School me on nitrous dry kits

[propellerhead]

I read several FAQs and threads and got a bunch of knowledge. Here's my personal FAQ, as it relates to my 2004 Mustang GT with a fairly stock engine. Please fill in as required.

1. A dry kit sprays N2O before the MAF and relies on the car's EFI system to provide the additional fuel. Depending on the amount of nitrous used, the stock injectors and fuel pump might not be able to provide enough fuel. Hence, dry kits are usually good for 50-125 shots only. True?

2. Anything over a 100 shot in a dry kit will require injector and fuel pump upgrades. True?

3. Anything over a 125 shot in wet or dry will require upgraded pistons and other internals. True?

At this point, I'm leaning towards a dry kit since it has less parts, which means less things to fail (like stuck solenoids), which means a lower risk of kaboom. If #3 above is true then I don't plan on going above a 100 shot so a dry kit makes more sense.

Am I on the right track?

 

[03ghoststang]

I read several FAQs and threads and got a bunch of knowledge. Here's my personal FAQ, as it relates to my 2004 Mustang GT with a fairly stock engine. Please fill in as required.

1. A dry kit sprays N2O before the MAF and relies on the car's EFI system to provide the additional fuel. Depending on the amount of nitrous used, the stock injectors and fuel pump might not be able to provide enough fuel. Hence, dry kits are usually good for 50-125 shots only. True?

2. Anything over a 100 shot in a dry kit will require injector and fuel pump upgrades. True?

3. Anything over a 125 shot in wet or dry will require upgraded pistons and other internals. True?

At this point, I'm leaning towards a dry kit since it has less parts, which means less things to fail (like stuck solenoids), which means a lower risk of kaboom. If #3 above is true then I don't plan on going above a 100 shot so a dry kit makes more sense.

Am I on the right track?

1) yeah the nitrous is sprayed seprately from the fuel and the injectors add the additional fuel.....

2) but i would upgrade no matter what

3) im sure that would be necessary

 

[hotpony]

NOS is not sprayed before the MAF, it wouldn't make a difference anyhow if it was because it reads MASS AIR FLOW, so basically the NOS goes down into your combustion chambers basically increasing the compression ratio, this results in the pistons sucking air faster, which in turn, brings more airflow in through the MAF. Now this is going to lean the vehicle out initially so with the output of the O2 sensor combined with the reading of the MAF, this is where the AIR/FUEL ratio is adjusted.. This is the theory anyhow. With a wet system the O2 sensors never reads a lean mixture so no more fuel is attempted to be added, and if it is, it's usually a minimal amount making it more reliable in the long run..

As far as going with a Dry instead of a Wet system due to the amount of parts, that's not a very good reason, solenoids do get stuck but that's a pretty rare case, most nitrous mishaps are due to broken momentary switches or people using them incorrectly, like spraying nitrous into an engine while not at WOT and under no load.. You want a window switch which will only allow the momentary switch to operate between a certain RPM, such as WOT between 2500-6000RPM.. Anything below 2500 the nitrous is not allowed to be introduced to the engine..

Dry kits do work but upgrading the injectors is a pretty big must, and in this, the pump will need to be upgraded as well.. An adjustable fuel pressure regulator will need to be installed for tuning issues as well as a timing retard or a chip to be burned. Most of the guys I know run a dual position switch for NA and NOS, NOS retards timing at certain RPM's under certain conditions where as the NA mode does not..

ZEX is making a pretty fail-safe system which was proved by MM&FF to make a descent amount of HP. There's was a wet system which had the controller built-in so it would account for vaccum and fuel pressure as well as nitrous flow all in one system. Very nice, very easy to install, pretty darn cheap as well!

Good luck, nitrous can be fun, just make sure you don't cut corners, or you'll be rebuilding more motors than you'd like to

 

[Pughman]

i have the zex dry kit, with just colder plugs, and i only have it on the 75 jet. have had no problems after 1 bottle .....

 

[propellerhead]

NOS is not sprayed before the MAF, it wouldn't make a difference anyhow if it was because it reads MASS AIR FLOW, so basically the NOS goes down into your combustion chambers basically increasing the compression ratio, this results in the pistons sucking air faster, which in turn, brings more airflow in through the MAF. Now this is going to lean the vehicle out initially so with the output of the O2 sensor combined with the reading of the MAF, this is where the AIR/FUEL ratio is adjusted.. This is the theory anyhow. With a wet system the O2 sensors never reads a lean mixture so no more fuel is attempted to be added, and if it is, it's usually a minimal amount making it more reliable in the long run..

