cylinder liners

Having bored and honed the cylinders for my latest loco I find there is still evidence of porosity, I then worked out its nominal tractive effort and find that it is not far short of the total weight of the loco. I'm considering sleeving down the bores from 1.25" to 1.125", a reduction in area of 30%. I'll then add some ballast, but can't get much in, say 10 lbs. I can get PB1 and LG2 cored bar, I imaging LG2 will be more machineable. Much the same price.

Apart from 'you should have done the sums first' anyone got any comments? I can get dry ice fairly locally, and heat up the cylinders in the oven to say 150C, should go together easy enough.

I've done much the same on my Princess of Wales cylinder block. The centre looked like swiss cheese when I bored it to 1.5", I couldn't return it as Reeves had changed hands by the time I found out, so I bored out further to 1 5/8", about the maximum that I dared, and fitted PB liners of 1 3/8" bore. I went for the 1/8" wall thickness to keep the liners fairly sturdy for pressing in, (no dry ice!), the end covers also help retain them and it looks OK, though I've not completed the loco yet. My guess is that the reduced bore won't be too noticeable. As a single-wheeler, PoW will never be a load hauler!

BTW, isn't your area reduction ~20%?

Go to the top of the class, my maths went wrong, perhaps I'll reduce it to 1.0625", a 28% reduction

Food for thought. I am having very early thoughts about "what next" The cylinders are at the forefront. I am thinking in terms of inside cylinders machined from steel and then lined. Theory is that the ports (slide valves) can be cut right through to the bore, hence steam passages can be parrallel to the bore. The press fit/locctite liner then sealing the ends of the ports. My current plan is a cast iron liner with 3mm wall thickness. But the earlier post here suggests PB. What do you all think.

Regards, Bruno.