Nitrous Oxide for those good time vibes

[WildHorse]

So when's a tune required ? 125 shot and over ?
I've read under a 100 none required .

Maybe @engineermike would know ?

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[K4fxd]

I suppose it depends on if it is a dry or wet shot. Either way I would want port injection over fogging it under the TB.

I'd give a better answer but I haven't tuned one.

 

[NGOT8R]

The general rule of thumb is to retard timing approximately 2 degrees for every 50 hp. If you can adjust timing yourself with your tuning device, you should be good to go with a wet kit.

I had a tune made for mine, especially since I would be running E85 with nitrous. I don’t even have a 93 nitrous tune.

 

[WildHorse]

I suppose it depends on if it is a dry or wet shot.

Wet.

The general rule of thumb is to retard timing approximately 2 degrees for every 50 hp. If you can adjust timing yourself with your tuning device, you should be good to go with a wet kit.

Yeah a wet kit. Wouldn't the knock sensors take care of that IF knock occurs ?

 

[NGOT8R]

Wet.


Yeah a wet kit. Wouldn't the knock sensors take care of that IF knock occurs ?

I’m not sure, but maybe. I just let the tuner do thing because that’s way out of my wheelhouse.

In addition, I imstalled NGK 6510 plugs (one step colder) gapped at 0.28.

What I can say for certain is, you’re gonna love that extra kick.

 

[engineermike]

I tuned one local car for nitrous and I’ll post here what I also told him: there is no good answer.

I think I would prefer the dry shot but it would take some real experimentation with the aiming of the fogger nozzle to ensure the maf reads the flow correctly. That said, “we” don’t have total control of the throttle blade, so there is little/no assurance that the nitrous won’t be on with a closed throttle and bad things happen like IM explosions.

The wet shot has even bigger problems. If you do it with a plate or single nozzle, the manifold distribution of fuel is positively awful. And that’s not the worst of it. The pcm retains final say over cutting fuel no matter what the tuner does. The tuner can disable spark retard and enleanment but not fuel cut. It’s a safety feature and the pcm’s last resort to shut things down if it sees a problem. But the pcm can only shut down what’s going through the injectors, not the nozzle. So the pcm decides to cut fuel but it only cuts 75% of it, leaving the engine running at 60/1 a/f ratio. And bad things happen.

In general I don’t recommend it.

But on the local car I just limited it to 26 deg timing on e85 and a 125 shot.

 

[K4fxd]

Wouldn't the knock sensors take care of that IF knock occurs ?

In theory they should, but with nitrous it may knock harder and faster than they can cope with.

If you do it with a plate or single nozzle, the manifold distribution of fuel is positively awful.

This is why I would port inject it. If I were doing it on my car I'd plumb it under the intake manifold.

So the pcm decides to cut fuel but it only cuts 75% of it, leaving the engine running at 60/1 a/f ratio. And bad things happen.

This is why I think a wet system is better. There will always be fuel for the amount of nitrous. It will still go lean but not as lean if the dry shot keeps sending nitrous and the ecm shuts off the fuel.

 

[NGOT8R]

When I first got into using nitrous in 2000, I used a wet nozzle kit (75 hp) and lost a motor on a brand new car. I was greedy and making hits back to back with no cooldown in between and it cost me.

In 2004 I decided to try nitrous again on my brand new Mach 1 (100 hp dry kit). I had bigger injectors (42lb) and of course a custom tune. I did have a recurring lean spike on the initial hit, but it never posed a real problem. The tuner tried his best to tune it out, but could never get rid of it completely. That car ran great and I had no issues with it on nitrous.

In 2013, I returned to nitrous (100 hp wet nozzle kit) on my brand new 2013 GT, that one was a Bama tuned car and surprisingly, it ran great.

I now have a wet kit (plate) on my 2019 Bullitt and the one thing that my tuner told me that the two previous tuners didn’t was to set nitrous turn on rpm at 4K instead of 3K, to allow more airflow into the engine before introducing nitrous, to help with distribution.

While I know nothing is foolproof, I do take my safety features very seriously, to try and reduce the likelihood of something going bad. Things like low and high fuel and nitrous pressure, rpm and tps activation and testing my E85 (I won’t spray if ethanol content is below 85%). I also think a good controller is extremely important when using nitrous.

Having said all of that, I do believe direct port is the best option for anything over 150 hp. That is as high as I’m willing to go with the plate.

 

[K4fxd]

That is as high as I’m willing to go with the plate.

I don't like plate systems on a manifold designed to flow air only. I know nitrous is a gas but I still would not use it.

Maybe on a 75 kit but it would bug me till I plumbed it to each intake runner.

 

[NGOT8R]

I don't like plate systems on a manifold designed to flow air only. I know nitrous is a gas but I still would not use it.

Maybe on a 75 kit but it would bug me till I plumbed it to each intake runner.

Agreed, direct port will offer the best distribution. The only downside to it is, it can be a PITA to access components (solenoids or any of the 8 nozzles) if the system develops a leak. Aside from that, it’s a killer setup.

 

[WildHorse]

I think I would prefer the dry shot

Yeah no offence, but that's not the best way to do it.
Why put extra strain on the fuel system ?

Also it'll be a wet plate system behind the TB, so the MAF will have
zero clue it's there. 50-75hp max.

 

[K4fxd]

Also it'll be a wet plate system behind the TB,

The rear cylinders are going to be lean front cylinders are going to be rich. Wet fuel distribution in these manifolds suck. I would do like @NGOT8R and only trigger it above 4-4500 RPM.

Actually I'd run it dry or plumb it for direct injection.

Let us know how it works, however you do it.

 

[WildHorse]

Right so now I see what yer talking about running a "dry" shot . Wet could pool and if it somehow ignites - as @engineermike said, bad things will happen.

So I'm assuming for sure a dry shot of 50/75 HP will definitely need a tune, correct ?

 

[K4fxd]

So I'm assuming for sure a dry shot of 50/75 HP will definitely need a tune, correct ?

It may or may not. If your injectors are up to the task it might run just fine. I would tune out some spark advance and I'd richen it up a tad, then log and fine tune from there.

Since @engineermike has done one I'd ask him

 

[K4fxd]

Wet could pool and if it somehow ignites - as @engineermike said, bad things will happen.

Even dry it could ignite. I doubt at these levels it will happen. I think something else would have to f@ck up first.

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