NITROUS OXIDE ( nos / n2o ) advice forum

An easy job but one that puts many a "newbie" off doing it themselves !
This isn't intended to be a definitive manual on fitting injectors, nor am I above criticism. If you have something to add then there’s a box below titled "post reply".
Questions are also welcomed; if it’s for a specific application then a picture is of great help.
I use Loctite products and will use their product codes but also add a description of what it may be called if made by another manufacturer to help you cross reference it.

Firstly think about the job, it’s no good mounting injectors perfectly only to not be able to shut the bonnet or get your plugs out. Sounds obvious but it's been done before. :roll:

Single carb engines
With a bit of imagination a simple bracket to hold the injector above and pointing down the carb throat can easily be made, just make sure there are no screws or nuts and bolts to come loose and end up in the engine !
Grommet the air filter base plate to pass the injector pipes through.
Great for sneaky installs !
(See "mounting injectors into thin steel" later)

Or use a "plate". This is an adaptor that fits between the carb and inlet manifold, drill and tap it to fit the injector into but think carefully about how you aim it, whatever you do avoid a plate that uses 2 spray bars to distribute the nitrous and fuel. Unless professionally modified they won't distribute evenly to each cylinder, even when modified they won't be even right at the point of activation so leave lawn sprinklers in the garage and fit an injector / injectors to it instead.
(See "mounting injectors into aluminium manifolds" later)
(Yes I fully expect grief for this one, before you do, connect one up and video it spraying into free air or better still a vacuum chamber, watch the video carefully and THEN post your reply)

Or use direct port; this is when an injector is mounted in each cylinder runner, see "mounting injectors into aluminium manifolds" later.

Twin carbs (Webers or individual throttle bodies with no plenum chamber)
Easiest way is to use a direct port kit and drill a hole in each inlet trumpet for the injectors; it can also be done using a similar idea to the single carb using brackets that point the injectors down each inlet.
(See "mounting injectors into thin steel" later)

Or fit the injectors into the manifold, again see "mounting into aluminium manifolds" later on.

Twin carbs WITH plenum chamber or air box.
Because of the dead air areas that can occur its best to stick to direct port and fit individual injectors to each trumpet, an injection manifold flows air differently to a simple air box and unless you can tell the difference play safe or ask

Fuel injection cars with short, horizontal or downdraft plenum chambers / inlet runners
Single injector mounted about 6 inches from where the inlet runners split into 4 or whatever usually works great.
Usually this will be into the rubber pipe so see "mounting injectors into rubber pipe" later.
If you have a MAF sensor then really you need to mount the injector between 9" and 12" BEFORE it or just after it so it doesn't freeze, ASK !

Turbo'ed
Usually the same as above, generally it’s better to mount the injector further away from the engine but after the intercooler, this gives even more time for the nitrous to cool the hot charge even more than it does already. If in doubt ASK !
Usually this will be into aluminium, thin steel or rubber pipe so go and look for the relevant mounting information later.

Supercharged
Mount the injector AFTER a centrifugal charger and BEFORE a positive displacement charger when you can, a centrifugal will tend to separate the mixture by throwing the fuel outwards which will give a leaner mixture for part of the time but the mixture actually helps positive displacement efficiency. If in doubt ASK !
Usually this will be into aluminium, thin steel or rubber pipe so go and look for the relevant mounting information later.

Fuel injection with long, uphill or tightly bent plenum chambers / inlet runners
Usually best to fit direct port kits, single injector kits can and do work but mixture drop out can cause problems, someone's bound to have done it before so if in doubt ASK !
This may be into aluminium or even plastic manifolds; do I really have to tell you where to look by now ?
And what should you do if you're in doubt ?


The injectors
Take them out of the bag and you'll find an injector, two spacers of different thickness' and a "top hat" threaded washer.
Tiny aren't they ? Have a really good look at them because once fitted you won't need to see them again. Wizards jet their systems at the solenoid which has numerous benefits;
1. Better performance
2. Smaller injector (better for tight places)
3. Lighter injector (easier to mount since it causes less stress)
You may hear tales that the Wizards injector doesn't atomise the fuel perfectly, these aren't tales they're true. What they do is atomise effectively at just about ANY distance, give me effective over theoretically perfect any day.
Most of the stories about how single injectors not working or causing distribution problems stem from theoretically perfect injectors not atomising effectively at the distances involved, use a single injector before using direct port whenever possible with this system, it works brilliantly and isn't the "poor relative" its made out to be. In fact direct port is far trickier to get right than you would think, carries more risks and can even be slower.
(The last time this argument came up it ran for days ! It felt like it was the Wizards against the world for most of it. If you want to kick it off again then click on the button "new thread" and have fun, I’ll see you there)