As far as going with a Dry instead of a Wet system due to the amount of parts, that's not a very good reason, solenoids do get stuck but that's a pretty rare case, most nitrous mishaps are due to broken momentary switches or people using them incorrectly, like spraying nitrous into an engine while not at WOT and under no load.. You want a window switch which will only allow the momentary switch to operate between a certain RPM, such as WOT between 2500-6000RPM.. Anything below 2500 the nitrous is not allowed to be introduced to the engine..

Dry kits do work but upgrading the injectors is a pretty big must, and in this, the pump will need to be upgraded as well.. An adjustable fuel pressure regulator will need to be installed for tuning issues as well as a timing retard or a chip to be burned. Most of the guys I know run a dual position switch for NA and NOS, NOS retards timing at certain RPM's under certain conditions where as the NA mode does not..

ZEX is making a pretty fail-safe system which was proved by MM&FF to make a descent amount of HP. There's was a wet system which had the controller built-in so it would account for vaccum and fuel pressure as well as nitrous flow all in one system. Very nice, very easy to install, pretty darn cheap as well!

Good luck, nitrous can be fun, just make sure you don't cut corners, or you'll be rebuilding more motors than you'd like to

Thank you for the insight on the theory. That's what I was looking for.

I read a few manufacturer's websites and they claim their dry kits do not need upgrades to stock parts under 125 shots. This is the limit I'm trying to get confirmation on.

 

[uhoh5.0]

I have been researching this pretty thoroughly too, and here is whatt I've come up with:

The first debate always seems to be between wet and dry kits. I'm not really going to get into that too much, I'm just going to provide the conclusion I came up with right or wrong. Here goes, the wet kits are probably safer in the sense that fuel and nitrous are added together usually thru a "nozzle" that atomizes the fuel partices using the high pressure of the nitrous liquid. This is a positive as it allows for an even mixture of nitrous and fuel to be added to each cylinder and the risk of one cylinder running lean is slim. However, the biggest drawback and the reason I would be leary of this type of kit is the chance of fuel puddling in our intakes and the chance of a backfire and the stock plastic intake exploding which does happen (just try the search feature).

So, this leads me to the dry kits. On the older cars that used a return-style fuel system in my mind this is the perfect kit. Most people agree that a dry kit doesn't "hit" as hard as a wet one but to me, the advantages are pretty good. But the catch is with our cars using a returnless style fuel system you can't bump up the fuel pressure on your own so the traditional dry kits that spray just before the throttle body and use nitrous pressure to raise fuel pressure won't work. Therefore, there are only 3 options that I know of for using a dry kit on our cars. 1. The edlebrock dry system that uses a fuel pump booster (similiar to the kenne bell boost-a-pump) to send extra voltage to the fuel pump when the nitrous system is activated. 2. Spraying the N2O thru the mass-air and hoping that the ECM can accomodate with extra fuel thru the stock injectors. 3. Spray the dry kit just before the throttle body and have a custom tune made which is created while on a dyno to account for the lean condition the N2O would otherwise cause.

Now, from the people I have spoken to, here are the problems with the previous scenarios. #1. This kit comes with only an 80hp jet that seems not to produce anywhere near that amount of horsepower. And in general you run the risk of a cylinder still running lean because the stock intake doesn't direct airflow 100% evenly between the 8 cylinders, and the stock 19lb injectors are not "matched" and don't always provide the exact amount of fuel to each cylinder. #2. Those whom I have talked to that have verified this set-up on a dyno say that results are shaky at best and that runs are not consistent, the MAF element can freeze and ruin, and as previously mentioned you don't know if 1 or 2 or more cylinders are lean. And finally #3 seems to be a perfect scenario, until I spoke to someone who had a flip-switch with a dedicated N2O tune that didn't "flip" one time and he blew his motor because there was no way to know that the "tune" hadn't activated (Jim Fitzgerald). Anyway I hope this helps some and further sparks the reseach of a good dry kit. Sorry I'm a little (or alot) long winded.

