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Any one try nitrous yet? If so what are your results ?

AA wrote:

There is a way to manipulate the MAFF signal to demand more fuel using what's called an AFC (air/fuel calibrator). How you would use it with N2O I'm not sure. I imagine the makers of nitrous kits have found a way to do this. It's a key part of using the stuff. The thing is, blown motors need LOTS MORE fuel to keep up.

THIS is what I currently plan to use in conjunction with a small (55) dry shot. It's abilities are similar to a MAF translator with some extra stuff as well for timing but I'll only be using it for manipulating the MAF signal for more fuel while it's spraying. It's easy enough to use that you can just about throw in your jet size and forget about it. Obviously you want to make sure to check it and tweak it. IMO it's the only good way to run nitrous on an L67 still equipped with a blower other than a very expensive direct port system like THIS where you have wet nozzles sitting underneath the injectors (not ideal for street fuel economy/drivability) or something custom-plumbed to the intake manifold which hasn't had much recorded success on these engines.

I've got the ZEX dry system (no maf controller yet) fully installed now and I'm trying to find somewhere to fill the bottle to do some initial testing but the place I like doesn't replenish their supply off season.
After searching the internet a while, I found someone on a maxima forum who posted some of his technical findings using that kit.
link to his thread
What I'm gathering from his postings is that his car is boosted and with the application of the 55 shot jet combo, the kit bumps fuel pressure 10psi or more. There is a discrepancy with that because on a later post, he says 15-20psi. If you read into it some more, it looks like he's having some fueling issues on the increased fuel pressure (presumably due to the fuel pump failing to maintain the fuel pressure and volume for more than a moment or two) and I would be concerned if I would have a problem like that. I'm running a PRJ fuel pump and 42lb injectors. If fuel pressure already gets around 60psi on boost, I would be a bit concerned about what would happen if it hits 70-80psi. The last thing I need is to have fuel dropping off while spraying and I wouldn't know about it until I either felt the drop in power or watched KR. (I have no in cabin FP gauge)

I received some money for Christmas... n00b questions:
With 42.5# injectors, will my stock fuel pump keep up with the demands of nitrous?
Will a dry shot destroy the coating on my rotors?
With the ZEX smart-n20 thing, if it only shot at WOT, would the cooling effect also allow me to run a smaller pulley (possibly just for track use)?
Is a 50 shot the way to go, or could i do a 65?
Would i need a wideband o2?
Im looking at contacting ZZP for a dyno tune. Would you guys trust them to tune for nitrous?

Thanks for any and all help!

I'm no expert on the subject, but I think an upgraded fuel pump would be in order. I would imagine it would have an effect on the rotor coatings. A wideband is a good thing to have. ZZP would be a great place to get a tune if you're near them. Otherwise find some reputable tuning shop in your area.

I was considering nitrous until I discovered how much it cost to fill the bottle. ( anywhere from $4-$8 per lb ) and a 10lb bottle will only give you a handful of really good strong shots before it starts to fall off.

96_Juggernaut wrote:

I was considering nitrous until I discovered how much it cost to fill the bottle. ( anywhere from $4-$8 per lb ) and a 10lb bottle will only give you a handful of really good strong shots before it starts to fall off.

That's somewhat true but a bottle heater helps with that. Had I known how important it would be, I would have gotten it from the very start. Where I go it's $4/lb and I don't use it all that much. Most of it's use is trying to tune new setups. One track day will easily kill a bottle. What bugs me more is that even with milder shots, the pressure drops during use so as you are going down the track which happens no matter how full the bottle is, you're getting richer and richer unless your nitrous kit has the ability to account for that change in bottle pressure.

The zex kit I was looking at (same one zzp sells) says something about how it has some sort of active bottle pressure regulator to maintain the proper fuel mix. Is that kind of what you're talking about? Nitrous seems like a black magic, and I don't want to blow up my car, but it seems like a really good, inexpensive way to have more fun at the track.

Sir Psycho Sexy wrote:

I received some money for Christmas... n00b questions:
With 42.5# injectors, will my stock fuel pump keep up with the demands of nitrous?
Will a dry shot destroy the coating on my rotors?
With the ZEX smart-n20 thing, if it only shot at WOT, would the cooling effect also allow me to run a smaller pulley (possibly just for track use)?
Is a 50 shot the way to go, or could i do a 65?
Would i need a wideband o2?
Im looking at contacting ZZP for a dyno tune. Would you guys trust them to tune for nitrous?

The fuel system concerns heavily depend on what nitrous kit you are using. It depends on how the kit introduces the extra fuel. If it's like a ZEX dry kit, it's ramping up fuel pressure above boost-reference so you get more force behind the injectors even though they are doing the same thing otherwise - more pressure behind them, faster fuel will flow out. In that case, the injector size wouldn't actually matter much as long as they are working fine without nitrous however the fuel pump would be taxed enormously which is why the kit is limited to small shots. I'd say for otherwise N/A vehicles, the levels of that kind of dry kit are realistic but for us, it's just too much for the stock fuel pump IMO. When I was using that I had 70-80+psi fuel pressure while spraying and actually ruptured a brand new fuel pressure regulator diaphragm. (could have been defective). Anyhow, options for us not wanting a wet kit are kinda limited. I'm using a maf controller that changes the maf output signal digitally so when I spray, the pcm suddenly sees a a bunch of extra air and fuels accordingly which works terrifically as long as bottle pressure stays consistent to how you tuned it and you don't run out of maf room digitally which is what I'm working on fixing now. The controller I use was made by Harrisspeedworks but I think they went out of business. Figures... Direct port enables the use of a wet system without hurting the blower so you have freedom there but very expensive to get a whole kit together.