Mounting injectors into flexible rubber pipe
If you have a hole or gasket punch then what are you waiting for ? Punch out the hole just big enough for the injector, if you don't have a punch then you can use a normal drill bit or a "step drill" (a multi size drill bit that looks like a Christmas tree) DON'T use a cone drill, you're guaranteed to snatch on the rubber and end up with a hole you can drive through, you'll need a bigger drill bit than you think because the rubber will stretch away from the bit as you drill, using a 13mm bit to drill a 10mm hole isn't unusual ! If all else fails a rough file usually helps after the drill has been through. Now push the "top hat" into the hole from the inside and screw the injector into the "top hat" using the spacers to adjust how far the injector protrudes into the pipe, you want it to pull the "top hat" tight and have the outlet holes CLEAR of the pipe surface, too far in is better than not far enough and blocking the outlets, they're pretty small and low profile anyway so don't worry about disturbing the airflow, worry about blocking the outlets !

Mounting injectors into hard rubber pipe
(Some motorcycle inlets on air-cooled dinosaurs spring to mind here)
As long as the rubber isn't really old you can usually drill the rubber slightly too small and actually thread the injector into the rubber, Make sure you thread it in far enough, you want the discharge holes well clear of the rubber pipe, too far in is better than not far enough. When finished make sure you blow through the injector in case you got bits of rubber stuck in the outlets, with only gravity to feed them you can't take chances. If you can't do that then use the "Top hats" as with flexible rubber

Mounting injectors into thin steel / aluminium pipe
Get yourself a "step drill" (a multi size drill bit that looks like a Christmas tree) and a round file if you use a normal drill bit you'll just end up with a triangular hole that’s too big, denting the location you want to mount the injector always helps with this stuff, ideally you want a nice flat area about 3/4" in diameter. If you can't or don't want to dent it then fine, just be very careful drilling the hole, since you might end up with two sides of the hole the right size but the other two sides the next size up !
Drill the hole JUST big enough to get the "top hat" to sit in and use the spacers on the injector to pull the "top hat" tightly into the hole, if it won't go then file the hole slightly until it does. You want to end up with the "top hat" sitting flat on the inside of the pipe and the injector outlet holes well clear of the "top hat" with the spacers nice and tight.
With a lot of care and a sharp knife the spacers can be trimmed down a little to get it perfect, don't worry about it because they hardly disrupt the airflow anyway, fit them too far in rather than not far enough to clear the outlet holes in the injector properly.
Finally add a few drops of "oxygen sensor safe" sealant under the "top hat" to make sure it doesn't leak air.
I use Loctite "superflex" / "Ultra black" or Valco "all in one silicone"
Depending on what I can still squeeze out of a tube, just make sure its Oxygen sensor safe on a modern fuel injected car.

