My comments about plate distribution problems are directed to the LT1 intake. Whether this is directly applicable to the LS1 systems, I don't know. But look at the logic, and try and think of any reasons why it would not apply to the LS1 intake manifold as well.

Look at where the plate sprays, then look at the spacing to the #1/#2 runners compared to the #7/#8 runners. A wet system consists of two phases.... vaporous N2O and tiny liquid droplets of fuel. It has to turn corners of various radii to enter the intake runners.

Its much easier to "bend" a gas phase flow around a corner than it is a liquid phase component with its significantly higher density. The droplets want to go straight, even though the gas-phase nitrous is turning the corner. Lots of nitrous might make the sharp bend to #1/#2, but the fuel droplets aren't going to be able to make that turn as easilly..... now you have uneven N2O/F ratio in each cylinder.... some may be rich, others will be lean. Its simple physics.

Now, when you "tune" the system, you have to address the leanest cylinder, meaning you will most likely be running too rich in some of the others, and giving away power. Some aftermarket ECU systems, like the MoTeC, allow you to address the uneven N2O/F mix by trimming the "normal" A/F fuel supplied via the injectors to each individual cylinder. That allows you to balance things back out, and maximize the utilization of the nitrous.

And, the maldistribution is not limited to WET systems. It can be a problem even with a dry system. You need space for the air and nitrous to mix uniformly before the flow enters the intake runners. Spraying a dry system well in front of the throttle body solves this problem, and promotes uniform mixing/distribution. The data I have seen on plate distribution, from the guys at Second Street Speed who set up my 300 dry shot system, was enough to convince me I didn't want a plate behind the TB. (I was the one who suggested the plate). Even though my MoTeC can be tuned for fuel trims and igntion timing trims, by individual cylinder, it made no sense to accept running a few cylinders with less nitrous/less HP than the others, reducing the total HP from the system.

I'd like to hear more from the nitrous "pros" who represent the Supporting Vendors. What is their experience with plate systems in the LT1. Does my explanation make any sense to them? Has the plate designer addressed these specific issues with the layout of the spray bars and nozzles?

My technical experience with two-phase flow issues is not with nitrous systems. But I have studied high speed photos showing the interaction of sprayed liquids with in an effort to determine why gas/liquid scrubbing systems did not measure up to their predicted performance, and the affects of inertia on a drop(let) of liquid can not be ignored. I put a lot of trust in Second Street, because of there extensive experience specializing almost exclusively in dry nitrous...... and no, its not a "lazy mans" system, if done right.

 

And let's give the sticky a try..... not my forum, but doesn't seem to be a lot of coverage here.

 

Ok, I'm thinking out loud here, so bear with me.....As I understand, and correct me if I'm wrong, but you can only "mist" or atomise fuel (from a liquid state) to a certain point before it becomes a vapor. (I understand what you're saying, I'm just trying to word it.) A vapor would be the ideal condition... In order for it to become a vapor, it needs to be heated somewhat... I am unsure how fuel reacts to mild heat before reaching the flash point. Also the IC engine runs basically on fuel vapor, not the liquid. Seeing as the vapor is more flamable than the liquid.
--I read an article about the NOS plate system that stated that they found a jetting that allowed a very fine atomization of fuel. Again, you mentioned about the heavy fuel having to cut a 90* turn to enter CYL 2... Runner for 2 would be on right side, correct? Cyl one is front right, but the runner is on the left side back slightly.-LS1.... LT1 Runners 1+2 would be about a direct shot into the CYL.... I'm not too familiar with the LT1 intake.



Ohhh.... Ok.... As the 'mist' of Gasoline is injected into the manifold, combined withe heat, it becomes vaporus after a period of time. Hence why injected a certain distance before the TB.... A DP kit would use the hot intake valve combined with the velocity of incomming air to aid in atomisation? I suppose that's when N2O timing would come into play. Given Valve overlap, the nitrous would need to be injected after the exhaust valve has closed, or before? If it were after, you probably wouldn't get a 'full' clynder's worth of vaccuum. -If you catch my drift. (like I was saying, I'm trying to find a way to word what I am thinking.)

