Why do MTH steam engines generally smoke more robustly than their Lionel counterparts?

I'm not technically adept but I believe that MTH uses 'hotter' components to achieve the prolific smoke output in their steamers. We have a new Legacy K4 that puts out a lot of smoke volume-wise but it is not dense at all. I have to have the track voltage at 18v before you can even see it!

By contrast, our MTH locomotives smoke beautifully at 15v and above...

The MTH smoke unit uses two heaters.  The Lionel system uses one.   More is better in some cases.  The smoke fan motor that Lionel and MTH uses is the same part.  The impellers will interchange.  The recent Lionel locomotives do smoke very well.  The most common smoke resistors used by Lionel are 6 OHM and 8 OHM.  I have with great luck taken Lionel engines that use an 8 OHM element and put 2 MTH elements in.  The MTH elements are 16 OHM and when connected in the unit read 8 OHM.  Same as Lionel. 

Marty, that's a really good comparison. Thanks for sharing the info.

From experience I find that the amount of smoke is dependent on how the wick wraps on the resistors. In the MTH units, the wick should have contact with both resistors.

I had a tendency to cut an MTH replacement wick in half because it looks to be too long.  WRONG move! 

Just to clarify what Marty said. 6 and 8 ohm resistors are found in fan driven Command engines. Piston units use 18 or 27 ohm resistors and connected to track AC. 6 and 8 ohm units are driven by regulated power. Don't put a 6 or 8 ohm resistor in a piston unit. It will put out a lot of smoke for very short time, then nada.

Pete

You can really improve Lionel smoke production without changing elements simply by trashing the big wad of packing, then cut off the fiberglass sleeve around the resistor, then replace with a 4" length of tiki torch wick wrapped around the resistor.

This opens up the fluid chamber so that the air can move easily, plus it gets plenty of fluid into close contact with the element.

Also you should drill out the air intake hole if it is less than 3/16" diameter.

Rod

The wicks come in two shapes - tubular, like rope, different lengths and diameters, and flat, approx. 1/2 wide.  I think the flat style is more for a hurricane lantern, as opposed to the Tiki torch, but I'm no expert. 

I've had good luck with both the MTH and Lionel fan driven smoke units folding the batting up to fill the chamber and having it firmly in contact with the bottom of the resistor, but not all around it.  I do take pains to allow the air flow from the fan through the chamber by the resistor.  I've been generally pleased with the Legacy smoke from the fan driven smoke units, but my Legacy C&O 4-6-0 doesn't smoke as well as I'd like, however it's a puffer.  I have yet to take it apart and see if it can be improved.

I do the same treatment of the wick with the piston smokers and that works pretty well too.  Obviously, the puffers won't put out the volume of smoke that the fan driven units do.  I do cut off the sleeve from the puffers as my first step, those seem pretty useless.

I drill out the intake holes to 1/4" on fan driven units if they're smaller, that helps as well.

Pete and Rod gave good advice.  I would suggest that anyone with a smoke problem view the Lionel video that Mike Reagan did.  It is a huge help and does give results.  A big problem I see often are guys (also gals)  adding fluid to a hot (power on) smoke element.  Shut it off for a few minutes and then add fluid.

My local outdoor living store has three types of round tiki torch wicks: Fiberglass, cotton,  nylon. Is one preferable to the other as replacement wicking in smoke units?

Marty,  why is it inadvisable to not add fluid when hot?

Yep, it crystallizes on the element, at least that's what it looks like.  I've found them covered like that, cleaning them off really improves the smoke output.

I think on Lionels high end engines they have done a good job of providing good smoke units. But, on the starter market product it's a different story.

I find the problem with such engines that come with sets like the Polar Express is not so much the smoke generator but the constant voltage board they use to drive them.

If you put the engine in neutral and drive the system above eight or nine volts it smokes pretty good. But, unfortunately most toy trains are run at four to eight volts and below seven volts there is no way that board will produce smoke beyond a slight wisp. At run speed you can smell the smoke production but you see nothing .

As I stated above when you park the same engine and throttle the transformer three quarters of the way up you will see alot of smoke, though if you tried to run at that power the engine will probably end up flying off the track at the turns.

Marty brought up an interesting point about the MTH two 16 ohm resistors in parrallel. When they put two 16ohm resisters side by side like that they do form an eight ohm total resistance but the working wattage of the resisters double. In short, they can stand up to more heat that way.

The smoke question has always been an item that I took for granted, with little thought about what made them go. But since we started to delve into the subject I have formed a real appreciation for the engineering that goes into even the most mundane accessory.

A simple fix for the lower-end locomotives is to simply use a few sets of back-to-back diodes to drop the voltage to the motor.  This allows for higher starting voltages, and will give the smoke unit enough juice to smoke properly.  For almost any can motor locomotive that isn't going to be hauling 30-40 cars, 1A diodes should do, but maybe I'd try to fit some 3A ones in there.

Hi all,

There are also some differences in the way MTH controls their smoke units.  The resistors are not fed a constant voltage.  The power to the resistors is pulse width modulated, just like the motor control.  That's how manage the MIN, MID, MAX settings under DCS and the conventional trim pot controls.  They also control the fan motor to produce a crisp puff of smoke.  If all they did was turn voltage on and off to the fan motor the fan would coast in between pulses.  However, they add a brief reverse voltage to the fan motor at the end of each puff.  That stops the fan from coasting.  Both of these features are included in MTH's patent #6,457,681.

I have a couple of 27 ohm wirewound resistors, I'll have to see what some of the more anemic smokers have in them.

Dave,

I always enjoy reading your MTH insights!  Thanks, for about the millionth time!

- walt

I am using the fiberglass.

I used the fiberglass wick, I'm sure the cotton is a bad choice, don't know about the nylon.

Exactly how do you install TiKi wick? It seems too thick to push under and over the resistor.

Thanks!

You cut the thick outer sleeve off and use the fibers in the middle of the wick.

Thanks!