Mounting injectors into aluminium manifolds
Ok, two ways of doing this, I usually use the hard way unless the manifold turns out to be too thin walled, if it is then I use the "thin wall pipe" instructions.
The "hard way".
File a flat area about 1/2" in diameter where you're going to mount the injectors, this isn't critical but makes life easier in a number of ways !
Think carefully about how you want to aim your injector, mounting into aluminium is one of the few times you can effect how it aims and not always for the better.
Using the right size drill for your tap (drill undersize to begin with) drill your hole, use a cutting fluid and you'll have a nice smooth hole the size you drilled, don't use cutting fluid and you'll almost always end up with a bigger rough hole from the aluminium sticking to the drill bit and ripping rather than cutting.
Cutting fluid isn't engine oil, grease, ear wax or any other substance, its called cutting fluid for a reason, it helps cutting ! There are very few substances that help you cut, drill or tap a hole, most normal lubricants actually make the job worse by forming a hard plating when subjected to the forces involved, cutting fluid isn't just maintenance spray in a can, its cutting fluid ! When you tap your hole and it rips the threads out as you do it because the aluminium has galled (stuck) to the tap or the thread is really loose because it was drilled too big for the same reason maybe you'll listen !
Lesson over and hopefully a nice hole drilled.
If you've never used a tap before or if this is a brand new tap then get some pieces of steel and tap a few holes, apart from practice it takes the very sharp edge off the tap which helps stop it grabbing the aluminium and gives you a tighter, neater thread)
Now put the tap in a proper tap holder (yes, I’ve used spanners too when I’ve had to, didn't make for an easy thread though did it ?)
Holding the tap as perfectly straight with the hole as you can and pressing firmly down on to it turn it clockwise until it bites into the aluminium properly, now carefully turn it anticlockwise a little until it "breaks" the swarf created, if it comes out then you didn't go far enough in to start with, if it won't turn anticlockwise more than a bit then you went too far in to begin with.
Be gentle when you break the swarf and blast it with cutting fluid to help keep the hole clear so it doesn't jam and ruin the thread, if its really stuck then be patient and work it back and forth until it goes, forcing it will almost always ruin the thread.
Now keep going but once the first thread is cut you don't need and shouldn't press on the tap, it will cut on its own. Remember, forward a bit to cut some more, backwards to break the swarf, keep going until the hole is threaded all the way.
Now clean off any swarf and cutting fluid and if you have any sharp bits of thread sticking out of or into the manifold then gently remove them with a file, large drill bit or a knife.
Spray the threaded hole with Loctite 7063 or electrical contact cleaner until you're sure it’s clean of any grease.
Spray the injector too; make sure there isn't any grease or oil on the threads.
Use a drop or two of Loctite 2701 high strength lock and seal or Loctite 243 medium lock and seal, thread it into the hole, aim it how you want with the outlet holes well clear of the tube wall and leave alone, don't touch until cured (2701 takes 6 hours, 243 takes 2 hours, both can be accelerated with Loctite 7240 accelerator, if temps are below 5 degrees C then it should be used anyway)
Once cured this is "fit and forget" Consider it for all intents and purposes welded in. if you want to then a good fitting spanner can still remove them or adjust them but expect a fight !
If you do adjust the position or just want to be absolutely sure then use a drop of Loctite 290 "wicking grade" sealer, this stuff will seep into any thread or joint even when already tight and seal it after 3 hours, its also great for repairing porous castings but don't accelerate it, keep the part above 5 degrees C and wait.
If you made a mess of the hole or the thread and are sitting in the corner crying then get some Loctite 638 retainer and use that to hold the injector in, it isn't meant for this job but it works, even on ripped out threads.
If you ever want to remove the injector after using this then even if the thread was ok before it'll be destroyed now. This stuff has got me out of the smelly stuff on many a memorable occasion and it doesn't mess about.
If you've gone beyond even what 638 can do for you then don't reach for the noose just yet, Find your local hydraulics or pneumatics supply place and ask for a "flanged blanking plug" the next size up, drill and tap again for that, Loctite it in and try mounting the injector somewhere else or use a "flanged reducing bush", again drill and tap to suit, Loctite it in but you won't get one with this thread so you'll need to drill and tap it to suit but it will get you out of trouble.
If all else fails get the mess welded up or a new manifold and either practice some more or find an engineers that'll do it for you !

Mounting injectors into plastic manifolds
If its thick enough then you could thread it as with an aluminium manifold, don't tap the thread all the way through, keep taking the tap out and trying it for size, you want to end up with a good tight fit but not one so tight you need a big spanner to thread the injector in, use a drop of Loctite 5331 low strength sealer to seal it, and use the spacers to give you a nice tight solid injector, using any of the normal grades of lock and seal will mean the thread WILL rip out if you ever remove it.
Try the sealer first as some will react with some plastics and make them soft.
Some plastic manifolds have been known to crack around the hole after a while but if you're in any doubt then just use the "thin wall pipe method"
DON'T whatever you do thread an American style fogger into a plastic manifold, the extra weight, and stress of jet changing WILL crack or rip the thread out of the manifold.
I hope that helps

WOW That's some goooood info!

not bad for a "newbie" eh!

lol

Why thank you for your appreciation, I thought that since we were having a "fresh start" over here we'd better start re-stocking the pond so to speak.
I've got a few more to come yet, I just wish i could type faster or with more fingers !

Loopy,
Get the F**K off here and sort that electrical problem (or is it too bloody cold???)

Seriously thanks for the input, I haven't had time to read it all but knowing you it will be correct so thanks for the time and effort.

