empirical data for my 41 Dodge

[GTfastbacker]

Hello there,

Now that our D19 Coupe is finally registered and insured in Germany, we can soon do the first test drives at weekend.

(1941 Dodge Business Coupe D19, bone stock, P18 engine)

 

To understand whether our car is running properly, I would like to ask for some empirical data:

Top speed under normal conditions (please not down hill Pikes Hill with a tailwind 😉 and strong solar winds from the back)

 

Normal travel speed on the highway/interstate

 

Normal average fuel consumption

 

Normal oil consumption

 

I have already noticed that the performance cannot be compared to our 427 Ford, but I would like to understand how little is normal.

 

Thank you so much

Joe

[Sam Buchanan]

Congrats on achieving official blessings from the powers that be!

 

In regard to "normal" highway speed (wow, this is a subjective topic...) you can derive some numbers and go from there. These engines are rated for max power at 3600 rpm. Can this rpm be exceeded? Certainly, but those sharp Mopar engineers considered this a good redline for longevity for these long-stroke engines. A general rule of thumb is to limit sustained highway speed to less than 80% of redline rpm.

 

Most likely you don't have a tach in your car but you can calculate some numbers for your car. You just need to know tire diameter and final drive ratio. My P15 has 1:1 transmission ration in third gear and 3.91 rear end ratio. Verify the numbers for your car. Then use a calculator such as this one to determine engine rpm at various speeds.

 

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

 

Using the above mentioned rule of thumb I get a reasonable sustained highway speed of 55-60 mph and the engine seems happy at that rpm. I've never calculated fuel mileage because it is a moot point for me, my F150 gets better mileage and has air conditioning if I'm concerned about such things.

 

There is no "normal" oil consumption, kinda like asking someone how much food we should eat......just keep enough oil in the engine to compensate for usage and leaks.

 

Enjoy your new ride!

Edited July 12 by Sam Buchanan

[Plymouthy Adams]

yesterday's cars as that of today were engineered to perform with peak torque at lowest RPM to sustain said torque associated with the gearing to drive the vehicle of X weight over X road conditions at the time.....as roads and technology improved, the number have gone down needed to perform.   OD cars are geared to travel the posted highway speed at 200 RPM below peak torque with the 200 RPM in reserve to crest overpasses and slight rises in the highway without need to kick down to a lower ratio.  Mopeds today are as fast and capable of top end speeds most drive these hulks today shy totally against sustaining.  Any speeds above the selected gears to match peak torque will require RPM...sometimes a substantial RPM increase....don't forget weight in the equation.

 

A well maintained and tuned vintage car while cannot achieve many levels of performance of today's modern car, they can still be driven with regard to their limit safely and at speeds not to impede flow of traffic.   If you choose not to drive at posted speeds, then utilize secondary highway and enjoy the scenery and the joy of driving.

Edited July 12 by Plymouthy Adams

[FarmerJon]

I have always driven my P15 like a normal car. I keep up with traffic, and have little problem passing slowpokes. I DO give an extra car length in following distance. 70mph is pretty common when I am on the highway,  but have hit 85. My car is mostly stock, but does have the exhaust manifold split and dual exhaust run, and a tall edmunds style, low restriction air filter.

 

By the numbers, your top speed (assuming stock 4.10 gears and 28.3" 6.00x16 tires) is 73mph. 

I get around 16mpg, with around 20% highway and the rest town with light traffic. 

I leak more oil than I burn, but usually add a quart every 500-1000 miles, which equals around once every other month.

 

[greg g]

Gutenberg morgan.  My 46 ply,outh business coupe has 47000 miles on a rebuilt 1956 230 cu in engine.

I usually drive on non interstate highways at 55 to 60 mph.  It gets 17 mpg. Idle vacuum is 20 inches through dual carbs on a Fenton intake manifold. It runs at 170 degrees with the original radiator, with 42 psi oil pressure.  It consumes or leaks 16 ounces of oil per 700 miles.  I use 15w40 non synthetic diesel engine oil.

Our car usually gets driven about 3 to 4 thousand miles annually, with at least one trip of 250 miles or more.  I have my travel kit with oil, Brake fluid, fan belt, a set of points, a set of spark plugs.  I also carry a spare ready to go distributor, a tow rope, jumper cables, a couple fuel filters, ground cloth, gloves, clean up wipes, a small tool box and small trolley jack.

 

Three years ago we installed an over drive trans which boosts gas mileage to 19 to 21 mpg and reduces engine revs at ~60 mph from aprox. 3200 to about 2400.  

Here in the middle of New York state, we have state or county highways that parallel our interstate highways and provide a driving experience more in tune with the cars design and engineering. The speed limit on these roads is 55 mph, but most traffic moves at 60 or so between cities villages and other built up areas.

Is your car a real Dodge, or is it a Plymouth with Dodge badges and trim?  Chrysler had many variations and varieties of export vehicles, or is yours an imported USA market model?  Put up some pictures when you can.

 

 

 

 

Edited July 14 by greg g

[greg g]

 

Edited July 13 by greg g

[Veemoney]

I have a 53 flathead in my 47 pickup truck. It is all stock except for shaving the head to increase the compression. Mine was set-up as FarmerJon shows in his calculator snapshot. There are variables that I feel effected normal driving speed for me that you may or may not have . 

 

I experienced similar fuel and oil consumptions as others on the thread. My normal driving speed with the truck trended around 45-55mpg mainly due to not wanting to push the rpms up higher and the bias ply tires which tended to follow any crack or path worn into the road. They also transmitted a firmer ride, and I had more rattles at the higher rpm. When I switched to radial tires my normal driving speed increased and a few years back I change my rear gearing to 3.54 which is a much more relaxed ride and enjoyable at 60-70mph. 

 

[GTfastbacker]

19 hours ago, greg g said:

 

Is your car a real Dodge, or is it a Plymouth with Dodge badges and trim?  Chrysler had many variations and varieties of export vehicles, or is yours an imported USA market model?  Put up some pictures when you can.

 

 

 

 

 

Hi Greg,

 

the car came from CA and spend his last 20 Years in Kansas. We bought it there last Summer.

 

Its in very nice condition and we drove this week 300mls without any issues.

It gets 18mls from a Gallon. Oilpressure us near 60psi with 20w50.

Temperature  at 160 deg.

 

we got the ole tube radio working with a home made AM transmitter and iPhone, so we can let Frank Sinatra sing nasally through the tin can.
Periodic correct Low Fi

 

 

 

 

[greg g]

Very nice.  Love the front design. Dashboard is in great shape.  Hope you have many trouble free drive

[greg g]

Out with some friends, under the bonnet, ready for the weekend.

[Plymouthy Adams]

Greg, like the pic-I-nik paraphernalia, is your water jug by chance crockery lined?    I have an old Alladin that is as such with aluminum cap and cup and they are very hard to come by these days in serviceable condition.   Probably have fully 4 outfitted picnic baskets but just the one water jug.  Photo lifted from e-bay but just what I have 

Edited July 15 by Plymouthy Adams

[greg g]

Liner is plastic.  Exterior is metal.  If you asked me where it is, I would right now just be guessing. The green plaid cooler was sent along to Mark Duggan.

Edited July 14 by greg g