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Questions for those running N2O...


LanceVance

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I've been contemplating putting together a simple wet nitrous system for my L28ET build and I wanted to throw out a few ideas out to get peoples opinions. Firstly, let me outline my wants for the set up:

 

1.) It has to be clean. I've spent a lot of time making the engine as clean as possible; everything will be tucked and shaved and having a bunch of extra lines running all over just won't do. I'm not trying to hide the fact that I'm using nitrous, in fact the tank will be in plain sight.

 

2.) It has to be simple. I will hardly ever have the opportunity to use it (think 2-3 strip visits per year), so a fancy direct port, multi nozzle system is overkill to the extreme. It's mostly about having fun for me, not being super competitive.

 

3.) It has to be affordable. I have no problem spending money on quality components (although I can do without the purple anno) and I don't plan skimping on things such as the tank or solenoids, areas where safety is concerned. But as I previously mentioned, multiple nozzles and fancy extras are not needed or wanted.

 

Okay! Now my questions:

 

My ideal place to mount to mount the nozzle would be the core plug on the back of my intake manifold. I like this because it is simple to drill out, and install the nozzle with a couple of nuts and some rtv, the plumbing is short, and the solenoids could easily be hidden in the cowl area without being far from the nozzle.. Besides the ease of mounting, it is also 100% reversible where drilling holes into my shaved manifold is not!

 

The question here is will this be able to evenly fog the intake chamber despite being opposite the throttle opening? I'm no fluid dynamics engineer, but images of pissing into the wind come to mind...

 

My second choice would be to mount the nozzle in the intake pipe, post intercooler, where it comes through the rad support. I've already found a nice low profile nozzle that could fit nice and snuggly at all the right angles, allowing for the plumbing to be tucked along the top of the fender. The issue here is the distance from the throttle body, and the recirculating BOV in between them; there is also the issue of the bends in the pipe creating the opportunity for pooling.

 

Will I have issues if the BOV opens and some of the mixture gets sent through a hot turbo?

 

Is the nozzle too far from the throttle body (everywhere I read says 6" is ideal)?

 

Are the bends a big enough issue to make this unsafe? I'm having Casey (SenzaPari) fab up a nice pie cut piece for this section and the bends are looking very smooth and gradual...

 

Lastly, I'd like to ask for any general advice, or ideas that you might have. I know I'm not the first to go down this route, so if you've got an idea that you think fits my plan then please share it!

 

Thanks HybridZ members, and sorry for the trademark long winded post!

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Spray bar in a spacer behind the throttle body. Think of the kind you bolt between a carb and intake on a v8. Could be really clean install if you plumb the lines under the manifold or tuck them up by the thermostat.

 

Or you might be able to put it where the cold start valve went.

 

My 2 cents.

 

And as an aerodynamist, putting it at the end of the manifold will not lead to even cylinder distribution.

Edited by ctc
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Spray bar in a spacer behind the throttle body. Think of the kind you bolt between a carb and intake on a v8. Could be really clean install if you plumb the lines under the manifold or tuck them up by the thermostat.

 

Something to consider, though I'd like to avoid doing extra ($$$) fab work. I'm running a ported manifold and weber TB, so I doubt there is a ready made piece like those using 240sx TBs.

 

Or you might be able to put it where the cold start valve went.

 

Long gone!

 

IMG_20121130_195453_zpsd7b0c41f.jpg

 

And as an aerodynamist, putting it at the end of the manifold will not lead to even cylinder distribution.

I figured as much, but I was hoping someone would prove me wrong. Thanks much for the advice!
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His cold start valve port is definitely gone ;)

 

I second the option of running it in a spacer behind your Weber throttle body. 

Alternatively drill and tap the manifold behind the throttle entrance. 180* from where the cold start used to be.

Edited by cockerstar
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His cold start valve port is definitely gone ;)

You know that better than even I do!

 

I second the option of running it in a spacer behind your Weber throttle body.

 

Let me know when your CNC rig is up and running and we'll see what we can come up with...

 

Alternatively drill and tap the manifold behind the throttle entrance. 180* from where the cold start used to be.

I don't see the day every coming that I cut into that manifold Ryan! If I ever did, it would be a proper, no holding back direct port set up. Perhaps you could CNC me a dual channel fuel rail that stays in line with my penchant for cleanliness? Hmmmmm....