Regards

I have about 3.5 ft of piping from my front mount IC to the TB. Should i attempt to put the nitrous/fuel jet right after the IC's end tank?

Second point:
My blow off valve sits about 6" from the TB, for lag reduction purposes of course. Would putting the nitrous/fuel jet (wet system) before the blow off cause any trouble with venting a fueled charge into the engine bay?

Thanks,

Serge

Serge>
I presume your inlet piping curves away from your IC and then straightens up for the run into the TB, i'd place it where the pipe straightens up to give it a good distance while still having a pretty straight path down the inlet.

The Dump valve won't cause problems, it's only open when you come off the throttle and thats when the nitrous system will shut off, UNLESS your dump valve is being opened by the excess boost spike that can sometimes occur when running nitrous but that isn't common.
By the way, did you realise you could improve intercooler effeciency by moving the dump valve to the hot side of the intercooler ? That way you won't be dumping cooled charge, only hot charge and it'll improve how much the intercooler cools.
I've yet to see a good reason for mounting them on the cool side apart from helping cheap diaphram valves last longer and the pipework usually being easier / dump valve being in a more visible place.

Loopy, thanks for the helpful post re nozzle location.

I'm in the process of doing an install on a Skyline GTST. I want to keep the pulsoids and lines in as cool a place as possible which is just behind the nearside headlamp. My problem is that the place closest to the pulsoid where I want to mount the nozzle would mean that the pressurised air and the nitrous/fuel charge has to follow a 90 degree bend in the alloy pipework before straightening up for a straight run to the throttle body.

With the air being forced through by the turbo would the charge be sufficiently mixed by the time it reaches the throttle body. Personally, I can't see a problem with the 90 degree bend, and moving the nozzle to the throttle body side of the bend would mean having the pulsoids and nozzle in a hot part of the engine instead of a cool part. I'm guessing it's swings and roundabouts in this situation!

I'm trying to picture what you are talking about in my head but I am not sure I am folowing without an actual picture.

The 90 degree bend should not be too crucial as many applications are set-up like this. Just make sure that the nitrous/fuel mixture don't have to travel a long distance or uphill before getting to the intake manifold as fuel drop-out can occur. Good job on mounting in a cool place.

Pete, If it keeps your solenoids cool and your lines short then don't worry about a 90 degree bend in a turbo inlet, just make sure you aim it to swirl around the bend and not straight into it.
I'd put cold solenoids and short pipes above a 90 bend any day of the week.
You avoid them when you have an easy choice, thats all.

The theory I’m familiar with regarding placement of the dumpvalve after the IC centers on minimizing the part of the entire charged tract that depressurizes when the dumpvalve opens, thus minimizing lag on up shifts due to repressurization.

On another note, I’ve come across the theory of maximizing the length of nitrous line between solenoid and jet on FWD cars, as the softer initial “hit” (as the gas needs to fill the volume of this length of line first) is less likely to upset traction.

Any thoughts on this?

Thanks,

Serge

Highpower has the jet in the the outlet of the solenoid body so it softens the hit already over the competitons styles, then a progressive controller can top this off for the ultimate in traction control and delivery.

I can't say i've ever even heard of that theory, I certainly couldn't say it really stands up, nor can be felt.
(Cosworth certainly didn't seem to agree, perhaps for differing reasons though)

Oh i've come accross the long nitrous line theory before alright.
Its provided many an evenings amusement.
American kits tend to have an initial lean out which shocks the driveline (doesn't do the engine an awful lot of good either and restricts your jetting too)
Rather than bodge about with lengths of pipe and have varying effects from one minute to another why don't they keep the pipe as short as possible and use a small circuit to delay the solenoid by a few M/S ?
Leave it in the "myths and legends" folder with the rest of the American rules.

Racetested, here is where Thor have mounted the pulsoids and nozzles on a customers Skyline GTST, saying that nozzle should be as close to throttle body as poss, and line should be as short as poss.



I think they've taken this to the extreme at the expense of having it all situated in too far a hot lccation. The nitrous line has exploded a couple of times. Also this is a turbo car so I intend to mount my nozzle a lot further away from the throttle - i.e. in the rubber pipe on the inlet side of that 90 degree bend in the top metal pipe. adjacent to the power steering fluid res. Does that clarify what I meant?

My pulsoids are mounted right behind the nearside iheadlamp and line only needs to be 10 inches long.

