Simple question I think.

When you add nitrous I'd suspect you'd want a custom tune, correct?

If that's correct how would that custom tune work , since it would change the AFR, to when you don't use nitrous and run normal and hard?

 

You can set it up many ways depending on if its a dry or wet nitrous kit. With a dry timing/fuel are tuned into the pcm to allow for both na and nitrous performance driving. A wet kit can be self reliant on a stock tune. But any performance tune will need a timing device or pcm IAT tweek (typical method) to get the desired timing when spraying. You tune the engine for best NA power, then using that tune and playing with nitrous jetting you further dial the timing/fuel in for best na/nitrous performance.

 

Joey,

Thank you.

Dry: I get the base tuning, but how does the PCM know when the system is under nitrous so it adjusts timing accordingly? Would there be some type of 'switch' to press to signal the PCM to change to a different map, or does the PCM figure it out by itself?

Wet: With wet, here too, how does the PCM know when you'er spraying. I do understand that the wet is a compensation to keep fuel levels good, keep the temp down and detonation down. Is wet sufficient by itself with no PCM adjustment, except for the it]\the NOS system uses adds more fuel when triggered, via a piggyback FI or ?. I'd guess you'd have to tune to the nitrous in order to get your AFR set right under spray. Am I correct?

If it is largely ,just tuning thePCM for N/A, then dry or wet the PCM senses the detonation change potential and makes adjustments, nitrous seems like a reasonable (safe?) method to increase HP on demand and get to 500 rwhp on a base 09.

What am I missing, need to ask but don't know t ask?

Thanks again.

 

Most setups will, for example, cause the pcm to see an IAT value that normally cant be reached. Then in the tune timing can be +/- and fueling can be modified as well to gain the desired timing and air/fuel by editing those select tables

 

get in touch with forum member SPINMONSTER for a dry settup

 

a Dry kit you will spray before the MAF like at the air filter. The PCM will ADJ for the DRY kit.
BUT you still need to check that tune with a WB and may need to adjust to get it right. Timing will need to be pulled for Nitrous in the tune
rule of thumb is 2* for every 50 HP of NOS

As for Timing there are a few different ways to do the timing. we always do the timing pulling in the main timing table just to be safe. With Nitrous you cant ever be to safe!

95% of the kits we do or install are all wet kits as you can keep your normal tune the same and just do timing. The wet kit will do all the fueling for you and you wont need bigger injectors and such to keep up with the fuel demand you need. You will adj your AFR on the spray with your jets

 

What devise do you need to switch between maps? If I'm running a plate kit and want to maximize my NA tune and want to get the full potential out of the spray. I've hear people pulling timing on their NA tune so that when they spray everything is good but then you lose power on that tune. So how do you avoid that?

 

Bump

 

bump

 

The tough thing about dry shots is the tuning. Once that hurdle is overcome, there is no fuel solenoid to fail.

My preference is a dry shot. My dry shot set-up version is different than most. I dont do the fueling by pointing at the MAF for artificial air flow readings to richen up the shot. Tuning is dependent upon real value changes using HPtuners and I give exact tuning info in this post.

The usual tuning for a dry shot is to use one dry nozzle pointing toward the MAF to get a concentrated shot of air on the MAF making it think the incoming air is filling the entire volume of the MAF unit and the PCM commands more fuel to be dumped. You also had a hard time adjusting it a little richer or a little leaner. Aiming nozzles can max out the MAF sensor too at one point. You can set up the HPT scanner to log MAF frequency to see where you are at but there is a simple and much more accurate way to tune a dry shot. Another tuning problem is timing; it is adjusted with a timing tricker box and you never know if its working because they intercept the signal from the crank and the scan always shows the commanded timing even if the timing is being pulled.

My final methodology for tuning was to make a passive circiut with parts from radio shack for 11 bucks and have the dry nozzles far from the MAF on my dry shot. This set-up isnt critical for nozzle location because the IAT circiut adds the fuel not the hit on the MAF. The MAF then gets a more even hit instead of a concentrated hit and its actually near the commanded PE a/f ratio. To get it richer I used an IAT tricker circiut. Its nothing new and wires like this:

I didnt cut the wires since a failure would then potentially alway have my car pulling timing from an open in the resistence. I simply used a resistor to short them when the actual shot fires.

The N2O would mix evenly prior to getting to the MAF and the even flow of air keeps the PE exactly at the commanded PE which is 13:1. The reason for this is that the shot will have the added fuel from a more predictable metered way without relying on the nozzles pointing at the MAF element try and guess method. I will be able to add as much fuel as I want to get the a/f to 11.8:1 where I want it (you can target any a/f ratio you want). To maximize the car's N/A operation, I wanted the circiut to pull timing and dump additional fuel only while my thumb is pushing the trigger button on my T-handle and not always while the system is armed. Off the button my car runs the hottest max effort tune I could do to my car.

Nozzle location: sorry the install isnt stealth which I just dont understand. It not a curse to have a bottle. Its a legit power adder with drag race classes.


I intercepted the signal at the MAF and installed a relay to to change resistence to the MAF's IAT sensor. (this same relay provides the ground for the relay to the nitrous solenoid so if this circiut fails due to the relay, the N2O wont fire). For those not familiar the IAT is a themal resistor and varies its resistance with the temps it is subjected to. The IAT or intake air temp sensor does exactly what it says; it measures the temperature of the incomming stream of air. In the case of my firing the nitrous the resistance is changed to make the car think that the incomming air charge is 199 degrees. Now unless you live and drive on the surface of Venus, the IAT's will never hit 199. The amount of timing is one degree more in the summer. I pull 1.5 degrees per 50HP. Now for the cool part of the tuning.

