So Ive kinda been looking ahead to next years(well I guess the end of this year) winter project. Ive been kinda doing some looking at nitrous kits. Holy heck at all the different setups! Thought Id post a thread trying to learn a little insight before hand. So for those of you who have or are proficient with a setup in their C4, what do I need to know? So I see theres “wet” and “dry” kits. Different bottles, sizes, different setups, etc. Other accessories like heaters, nozzles, purge kits, gauges, etc...

So what am I looking for performance wise? I guess whatever I could get away with safely. The top half of the motor has 195 AFRs, ported intake, bigger cam, etc but the bottom end is stock. What would be the reason for the nos? Honestly, just something to toy with on occasion.

And lastly, tuning...My car was dyno tuned after the heads, cam, etc. Would it need a re-tune with the nitrous?

Again, just looking at options for now and looking ahead. Any advice or expertise would be greatly appreciated.

 

What is your current compression ratio?

I put a 125hp kit on a 95 Z28. No major modification just your usual bolt on stuff like CAI, Cat-Back, Shifter... etc.

Nitrous can be cheap and easy. Unless you want it safe. Like any other forced induction this starts to become a slippery slope.

First, if you are going over 50hp, do a wet kit. Otherwise you have to address the additional fueling needed in the tune. To be completely honest, even with a wet kit, you will probably want to get it tuned to run the shot. to get the most out of it.

You absolutely want a purge kit. This allows you to purge the line and have liquid nitrous at the jet when you are ready to hit the button.
Bottle warmer, pressure gage, and a remote opener are also nice things to have. The nitrous flow can be affected by the bottle pressure, knowing what that pressure is and being able to control it is important to extract the most out of your kit. Depending on where you mount your tank, you may not be able to always reach it when you want to use it and you probably don't want to just drive around with it open all the time either.

My kit I had wired with an arming or "on" switch, a WOT switch, and ran and MSD box that allowed use of a window switch as well. No spray unless the kit was on, over 2500RPM and at WOT. You do not want to get a wet shot nitrous fire! So you have to make sure there is air velocity in the intake manifold. My kit was a Nitrous Works.

Like with most things, there is quick and dirty and then there is the right way. Your long term results will reflect the path you take. Noitrous done right isn't that much cheaper than other forms of forced induction. All have their pluses and minuses. Aslo for brands, just like Procharger and Vortech, there are various brands that all do the same thing. Shouldn't matter much on brand name, just get quality components. Good luck.

 

https://www.corvetteforum.com/forums...4-150shot.html

 

Theres a couple limitations with nitrous that got so annoying I ditched it...

First - the hit is biggest the moment the switch opens.

as RPM increases, the torque gain falls way off

I recommend spraying at idle for drag racing, but if you dont have traction - youll bounce off the rev limiter before you can let off . Risk of floating valves, etc.


next, if you are spraying anything short of a full bottle. You will NOT get the full hit of the nitrous.

i want you to stop and digest this for a moment...:

this would be like if you floored it with 1/4 tank of gasoline and you werent as fast as if you had a full tank....

can you imagine how annoying that would be ?well, thats the case with nitrous.

so some internet genius is going to come here and tell me you need a bottle heater.

nope! It wont matter.
If you spray nitrous at 1050 psi and your 10 lb bottle is full,

then use a bottle heater to heat up a half empty bottle to 1050 psi.....

you STILL wont make as much power as you did with a full bottle.
It has to do with the ratio of liquid to gaseous nitrous in the bottle that gets flashed in your intake ducting.


you will want to research ways around this limitation.

15 lb bottle? Twin bottle setups?
i saw something once that claimed it used nitrogen to ‘push out’ liquid nitrous at the bottom of the bottle....

 

The top pull is n/a. 93 vert 6spd with hotcam kit and tpis long tube headers. Alvin@pcmforless tune

the bottom pull is the same thing with an nx 100 wet shot (10 lb bottle with heater at 1050 psi)

note that the nx recommend fuel side jetting made it rich, so i was only getting a 70 rwhp increase and I had to go 2 fuel jet sizes leaner to get what you see here.


note how bad the torque falls off (with rpm) after the initial hit. I think they make ‘nitrogen assisted’ devices and stuff to get Around this drAwback.


im so much happier with my supercharged meth/water inj setup. I make more power and happily gun it everytime i want, not worrying about using up nitrous.

that said, im thinking about adding a small shot of nitrous back in it for drag racing bc it cools down the intake charge that gets heated up with boost

 

This too. I have seen people make spray bars for their Intercoolers and spray compressed CO2 or Nitrous over them for the same thing. I have also seen people use a small 50hp dry shot in their intake tube for just that very reason. Would be interesting to see the results on dyno back to back.,

 

Yes, because pressure and jet orifice size are constant... well you aim to keep your pressure constant. This provides the same flow at 2500RPM as 6000RPM. Obviously there is more concentration of oxygen rich N20 to outside air at lower RPM/CFM air movment.

I didn't know I was a genius, but here we go...

Yes it will


While this is true, a bottle heater does make a difference. Maybe it is the climate I live in, but if you have a Nitrous Bottole at 1050PSI when it is 80* outside, what do you think the pressure will be when its 40* outside. You can use gas laws such as Boyle's law and Gay-Lussac's law in how volume, pressure, and temperature are related. While a bottle warmer will not solve all ills of a nitrous system. It does at least solve constant pressure and temperature to ensure proper flow. Even a full bottle will flow differently at 90*F than 50*F. When the orifice is a constant and pressure is varying, so will flow.

This is true, but a bottle heater and purge kit help reduce variation, not eliminate it. I think one of the big components is, the release of liquid and drop in pressure is faster than the heater can make up for. As well as when there is less liquid and more gaseous volume, it takes a lot more to build pressure.

