Thoughts on Nitrous.... Single fogger or direct port best for a dry setup?

Hey guys,

Thinking about having a dabble in the world of Nitrous for a bit of a laugh.

It seems to be one of those topics though where there's a zillion conflicting opinions.

My engine is a 4cyl NA with a single throttle setup.

My initial thoughts were that direct port setup would be the best way to go.

But reading some comments people say that you can end up with uneven cylinder distribution this way, if there are different bends/lengths/etc of the hardlines to each cylinder.

So having a fogger pre throttle body maybe makes sense instead.

Has anyone here had any experience with either/both?

I'll only be running a 50 shot or there abouts, so maybe it's just best to keep it simple.

I like the idea of a PWM controllable solenoid, to trim down the lower rpm level of the shot.

However do these truly actually give an even distribution of nitrous? Or if you ran it at say 500hz, would it end up with lean and rich combustion events from the pulses.

One of my goals is to avoid blowing the engine up haha.

Love to hear your guys thoughts.

Here are my thoughts for setting it up so far.

Using a link G4+ Xtreme, so I've got enough inputs and outputs to do some cool stuff compared to randomly firing in a wet setup haha.

So I'm going to start with a digital input on the dash which arms the system.

First thing this will do is look at bottle pressure sensor.

If pressure is below 900psi (or whatever) it will activate the bottle heater via relay. (Bottle heater has built in thermostat too as safegaurd)

When the pressure reaches the minimum acceptable level it will trigger a timer which activates a relay for the nitrous purge for the first 1/2 a second of the timer (or whatever... Or maybe manually activate this)

The nitrous solenoid will be activated by another analog output which is triggered only when certain conditions are ready.

rpm over 5000, ECT over 80, TP over 90, and 2nd gear or higher. (will need to use virtual aux to have this many conditions)

When the nitrous solenoid is activated, it will switch to a 4D ignition map which trims a few degrees out of the main table. and it will switch to a secondary fuel map that has the axes of engine rpm and nitrous bottle pressure. As you're only ever running at full throttle so MAP etc is less relevant. (Maybe? Is this even possible when you're running modelled fuel equation?)

Hopefully this will compensate for varying amount of nitrous coming out relative to pressure, to prevent running lean if the bottle gets hotter than intended.

When the nitrous solenoid switches off, if possible I think it would be cool to have a timer that holds the fuel map on the nitrous map for 1 of a second or something like that. So it keeps heaps of fuel in there on gearchange, and if there's any latency in the solenoid shutting off, it doesnt happen faster than your fuel table decides that there's no nitrous anymore.

What sort of goal AFRs would be best for a nitrous setup?

12:1 or 11:1 something like that?

It would be cool to have a PWM based controller so you could actually run say a 100 shot or something without blitzing your rods at the lowest rpm that you activate it at. (As I have a standard engine with fairly wussy rods)

It seems the overwhelmingly popular choice for nitrous kits is a wet setup, often on carb engines with zilch in the way of feedback or datalogging etc... And it also seems the overwhelming opinion is that nitrous will blow your motor up because lots of people seem to.

Thinking about this though, what are the likely reasons for a wet nitrous setup to blow a carb engine up?

-Lack of control over ignition timing if its vaccum advanced or whatever with just a few degrees randomly pulled out.

-Lack of control over fuel, if people are trusting the jetting sizes to not blow their engines up as the kit comes out of the box.

-Lack of control of the ratio of fuel and nitrous, if fuel pressure drops or nitrous bottle pressure goes higher or lower than expected.

-Lack of repeatability over when the nitrous activates, if it's manually activated by a button press. (Turn it on too early and nuke your rods/pistons)

-Lack of any safegaurds, in terms of knock sensing or using o2 feedback to turn system off if a lean condition is detected or whatever.

-Lack of control over cylinder distribution of nitrous/fuel if you're using a large shot and fuel falls out of suspension on the way to different runners.

It seems like a well thought out EFI setup can overcome all of these obstacles!

And have a setup that can be used many times over without spinning the roulette wheel for blowing your motor up or not.

I'd say 75% of the people I've talked to have said "Haha you're crazy / going to blow your motor up"

Well, that's possible as with anything. But I think the odds become lower and lower, the more thorough your setup is... And the majority of nitrous setups are super basic.

Cant wait to get it setup and have a tinker with it.