I just bought a kit from asu1974, and will be installing it within the next few weeks. I understand the basics of running nitrous, and will only be running a 50 shot.

My question for everyone is why will you blow your engine if you're spraying after fuel cut or before the engine is started?

I know N2O isn't flammable by itself, and in a stock engine after fuel cut you still have air in the combustion chamber without fuel. Why does nitrous change this at all?
-hype

 

Simple answer to your questions is because you are causing a LEAN mixture.

You are correct. Nitrous by itself is not flammable. In order to work in a combustion environment, it will have to be mixed with fuel to create a controlled explosion (combustion) and then the oxygen in the N2O is released which then allows for more fuel to burn which then gives you more power per stroke. Heck of a run-on sentence, huh?

In other words, if you release the oxygen in the N2O at the wrong time you create a situation of too much oxygen which in turn reacts with the aluminum in your piston/engine and causes a hole in your piston. This is why detonation (pinging) is a big no-no when using N2O. Pinging is caused by an early detonation of the mixture. Kinda like premature eja.....oops, nevermind. You get the pic.

Nitrous only works when it is heated enough, around 575 deg, the oxygen molecules are released which in turn, as stated above, allows for more fuel to burn per stroke. Detonation can only be controlled by two things: timing or compression ration. It is aided by better fuel, i.e. super is less prone to pinging hence the octane rating, but it is difficult to control in our cars.

How's that for a short answer....

 

Fundamentals of Combustion

That somewhat makes sense, but I still don't fully understand why that is. Let's say you are driving down the street at redline bouncing off the limiter. The fuel cuts, but there is still oxygen (and other gases) entering the combustion chamber correct? Nothing happens because there is nothing left to react with the oxygen.

If I'm understanding this incorrectly then why isn't it really bad for your engine when you fuel cut?

So with N2O added to the equation the only difference is that the N2O splits because of the spark, but there is no fuel to reduce temps, etc. hence the problems.......


-hype

 

You're partially correct. You are having other gases present at fuel cut off, yes. The only difference is that N2O is composed of 33% oxygen while the ambient air is 23% oxygen. If you mix pure oxygen with aluminum, you get a melt down reaction. The leaner the mix, the more oxygen it has or less fuel. When you are bouncing off the limiter, your fuel is intermitently cutting out. When the fuel is out, you are running straight N2O, which makes you very lean. You can pump in a ton of N2O, as long as you pump in a ton of fuel with it (basically). If you don't, pressures and temps rise way above the breaking point really really fast.

 

It just seems to me that the percent difference (by mass) of Oxygen between air and N2O isn't that big. It seems that bouncing off the rev limiter would cause major problems because of the fuel cut with the excess oxygen (lean mixture). The N2O must magnify the effects more than atmospheric air, but it seems like something is missing.

I've taken Chemistry and done combustion problems, but obviously I'm not able to apply what I learned to this situation for some reason.
-hype

 

Nothing is missing. That is it in a nutshell.