You can see this in a yard sprayer. When it is full, you pump it up in 4 or 5 pumps and away you go... but you won't spray very long before the pressure is gone. If it is near empty, you have to pump a long time to get spraying, but you can spray for a long time because there is not a lot of volume for the air to replace. In a nitrous bottle, this is all controlled by the heat added from a low wattage blanket. It's not enough to keep up with hit after hit.

Also forgot latent heat of vaporization. In the tank, it actually consumes heat to change state. With less volume of gas it is easier to maintain pressure and keep the nitrous in a liquid form. As the bottle gets emptier, more must be in gaseous form to maintain pressure. I think what you are getting at is as the bottle empties, more must become gas to have pressure. Gas is less dense that liquid... if you are not getting pure liquid nitrous to your jet, you will not get the same concentration of Oxygen Rich Nitrous as you did when it was a bottle full of liquid nitrous.

 

The yard sprayer example is a good one. Theres more volume coming out (with less pumps) then when you are near empty. Even if you pump it up a lot, you wont get the flow rate you did when the sprayer was full.



i had bottle heater, blanket, purge valve

A full bottle lets say Id see 950 psi, turn the bottle heater on now its 1050 psi. Id do a couple runs (not much use it seemed, and it gets used up fast).

so lets say Ive used up 3 lbs of nitrous, and theres 7 lbs left.

now i see 750 psi, so i use a bottle heater to heat it up to 1050 psi again and spray.

not the same result and it keeps getting worse and worse as the bottle gets towards empty.

whats the reason? Again, the ratio of liquid to gaseous nitrous becomes less as the bottle loses more and more ‘mass’ of nitrous.

now has tech changed today? I dont know. Maybe there is some doodad that fixes this problem. This was 15 yrs ago. That said i was using the best of the best, an NX system with heater, blanket, purge valve, safeties, window switch.

i even had expensive in-cabin electric transducer nitrous pressure and fuel pressure
gages in my line of sight at all times. I installed those once i noticed these drawbacks so I could more closely monitor whats going on.

now: can you get around this by heating a bottle up to a higher and higher pressure as it empties (higher than the 1050psi you used when it was full)? Possibly

Is it safe ??

or would a bigger bottle setup (15lbs or twin bottles) reduce this limitation ? Maybe. 10lb bottle like i had might be great for a Honda but turns into less and less on a v8

Otherwise I want to be clear about this drawback to nitrous before someone spends their money and becomes disappointed with the result when they may have been happier putting it towards a supercharger (as I wish i had initially done)

 

Because you keep having to reduce the volume of liquid to convert to gas to maintain pressure.

I was trying to convey the number of pumps to maintain steady pressure and flow but we are observing the same thing, just operating it differently.

The technology that needs to change is a way to maintain pressure and keep the liquid nitrous liquid. The yard sprayer I used as an example has a way to replenish pressure with an external force... pumping in ambient air to maintain pressure. I fully believe if you had a PLC that monitored pressure and could adjust the pump rate, you could maintain pressure and flow in a yard sprayer. There is no such method in a nitrous system so flow goes down as pressure/temperature change. I firmly believe what you are seeing is the heater can't keep up during a 1/4 mile hit and it only gets worse as the bottle gets empty. Resulting in less and less pressure at the upper end of the track, which is less and less flow due to the ratio of gas to liquid volume. Of course, even witht he yard sprayer, nozzle size would play a role in how fast volume is released and needs replenished. A 50hp shot is less affected at the upper end of the track than a 250hp shot in the % of additional power you lose.

Another issue I have seen in some installation is bottle position. If the internal tube doesn't stay submerged during hard acceleration, you can have issues keeping liquid nitrous flowing. This too becomes more of an issue when the bottle starts to empty.

Most folks think you put a bottle in your car, mount a plate, mount switch, and go. Cheap and fast... until you really start digging into the details. Nitrous like everything else has it's limitations and what it does well. There is the right way and wrong way.


You mentioned using Nitrogen to force the nitrous out, but I wonder if that is not filling a bladder in the bottle. As Nitrous volume decreases the bladder fills to reduce the internal volume of the bottle. Like an accumulator? Then the bottle will always act as near full.

 

All I can say is wow at all this in depth information. I wont lie, whats enticing is the “best bang for your buck” performance but wasnt aware of all the fine details. Definitely glad you guys have pointed out the issues/scenarios which was my main reason for the post. I would love to go the blown route but I will say, the reason I wasnt looking to supercharge was b/c of the unreal price involved to go that route. The charger alone on the low side is 4 grand. That doesnt consider all the other involved costs in setting it up to match whats already there. The AFRs would probably have to be changed out since the compression rate would come down drastically as opposed to the current high compression. Just so much to change and money to do it right.

After all the information Ive gotten from you guys, my best bet is to probably just leave well enough alone. Considering its barely driven as it is, is it really worth it? Nope!

 

Best bang for your buck amongst power adders for sure if you use the bare bones minimum to make a system work. Once you factor in all the extra goodies and safety nets to polish it into a rock solid system like pusher systems, blowdown tubes, window switches, remote openers, fuel pressure safety switches, line filters, solenoid maintenance, progressive nitrous relays, quality bottle brackets, various lines and AN fittings, pressure gauges, direct port alterations, complete stand-alone fuel systems to supplement the bigger shots, it could make one consider a forced induction alternative.

Also, if one really gets into it, then you’re looking at purchasing 60lb or larger mother botttle(s)and building your own filling station to fill your own bottles. Holley offers a kit for about $1100 or so as the foundation to set up a DIY fill station. You still need to supply your own mother bottle and compressed air source.

 

100%... and you have to keep filling as you use it. Once you get a solid system together and pay for bottle refills, the supercharger route is about the same investment long term if done right.