A dry shot won't hurt the supercharger rotors.

Cooling effect to smaller pulley, no. For one you don't ever want to make an extenuating change that relies on the nitrous system like that. Even if it is just at the track, it's still going to have a sudden lean tendency at any point leading up to WOT. I really don't ever suggest to run a smaller pulley than you normally do at the track due to the immediate tuning affects and harsher driving conditions. If you blend in some race gas and cushion yourself that way, then you can get away with a little more.

The difference between a 50 and 65 zex shot is quite tiny but regardless, start as small as possible and see what it does first then when it is right go more.

I would highly highly recommend having a wideband and something to datalog with since everything with nitrous will be occurring when it's running in open-loop and you really have no way of knowing what's going on except for by feel and reading spark plugs and what not - not a great way to work. I'd feel slightly more comfortable trying it the old school way like that on a totally stock problem-free car but really, ignorance is never a good thing.

ZZP could tune your nitrous competently but make sure everything is solid before wasting time which is quite directly money in that case. I'd figure they'd hook up a temporary wideband and put it on a dyno which will get it tuned quick if it isn't garbage to start with.

Thanks for the awesome reply! An upgraded fuel pump isn't a whole lot, so I would probably do thY before hooking up the nitrous. I think that I will take the car to zzp to tune, partially just because I want to put in on a dyno anyway.
Aren't you not using the zex nmu? What are the drawbacks to the buttonless smart nitrous setup? I am absolutely clueless when it comes to tuning. Scott did all of my previous tuning for me.

turtleman wrote:

96_Juggernaut wrote:

I was considering nitrous until I discovered how much it cost to fill the bottle. ( anywhere from $4-$8 per lb ) and a 10lb bottle will only give you a handful of really good strong shots before it starts to fall off.

That's somewhat true but a bottle heater helps with that. Had I known how important it would be, I would have gotten it from the very start. Where I go it's $4/lb and I don't use it all that much. Most of it's use is trying to tune new setups. One track day will easily kill a bottle. What bugs me more is that even with milder shots, the pressure drops during use so as you are going down the track which happens no matter how full the bottle is, you're getting richer and richer unless your nitrous kit has the ability to account for that change in bottle pressure.

I had a buddy running nitrous and he said the same exact thing. the second you start spraying the bottle temp drops and the pressure goes with it. And the power received from the shot is directly related to the bottle pressure. I'm sure a bottle heater would help but im not sure it can keep up with the drastic change in temp from a 1/4 mile pass. I'm sure something will always be lost.

im considering trying out the zex dry kit with a 55 shot, and the thrasher adaptor plate. im just wondering if my injectors and/or fuel pump would be overtaxed at wot. my injectors were just replaced with stock reflowed ones, and fuel pump is stock.

h20man wrote:

im considering trying out the zex dry kit with a 55 shot, and the thrasher adaptor plate. im just wondering if my injectors and/or fuel pump would be overtaxed at wot. my injectors were just replaced with stock reflowed ones, and fuel pump is stock.

In regard to the ZEX dry kit, the injectors don't matter at all. The fuel pump will be heavily taxed though since it is needs to deliver some extra fuel while working against higher pressure. Although it seems wrong, IMO you kinda want want to start with the leanest fuel setting (lowest jet setting) and see how much you can spray (nitrous jet) with it while keeping afr reasonable even if it's a tad lean. That's better then being right on or rich and then suddenly going lean when you're in the middle of spraying. Don't start throwing higher fuel jets in it if you don't have to because you'll overwhelm the fuel pump really quick with excessive pressure.

Would you recommend an upgraded fuel pump to be safe? If so which one I heard the zzp one isn't great

h20man wrote:

Would you recommend an upgraded fuel pump to be safe? If so which one I heard the zzp one isn't great

It's hard for me to say positively because I don't have pressure vs flow data on the stock pump to compare an aftermarket to but based off the general design, a gerotor pump (like the walbro ones sold for our application) will probably do better under higher pressure than the stock so in this instance I would say it's worth it. You'll probably want to go with the PRJ racetronix. It's the same walbro 255lph high pressure pump that you can get anywhere but modified with the stock venturi setup. It's worth the extra few bucks IMO. I think I have mentioned earlier in this thread that the ZEX dry kit was probably intended for non boosted applications where fuel pressure to start with isn't over 50psi or so at WOT so bumping it up to 60-75psi isn't as devastating as going from 60+psi reference pressure (depending on your s/c boost) to 70-85psi which is right where a lot of fuel pumps start bypassing to relieve pressure and you don't want to be there. (this is why you don't want to use the biggest fuel jet which you might intuitively think is safer) Using that ZEX kit, I'm pretty sure I was hitting easily 15-20psi of extra fuel pressure with 1100psi at the bottle so the kit definitely ramps up that fuel pressure pretty good. Their jetting for fuel vs nitrous is rough at best. Not tryin' to discourage you but it's good to know going in what's going on with stuff

Thank you for the response, you have alot of knowledge and I appreciate you sharing it with me, I will be looking into this fuel pump what this pump outflow our stock injectors or should I just go with 42lb

*would this pump outflow stock injectors

Sir Psycho Sexy mentioned using the extra 6 injector ports on a N/A LIM to mix nitrous/meth/ into the AF mix.

Why wouldn't this work? could the stock injectors be put to use?

You can definitely do something like that. Problem is n/a LIM with blower is not happening. On a turbo car that's running an n/a intake anyway, that would make sense to do.

Have a look at this


PRJ set up two cars that I saw like this with foggers on fuel injector adapters. I would imagine that hurts fuel injector spray but eff-it 'cause racecar