Excellent job in getting an image posted.Important step in your design process.
I suggest a new sketch that shows the entire room, and where you add some dimensions to the sketch, so it is easier to picture what the sketch shows.
I assume from your initial description (that you had a 9x13 feet area in your basement) that the front wall from the RR workbench to the lower right hand corner is 13 feet and the right wall from the lower right hand corner to somewhere up along that wall is 9 feet, but it is not possible to say from your description whether that e.g is allowing for some distance between the layout and the furnace, or whether you need an walkway/aisle between the layout and the furnace.
It is also not possible to tell whether your layout has air space rights above the two workbenches you show.
First impression - I would still have considered an N scale, and doing an 15-18" deep L shaped shelf layout on simple wall brackets on the two walls shown, with turnback curves (which can be done in a 30x30" blob in N scale at either end.
The question that you are asking is not really making sense. The answer is exactly the same in N scale as in H0 scale. The smallest (sharpest) turnout you can use depends on what kind of trains you run and what type of railroading you are trying to simulate. Larger frog number turnouts for higher speeds and longer equipment, lower frog number turnouts for industrial trackage in cramped conditions.
But since you are comparing H0 scale and N scale - the relevant question is not how sharp turnouts you can use, but how much layout length a group of turnouts (of some suitable sharpness) will take in H0 vs N scale.
Here is a yard ladder for a small four track yard in H0 scale, using Peco code 75 medium turnouts:
Center-to-center distance between adjacent tracks are 2" - which corresponds to 2" * 87.1 = 174" = 14.5 feet.
Here is the same ladder in N scale, using Peco code 80 N scale medium turnouts:
Track distance is 1.3" (since I haven’t cut down the turnouts). That corresponds to prototype track distances of 1.3" * 160 = 208" = 17.3 feet.
But as you can see - that yard ladder takes 22" of layout length in N scale, 40" of layout length in H0 scale. Yard also takes a little less depth (6" vs 10"). But that is usually not that critical - it is length we tend to run out of first on a model railroad layout.
TMHO you have forgotten something. In the 102 Realistic Track Plans, published by our host, Andy Sperandeo is showing you the way how to do it.
I will give you three rules of thumb, they are mine and in the end you have to make up your own rules. John Armstrong called it, in his famous book Trackplanning For Realistic Operation chapter 5, Operating reliability through standards.
devide the prototype length of your longest car by 5, and you have a pretty good idea of the mimimum radius in inches in N-scale. (In HO devide by 3)
devide the prototype length of your longest car by 10, and you have a good switch number in N-scale.(in HO devide by 10 or 12)
So, if you want to run modern 90 feet long autoracks in N-scale you end up with a 18" radius and #9 switches. As you may have noticed a 18" radius is considered to be a good minimum radius in HO as well, alas for a freight only branch in the 50"s, where the longest cars and diesels were 50 feet long.
maximum train length is 40% of the length of your room. When your room is 11 feet long train length can be 0.4X11= 4.4 feet. Eight modern autoracks are 4.5 feet long in N-scale, and you still have two add an engine or two. (In HO ten 40-feeters are also 4.4 feet long)
The questions asked are always about your scale, era, locale and kind of railroad. The answers pretty much determine the appropriate radii and switch numbers.
In the very same 102 trackplans, Andy Sperandeo also explains how to design by “squares”; another invention of John Armstrong; it takes the radius as the important design value. A bullit proof approach to get a quick idea about what will fit, and bulletproof also against overly optimistic designing.
Paul
BTW John Armstrong wrote his book almost 50 years ag