The IAT not only controls the timing curve from the IAT base spark table but on the fuel tab there is an IAT vs. Injector flow rate table (this is on the general fuel tab for C6's and the PE tab for C5's...in the C5's case its an adder for the commanded PE). In this table IFR is changed according to IAT temps. In the following screen shots of my HPtuners editor, the IAT base spark and IAT vs injector flow rate are pictured. In this first screen shot you can see where I typed in -4 degrees in the high end of the table.



In this next table the IAT vs injector flow rate adjusts the fuel to where I want it. Smaller values richen the shot. The IFR is lowered making the PCM think it has smaller injectors so it makes them dump more fuel. When you first set this up, add a good amount of fuel and pull more timing than you think you will need until you fire it a few times and scan the timing and see the wideband's final a/f ratio:



In my case the 199 degree input instructs my car to dump 8% more fuel than normal. If I want 1% less I type that change in If I want 2% more I type that in. The best part is that it all shows up in the scans. Wet shots need to have constant bottle pressure to maintan a a/f ratio (which it never is) and the only way to richen it up is to change the fuel jet. I just type in what I want and it works flawlessly.

Initially, I scanned the car safely in my driveway (later in use with a 22 shot then 50 then 75 then 100...)and bypassed my WOT switch to allow the IAT circiut to adjust the timing -4 degrees and add 8% fuel while sitting safely in my driveway and simply revving to 3500 where my shot pops in(this was without the bottle open just to see if the fuel gets dumped and timing gets pulled. The scan showed 42 degrees at that load and rpm and without moving up or down on the gas pedal and triggering the circiut, the timing fell to 38 and the long term fuel trends jumped down 8%. I wish I had saved the scans to show some screen shots but the system workd flawlessly and ends the debate in my mind of wet vs. dry.

Now some safety issues. The relay in the IAT tricker needs to be operating to supply the ground for the relay that triggers the solenoid so if the tricker doesnt function, the N2O doesnt fire.
1) The air and nitrous mixes fully to get an even reading and not a concentrated hit in the center of the MAF. This gives predictable fueling. Keep in mind that the MAF isnt used for adding the fuel on this dry system. It finds a baseline for the incoming air and the additional fuel would be added even if there was no MAF. This is the same operation as the harris sped works box. It doesnt need an MAF and it doesnt need the nozzles pointing at the MAF
2) The lack of a concentrated hit keeps the MAF frequency from maxing out and lets you run a bigger shot than you normally would be able to if you used the MAF to add fuel by concentrating the shot on the element.

I dont have to worry about a dry hit heading over the MAF and leaning out or an MAF failure. I have consistency and a degree of control that makes it so versatile. If I want say 1.23% more fuel, I enter the exact value to the decimal (98.77) in the IAT vs. Injector flow rate table. No messing where nozzles point. If the MAF fails, no problem; it isnt what adds the fuel. In the case of my speed density tuned 2005 I dont need the MAF to even be there and the MAP/VE would calculate the fueling and still compensate to the commanded PE. I have a permanently mounted XD-16 Lc-1 wideband to monitor fuel. The fuel curve never spikes lean on the shot engagement. When you come off the pedal the car isnt under load anymore and doesnt need a sustained rich state. I couldn't get the car to spike lean before or after the shot even staying on the pedal.

I dont like the fuel solenoid and the fuel in the intake manifold idea but so many run it without issue so its up to you. I wanted to just offer an alternative.

If you are going to do this you need to get the MAF patch to extend the frequency limits for the MAF or you can potentially max out the MAF. For those that dont know what it is, on the HP tuner's editor click the operating system button in the upper left corner. A write-entire must be done to enact these changes. If anyone has questions about this system or is close by and needs a hand with its install, shoot me a PM. All my work is shareware and I share secrets. (I guess that means they arent secrets). No charge, just make a ST Judes donation.

Keep in mind that the fuel injectors need to be big enough to supply the needed fuel for the additional requirement. If you have 90% duty cycle with a H/C car and you add a 125 shot you are over the line. Think 40lb'ers for a 500rwhp car which is likely more than 550-600rwtq. Go bigger for silly numbers. Also remember that the fuel pump isnt going to support 600/700 without a boost-a-pump wet or dry. 600HP from a supercharger isnt like the 600rwhp from the bottle. The TQ is 500 for a 600rwhp S/C car and close to 700rwtq for a 475 rwhp H/C car on a 125shot. They call it TQ in a bottle.

Hope this helps.

 

Several companies also make timing controllers to work with n2o. They will adjust timing when n2o is armed. Lingenfelter makes a very nice one.

 

Feels like I just came out of engineering school. Great write up.

 

I told you

 

Yes, you did.

 

Given what Spinmonster shared, what is a reasonable amount of (nitrous) TQ for a base A6 (auto tranny) to last?

 

0

 

That would be a good question for subfloor

 

Nice write up! I've talked to a couple of shops and it sounds like they use a resistor to detect a false reading in IAT's which pulls timing on a wet kit as well. I guess any car that has nitrous can run it like that. It seems to be proven that it works and is cheaper than buying a LNC-2000 at 275.00 and then having to wire that in. Also I believe on a dry shot equals out to more horsepower to the wheels than a wet shot.

I will be doing a Nitrous Outlet plate kit. We will see out it all turns out. I think at the end of the day no matter what kit you use as long as the TUNE is on point you should be fine.

 

lnc 2000 , cheap and can change ur shot without having to retune.

 

I use a device I came up with that cheats the flex fuel tables. When triggered, it tells the ECM that there is 100% alcohol content, so the ECM ends up using different timing (and fueling if using a later ECM with an alcohol PE table) that is fully tunable and leaves every other critical sensor (IAT, ECT) functioning normally.