How does the weight of Gasoline vapor compare to the weight of Nitrous Vapor? -Heavier? A heated fuel hose might be a dumb idea, right? Just curious. .....But there is no oxygen in that line to support ignition.......Just wondering if there was a better way to atomise fuel. Move the nozzle farther upstream?

Hence the efficency of DP, correct? Stupid question, but is there another system that would be more or AS effective as DP?

I would also like to Hear from our nitrous Vendors and/or testers..


One last one for this response... What causes sneeze or backfire? Fuel puddling in intake due to too low RPM engaugment? Valve overlap igniting fuel vapor in intake?

 

What you are overlooking with regard to the fuel being in ONLY a liquid phase in the intake manifold, is the fact that when the nitrous pressure drops across the plate (from ~1000psi -> 0psi) the liquid nitrous flashes to vapor, absorbing a huge amount of heat. This heat comes from the surrounding air and the fuel, and drops the temperature of both. Fuel can not vaporize when its cooled below its flash point.

As it approaches the intake valve, it will absorb heat and vaporize, but by then its too late.... any maldistribution caused by the mixture making a turn frmo the plenum to the runners can not be corrected.

The reason Second Street likes a dry system is because it eliminates these issues. By over-sizing the injector, you can get some degree of control over the air/fuel/nitrous mixture, because you can limit a large part of the injector's pulse width to the time the intake valve is open. Even in their 6-second Pro-5.0 Mustang, they use the NOS NOSzles, for nitrous only, still relying on the injectors to spray the fuel at the right time, and to atomize it. The NOSzles solve the issue of cylinder-to-cylinder N2O distribution in that case.

In a DP (wet) system, N2O and fuel are flowing constantly, much of the time against a closed intake valve. Where does that N2O and fuel go.... is there reversion to the intake manifold? In the dry DP system, the nitrous is always flowing, but the fuel is not.

 

I did NOT even realize that... ... For some odd reason I overlooked the constant flow... I must have been thinking of injector timing for the regular fuel system. My thoughts got jumbled.

 

I agree that there is not a one size fits all, but in the lt1 setup, I personally feel that the dry system is inferior to the wet, I'm not saying that it doesn't work.

 

Nozzle over plate anyday.

 

2 nozzles go in the lt1 plate

 

I appreciate the input from everyone. It really helped. Injuneer, again thanx. THe Physics stuff was eye opening.

I'm gonna go with a dry system just because of what was discussed about the weight of the fuel droplets. And the Nitrous temperature does not really help the fuel atomization with the wet kit. -My opinion.

Any recomendations as far as MAF sensors? 85mm MAF? ZO6 MAF? I am sure I will need a tune as soon as I get it all hooked up.

I would like to hear some sponsors feed back as far as testing and what they have found. I am not looking for a biased opinion, or someone who is siding w/ 'X' kit. Just findings of mixture or what not... THanx again for all the help guys!....

 

I'm not trying to post ***** here, I feel this deserves it's own square.

When I posted this I was not looking for a all together SUPERIOR kit.. I am looking for pro's and cons of BOTH kits. I believe both have their benefits and some prefer dry and some prefer wet. All suggestions are appreciated. Also, please state why you would prefer each kit or what your reasoning was when you bought it.

Thanx again!

 

Stay with the stock MAF, descreen it if you must. Also, nitrous temp is important to keep a consistent flow of nitrous, but does not affect atomization.

 

I think I'll put the screen back in. I think it'll help distribution over the sensors for more efficient operation.

What size injectors? Pump?... Wait, I'll search it...

 

i would do 28-32 lbs injectors would be plenty, 28 would be cool for a 100, and I would suggest a fuel pump since you decided to go dry.

 

Allways remove the screen when do a dry hit. The reason being, the cold nitrous will collect on screen and cause a restriction/blockage.
Here is a good wet vs dry thread for insight.
Wet vs Dry Thread
Robert

 

robert knows his stuff