Layout Transformers

For single train operation, the V is just fine.  Its rated at 150 watts.  More than enough for postwar/modern train running.  Adding more track does not mean you need a bigger transformer.  You just need more power feeds to the track.  When you start running multiple trains from the same transformer, then you may need to get more power.  Postwar trains will draw more power than modern ones.  Pullmor motors are no where near as efficient as the can motors of today. 

As your layout grows, I would get a bigger transformer for the track, and move the V to power all your accessories.  You can run a fairly large amount of accessories off that transformer.  If you only ever run two trains at one time, the V should perform well without having to upgrade anytime soon.

With the price of postwar transformers dropping all the time, I would consider a postwar zw as an upgrade.  They can be had for under $200 and it will give you whistle and direction control built in.

I would add a Z, just to be safe.

When using a large transformer like a "V", I suggest adding external circuit breakers to each of the hot posts that are in use. I mean the "A", "B", "C", and "D" posts.

There are two reasons:
1 - the internal circuit breaker is there to protect the transformer. A lot of current can flow before it trips, and sometimes it never does. Wires can get hot enough to melt insulation and burn anybody who is unfortunate enough to touch them while they are hot.

2 - the internal circuit breaker only protects circuits that include the common terminals ("U"). It is possible to have a short across two of the hot posts that would not be protected.

Since you have two locomotives with electronics (even though you use them in conventional mode), adding TVS surge protectors would be a good idea too.

There are many choices for protection, and there have been many threads on the subject.

ALDOVAR,

   Here is how I look at your situation, sooner or later your boys are going to want to run more than one Remote Control operated engine, probably a couple at the same time.  IMO I would save my money and 1st purchase at least an old ZW,  Jim here on the OGR forum rebuilds them like brand new, I own 2 of his rebuild ZW's right now.  I always advise everybody to have enough power to expand, so if I were you I would save my money and purchase 2 old refurbished ZW's one for each boy.

PCRR/Dave

Unless you plan to run dual motored locos the V should have enough ponies to run two trains and some lights.  However, as previously mentioned more power feeds will be in order.  And be sure to heed the above advice of Mr. C.W. Burfle, who is a very knowledgeable fellow.

If, down the road, you eventually find that you need more power you can add a good used LW or 1033.  This should prove to be the least expensive option.

Pete

If you are going to expand your power needs as far as a transformer is concerned the post war ZW is a good transformer, it has plenty of power(275 watts). The post war ZW has whistle and direction control for two of the four outputs(handles A and D), and like somebody else mentioned you should adds in circuit breakers to the A, B, C, and D terminals. 

If you just want a transformer with power then a post war Z transformer will do as it has four control knobs to supply four different tracks with power. However it too will need better circuit protection as the breaker inside is rated at 15 amps, you should add smaller breakers at each terminal post; A, B, C, and D.

Another transformer that is nice and has 2 train ability is the post war KW, 190 watts and has 3 accessory voltage outputs.

The LW or 1033 is a nice transformer but is only a one train transformer with accessory power(if I am correct).

Lee Fritz

The LW or 1033 is a nice transformer but is only a one train transformer with accessory power(if I am correct).

This is true, but either one would supplement the OP's V quite nicely and would be an economical solution.  I think it's okay to use more than one transformer to power a layout. 

Pete

1033 transformers were very popular and are quite common. They can be purchased for under thirty dollars in my area. The 1044 is an updated version of the 1033. The modern era 4090 is basically the same too.

My personal favorite single train transformer is the LW. They are more expensive.

If you are looking to purchase an additional transformer, and have the cash, I'd go for a ZW. 
Don't forget to add the external protection mentioned above.

With any used transformer purchase, be certain you are purchasing from a reputable person who will stand behind it. Any postwar transformer should be inspected (and repaired if necessary) before use.  They can be almost 70 years old.

Another thing to consider is that if you use say 2 LWs or 1033s instead of one ZW it may prevent a fight or two as to who gets to run the trains, allowing each operator to have their own transformer. Two people using one ZW might get a bit too cozy for some rowdy little boys.

J White

Thank you all for the advice and suggestions. I do have the TVS on my V now as I saw on another thread. Circuit breakers are the next step. Sounds like in the short term, the V is still a great option for the layout in the near future. It is something I could never give up and will be involved in some way in the layout. Too much sentimental there.

At some point going to the LW's for each of the boys would be a great idea, maybe set up two loops for them so they can race each other! Get some real light weight MPC locos and see who can complete a circuit with their load intact. :-)

Note that the V and Z have higher output voltages than any of the other Lionel transformers.  These are good candidates for having modern whistle/bell controllers in series that cause a voltage drop even when no buttons are pressed.

A 150-watt V should have no trouble running 2 trains with a reasonable number of accessories.  By al means, use external breakers as CW suggests.  I'd recommend 7 amp breakers.  A TVS provides no protection to the transformer.  It's for voltage surges, not overcurrent.

So, good news. I was pulling Christmas stuff out last night and found a box of stuff my dad gave me a few years ago. Inside was some ornaments, garland, and a very clean, almost new looking TW and a 1033 that is a bit rough around the edges and needs a new cord.

The TW was so nice I used it on the Christmas layout. 

Except for the whistle, there's no reason not to run the "v", . Consider the MRC transformers, they are quite good. and have metering to boot.

Be certain to pay attention to the terminal markings on the TW. If possible get a copy of the instructions.
The TW is an oddball unit with two physically separate transformers inside.