 

[jstreet0204]

I have been researching this pretty thoroughly too, and here is whatt I've come up with:

The first debate always seems to be between wet and dry kits. I'm not really going to get into that too much, I'm just going to provide the conclusion I came up with right or wrong. Here goes, the wet kits are probably safer in the sense that fuel and nitrous are added together usually thru a "nozzle" that atomizes the fuel partices using the high pressure of the nitrous liquid. This is a positive as it allows for an even mixture of nitrous and fuel to be added to each cylinder and the risk of one cylinder running lean is slim. However, the biggest drawback and the reason I would be leary of this type of kit is the chance of fuel puddling in our intakes and the chance of a backfire and the stock plastic intake exploding which does happen (just try the search feature).

So, this leads me to the dry kits. On the older cars that used a return-style fuel system in my mind this is the perfect kit. Most people agree that a dry kit doesn't "hit" as hard as a wet one but to me, the advantages are pretty good. But the catch is with our cars using a returnless style fuel system you can't bump up the fuel pressure on your own so the traditional dry kits that spray just before the throttle body and use nitrous pressure to raise fuel pressure won't work. Therefore, there are only 3 options that I know of for using a dry kit on our cars. 1. The edlebrock dry system that uses a fuel pump booster (similiar to the kenne bell boost-a-pump) to send extra voltage to the fuel pump when the nitrous system is activated. 2. Spraying the N2O thru the mass-air and hoping that the ECM can accomodate with extra fuel thru the stock injectors. 3. Spray the dry kit just before the throttle body and have a custom tune made which is created while on a dyno to account for the lean condition the N2O would otherwise cause.

Now, form the people I have spoken to, here are the problems with the previous scenarios. #1. This kit comes with only an 80hp jet that seems not to produce anywhere near that amount of horsepower. And in general you run the risk of a cylinder still running lean because the stock intake doesn't direct airflow 100% evenly between the 8 cylinders, and the stock 19lb injectors are not "matched" and don't always provide the exact amount of fuel to each cylinder. #2. Those whom I have talked to that have verified this set-up on a dyno say that results are shaky at best and that runs are not consistent, the MAF element can freeze and ruin, and as previously mentioned you don't know if 1 or 2 or more cylinders are lean. And finally #3 seems to be a perfect scenario, until I spoke to someone who had a flip-switch with a dedicated N2O tune that didn't "flip" one time and he blew his motor because there was no way to know that the "tune" hadn't activated (Jim Fitzgerald). Anyway I hope this helps some and further sparks the reseach of a good dry kit. Sorry I'm a little (or alot) long winded.

This is one of the best posts I've seen on Dry vs Wet kits. Good job

 

[propellerhead]

I agree although it's not a wet vs dry kit thread...

 

[uhoh5.0]

I was basically just trying to provide some background on nitrous kits before I got into the specifics of dy kits. I too am interested in a dry kit, but I have yet to find something I'm really comfortable with. One thing I forgot to mention was that at least in theory a direct port kit like the one from NOS would solve all of these problems. But to me, the price is just way out there. Again, just my 2 cents right or wrong.

 

[LaserRed01GT]

It makes a critical difference whether or not the N20 is sprayed before or after the MAF sensor on anything over a 75 shot. The N20 liquid density at boiling point is 76.8 lb/ft3 (1230 kg/m3) and the N20 gas density at 70°F 1 atm, 0.1146 lb/ft3 (1.836 kg.m3). Additionally the N20 has roughly 1.5 times the vapor density that the air does. This is just a fancy chemical explanation for why the N20 cools the incoming intake charge so much and makes the incoming air so much more dense.

Stored under pressure, the N20 remains in a liquid form until it is allowed to escape that pressure. Once it escapes that pressure, it becomes a mixture of vapor and gas then eventually all gas. When the N20 is sprayed into the intake system, it can reduce the incoming air charge by 50°F - 100°F.

This makes the incoming air much more dense, or much more mass per given volume. The MAF sensor will recognize this denser incoming air and the pulsewidths will be increased accordingly. If you spray the N20 past (TB side of MAF) the MAF sensor the MAF sensor will not be able to recognize the denser incoming air and will not be able to appropriately control the fuel delivery via the injectors.

