Greg,
" About the ether. If the ether has a high cetane number (CN) of ~95 and we are mixing 35% of it with kerosene which it seems is near CN 40. What is the final CN of the fuel? I would think it's higher than the 2% Amsoil mix, but they run at simliar CR."
Combustion is a complex thing, my take on your findings are even though the cetane No of the 2 mixes maybe different, but still yeilding similar results is due to the differing burn rate of the 2 fuels, the cetane no determines the start point of combustion then the composition of the fuel molecules takes over to determine the burn rate. That is the higher cetane fuel may start burning sooner but actually burn slower than the lower cetane fuel therefor they both require the same CR to get optimum performance.
Aditives like amyle nitrate I beleive dont change the cetane No but increase the burn rate, this is why adding too much makes compression settings go crazy, you need suffient compression to instigate combustion but the burn rate is too fast requireing the compression(ignition timeing) to be backed off, but now its falling behind the cetane of the fuel.
Ignition improvers work in different ways too, some increase in burn rate as pressure increases wereas some reach a pressure were the burn rate starts to drop off.
An interesting site on burn rates is :- http://nakka-rocketry.net/ allthough the fuel is different the studies on burn rates and the use of different burnrate modifiers is the same in principle. Read the sections on burn rates and burn rate modifiers/enhancers I beleive it will give you more insight into whats happening in the diesel fuel mixes.
Stewart