 

Here's a new question, any reason not to do something like this:

 

ssts-0912-26hidden-nitrous-revealedthrou

 

The entry point could be hidden up near the rad support. A simple hard wire bracket could easily be made to support the ends keeping them from vibrating without blocking any measurable amount of air...

Edited by LanceVance
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I was thinking about adding a small nitrous shot to my car to help with spool-up until someone on another forum posted this picture...

The owner made two large mistakes there:

 

1.) He left the bottle in the car while it was parked in the sun, on a hot day, for a prolonged period of time. This is a no-no, and there is no reason to do this with quick disconnects and bottle carriers so readily available.

 

2.) He used a tank that wasn't equipped with any sort of pressure relief valve. Any name brand, purpose built tank should have this safety feature. His has clearly failed, or more likely was never equipped with with one.

 

Someone else's failure is hardly reason to give up something yourself. Just realize that you are working with something that is potentially hazardous. Educate yourself and use the proper safety measures and you'll be fine.

Edited by LanceVance
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Any throttle spacer for the stock manifold/throttle body, the KA24DE manifold/throttle body, or the Weber throttle body could work. It's not like it's a difficult part to make, nor would it be expensive to have machined. Check the bottom side of your throttle body for an unused port/boss and see what you can find. Looks like there is some material there to work with.

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My experience with N20; gone through 30+ bottles and sprayed 150-175 wet in my mustang. I made a bunch of mistakes, decent size nitrous back fires, etc.

 

The key with it, is it is only as safe as you make it. Having the appropriate safety measures like a window rpm safety switch is very important unless you are running this via a standalone. Pressure pure, etc. 

 

I don't think any of the suggestions made for nozzle placement will be optimal. You should have the nozzle 3-6" in front of the throttle plate, with the straightest path possible. Atomization is critical with a wet shot, and placing it behind the throttle plate doesn't seem as this will occur. Paths to runners could separate this process and give unwanted results/performance.

 

I wouldn't worry about puddling, unless you are running a large 'shot'. Velocity is going to be important to avoid that, and if worried don't spray until the upper RPMS'. In my case, I was spraying 150 above 4k and never ran into any issues. I would run the nozzle in the pipe between the intercooler/throttle body. If you attached a picture we could gauge how large of a 'bend' you have. There are also controllers that will progressively spray via RPM to ensure items like velocity are present.

 

As for the BOV; having fuel go through the turbo isn't directly an issue, as this is how some blow through setups are. Some will state that the gas drop lets 'can' damage the compressor wheel, but you will have to further research that. I would further look into any residual fuel going through the intercooler. I am not mentioning the N20, as it is an accelerator to the fuel, and why I am only mentioning the fuel. Is there a reason why you cannot vent to the atmosphere and possibly avoid this worry?

 

Keeping this looking clean should be easy; place both solenoids in a fender and only run the two stainless lines for the nozzle. I hid every aspect of my N20 system. My purge would run under my car, and I would only purge when doing a burn out to keep the noise/puff cloud a secret.

 

I have only touched on some points to get started and didn't go into full detail but can certainly share all my explosive experiences...

Edited by CarJway
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...it is only as safe as you make it. Having the appropriate safety measures like a window rpm safety switch is very important unless you are running this via a standalone... 

I wasn't really planning on getting very technical here, just an arm switch and a WOT switch. Once I'm off the floor I'm off the juice which should work well enough for what I'm wanting out of it. Is a RPM window switch necessary for a set up like that? I don't really plan spending a lot of time bouncing off the rev limiter. I will be running MS, so the opportunity to upgrade will be present should I ever desire.

 

 

I don't think any of the suggestions made for nozzle placement will be optimal. You should have the nozzle 3-6" in front of the throttle plate, with the straightest path possible. Atomization is critical with a wet shot, and placing it behind the throttle plate doesn't seem as this will occur. Paths to runners could separate this process and give unwanted results/performance.

I've been considering more and more just putting a small bracket within the intake pipe itself and mounting the nozzles to it. This would allow for optimum nozzle placement, and with solid mounting points (bulkhead fittings on the insertion end) should make vibration a non issue.