N20 absolutely DOES NOT increase the static or dynamic compression ratio. The way N20 makes more power is by way of a chemical reaction. At roughly 565°F, N20 breaks down independently into N (Nitrogen) and O2 (Oxygen). The additional O2 present just after ignition increases the potential for combustion by allowing for more O2 which consequently allows for extra fuel. The resultant BMEP (Brake Mean Effective Pressure) pressures will increase. Some confuse this with compression ratios. Higher cylinder pressures result in more power and in turn provide more of a scavenging effect through the intake valve during valve overlap.

The advantage to running a wet setup is that you pull the additional fuel off the rail and inject it directly into the intake. This allows people to run a larger shot while keeping the stock fuel pump and injectors. The disadvantage to a wet setup, like you said, is the increased chance of a nitrous backfire in the intake. But, if you have all of the proper safety equipment (ie. properly pilled window switch, WOT switch, FP safety switch, etc.) you should not have any problems.

The advantage to running a dry shot is the simplicity of the install and a decreased chance of having a nitrous backfire. Like some others already mentioned, it is normally required to upgrade the injectors and pump for anything over a 100 shot on a dry setup.

For what it's worth, I have run about 7 10# bottles so far on my 125 HP wet shot with the mods in my sig on stock injectors and pump. I did have a N20 backfire a while back that took out the intake manfold, but we traced the problem to a faulty TPS WOT sensor. We ditched that and went to a conventional microswitch for WOT and have not had a single problem since. My A/F at WOT stays right around 11.5-11.9 which is pretty comfortable on 125 wet shot.

Your tune is everything.

 

[propellerhead]

I was basically just trying to provide some background on nitrous kits before I got into the specifics of dy kits. I too am interested in a dry kit, but I have yet to find something I'm really comfortable with. One thing I forgot to mention was that at least in theory a direct port kit like the one from NOS would solve all of these problems. But to me, the price is just way out there. Again, just my 2 cents right or wrong.

I think we're both on the same track. I like the simplicity of a dry kit. Simple means reliable. Reliable means safe. Lower costs is also a plus.

If you spray the N20 past (TB side of MAF) the MAF sensor the MAF sensor will not be able to recognize the denser incoming air and will not be able to appropriately control the fuel delivery via the injectors.

True. The few dry kits I looked at have a line to the fuel pressure sensor or regulator to tell the fuel system that we need more fuel.

The advantage to running a wet setup is that you pull the additional fuel off the rail and inject it directly into the intake. This allows people to run a larger shot while keeping the stock fuel pump and injectors. The disadvantage to a wet setup, like you said, is the increased chance of a nitrous backfire in the intake. But, if you have all of the proper safety equipment (ie. properly pilled window switch, WOT switch, FP safety switch, etc.) you should not have any problems.

The advantage to running a dry shot is the simplicity of the install and a decreased chance of having a nitrous backfire. Like some others already mentioned, it is normally required to upgrade the injectors and pump for anything over a 100 shot on a dry setup.

You are confirming my findings so far. Thanks.

This leads me to my next concern. It seems the dry kit and the wet kit are essentially the same and the main difference is in how the additional fuel is provided. The amount of fuel added is fixed and predetermined by the manufacturer of the kit, wet or dry. With a dry kit, the N20 kit tells the EEC via the fuel system to dump more fuel through the existing hardware. The fuel is added into the combustion chamber and is atomized, just the way the engine was designed. The wet kit adds the fuel by an additional fuel line. It dumps the fuel into the intake airstream. The EEC has no clue that the air and fuel amounts have changed. With this I still think the dry kit is a better design in that the fuel is delivered via the existing hardware and not just tapped into what is supposed to be a clean airstream. Plus, with the dry kit the engine's computer is aware of the changes and can adjust other stuff accordingly, if necessary. The only drawback I see with a dry kit is that you can only increase the "shot" up to the capacity of the fuel system to deliver the necessary fuel.

Who agrees? Who disagrees? Why?



PS. Thanks for engaging in this discussion. I get tired of responses like "Go wet!" or "Dry kit FTW!"