Here is my motor. I originally had the injector placed before the TB and I was getting severe fuel drop-out as the intake pipe does go uphill also. My solenoids had to be mounted where they are, not the best spot but this will change once I swap to a centrifugal blower.

A turbo motor that is pushing behind the mixture may work out better as I have seen on a few applications. I can only say give your idea a try and see what happens. Don't be to critical on some installs as long as they aren't completely bogged up. Some things are trial and error especially when you have an application that doesn't lend an easy job to a perfect install all the way around.

The nitrous line should be covered with a heat reflector also in this application.

Cheers Denny.
I've just noticed from the pic I posted that the intake does run a bit uphill but not sure if this is uphill enough to cause fuel dropout. Think I'll aim the nozzle to a high point before the bend and hopefully it'll swirl through ok!
I suppose the best option would be to tap that intake pipe at the highest point but then that means much longer pipe after the pulsoids again...

You may be better off than I was because you will have a push of boost behind the mixture. Here is another application where you can see the injector way down low and has to travel straight up on this style of manifold but it was a turbo motor also. The customer has since gone to direct port but ran a 100 shot all last year with the single point with no reported problems. This is what I mean by trial and error. As long as you keep the testing power levels low enough and move up in small increments you should not harm the motor.

Petermills,
Good to hear from you, glad to hear you're getting it sorted.
The Thor fit of the injector is the best option.
The Pulsoid location is OK but if there is a cooler location within 12" then that may be better (as you suggest behind a headlamp).

I suspect the pipe problem is due to the route they've taken to get to the Pulsoids as it looks like they've run it across the back of the bulkhead (which is the worst place possible).

I'd better have a word with them about it.

Regards

Cheers Guys.

Trev, the nitrous pipe on the Thor instal has since been relocated but the pulsoids are still in the same place.

Denny, thanks for the second picture of the instal with the nozzle really low down. That's kind of making me feel a bit better as this afternoon I have punched a hole and fitted the nozzle in the location I mentioned - the rubber tube before the 90 degree bend. I went ahead and did this even though Ant had said that an uphill route isn't very good. I just couldn't quite bring myself to drill and tap the metal intake as it was too cold and damp! I've directed the nozzle so that the outlet should cause the nitrous and fuel to go across the bend and towards the straight section of metal pipe therefore overcoming the problem. Trial and error - I quite like that! Fingers crossed now though.

Hopefully this'll work out ok but if not then I'll be plugging the hole I've just punched and then drilling and tapping elsewhere. It'll just have to be on a warm day.

When it's all running I'll stick another thread up somewhere to report whether or not my location is any good.

Pete> Trevor has said that Thor have put the injector in the best place, now i can't argue with him, he's got one hell of a lot more experience than i.
But, I would personally have mounted the injector roughly where the nitrous pulsoid mounting nut is and mounted the pulsoids on the power steering bracket, at least as a trial.
Putting yours in the rubber link pipe before it is pushing things slightly, but with such a decent sized (smallish) inlet pipe such as it is i don't think you'll have a problem.
It really isn't ideal, but then is it ever ?

"Cooltube" pipe insulation and solenoid heat shielding is always a worthwhile job (that reminds me, i must do mine sometime )

Peter,

You'll probably get away with it on 25 bhp jets and possibly 50 but I certainly would move it at the earliest opportunity to the Thor location.

Make sure you seal the hole in the hose when you do that as you could lose boost otherwise.

Regards

Man I'm worried now in case my nozzle position turns out to be totally pants! Off to the motor factors tomorrow anyway to get a suitable size drill and a tap so I can position it in the metal pipe where it straightens out.

You may have difficulty on a Saturday.
Its an awkward size comared to "normal" threads.
Its basically a sensor size, so it may be worth trying a garage.
You need an
M10 x 1.0 pitch tap and a
9mm or 11/32" drill bit (I use 11/32" it give a tighter thread in junk alloy)

I had to many complaints on finding proper taps and such that I just went and bought a whole bunch and supply them with the kit now. My goal is to make the install as easy as possible.

You don't need a tap, you can use the same retainer that you've used in the rubber hose, so all you need is a drill, just a bit bigger than the start of the taper on it.
If you want to tap it the thread is 10x1mm (metric fine).
You don't need to panic to get it done, as I said you should be OK up to 50 bhp as you are.
We can then loan you a tap and drill if you want it.

Regards