Nitrous: Direct Port vs Single Nozzle on a boosted vehicle

[Alky V6]

Well the concern was unbalancing the distribution on an 800-1000 hp application. Sure, the nitrous is only a 75 shot, but if it causes one or two cylinders to run lean... ouch

Start out with a safe shot and check plugs after a hard run. You'll see if you have a distribution problem. If all the plugs look good, step it up a little and so on.

Just make sure you shut off at the end of the run to get a true reading from the plug. You could also use individual EGT readings if you have the equipment.

 

[Pronto]

Interesting, I've never heard that before. I'll have to re-read the rulebook. I can't imagine why it wouldn't be allowed.

-BC

My understanding is they don't want anything being sprayed freely in the engine compartment. As for the water sprayers they don't want water dripping on the track.

 

[Alky V6]

The cooling effect is substantial. I saw about 45 deg IAT downstream of the hose if I recall.

If I had melted or otherwise hurt plugs I'd be pretty darn upset. Major engine damage is not far behind. Something is/was drastically wrong in your approach, at least for a moment to see that damage (as you no doubt know).

TurboTR

Oh, I wasn't a happy camper about it. A couple of the plugs lost their porcelain and went through the turbine wheel. That, by the way, gave me the reason to step up to a T76 from a T70. Among other things, the mixture wasn't strong enough and the fuel began to preignite. It could have been much worse. Like some broken rods. I jumped into that test way too quickly. One of my stupid moments. That is why I emphasize everyone to be very careful with this stuff. Small steps if you're learning.

I now have a larger wastegate, a larger spare turbine housing, a better nitrous retard system, know how important it is to properly prep your spark plug ground electrodes for a full on nitrous pass, and more importantly, I now understand how much fuel this monster wants. It's questionable that my current fuel pump would be able to handle a full pass with the 200 shot system on. The next series of tests I plan on doing will be to find out just how close to capacity I'm runnng the fuel system with the present tuneup.

 

[Alky V6]

A few differences between port injecting or injecting with a single nozzle.

The first thing to realize is that nitrous absorbs heat energy from the surroundings as it changes state from a liquid to a gas. This is what gives it the cooling effect.

Nitrous is more dense in its liquid state. More oxygen content per volume.

Gaseous nitrous will distribute better that liquid nitrous.

In a single nozzle setup, it is important that the nitrous changes physical state before it has to make turns in your inlet tract. Liquid just doesn't make sharp turns as well as a gas.

When the nitrous changes state in the inlet tract, it will cool the overall inlet charge and make for a denser overall inlet charge.

Port injecting nitrous will have less of a cooling effect on the inlet tract, but will have a major cooling effect during the compression stroke, since much of the nitrous will enter the cylinder in liquid form and will be changing state inside the cylinder, cooling the combustion process more directly. Another fine point about port injecting nitrous. Since much of the nitrous is entering the cylinder in a liquid form, much denser than when its in a gaseous state, you end up with a supercharging effect of the charge as the nitrous changes state from liquid to gas directly in the cylinder.

 

[TARZAN]

As I beliee has already been said, I'd have to say the size of the shot would come into play here. On a mildly modded car, with less than a 100 shot, I'd go with a single nozzle.....on a turbo buick, if I were gonna spray more than a 100 shot, it'd most likely be direct port. Theres too much of a history of starving cylinders, and I wouldn't want to run a power plate to try and fix it, because it'd become too restrictive beyond a point....I run a 50 shot on my car, have for awhile now, through a single nozzle and its worked great. Gives INSTANT spool, cooler intake temps, and gives a lil bump in power when needed elsewhere .

-Will