First, my thanks to those who offered suggestions re the winker. I disconnected it from the steam loop and it delivers oil as it should. To the question. When I first got the car it would run at 35 MPH on the level with the burner coming on for perhaps one minute to get the pressure up to 600 PSI, and then off for perhaps 30 seconds to a minute. Now it fires continually at 35 MPH, and stays at about 525. There are two changes of which I am aware: I set the cut-off back to 575 PSI, and I've taken the insulation off the engine. (It was fibreglass batting, tied on, and I'm going to replace it with proper foil-backed lagging.) Would either of those changes account for the difference, or is something else more likely? The burner seems to fire about as before, taking 10 minutes from dead cold to get the needle off the peg, and then another 4 minutes to get up to pressure.

Dear Ian, You pretty much have answered your own questions with the correct answers. Proper insulation on all of you hot items makes a big performance difference on evaporation efficiency. Wrapping the boiler is most important because of the huge boiler surface area open to the cool air blowing by it. Secondly, this is November and the cool damp air also kills your ability to retain heat in the boiler. The summer's warm dry air is the best time for getting the best performance out of your Stanley. I have driven our Stanleys in the snow and the freezing temperatures really slows them down. An important fact about your burner firing all of the time with out cycling off: It is a very good thing that you can keep your fire on as long as fuel is not being wasted. A continuous fire on the super heater keeps up the super heat and conserves your boiler's water by getting more work out of the super heated steam. When ever the main fire is off, there isn't any super heated steam being warmed up. That makes a big difference in the performance of your Stanley. With our manually fired Stanleys, we can turn down the main fuel supply knob to reduce our fire so that the fire will be "just" continually on. That works well until you discover that you are now climbing a hill and your boiler's steam pressure has dropped below 300 pounds and you have slowed down with IC car traffic piling up behind you.



Edited 1 time(s). Last edit at 12/02/2011 03:58PM by SSsssteamer.

Thanks, Pat. I don't mind the burner firing most of the time: it's just a puzzle. I have the feeling that I don't have the fuel on as much as I did when I first got the car. I'll try turning it up a bit and see if that makes a difference, more in the spirit of curiosity than performance.

Time for a little thermodynamics lesson. Expanding on what Pat said and adding a little bit myself. As you increase the pressure on the boiler the amount of energy (enthalpy) required to turn the liquid water into steam decreases. Let's put it this way. The car I normally operate was set at 525 psi someone moved it up in the spring to 550 psi and in the summer we were driving it with a clogged burner. It was moving at 20 mph at around 450 psi before it would be more like 15 mph at 425-450 psi. Big difference when you think about it.

Now onto the lesson and assuming that you don't have a feedwater heater which you probably do. assume temperatures T1=75F and T2=50F for the summer and winter and P1=600 psig and P2=525 psig for what it seems to run at now

The change in enthalpies are:

∂h1=1146.774 BTU/lbm

dh2=1172.774 BTU/lbm

Most of that like 99% of the difference does come from the temperature. So I would say Pat's answer of the change in temperature is probably the right one.

Another way to express this would be:
assuming 5 gallons of water in the boiler what is the extra fuel spent.

m=41.75lb of water in boiler

so
Q1=m*dh1=47877.8145BTU

Q2=m*dh2=48962.73BTU

assuming perfect transfer of heat which I know isn't true but whatever
your using about 1 or 2% more fuel. But when you add in things like heat loss from you lack of insulation on the engine and the fact things aren't ever a hundred percent efficient. Then it may be more like 5% more. Also I just calculated the energy to heat the boiler in the first place. The lower pressure steam would require a higher steam rate for a similar amount of power, so you use more, but it also takes more energy to make the steam. So your burner works harder.



Edited 1 time(s). Last edit at 12/02/2011 04:35PM by Stanleyguy101.

Dear Ian, Another thing to consider is: "are you are still using the same fuel blend as you were first using when you car was firing so well?" Changing the BTU's per gallon (or fuel blend) will directly change the firing rate of your Stanley. I find that Kerosene has the highest BTU/gallon and is also the cleanest burning fuel that I can find locally. When changing fuels, I also find that it takes about three tank fulls of fuel to be consumed before you have an accurate idea of how the latest fuel that one is using is performing.

That's a good point. I mix used crankcase oil with petrol. The ratio is typically 10 parts gas to one part oil. Petrol has 8,300 kcal/L, while bunker oil has about 9,700 kcal/L, a difference of about 17% However, the ratio is not constant, and it might make a difference, but I don't think it would be noticeable. One of our local industrial insulation specialists has given me an off-cut of 3M duct insulation, used to wrap range hood vent systems. Fire resistant, high R value, foil both sides. I'm going to wrap the engine in it, and see what that does. (When the weather warms up.) I'll let you know. By the way, where do you get kero?

I pay about $4 a gallon for kerosene at the Bulk Distributor plant in the next town. Cenex is the closest one to my home that has it in stock.

Not only do I have a preheater, I have a condensing car, and after about 20 minutes of running the whole water tank is somewhere around 60 C. Makes the floorboards nice and warm for cold days. Not so nice in mid-summer.

Buck a litre, huh? That's cheap. By the way, did you know that the first commercial distillation of kero was done by a Canadian, who moved to the US (with his process) because the Canadian coal monopoly convinced the court that kero was essentially coal?

Dear Ian: Vintage Steam Products offers a boiler insulation that has been used very widely and very successfully for decades.

Our #249-250 Fiberfrax 550F & 970J Paper is usually wrapped around the boiler in three layers.

Our #266 Diplag 95 is a tough, texturized, white fiberglass cloth insulation impregnated with a water activated adhesive finish.

It is completely asbestos free, will not decay or sustain mold nor contribute to metal corrosion. It is easily cut and when wet conforms well to irregular surfaces.

We also supply a lot of #251 Fiberfrax Caulk. Sold in caulking tubes, this material is great for sealing cracks around the burner and for packing the valleys on the surface of your burner grate.

It consists of ceramic fibers dispersed in a very sticky sodium silicate based refractory binder. We sell this material to ceramic studios and to blacksmiths who use it to repair and rebuild their forges.

Very best wishes!

Don & Carolyn Hoke

Wanted: Parts for 1924 Stanley Model 750 and 1925 Stanley Model SV 252. We buy steam car parts and literature. Visit the virtual steam car museum at www.virtualsteamcarmuseum.org.

For all your steam car needs, visit www.vintagesteamproducts.com.