 fuel consumption

Hello everybody,

Let me ask: How much fuel should a 1940 special Deluxe 4door take normally?
Have been out with my 1940 to a vintage car meeting last sunday, I guess it was first time since maybe 1960 the car did run more than just around the corner. So some surprises came up.
1st as I wrote in another topic, the motor did run out of gas when driving faster than 50mph. After some road tests I am sure now the problem is a corroded gas tank and the rusty particles block the line at first beginning inside the tank.
Did remove the filter in line just behind the tank and connected the tanks end with a long hose and did try to blow air in and at first moment it was as hard as you try to blow up a kiddies ballon, after blowing the dirt out it was easy and I could her it bubbling at the opened filler plug. There must be an awful muddy mess inside the tank after decades without driving regularely.
2nd:
Now complications begin: We in germany think completely different how to calculate what a car needs. We calculate in how many Liters for 100 kilometers.
I know your way of calculating is usually how many miles per gallon.
Did try to find my lost mathematics anywhere in my old stupid brain to convert it.
Maybe I am right: We did drive 128 miles there, start with gas tank filled up until it reaches the filler plug.
After these 128 mls I did fill up again and did need 32,66 Liter which is 8,62 gallons.
So in german system the car did need 15,9 Liter per 100 kilometers.
In US-System it is 14,84 miles per gallon or 6,73 gallons per 100 miles.
I did think and calculate everything twice, so it should be ok.

It was a warm, sunny day, we were three people in the car, no luggage, and just straight on overland, no stop and go, no big hills or mountains.

Comparing that measured out consumption with results of a road test result from an official chevrolet switzerland advertise 1940 it sounds a bit too much for me. They from switzerland wrote something about 10,8 to 12 Liter per 100 kilometer. That is less than the 15,9 mine did drink.
And not to forget, I could not drive fast because of the clogged fuel line and as well I am no race driver, even not with a vintage car. But the 1940 has a modern downdraft carb, and my gone 1931 with the updraft which needs more fuel in general did for sure take less than the 1940 now does.

Must say, maybe it could go down a bit after some service which is not done yet.
Means checking and maybe adjustment of intake/exhaust valve play, ignition (timing?), advanced spark, carburetor.
Before digging to deep under the front hood I want to ask you about your experiences.
So, in conclusion, is 14,84 mls/gallon ok or sounds it as too much for you?

Regards
Stefangermany

Not sure the btu/gal or Kcal per liter in the gasoline in Germany. That will be a factor. On 100% gasoline you should get 18-20 miles per gallon (mpg) or 13.07-11.76 l/100km. With 10% ethanol that would be 16-18 mpg or 14.7 - 13.07 l/100km. Those figures will be with a moderate load and mostly highway driving at 40-55 mph (64 - 88 km/hr).

If I remember correctly, the car has five people in it. I think it did rather well and I know that you were thinking that too.

Sounds about right.
Charlie

My '38 gets around 17-18 MPG @ 50 MPH. It drops to around 12-14 @ 60. She just doesn't like being pushed that hard.

At 50 MPH they will usually give about 17 MPG. At 65 MPH 14 or 15 MPG.(with the 4.11 ratio). A mile or to to the alln better with the 3.73 ratio.

The General Motors proving ground test was as follows. This is with a 600 pound load and a steady speed going with and against the wind.
30 MPH 20.9
40 MPH 19.4
50 MPH 17.8
60 MPH 15.6
70 MPH 12.5 MPG
This is pretty close to what my 1939 did with the 4.22 ratio.
To do a real test the trip should be about 400 miles to cancel out the highs and lows such as how full the tank was at each refilling
The 1937-1940 cars did not give the best milage. The 1941 and up gave about 2 MPG better. YOur low compression ratio with the later flat top pistons and 1940 head will reduce power as well as reduce the fuel milage. A 1949-1953 216 head would solve that problem.

Gene,

Did your PG fuel consumption data actually say "with and against the wind"? If it did, I'm surprised. I spent 15 years doing that type of testing and rarely went through a week without doing it at least once. If a wind was present we always ran with a cross wind, not with or against the wind (one of the reasons we had a North/South straightaway and a East/West straightaway to pick from). If there were white caps on the lake the test was held off until there weren't any (12 mph wind or less). The fuel consumption tests were run twice in each direction for one mile in duration at each test speed and the two check in the same direction had to be within 2 CC's spread and no greater than a 4 CC's spread between directions or the test was considered invalid. Everything was averaged from the four one mile runs to determine the MPG at that speed increment.

All vehicles using a common drive train system within a given vehicle line were tested at 600 lbs. over the heaviest optioned vehicle within that vehicle line. Coupes, sedans, convertibles, and station wagons all weight differently. Test weights were determined by choosing the highest vehicle with the most options available and adding 600 lbs to that value. The 600 lbs. was considered a four passenger load and even in the 50's and 60's we all marveled at that 150 lb per person standard. On occasion we had to change the driver or observer to get down to the weight requirment.

I should have said a two way run which I always pictured going with and against the wind.

I have been averaging 17-19 mpg with a 1940 with the optional 3:73 gear ratio. My 40 can cruise for hours and hours at 60. I drove 604 miles from the 6 cylinder tour in Illinois to Ohio in one day at a steady 60 mph. No problems with the engine, babbitt bearings or anything else other than a sore butt.

dtm
ps. Maybe with the gas at $4/gallon I should be driving slower?

Hello Mr. toolman,
please dont cry about maybe 4$ per gallon! You should know we in germany have to pay actually around 9$ per gallon and the end of the climbing ladder is still not in sight!

Regards
Stefangermany
(filling up in Austria, living at the border to, paying 8$ per gallon there and feeling not really good about the price)

In general, thanks for all advice, it tells me my 1940 guzzles a bit too much, I should set her on diet.
Next should be a big service, valve clearance, ignition settings, carburetor adjustment. Maybe I bring her to the point to drink moderate.
But I will wait for Mike Bullers visit here in early may to let him see the car for some advice.

Stefangermany