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As for the BOV; having fuel go through the turbo isn't directly an issue, as this is how some blow through setups are. Some will state that the gas drop lets 'can' damage the compressor wheel, but you will have to further research that. I would further look into any residual fuel going through the intercooler. I am not mentioning the N20, as it is an accelerator to the fuel, and why I am only mentioning the fuel. Is there a reason why you cannot vent to the atmosphere and possibly avoid this worry?

 

I suppose I could run open, although I doubt the old school HKS 'diverter valve' was ever intended to be ran that way. It's probably just my distaste for people putting loud BOVs on otherwise unmodified cars around that makes me want to run recirculated... If I go with the method I mentioned above it shouldn't be an issue either way.

 

I have only touched on some points to get started and didn't go into full detail but can certainly share all my explosive experiences...

Thank much for the thorough response, it is greatly appreciated. I'll probably be shooting a few more questions your way once I'm closer to putting it all together. Still have some time to study while I gather the parts, so I'll keep reading up on some of the points you've touched on.
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Window switch; unless you are controlling the solenoids via a standalone no switch is needed. As you will control this via the ECU. Set the juice to cut off 250-400 rpms before your redline. I give that buffer, for any type inconsistency in what you are using for a trigger. I had the same setup you described (WOT/Arm) and it cost me 2 head gasket jobs. For the small price of a window switch I think its needed.

 

Placing this in the pipe; since you are boosted, you are going to have to worry about sealing the lines going into the pipe. Vibrations wouldn't be my worry here, but rather sealing everything on boost. As well, placing this in your charge pipe with the bends might not be an issue due to positive pressure in the intake tract, rather than vacuum alone carrying Fuel/Nitrous. I never got into a boosted nitrous setup, but nozzle placement/bends might not be as critical.

 

BOV; I can see where you're coming from. But if anyone thinks your a ricer, let them see what a 'ricer' L28 is all about... I would probably go with an open to atmosphere to avoid any added complications.

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"I don't think any of the suggestions made for nozzle placement will be optimal. You should have the nozzle 3-6" in front of the throttle plate, with the straightest path possible. Atomization is critical with a wet shot, and placing it behind the throttle plate doesn't seem as this will occur. Paths to runners could separate this process and give unwanted results/performance."
 

 

Ditto: also the further you place the wet fogger upstream the 'softer' it hits.

 

BOV needs to vent pressure upstream of any fuel air mix, recirculating to turbo inlet keeps it quiet and can assist spool if put into the airstream correctly.

 

You really don't want the system filled with combustible Fuel/Air N2O mix.... "BOOM"

 

If you don't pick your BOV point carefully, venting to atmosphere dumps a big belch of combustible Fuel/Air N2O mix into the underhood area with hot exhaust manifolds, stray electricals, spark plug wires which may be suspect.... at best "Flamethrower" at worst.... "BOOM"

 

Really, most people just put the foggers in the intake runners...hardest hit and least impact on placement of anything else upstream of the throttle plate. Atmoization is not such a big deal with the current generation of Fogger-Style Nozzles.
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I'm afraid I was too busy yesterday to type a proper response to everything that was said, so please excuse yesterday's short post!

 

Window switch; unless you are controlling the solenoids via a standalone no switch is needed...

...I had the same setup you described (WOT/Arm) and it cost me 2 head gasket jobs. For the small price of a window switch I think its needed...

Sounds like very good advice, I'll start researching what it takes and the associated costs to add solenoid control to MS vs a standard window switch.

 

Placing this in the pipe; since you are boosted, you are going to have to worry about sealing the lines going into the pipe...

I'll most likely end up trying it out with two bulkhead fittings and some RTV on the outside. If that doesn't work I'll just have them welded in place. 

 

BOV; I can see where you're coming from. But if anyone thinks your a ricer, let them see what a 'ricer' L28 is all about... I would probably go with an open to atmosphere to avoid any added complications.

More than likely I would position the nozzles in such a way that it avoids the BOV path before venting to atmosphere. I like the recirculated sound and the help spooling up. You can see the valve in my gallery if it makes any difference to the discussion.

 

...the further you place the wet fogger upstream the 'softer' it hits...

 

Softer would be better here. I'm not really looking for the Fast N' Furious light bending, face melting hit.

 

BOV needs to vent pressure upstream of any fuel air mix, recirculating to turbo inlet keeps it quiet and can assist spool if put into the airstream correctly.

