400ex cdi questions

[thumperex05]

i have an 05 400ex (440) with stage 2 hot cam, ported and nos, and lte duals. my question is should i use the stock cdi or an aftermarket with an advance ive heard that its not good to run nos with advanced timing, i dont want to blow it up on the first pass so any help would be great. thanks.

[GPracer2500]

I've not run nitrous but I'll share what I think I know about it anyway. So, take my advice with a grain of salt.

I wouldn't advance the ignition. The extra oxygen introduced by the nitrous oxide speeds up the burn rate substantially. Have too much ignition advance and the burn may complete too early. Ideally we want peak cylinder pressures to occur somwhere around 18 degrees ATDC. If it occurs closer to TDC then power suffers and detonation becomes more likely. If anything you'd want to retard the ignition advance to make the best use of nitrous oxide (depending on how much is used).

Also, make sure your feeding the engine enough fuel. The nitrous oxide itself doesn't really burn--its presence just allows you to burn a bunch more fuel.

$0.02

[thumperex05]

thanks thats exactly what i wanted to know and you made a good point with retarding the ingnition do you know of a way for me to do that, i dont think there is anyone making cdi boxes for that right now. lol

[dork]

try MSD and dynatek.