Not clear to me, these were also long ram propane conversions?

Also thought Propane is always best suited when a decent upgraded CR can be added to solution, which you did not mention?

I would also think Propane on a long ram setup would be a rather "hot" temp wise intake charge, because of long exposed rams and lack of heat of evaporation contribution of the fuel.

Installing a propane fuelsystem on a low compression 'turd' (smogger) engine only results in ending up with a bigger turd engine.
Propane likes its own set of properties in an engine like proper timing-curve and increased compression ratio for instance.
If a gasoline engine is not optimized for a different type of fuel, it will orcourse never make more power.

For long ram intakes, propane, being a dry gaseous fuel, would be better to use as there's no chance of fuel re-clinging to the tube walls again during cold intake temps and slow airspeed during idling for instance.
Also carb heating is not desired as it only makes the air less dense which means less fuel entering the engine.

The long ram could indeed be functioning as a heat sink so maybe a reflective coating or other kind of thermal barrier would help here.
But we might be straying offtopic as I don't anyone converting there longram system to propane that easily here

Isn't there a financial advantage in your country to convert your cars and light trucks to propane?
BTW both of those vehicles had low compression H.D. industrial motors for regular gasoline, not optimized for propane.
I spent nine months in Germany in 1967/1968 in the U.S. Army, I was shocked on how much the government fuel taxes where on gasoline over there back then
I remember paying around 23 cents for premium a gallon in SO CA before I got drafted in 1966 and a tiny bit more two years later
A G.I could by fuel ration coupons for gas from the PX on base with no taxes on it for 21 cents a gallon for regular or 23 cents a gallon for premium and the Germans were paying 91 cents a gallon up to 95 cents a gallon out of the same pump(fuel was sold by the liter, not gallons but the math worked out that way back then)
I hate any government that doesn't serve the people who pay there salary as safe and efficiently as possible

Yes propane is popular overhere because it is less taxed then gasoline.
1 Liter of (liquid) propane (LPG) is about €0.58 ($0.66) x3.785 = $2.55 p/gallon.
1 Liter of Gasoline is about €1.58 ($1.80) x3.785 = $6.81 p/gallon.

My daily driver is a '73 Dodge Dart with a 11.3:1cr iron headed 360ci under the hood and runs on propane.

Propane as normally used has a big disadvantage, that being that when it is vaporized and heated it takes up a lot of room in the airflow. The most power is made when the fuel goes into the combustion chamber in very small droplets which then vaporize for combustion. And if a very small percentage of the liquid fuel vaporizes in the intake manifold it cools the charge down and makes the air denser. So contrasting that wiht propane which is all vapor before it passes the intake valve and you can see part of why it doesn't make power.

I think there is power to be made using the propane's latent heat of vaporization to cool the charge down, possibly even using some sort of eductor effect to induce more air into the chamber.

R.

So how is liquid Propane metered in this typical automotive format? Seems with a boiling point of -50F ?, it would be rather difficult to get it even past the intake valve.

dogdays is correct; Propane lacks the cooling properties gasoline has because it doesn't vaporize anymore after the 'convertor' (vaporizer).

Liquid propane injection works through a convertor, in-tank pump and fuel-temperature sensors and let the ECU compensate injector timing, because a 'warmer' fuel will mean there's more pressure behind the injector, so a shorter injection time is required. I'm not sure if the fuelpump-pressure from the tank is regulated as well but wouldn't be surprised if they do.

Besides the low boiling point, liquid propane is also under pressure. So the moment it's injected, not only will it return to vapour quickly, it also depressurizes which draws more heat from the surrounding.

I remember reading a article about how much BTU each type of fuel contained in a liquid gallon, diesel then was suppose to have around 230,000 BTU (at the time of that article) (the new low emission diesel fuel now has around 130,000 BTU is what I've been told on here ) premium gasoline had around 110,000 BTU, methanol alcohol had 89,000, ethanol alcohol had 85,000, propane (I may have these gas liquid gas figures mix up ) had 58,000, butane had 57,000 and natural gas had 55,000.
I don't think this article show Nitromethane fuel numbers
If I am remembering these numbers correctly you can see why most big commercial trucks, trains and ships use diesel power for moving stuff

Heavy engines and equipment needs torque to get moving or do work. The best way to create torque is to build compression.
With high compression you need a fuel makes use of this and works in such an environment.

A long stroke crank design also plays a big part in max torque output applications.

Long stroke allows short, light, flat piston with high static CR.

There is some information concerning the long ram set up in this book. I can't remember how much but i do remember seeing charts that illustrated how much more torque they produced and where in the rpm range:

Scientific design of exhaust and intake systems

30" tubes, tunes at 2,800.

We are jumping around here on different subjects, the long stroke comment I made was in reference to the solutions another suggested on moving "heavy' vehicles, and the "thinking" the best way to gain torque was thru compression which I am not in agreement with as an end all. In gas powered typical street applications, with pump gas there is effectively a CR limit, and any gains chasing smaller CR increases eventually results in diminishing returns.

However there is practically no limit on increasing stroke, and the benefits from larger crank leverage that affords in achieving greater output torque numbers is also nearly unlimited. I am not for a second stating there are not downsides by increased stroke, mainly its a better design path for gaining increased torque then approaching a capped CR limit.

And since we are now discussing different formats here, most heavy "vehicles" are diesel, have long strokes, have heavy pistons, and pistons are often contoured.

Stroke producing torque was identified as mythical around 1940.