N.O.S. and efi

[NewEnglandRaceFan]

Another most likely stupid question..
but, when you add nos to the intake charge it,because of it's temp. causes the air to contract and make it denser. this has a bigger effect with a fogger type system over a plate type that cools the charge as it's entering the intake, unlike the fogger that cools the charge after it's already in the intake ports..
will this affect injector spray pattern, and should the efi injector be before the fogger nozzle, or after it.. ?
As I'd think the nos injection point would as the air contracts at that point to pull the fuel from the efi injector towards the nos charge injection point, pulling it away from the intake valve if the fogger nozzle is above the efi fuel injector making any reversion even worse.. am I over thinking this.. or does placement even matter.. or at what point does it come into play?(i.e. 250 shot,400shot)
for this question it be bank/batch fire not sequential .. but does the answer change with different injection disciplines?

[Orange65]

Another most likely stupid question..
but, when you add nos to the intake charge it,because of it's temp. causes the air to contract and make it denser. this has a bigger effect with a fogger type system over a plate type that cools the charge as it's entering the intake, unlike the fogger that cools the charge after it's already in the intake ports..
will this affect injector spray pattern, and should the efi injector be before the fogger nozzle, or after it.. ?
As I'd think the nos injection point would as the air contracts at that point to pull the fuel from the efi injector towards the nos charge injection point, pulling it away from the intake valve if the fogger nozzle is above the efi fuel injector making any reversion even worse.. am I over thinking this.. or does placement even matter.. or at what point does it come into play?(i.e. 250 shot,400shot)
for this question it be bank/batch fire not sequential .. but does the answer change with different injection disciplines?

Currently, the EFI injectors go above the nitrous injectors- that is, the N2O injectors are closer to the heads. Why? I know that there is some reason, but I am not sure what it is. I am about to add some bungs to an intake, and that is the way I plan on doing it.

[JeffMcKC]

Mine was the Spray above the injectors, the spray will get there first if its below them and under more pressure I would think that would cause issues when dry shots are fired

[Orange65]

Jeff's reply made me wonder about my response so I got to key board racing and found this thread:

http://www.yellowbullet.com/forum/showthread.php?t=449785&highlight=efi+bung+in+intake+with+nitrous

These guys know way more about nitrous than I do or ever will. Monte Smith gives some good info about running dry nitrous. I would think that wet nitrous would not need a delay on the fuel.

I would think that if you ran the injectors below the nitrous ports, it would just cause the engine to run rich for a little longer than if the nitrous port was below the injector.

[JeffMcKC]

Wet nitrous is a stand alone although the efi could help tune around it. More guys are now putting injectors to spray the back of the intake valve and phase them, the injector spray patterns have came a long way. I think a guy can tune for either

[38P]

am I over thinking this?

Yes.

this has a bigger effect with a fogger type system over a plate type that cools the charge as it's entering the intake, unlike the fogger that cools the charge after it's already in the intake ports..

While any vaporization cooling will start at the point of injection, I don't understand how a fogger would cool any more than a plate. It's the vaporization phase change not the nozzle type that does the cooling. Certainly moving the delivery point further from the cylinder (i.e. pre-throttle fogger versus direct port fogger) could impact how the vaporization affects in-cylinder temps.

will this affect injector spray pattern, and should the efi injector be before the fogger nozzle, or after it.. ?
As I'd think the nos injection point would as the air contracts at that point to pull the fuel from the efi injector towards the nos charge injection point, pulling it away from the intake valve if the fogger nozzle is above the efi fuel injector making any reversion even worse..

Remember that:

1.On virtually all batch-fired port EFI systems operating at RPM levels where you'd be using N20, the injectors are squirting most all of their shots while the intake valves are closed and the sudden hurricane of air moving at hundreds of feet per second when the valve opens is what carries the air-fuel mixture into the cylinder. Thus any "reversion" that could occur would be almost instantly reversed

2. The inertia effect of the column of intake air suddenly stopping for a few milliseconds while the valve is closed tends to ram air against the closed valve.

3. Reversions from overlap pressure differentials and manifold resonance are going to be a lot stronger than any minimal density changing effects from injection of N20. See the chart and equations in Harold Bettes' book Engine Airflow: A Practical Guide to Airflow Theory, Parts Testing, Flow Bench Testing and Analyzing Data to Increase Performance for Any Street or Racing Engine ( http://www.amazon.com/Engine-Airflow.../dp/1557885370 )

4. Hundreds of thousands of nitrous kits have been sold with N20 induction points well ahead of fuel injection points (often more than one foot from the injectors in the case of some pre-throttle fogger systems) with no apparent problems.

5. On the other hand, "You're lucky that 100 shot of NOS didn't blow the welds on the intake." (I'm not a big fan of calling nitrous "NAWZZ" (But Mrs. Outsider refuses to call it anything else . . . such is the power of Hollywood))

[38P]

Another point (clarification): Unless the restriction in your N20 system (i.e. jet) is right at the point of induction (which could be how a fogger has a slight "cooling" advantage over most plate systems), the phase change is going to mostly occur outside of the intake manifold at the locus of the pressure drop. Thus virtually all the cooling is from contact with the cold N20 gas.

[NewEnglandRaceFan]

While any vaporization cooling will start at the point of injection, I don't understand how a fogger would cool any more than a plate. It's the vaporization phase change not the nozzle type that does the cooling. Certainly moving the delivery point further from the cylinder (i.e. pre-throttle fogger versus direct port fogger) could impact how the vaporization affects in-cylinder temps.

well the difference is the plate the air hasn't made it to the port before the cooling action makes the air contract and make it denser,, the fogger does this after the air is already at the end of the port.. not even close to being the same

[Beagle]

how long does the air have to cool travelling 300 feet per second in a 5" tract?

[NewEnglandRaceFan]

how long does the air have to cool travelling 300 feet per second in a 5" tract?

how long does it take nos to lean backfire the intake to the moon?

[Beagle]

how fuc... errr... bad is the tune?

[NewEnglandRaceFan]

how fuc... errr... bad is the tune?

well, I'll be new to efi, it could be off just enough, this isn't a 150 shot, this is a duel set up that can surply 250 the 1st stage and 400 the 2nd.. worked great on my carb'd engines, but efi is a whole different ball of wax, the air isn't mixed with fuel until at the end of the port, unlike a carb that it's mixed before it gets into the intake..

hard to test it to get a/r reading before getting to lean and going boom or melting something, by the time you get the reading it's already took it's prize

[JeffMcKC]

Geek has done some dry shots before

[CDMBill]

There is an assumption here,, I think that we are talking drag race only, or maybe limited street use as in getting from one track to the next on Drag Week or a True Street event or the odd cruise night where part throttle performance really doesn't matter.

If it does then the set-up Wilson manifolds recommended to me seems to work well for street and other perfomance driving where part throttle response, maintenance throttle and other needs are important too. It appears that for best power the highest location for the injectors on the runners is optimal, on the otherhand for other needs including throttle response etc. across the RPM band injectors closer to the head are better. The location of the fogger ports follows.

[dieselgeek]

Mark, don't overthink it. Start with just one stage on a small shot. It's *ridiculously* easier to run a dry shot on megasquirt, and it's also at least twice as safe as running a wet/standalone system.

Heck, you've waited long enough that now some MS variants come with two independent stages of PROGRESSIVE dry nitrous control...