 

[propellerhead]

Here goes, the wet kits are probably safer in the sense that fuel and nitrous are added together usually thru a "nozzle" that atomizes the fuel partices using the high pressure of the nitrous liquid. This is a positive as it allows for an even mixture of nitrous and fuel to be added to each cylinder and the risk of one cylinder running lean is slim. However, the biggest drawback and the reason I would be leary of this type of kit is the chance of fuel puddling in our intakes and the chance of a backfire and the stock plastic intake exploding which does happen (just try the search feature).

I beg to differ on this. Dumping nitrous and fuel in the airstream near the throttle body won't assure a more balanced mixture in each cylinder. I'm guessing the four middle cylinders will get more of the nitrous/fuel mixture. With a dry kit, the fuel is added to each cylinder individually via the fuel injectors. If you know for certain that one cylinder is richer or leaner, you can adjust that with your tune. You can't do that with a wet kit unless you have a nozzle in each cylinder and you swap jets out.

 

[propellerhead]

Damn. I guess you can't discuss the pros and cons of a dry kit without comparing it to a wet kit. I was hoping to stay away from the dry vs wet battle. Hopefully we can focus on dry kits.

 

[LaserRed01GT]

I think we're both on the same track. I like the simplicity of a dry kit. Simple means reliable. Reliable means safe. Lower costs is also a plus.


True. The few dry kits I looked at have a line to the fuel pressure sensor or regulator to tell the fuel system that we need more fuel.


You are confirming my findings so far. Thanks.

This leads me to my next concern. It seems the dry kit and the wet kit are essentially the same and the main difference is in how the additional fuel is provided. The amount of fuel added is fixed and predetermined by the manufacturer of the kit, wet or dry. With a dry kit, the N20 kit tells the EEC via the fuel system to dump more fuel through the existing hardware. The fuel is added into the combustion chamber and is atomized, just the way the engine was designed. The wet kit adds the fuel by an additional fuel line. It dumps the fuel into the intake airstream. The EEC has no clue that the air and fuel amounts have changed. With this I still think the dry kit is a better design in that the fuel is delivered via the existing hardware and not just tapped into what is supposed to be a clean airstream. Plus, with the dry kit the engine's computer is aware of the changes and can adjust other stuff accordingly, if necessary. The only drawback I see with a dry kit is that you can only increase the "shot" up to the capacity of the fuel system to deliver the necessary fuel.

Who agrees? Who disagrees? Why?



PS. Thanks for engaging in this discussion. I get tired of responses like "Go wet!" or "Dry kit FTW!"

You can setup a dry kit to control the fuel enrichment through the PCM (EEC) and spray after the MAF. You enter a pre-determined fuel map based on data logs of dyno runs and/or street/track runs. It physically alters the VE tables, injector constants and/or offsets, and ignition advance and overall timing. But that can get quickly out of hand when things like weather and motor dynamics change.

Then there are kits like the ZEX that actually raise the fuel rail pressure to offer the fuel enrichment when spraying.

But, I like the spraying before the MAF on a dry setup. The MAF normally does a pretty good job of accounting for the denser cooler air and ultimately adjusting the pulsewidths accordingly. It's just important to get your timing dialed in and make sure that your injector duty cycles are not going over 85%.

The vast majority of people that break stuff internally with nitrous (namely the rotating assembly) do so under relatively low RPM when the torque spikes associated with nitrous are the greatest. Most of this can be alleviated by having a proper tune, making sure the bottle pressure is good (950 PSI-1050 PSI), having the car properly pilled, and always making sure the injectors are functioning properly and are under 85% duty cycle. I personally would never spray under 3500 RPM. There is just no reason to.

It is also a good idea to run an inline N20 filter. Smaller jets can often get clogged or contaminated.

 

[the98stang]

At this point, I'm leaning towards a dry kit since it has less parts, which means less things to fail (like stuck solenoids), which means a lower risk of kaboom. If #3 above is true then I don't plan on going above a 100 shot so a dry kit makes more sense.

Am I on the right track?

Your on the WRONG track. It is a very bad idea to rely on your PCM to control the amount of fuel going into the engine. If it fails to sense the extra air coming into the engine (the n2o), your engine is screwed. Solenoids may become stuck, but this is why you check them before you spray. If you want to be extra safe, buy a direct port system. Wet kits are in between direct port and dry kits. You don't want to cheap out when it comes to this kind of HP. Get a wet kit, and get the car tuned on the dyno. Stick to 100 shot. Your rods will be happy, as well as your intake manifold. Also upgrade your fuel pump...

