SERPENT99

Those who know me here know I have time but no money. I had a fuel solenoid, the N2O hose and a bottle left over from an old NOS plate system, I also had a new Compucar N2O solenoid that I got from Ernie Wrenn. Ernie owned Compucar up until recently, he gave me the solenoid to use in an experimental fuel fuel setup for one of my gas turbines. Ernie is hooked on turbines big time, he should be showing up at the drag strip with a jet car next season. I had some free time so I made my own N2O nozzle and added it to the other parts I had and put it on my LT1.


The nozzle should support about 200 horsepower. Inside the cross piece that the solenoids screw on to is where the jets go. I made the jets myself too. The fuel goes in and past the outside of the center core and out 2 holes that point down. The N2O goes in through the center core and exits through 2 holes drilled in the side of the little nub on the end. The N2O holes are in line with the fuel holes, when the N2O comes out it just shreds the hell out of the fuel stream. I found a jet calculator on line, I had the correct drill bits to make a set of 95 horsepower jets, .045 N2O and .025 gas.

My son and I just tested it, it seems to work pretty good, we hit the button in first gear at about 3500 and held it until we got up to about 100 mph. It definitly pulled a hell of a lot harder. I had datamaster going and as soon as I hit the button I could see the PCM pull about 10 degrees out. This is with regular gas and that's a little more than what it pulls out normally, it crept back until it only had about 7 degrees pulled out but it counted a few knocks so it popped back to about 10 degrees and hovered between 7 and 10 for the whole run.

Both O2 sensors stayed rich so I guess I didn't go lean. I'll have to put some good gas in it and try it at the dragstrip. I have an ON delay I'll use with a WOT throttle switch. A little delay and it will come on right around 3000 rpm after i leave. I'm planning on a window switch in the near future and maybe a low fuel pressure cutoff switch. If it works ok then I'll make some 150 hp jets, and when I get enough money to break stuff I'll probably make a set of 175 or 200 hp jets.


I can remove the whole setup and change jets or whatever in just a few minutes. I made a little fuel filter that can be seen in the line between the fuel solenoid and the fuel rail. Don't let those little plastic hoses fool you, I've burst tested them at 200 psi, they're used in the lasers I work on and they last for years in some pretty harsh enviorments.

I still have that huge plastic intake sound damper aka first base that was stock on the roadmasters and impalas with the LT1. I guess I'll put that back on to hide the whole setup.

Z28ricer

iTrader: (2)

Very interesting stuff, but i'd be concerned about the location of your nozzle, i'm quite sure people havent had the best time with distribution on LT1 plate setups sandwiched between the intake manifold and throttle body, so with how much more rearward that nozzle is mounted in the intake its probably hitting a lot harder on the rear cylinders than the front. I'd really consider moving it pre TB if I were you...

SERPENT99

unless you go direct port injection there will never be perfect distribution. The nozzle I made has 2 N2O ports with a 60 degree spread, I tried a few different spread angles and different size holes, what I ended up with gives a wide soft low velocty plume. Nothing shoots N2O to the back of the manifold.

About going before the TB- All the information I've read says it's best to have the nozzles as close to the cylinders as possible. Having the nozzles before the TB can cause a horsepower loss as the TB will have to flow air/N2O/gas as opposed to just flowing air. It will flow less air to compensate for the N2O and gas it has to flow.

If you know about using N2O why don't you help me out and give me some info about how much spark retard I should see. What are your experiences with sprayed LT1's?

Z28ricer

iTrader: (2)

The first thing actually wrong is the jet sizes you list,

You state you are using .045N/.025F for a "95HP" shot...
Heres NX's suggested Jetting for a 100 - 52N/33F
And another, more accurate, and closer to a final tune- 47N/27F

The second being for a 1000 lb bottle pressure.

NX's 75 HP 41N/24F, and the other the same, so your fuel side is a hair more than the typical 75 shot, and real close to the 100 shot on the fuel side, so you are quite possibly lean even if your sensors are saying you are rich, or you are running higher fuel pressure. It also doesnt seem you are running a nitrous pressure gauge, or anything to stabilize bottle pressure, so some info there would help.

Typical suggestions are normally 2* per 50 HP, and typically people with basic kits like yours on LT1's arent normally purposely pulling timing, just letting the computer pull the little that it may, i'd definetly look into why you are pulling so much, try a larger fuel jet and see what happens.

