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Nitrous Oxide in a Miata

20K views 11 replies 4 participants last post by  boston813  
#1 ·
So, who here is running Nitrous? Either in your miata or another car/toy? I plan to have the engine out this winter for an overhaul and cleaning so I was thinking that it would be a good time to drill and tap for direct port injection. The other thing that I was thinking was that if/when I decide to strap on a turbo I could still use the Nitrous. I have not decided on a manufacturer so any personal preferences that you have will be appreciated. I like the look of the ZEX direct injection kit and with a progressive controller it should be a good time. I am not looking for crazy power just a little more Umph in a straight line. Of course with any power adder there are some things that are needed for safe use such as wide band O2 and they are getting done regardless, so don?t bother to flame me with ?your going to blow up your motor? posts.
 
#3 ·
If you are just looking for a little more power using Nitrous, I dont think you really need the added expense of a direct port kit. For simplicity, I would look at getting a single fogger wet kit for maybe a 50hp bump in power. There really isnt anything to tune with a basic wet fogger kit sincethe nozzle sprays both the nitrous and the corresponding fuel. Just make sure that your fuel pump is able to add the additional fuel (shouldnt be a problem with a 50 shot), and dial back your base timing to prevent knock.
 
#4 ·
So, who here is running Nitrous? Either in your miata or another car/toy? I plan to have the engine out this winter for an overhaul and cleaning so I was thinking that it would be a good time to drill and tap for direct port injection. The other thing that I was thinking was that if/when I decide to strap on a turbo I could still use the Nitrous. I have not decided on a manufacturer so any personal preferences that you have will be appreciated. I like the look of the ZEX direct injection kit and with a progressive controller it should be a good time. I am not looking for crazy power just a little more Umph in a straight line. Of course with any power adder there are some things that are needed for safe use such as wide band O2 and they are getting done regardless, so don?t bother to flame me with ?your going to blow up your motor? posts.
If you aren't going with 100+ shot, then direct port is a waste of your money. Go with the standard dry kit for NA and a wet kit if you are turbo.

Dry kits don't put fuel where it isn't supposed to be, like the intake manifold, so you won't have any issue with that exploding. The nitrous is sprayed into the intake and the fuel is added by increasing the fuel pressure.

Wet kits put both the fuel and nitrous in at the intake, which is similar to running a water injection kit, due to the fuel cooling the intake charge. This affect also minimizes the likelihood of the manifold blowing up, which you won't get on a NA motor.

For a NA motor, the pills work as described by the manufacturer. 50 shot = 50ft/lb increase in TORQUE. That is also based on CRANK output, not wheel. These figures are normally come up with by using STOCK motors, so any motor work can make the nitrous produce more with the same shot.

For a FI motor, the pills are about 2 times what they are rated for, unless the kit is specifically marketed as a FI kit. There are a few ways to do nitrous on a FI car. You can spray low (3k rpm) to help spool a big turbo, and then disengage it when you hit boost (Zex makes a kit exactly for this). Or you can spray it on the top-end to make the power curve peak at max RPM. This is normally used on tracked cars, since it will abuse the motor more, but let you pull all the way to the top of each gear before you have to hammer the brakes for the next corner.

The Zex kit is what I would recommend, since it is easy to install, and adjusts the amount of fuel added based on the bottle pressure. I don't think they have a progressive controller for their kits, and they won't work with one, since they all run off a WOT switch and bottle pressure. I would DEFINITELY advise getting the bottle heater. I gained 18whp by just raising bottle pressure from 600psi to 900psi. Not bad for $123.

Anything else you need to know?
 
#5 ·
I thought about doing a nitrous setup once. But I started adding up the cost of the kit, bottle heater, remote bottle opener, purge valve, nitrous pressure gauge, etc etc etc, and the cost of filling up the nitrous bottle,... it ended up being as much as a home made turbo kit.

So that's what I did instead.

I guess if you are just going to do a single wet or dry fogger shot without the bottle heater, purge valve, etc, then it might be worth it. But in my opinion it's just as easy and just as cheap to build a turbo system. And with turbo, there's nothing to fill up, and the power is always there.
 
#6 ·
If you are just looking for a little more power using Nitrous, I dont think you really need the added expense of a direct port kit. For simplicity, I would look at getting a single fogger wet kit for maybe a 50hp bump in power. There really isnt anything to tune with a basic wet fogger kit sincethe nozzle sprays both the nitrous and the corresponding fuel. Just make sure that your fuel pump is able to add the additional fuel (shouldnt be a problem with a 50 shot), and dial back your base timing to prevent knock.
Most nitrous kits recommend pulling 2deg of timing for every 25shot increase for all but the 50shot.