 

[uhoh5.0]

I started a thread like this a few weeks ago, but really didn't get the feedback I was looking for. This is GREAT! And I also would like to focus on dry kits, but it seems like you always have to make reference to the other options to justify or verify a point. What seems to be a factor with a dry kit is that you solely rely on the injectors to add fuel, whereas a wet kit is throwing in some extra fuel to boot. That is all I meant by the wet kit having a far, far less risk of having a lean cylinder. Anderson Ford Motorsports also has a dry set up, but you have to buy their expensive and complicated (at least to me) pcm device, and it has parameters built in to allow you to tune each cylinder. But for me anyway, I have an 04' vert that I paid close to 30k for and I've probably put another 8k into it, and I still make a fairly large monthly payment on the car, so I guess what I am saying is that while many of the mods I have already done to the car could be considered "risky" I just have this fear of destroying my motor with an excessively lean series of runs. Thats why I have been trying to look into the "safest" N20 route or lack there of

 

[LaserRed01GT]

Your on the WRONG track. It is a very bad idea to rely on your PCM to control the amount of fuel going into the engine. If it fails to sense the extra air coming into the engine (the n2o), your engine is screwed. Solenoids may become stuck, but this is why you check them before you spray. If you want to be extra safe, buy a direct port system. Wet kits are in between direct port and dry kits. You don't want to cheap out when it comes to this kind of HP. Get a wet kit, and get the car tuned on the dyno. Stick to 100 shot. Your rods will be happy, as well as your intake manifold. Also upgrade your fuel pump...

People have been successfully spraying N20 before the MAF and the IAT for a long time. The IAT and MAF usually do a good job of working with the PCM to appropriately adjust the ultimate fuel control with the injectors which is injector pulsewidths.

Do you have any evidence showing that using a dry setup in this fashion has proven to not work 'enough' to discourage using a dry setup in this fashion?

Why is buying a dry kit a "cheap out"?

 

[uhoh5.0]

LaserRed,
You seem to be very knowledgable on this subject, what do you think would be a safe amount of N2O to spray thru the MAF sensor with a kit like the "Compucar Bottle in a Bag"?

 

[propellerhead]

Your on the WRONG track. It is a very bad idea to rely on your PCM to control the amount of fuel going into the engine.

A stock NA motor relies on the PCM to control the amount of fuel going into the engine. A supercharged motor relies on the PCM to control the amount of fuel going into the engine. A turbocharged motor relies on the PCM to control the amount of fuel going into the engine. Are those bad ideas too?

What seems to be a factor with a dry kit is that you solely rely on the injectors to add fuel, whereas a wet kit is throwing in some extra fuel to boot.

We rely on the injectors to add fuel in N/A, blown or turbo applications. I don't see why we can't rely on them for small/medium nitrous applications. As long as the amount of nitrous injected doesn't need an amount of fuel that exceeds the injectors, I don't see why the dry kit is a bad approach.



Another side topic: Does the 2004 4.6 have a returnless fuel system? I haven't read up on this topic yet but someone told me dry kits are not made for returnless fuel systems, or something like that.

 

[LaserRed01GT]

LaserRed,
You seem to be very knowledgable on this subject, what do you think would be a safe amount of N2O to spray thru the MAF sensor with a kit like the "Compucar Bottle in a Bag"?

In all honesty, you get what you pay for......in my expereince at least. From what I know about those Compucar kits is the actual quality of the components is actually not that bad. It's the way the kit is designed to work that is not all that favorable. I never ever like the idea of controlling the hit with a handheld button. You are just asking for carnage. Having a hardwired WOT switch or TPS switch is a must. I also question the delivery of the N20 through a plastic main feed line.

The Compucar solenoids are supposed to be decent. But another thing that I don't like is how they don't give you a RWHP rating for a specific jet size.

Technically speaking unless the bottle is bolted down, it is not NHRA/IHRA legal. The blowdown tube rule is not really enforced, but is a good idea.

I have heard of people using the Compucar "bottle in a bag" system with success, but if it were me I would spend the extra dough for a reputable conventional dry kit along with the safety accessories and WOT switch and bottle warmer. A FPSS is not a bad idea either.