Originally Posted by nilrem
to start, the auto ignition point(AIP) of nitrous oxide will need to be found - this appears to be rarer information than rocking horse rose food , then the avearge temperature of an exhaust manifold... if the manifold is a higher or very similar number, then you would expect the nitrous to ignite.
as an example, just using fuel :-
fuel has a AIP of 246°C
apparently exhausts are around 260°C
so theoretically the fuel would ignite on contact with the exhaust, however the fuel would also create a cooling effect... but thats about as far as i can go...
thats how i understand it...
There is NO available AIP for nitrous IMHO, the simple reason being that the AIP refers to ignition as a exothermic reaction with the oxygen in the air IIRC, and given that nitrous does NOT burn, never has burnt and never can burn in oxygen, it doesnt have one.
It PURELY an oxidising agent, it gets to about 360 degrees (IIRC, im sure a web search will show the exact value, but bear in mind it will vary in a manifold as its pressurised) and brakes down into nitrogen and oxygen, so that WOULD happen in the exhaust, which would mean a bigger number of moles present and hence a higher pressure (PV=NRT and all that).
This potentially would mean that the liquid you had injected would turn into a gas, and split into two seperate gasses, which is a massively endomthermic reaction effectively (its actually more about the latent heat of evaporation than the reaciton where it splits, but im trying to simplify it into one reaction for our purposes)
Now this endothermic reaction would massive cool the exhaust gas, which in turn would mean that the turbo was less likely to spool,(again PV=NRT)
Potentially if you are running very rich (which is typical on a turbo car) you may find that this extra oxygen now available means more of a burn can occur from the unused hydrocarbons, which potentially is also exothermic and also could lead to an increased number of moles present, so again would spool it more, I suspect this effect would be minimal though anyway, so Id try and guess the effects of the other too more really, unless you use a wet kit and piss fuel in too, then things could REALLY get interesting, lol
Anyway, ignoring that third point you basically have two completely opposite things happening, and I dont know the relative amount of each one to determine if the net pressure in the manifold would go up or down in the exact circumstances you are referring to, experimentation would be the only way to know.
However, the most important effect IMHO would I imagine be that the thermal shock would shatter the blades of the turbine.
I dare say someone has tried it at some point, and the reason you never hear of anyone doing it again since is cause of that meaning it doesnt work.
So bottom line, to answer your question, you have mistaken Nitrous for something that combusts, so all the effects you think will happen, wont do so, and the effects you would get instead, I dont think will do what you want either.