High-Tech Nitrous

Nozzle Tuning

Here is some random posts from myself and others on tuning the dry hits. You should be able to glean much information, as I haven't had time yet to put a good all purpose fuel tuning write up together. The HSW "Interface" has for the most part put most of these methods on the shelf, though some still need or want to use one of these methods. The next section contains the known good nozzle location pictures.

[Quote Robert56] Here's two more ways to tune the current dry hits. One is being used well on the new C6 Z06, it's the Power Adder vs IAT table. You log your IATs n/a then you log IATs on the spray. you'll easily see the difference. Then in the table you add an additional fuel multiplier (like in the PE table) in temp areas you only see spraying. The two multipliers are only added together when spraying and thus your new commanded a/f on the spray. Now some will not get a good IAT reading because of nozzle location and/or a pause before IAT picks up the spray.

The other way, and works good for nozzle(s) that are to far away and giving lean condition through out rpm band. This way uses a BAP. You can simply wire this BAP to be activated at the same time you go WOT. Then you can use the dash mounted dial to enter the desired A/F on the spray. It's basically a linear way to add fuel through higher pump pressure (kind of like the spike the pressure on the lt1 dry kits) and thus higher injector DC. Again only effects the tune while spraying.

Robert [Quote]

[Quote Robert56] Another method for adding fuel on dry hits is the CTS tricker method. You can use a resistor or potentiometer to dial in your coolant temp seen and thus add fueling, it's all in the tuner programs.

Here is the method that the ls2/ls7 generation computers are using, and it seems much better and quicker than the fuel adder vs IAT in the ls1/ls6 platform.

[QUOTE 427cicLT5]Hey Robert, In the ls2/ls7 hp software doesn't have the power adder vs IAT table.

I ended up using the injector flow rate modifier vs IAT table. The values work opposite of the regular PE table. Values are all set at 1 across the table stock and have temp values from -40 to 248 f. Setting the values to .900 will give about 1 full point richer AFR. When the nitrous is sprayed the cooler air kicks in the modifier and I get more fuel. Right now I have it set to come on at 50 degrees IAT. While spraying I've seen 30 degrees, I'll have to see how it goes when the outside temps get real hot. I might have to move up the activation point. Having the car with 12.8 to 12.9 AFR all motor, then setting the modifier to .900 will give the car 11.8 AFR while spraying. Rod [/quote]

So much out there tuning wise, someone needs to put together a complete dry tuning write up, someday maybe I'll try?

Don't forget the new EFI Live that has the nitrous Valet mod; a flip of a SW and you have an instant custom timing and fuel curve while spraying only. You could even set this up on relay to be automatic when spraying.

Robert[quote]

[Quote] Originally Posted by 383LQ4SS

Dont forget...its not the MAF your aiming at. Its actually the three wires. If you miss those...or a majority of the nitrous misses those...your in trouble.
Robert I know you have had good luck aiming the nozzle directly at the wires at close range...and it certainly will make it richer...but I just hate the thought of a nozzle moving a bit and the operator not seeing it. This is just my opinion.
Obviously if the operator is on the ball he will know by eye what his proper alignment is and would check it periodically. But there are many people out there who operate nitrous...not all are the type to even pop the hood and take a look from time to time.

Not to mention I have seen changes in components such as headers and manifolds make very drastic changes the the airpath prior to the MAF. Anything that increases the pumping effect can change what areas in the intake tract have the higher velocities and affect how nitrous flows past the MAF.

We just had a guy go from a 346 to a 383...no other changes. Same intake, smae dry nozzles, same exhaust etc. He went from mid 11s for an Af ratio to mid 14s on his same 150 dry shot. The only difference was the AMOUNT of air he was moving past the MAF. It changed the entire dynamic of the flow. He ended up going wet I believe.

Anyways...there are many ways to skin this cat...alot wont even need to worry about this stuff. But it does crop up enough to discuss options and preferred methods.

Putting the nozzle very close and aiming it definately works...just be careful and use something good to secure it.

But I would like the idea of something a little more foolproof...a little more repeatable...and a little more accuracy...maybe even adjustable without computer tuning Devil

[quote]

Nozzle Placement (known working spots)

Here is the quad nozzles on my Z06. They are about 3 to 4 inches from the MAF. What worked for this dual stage setup was: the first pair of nozzles for stage 1, we used one straight (sprayed ½ back into the air box to mix and become more diluted) nozzle, and one 90° nozzle for a 11.5:1 A/F ratio. Then when 2nd stage came on in 2nd gear (see the 1st gear lock out write up) the second pair of nozzles we used both straights and ended up with a final A/F ratio of 10.8:1. A little rich for some, but considering I was spraying a bone-stock long-block LS6, I wanted a little safety factor with combined hits of up to 285rwhp.

A close up of the same setup, showing one nozzle each of the 1st and 2nd stages. These are the nice stainless steel nozzles. The aluminum style often get that white paste' look from condensation. Note also, the use of tube 90° style fittings on the end of hoses. They are much less restrictive compared to hard 90° fittings often used.

Below: This is a single 45° nozzle, mounted to a Vararam CAI. The average a/f in this location was 10.7:1.

Below: This is an '06 GTO. I can't remember the A/F, but do know it work well.

Below: This location was good for 11.7:1/12.2:1 area.

Below: This is a Blackwing CAI for a C5 Corvette. This dual nozzle location running 90° nozzles, will produce in the area of 11.5:1 a/f

Below: This is the factory suggested location running the NOS 5177 dry kit with stock air box, a C5, but the F-bodies are very similar. This generally produces a lean a/f, in the high 12.x:1 area or higher. It's to far from the MAF for a good reading. Changing the 5177 straight nozzles to 90° or 45° and moving them to the neck area will eliminate this lean condition. On small hits, the suggested location will cause no real problems due to the fact that cylinder pressure is not to bad. Your call.

Below: This is a C6 Corvette, with a working location for a single 90° nozzle.

Below: This is a Halltech CAI (Vette) running a homemade mount with a 90° nozzle. The A/F was 11.1:1 / 11.5:1 in this location aimed right at the MAF.

Below: This is a K/N FPIK CAI, and another homemade mount, running dual 90° nozzles. though not noted, the A/F was very good, and this is really a very adjustable system (rotating nozzle(s) to let some spray passed the MAF to fine tune A/F).

Below: This another K/N FPIK Vette set up, belonging to Todd from LS1tech. I didn't note the A/F, however, saving the picture means it was/is a known working location.

Below: A K/N cone filter running a Spray Bar, A/F not noted. For the most part, if you have a A/F ratio that needs adjustment, you'll have to go into the tune because of the static nature of the Bar.

Below: This is another quad nozzle set-up on a Z06. The A/F was great, and though I didn't note the A/F, I do remember this system as working great.