1983Fbody

Pretty neat. are you running a seperate a/f guage or how did you know what the stock sensors were reading? -Ben

SERPENT99

i ran datamaster in the record mode.

heh heh I used to have a 69 malibu with dana 4x4 axles in it along with a TH400, dana transfer case and a 454. We called it the CHEVELLE FROM HELL

83 Crossfire TA

iTrader: (2)

I’d have to think about how I’d test this, but I’d still be worried that the rear cylinders are getting most of the N2O and the fronts are basically running NA, hell, stock LT1’s have a tendancy to run lean on the rear cylinders because most the airflow doesn’t want to make that bend right after the tb, and you’re expecting more then that out of this setup. All in all, you probably won’t hurt anything doing this way anyway as long as you keep the jetting down.

Pretty cool otherwise, though I’d bet that you’ve got close to the time and $ of a cheap fogger nozzle in it now.

I’m curious, what size are the outlets drilled? What did that pile of brass start as? I see what appear to be a couple of recognizable fittings but I’m not sure that I recognize much else besides the solder (I need to build a fogger/mister nozzle of sorts for something totally different and really don’t want to spend money on the “right” parts)

well, within reason, the location doesn’t really matter unless you’ve got some major restriction in your system. The vaporizing N2O and fuel in the plenum has the same effect on the raw airflow through the tb (at least as it will be measured by the MAF) as it will in the ducting before the TB. The issue becomes how fast/hard the N2O hits when it’s triggered. The farther forward it is in the inlet tract the softer the initial hit is, roughly giving a similar effect to your idea of en electronic delay to make sure that the hit doesn’t come in at too low an RPM mashing it off the line with a WOT switch. The advantage is that as long as you spray at a high enough rpm, mounting it further forward will result in a more homogenous mixture at all the cylinders.

I think that your setup might be very slick mounted right in front of the TB, on my LT1 car I actually modified the MAF to mount the nossle in the back of the maf and I loved the way it worked…

Retard isn’t necessary (it’s a safety thing rather then a tuning thing, since timing has nowhere near the effect on overall power production when you’re spraying compared to NA, retarding timing a little is _always_ safer, but not necessary. NX doesn’t recommend any timing retard with most of their kits.

As far as retard by the ECM, that would imply that the ecm is picking something up that it sees as pinging (the cooling of the intake, if anything will result in more timing), so I think you have a problem. I don’t remember seeing any abnormal pinging/retard on my LT1 at least no different then NA (nothing besides the normal bit on the shifts).

83 Crossfire TA

iTrader: (2)

Recommended jet sizes for N2O kits are usually given for the given hp increase with a 6:1 or so A/F ratio. You can usually make a lot more power with the same N2O jet just by leaning out the fuel jet, as long as you monitor everything to make sure that it’s actually happy.

They are also usually moved around some by the manufacturor’s recommended bottle pressure (NX seems to try to keep bottle pressure about 100psi higher then the rest), nossle opening sizes/flow and solenoid restriction/flow.

I really wouldn’t worry about it, seems like you’ve got starting numbers to work off of and then tune from there, who cares who recommends what. That and honestly I don’t know that I believe your hand drilled jets are accurate enough to quibble over a couple of sizes one way over the other.

rocluvr0013

'cheap' and 'n20' in the same sentence tends to scare me...

But it looks great and sounds like it works fine

SERPENT99

thanks for the input Crossfire. You have a good point, they do go rich with most N2O setups. About the jets, they are kind of tricky to get good flow control with. The hole size is one thing, the entrance and exit to the hole and the thickness of the material that the metering hole was drilled in are important. I keep all these dimensions the same and vary just the metering orifice size. I flow tested some of my fuel jets and I was suprised to see my results were very close to what my jet chart predicted. I haven't figured out a practical way to flow test the N2O jets. I could turn the system on and monitor the bottle weight loss but unlike the fuel, I can't just spray the N2O into a bucket and pour it back into the bottle for another test. It would get kind of expensive and the bottle pressure would also have to be controlled. I'll stay a little on the rich side and get my hands on a wideband O2 when I get a chance. I'd like to see the A/F ratio on all the individual cylinders if I could.

The actual outlet holes are .045, 2 for the gas, 2 for the N2O. The brass body was a hose barb and some solid brass hex stock I had laying around made the rest. The N2O outlets practticaly point right at the front intake runners but the plume is pretty full and it fans out really nicely. I should have taken some pictures when i tested it.

I thought about a fogger nozzle but I wanted something that would support about 200 horsepower and I really wanted to tailor the spray pattern/distribution,... and I had nothing to do. I have $0 in the whole setup so far.

rocluvr, cheap and N2O is ok, don't be scared. What's important is taking the time to figure it all out. it's the hasty hack jobs that scare me, and some hack jobs have money thrown in but it doesn't help. Thanks for the complements.