50shot - base timing
75shot - 2deg retard
100shot - 4deg retard
etc

More clarification on wet vs dry:

Injecting nitrous oxide into the intake mixes pretty evenly, due to both being gases. This allows for proper distribution of the nitrous to each of the cylinders. Is it PERFECT? No. That is why people do direct injection, to get exactly the right amount of nitrous and fuel into each cylinder. But under a 100shot, the difference in dispersal is tiny, and not enough to cause an issue. Now the fuel is added evenly thru the injectors, by raising the fuel pressure. This varies as well, due to the injectors having SLIGHTLY different flow rates, or old, etc. Again, not enough to be an issue on anything under a 100shot.

Injecting FUEL into the intake does not ensure proper distribution of fuel, due to it being a LIQUID being mixed with a gas. It is not injected using anything that automizes the fuel, like an injector, it just uses a spray nozzle. Therefor one or two cylinders will tend to get too much fuel and the other two will get too little. These is due to the flow in the intake manifold, and the properties of the airborn liquid droplets.
 
#7 ·
Most of my research has been done based on the ZEX kit since they seem to have a good package and good feed back. Is there another system I should be looking at?

OK, here are my thoughts on the Dry and Wet Kits
1. It uses the stock injectors to keep the air fuel ratio correct (as far as I can tell) - thats not necessarily a bad thing unless I go with a turbo kit later that tries to do the same thing.
2. I feel a little limited by the dry kit, what if I decided that I want more power later? - what is the power limit of the dry kits?
3. The dry kit is only $140 less than the direct port kit
4. The wet kit is only $70 less than the direct port kit.
5. I can't imagine that injecting fuel into the intake plenum will get me an even distribution, thats not what it is designed for.

As for how to set up the turbo with the N2O... I don't know what I want to do yet but it is good to know that a "100" shot becomes a "200" shot when used with a turbo (Do I understand that correctly?)

when it comes to controllers I have not been able to find what I am looking for. My dream controller would be a progressive shot based on the TPS but only when you are in gear. I don't think I am going to find what I want but I may just build it later. I should be able to modulate a pulse to trigger the Solenoids but that may be a little hard on the stock ones... again, that is something to worry about later.
 
#8 ·
Most of my research has been done based on the ZEX kit since they seem to have a good package and good feed back. Is there another system I should be looking at?

OK, here are my thoughts on the Dry and Wet Kits
1. It uses the stock injectors to keep the air fuel ratio correct (as far as I can tell) - thats not necessarily a bad thing unless I go with a turbo kit later that tries to do the same thing.
2. I feel a little limited by the dry kit, what if I decided that I want more power later? - what is the power limit of the dry kits?
3. The dry kit is only $140 less than the direct port kit
4. The wet kit is only $70 less than the direct port kit.
5. I can't imagine that injecting fuel into the intake plenum will get me an even distribution, thats not what it is designed for.

As for how to set up the turbo with the N2O... I don't know what I want to do yet but it is good to know that a "100" shot becomes a "200" shot when used with a turbo (Do I understand that correctly?)

when it comes to controllers I have not been able to find what I am looking for. My dream controller would be a progressive shot based on the TPS but only when you are in gear. I don't think I am going to find what I want but I may just build it later. I should be able to modulate a pulse to trigger the Solenoids but that may be a little hard on the stock ones... again, that is something to worry about later.
I don't know if a progressive controller would be feasible with the ZEX box or not. I was told it wasn't when I asked about it a few years ago. They might have figure out a way to do it by now.
...and yes, the cooling affect of the wet shot plus the already dense air charge results in almost double th power from the shot. So 100 = 200.
 
#9 ·
I thought about doing a nitrous setup once. But I started adding up the cost of the kit, bottle heater, remote bottle opener, purge valve, nitrous pressure gauge, etc etc etc, and the cost of filling up the nitrous bottle,... it ended up being as much as a home made turbo kit.

So that's what I did instead.

I guess if you are just going to do a single wet or dry fogger shot without the bottle heater, purge valve, etc, then it might be worth it. But in my opinion it's just as easy and just as cheap to build a turbo system. And with turbo, there's nothing to fill up, and the power is always there.
Well, the only thing you really NEED is the bottle heater and the gauge. So that's another $180-200. It's fun when you ca spray when you want and not have to have it "on" all the time like a turbo, plus no lag. WOT and it's at full power, just don't jump on it under 3k rpm.
 
#11 ·
No Happy controller box with the direct port kit, just the fuel and N2O Solenoid. I like the idea of limiting the number of "Black Boxes" in the system.

Wow, that 50 shot will last a long time with a 8PSI Turbo :twisted:
Image


Looks to me like it still has the "black box".