Been following with interest, I think I need to follow your example, as I've the puff of smoke at high revs.
I'll take it you need a compressor/compressed air to force it past the rings when you leave it to soak? Does it need to be pressurised for the whole time?
OK, so I don't think the compressed air is critical to this process, you could just let gravity do its thing.
All cylinders leak. Just depends how much. If you do use compressed air make sure you've got the car in gear and braked so you can't turn the motor over. You do not want the pistons moving.
The thing to do is take your time, be quite careful with the relevant chemicals. Get your car up and ready to drain and make sure you keep the stuff within your pan but not overflowing it. You DO NOT want this stuff going over the 'full sump' line.
So drain your oil first, then drain the stuff that leaks down.
Use some chopsticks or other small sticks of equal length with the plugs out so you get the cylinders all to half way. (they all line up heh) - this gives you 200ml of fluid to fill each cylinder. 1600 motor, 400 cylinder at half way.. 200ml.
That way you can put a good dose down and then come back in a few hours to put more down.
The thing is this, you're putting down volatile hydrocarbons. Those will happily soften whatever is stuck to the rings or in the ring lands. But you need _flow_ to actually move the dissolved stuff, so you will end up putting about a litre past each piston ring.
The "big idea" is that those volatiles will flow down past the rings and take some of the deposits with them as they go to the sump, while also softening the deposites further. The varnish will be hard at the start and soft at the end. Ideally you put through enough that a good portion gets solvated into the volatile solvents and _flows_ down the cylinder walls.
If you're going to do the compressed air thing, do it at the end, not at the start, that way you're 'forcing' more solvated carbon past now that it is really softened, if there is any deposit left.
Don't rotate the engine for a good while, while putting the chemicals in.
When you're done, put a teaspoon of motor oil down each cylinder bore so that you pre-lubricate the pistons before startup, then drain the sump, put in new engine oil and optionally change the filter. The oil won't flow out quite as fast as the volatiles.
The chemicals to look out for for doing the softening are..
Toluene
Xylene
Kerosene / Napftha
MEK (Methyl Ethyl Ketones)
Acetone
Any 'bulk' carb cleaner would contain something like these. You don't want pressurized stuff as the quantities aren't enough and it evaporates as soon as you try to use it.
You need Litres, uncompressed, not in spray form.
You could also use Gasoline and Diesel. Diesel is a great solvent not that different from Kerosene. And cheap. Gasoline evaporates a bit too fast imo, but I recon it'd work too.
These are common in varnish removers and paint thinners and they aren't actually that different from actual Fuel. Toluene is common in fuel and was somewhat responsible for the turbo era of F1.
The stuff on your pistons is varnish, which is why Acetone is so good. Acetone is also probably the least carcinogenic of the chemicals mentioned, although it's still flammable.
I recon over 24 hours you could run through 4L of the above chemicals. 200ML every few hours, per cylinder.