Forum » General Tuning Discussion » Tuning Nitrous oxide afr's

Tuning Nitrous oxide afr's

General Tuning Discussion

Discuss all things tuning in this section. News, products, problems and results. 

Page 1

Question guys, could someone give me a briefing on the benefits of tuning Nitrous oxide to the correct afr's i heard a tuner in the field mention it but Im just little confuse on how this one works, thanks.

Depends on what kind if nitrous you are talking about. Dry or Wet. A dry shot, you most certainly need to tune for it, as you are introducing the nitrous by itself, and need to give it the fuel to match via the tune. A wet shot typically has jets put into a special T placed before the throttle body. The ratios that you see with that, are set by changing your fuel jet or nitrous jet, (or both) intil you have what you want.

Nitrous is not too much different to any other power adder. You're artificially adding more oxygen and fuel and therefore increasing the load on the engine. I treat nitrous very similar to a turbo or supercharger with respect to the AFR so you're going to need to tune richer when you're on the bottle. How rich will depend a little on how big your shot is though.

This is why i love this forum the info i get is like nun other on the streets thanks alot andre and 13bjunkie , so im guessing once i could achieve this i would be more confident is using nitrous no worries of engine damage.

What kind of gains are you looking for?

Ive run ZEX wet kits on lots of cars without any issues at all. I think the most ive run is a 75 shot, which is more than enough for most street cars, LOL. I know guys however that make most of their power on nitrous as a power adder. Ive seen guys running staged 200-300 hp shots, its damn rediculous, and the setups are pretty far out of the spectrum of your average stuff.

the wet kits are intended for a fairly simple AND SAFE install. They have instructions on what jets to use for what horsepower levels, etc. Very easy to deal with. a 50 shot or so wont get you into too much trouble, and trust me, you know its there.

Hope that helped

yea i understand now

My biggest tip with nitrous tuning is to be very careful how low in the rpm you allow the nitrous to become active. Nitrous is a pretty basic constant flow system which means that at low rpm (when the intake stroke physically takes longer), there is more time available for nitrous to enter the cylinder. If you're running a decent shot on a weak engine this can be enough to produce too much cylinder pressure and bend rods. Just be aware of the peak torque values being produced and give some consideration to what you expect the engie components to handle.

With my own nitrous tuning I've had two different approaches:

If I'm using the nitrous to help improve turbo response and then shut off I'd use a smaller shot (50-75 hp perhaps) and allow it to become active at perhaps 2000-2500 rpm and WOT and shutting off again once the boost exceeds perhaps 10-15 psi - Bare in mind we still need to know the rods will handle the expected cylinder pressure.

If on the other hand I'm using a large shot (200 hp or more) then I'd be aiming to bring the nitrous in well past peak torque as I'm really interested in improving the high rpm torque/power and this will help reduce stress on the engine in the lower rpm range. Depending on the engine this might be 4000-5000 rpm and WOT.

Yeah we used to use a nitrous window switch on a few of our setups (on sr20det mainly) and we would have the nitrous come on at like 3000rpm. God i love that goofy gas, but it sure is damn expensive. I tend to build my setups more with quick spool and response in mind so that i dont need to have another power adder pick up the slack (=