I'm hopping that the nozzles mounted even with the BOV flange provides a nice balance, while avoiding sending fuel further up the intake path. When you say 'into the airstream correctly' do you mean angling the dump point downstream so that it creates as little turbulence as possible, or something beyond that? I suppose I could even angle it side to side to create a cyclone effect?

 

If you don't pick your BOV point carefully, venting to atmosphere dumps a big belch of combustible Fuel/Air N2O mix into the underhood area with hot exhaust manifolds, stray electricals, spark plug wires which may be suspect.... at best "Flamethrower" at worst.... "BOOM"

The BOV's location was decided long ago, with many other factors in mind. That said, I see no reason I can't keep it recirculated with the set up I outlined above.

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Problem is if you get any fuel/air/N20 mix recirculated through the turbo, THEN get a backfire....Bye-Bye compressor housing!

The bracket will be located in such a way that the ends of the nozzles will be beyond the opening for the BOV. Aside from that, the engine being under boost should keep the mixture moving in the right direction.

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You can blow the air into the inlet pipe from a 'T' fitting. This effectively creates an 'air knife' action disturbing smooth flow to the turbine inlet. If you have an MAF it could puke it out backwards and give some mixture control issues. Midway between the MAF and turbo inlet in this case would be the best compromise for it to re-laminate into airflow before going to the turbo and have least change of MAF disturbance. Dumping into the  inlet filter housing if using MAP-Based controls is also easy enough, if not somewhat hard to plumb.

 

You can blow it into the inlet pipe at an angle towards the turbo...better... But it's likely small diameter piping being used so it has relatively high velocity. Hit the turbine wheel the wrong angle and instead  of pre-spinning the turbine you act as a stall brake. Yes, you dropped pressure, but you tried to counter-rotate the wheel at the same time...sub-optimal. An angled entry into the end of a cone style intake filter, or into the filter base works pretty well but packaging can be difficult. It gives a reverse flow to the filter blowing off chunks of crap lodged in it (in theory) and is far enough upstream to get the flow back together by the time it hits the turbine wheel. Generally a MINIMUM of 4 pipe diameters of straight run is recommended, but 12 is a 'metering run' ...  

 

Blowing it in at a tangential angle with a  slight directional tweak to blow the turbine wheel in the direction it's already turning is ideal. Close to the turbo so the energy of the fast blow-off air can do some good. A turbocharger tachometer can show the speed level or sometimes increase when blowing off with that setup. Some setups have a diverter baffle to straighten out the flow or get a pre-spin going into the turbine for better efficiency. This can mean 3% better head out the discharge end. You would dump between that baffle (usually 4 piping diameters maximum from the inlet of the turbine wheel.)

 

We will not discuss moveable guide vanes and controllers.

 

Just keep the N2O and Fuel where it won't come out the BOV under any circumstances and you should be good. Everyone seems to want to put the fogger right on the TB piping. Personally I stuck it on the underside of the AFM outlet Flange. Nobody saw it. There is enough going on under there that black solenoids and wires covered in vacuum tubing don't draw attention at smog time (Tool Box locked down in Hatch Area under luggage strap huh......wonder what's in there?)

 

"I wish to avoid any unnecessary Imperial Entanglements..."

Obi Wan Kenobi to Han Solo

 

Words to live by!

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Tony,

 

Thanks for yet another thorough reply. I can only assume I'm asking the right right questions when you take the time to type that much out.

 

All,

 

Here is the plan as it stands now:

 

I will mount the nozzle within the pipe pictured above, held in place by a bracket that holds it where it will spray beyond the opening for the BOV.

 

The nozzle will be fed by hard lines that are fed into the pipe close to where it passes through the radiator support. This will be done with bulkhead fittings and a sealer, although the fittings can later be welded in place should they not seal completely under boost.

 

The solenoids will be mounted as close as is practical to the bulkhead fittings, while still keeping them hidden (the under fender area lends itself to this).

 

The solenoids will be actuated with an arm switch and a WOT switch; they will be further regulated by either a window switch or MS, whichever proves to be more practical for my build. I am using a crank pulley mounted trigger wheel for ignition, which should be very accurate so I'll probably cut flow at 250rpms before redline.

 

The BOV will be recirculated as originally planned, with special attention paid to the dump point. This will be angled in such a way as to help get air moving in a circular motion matching the rotation of the turbo's compressor wheel.

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