Nitrous Timing

Discussion in 'SN95 4.6L Mustang Tech' started by LazyDemonsTG, Jan 9, 2007.


  1. LazyDemonsTG

    LazyDemonsTG New Member

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    I have a 04 gt w/headers n exhaust... Just recently bought a zex wet nitrous kit, how do u retard the timing while sprayin or do u even have to for a 75 shot...... Also would it be safe to wire my nitrous to a push button instead of a window switch or do i just need to go ahead n buy a window switch...
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  2. 02GTdriver

    02GTdriver New Member

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    I just bought a 4 bank SCT chip for my Nitrous setup that way when im going to spray i just switch it to the Nitrous tune. Alot of folk will say that a 75 shot is fine on the Stock tune. but when i had mine dyno'ed after installing the spray i was lean. So i would recommend getting it tuned. also Grab ya some colder plugs NGK TR-6's are what i use. As far as the window Switch. they are nice i suppose but i just use the WOT switch that came with the kit. My arm button is in easy reach.
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  3. superstang01

    superstang01 Member

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    Do you HAVE to tune for nitrous if its only a 75 shot ,or should a stock tune work fine?
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  4. 98MACH1R

    98MACH1R I wanna put it in so bad, please help.

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    no you dont HAVE to have one but think about it this way if your going to spend alot of money and time on nitrous and taking to precautions for it, then just to have it mess up your engine because you didnt have it tuned? i run a 125 dry shot with a tune and ran a 75 shot without one but it started getting to me thinking i might screw something up so i just went a head and got a tune and now i dont have to worry about it now just my .02:nice:
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  5. the98stang

    the98stang Active Member

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    General rule of thumb is to pull 2* of timing per 50 shot. I wouldn't spray a 75 shot with getting it tuned on the dyno. But it's your engine, so that's your call.

    Definitely get a window switch. If you accidentally spray before 2000 RPM's say good bye to your engine.
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  6. LaserRed01GT

    LaserRed01GT Banned

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    Don't even think about using a push button to activate the nitrous. It will only be a matter of time before you kill parts like that. The only way to activate N20 correctly is to use a WOT switch. They have some TPS WOT switches out there but I have never had much luck with those. The traditional microswitch type WOT switch activated by the bell crank on the TB is the only way to go. You should also get yourself a RPM activated window switch. Do not spray below 3000 RPM.

    I would also suggest that you get your self a liquid filled N20 bottle gauge and a bottle heater to monitor and maintain proper working bottle pressure within the range that Zex suggests. It's not critical, but I would also get a FPSS (fuel pressure safety switch).

    There is no reason to pull any timing at all at WOT for a small 75 shot, but it wouldn't hurt to either get a flip chip with a N/A tune and N20 tune, or just have the car tuned to make better use of the nitrous. For what it is worth, I am running full total timing with my 125 wet shot with not a single hiccup.

    Did Zex include a relay for the arming switch?
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  7. SamMan

    SamMan New Member

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    +1
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  8. the98stang

    the98stang Active Member

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    Really? Why would Nitrous Express recommend pulling timing for even a 50 shot? I guess they have no idea what they are talking about :rlaugh:

    You may not have problems now, but I guarentee you WILL have future problems. Stock timing on a 125 shot is idiotic. Hello detonation, bye-bye engine :nonono:
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  9. Fast Eddie 41

    Fast Eddie 41 New Member

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    All nitrous companies will recommend that you pull timing with any shot.....of course.... it's called a legal disclaimer. As long there is nitrous oxide kits sold, there will always be the brilliant ones who install or use them wrong and then try to blame the nitrous comapanies for their incompetence. BTW, what personal tuning experience do you have with tuning these cars on nitrous? We have data logged several 4.6 2V's with less than a 100 shot and full total timing with never a single hint of detonation....you don't have to touch the timing on these cars with just a 75 shot. That 2° per 50 shot "general rule of thumb" rule was introduced by Jeff Prock years back and it appied to carbureted cars not EFI cars. Carbureted cars rely on vacuum or centrifugal advance to apply timing advance and ultimately total timing. EFI cars obviously have their timing controlled by the computer.

    On these cars with a small 75 or 100 shot, all you have to do is focus a few tables such as the global open loop fuel multiplier, WOT fuel multiplier, fuel load scaling, and the high/low injector slopes to dial in the a/f ratio on the wideband.

    Kevin has run over 10 10lb bottles that I know of through his '01 in just the last 3-4 months. We have never had one single hint of detonation or detonation induced pre-ignition. None of the 125 wet shot cars we have tuned have had the timing touched....you just don't have to if you know what you are doing. Wet hits aren't as sensitive to timing advance and total timing as dry hits are. Over 125 on a dry hit...then we'll start to play with the spark tables as needed. I'd also suggest that you watch how you throw around the word idiotic. No need for that :nice:

    Please share with us any personal experience that you have with tuning nitrous cars that may provide some differing evidence.
    #9
  10. LaserRed01GT

    LaserRed01GT Banned

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    I guess after 11 bottles, I am just going to magically have a pre-ignition or detonation fairy come jump inside my motor.

    Like Matt (Fast Eddie) mentioned. I have used Live Link to data log just about every single run I have made on N20. Especially the ones at the local 1/8th mile track. I also read my plugs after we go to the track and make some nitrous runs. Never a single sign of pre-igntion or detonation on the insulator of the plugs. I always keep pump 93 octane in the tank. I usually see around 26-28° at WOT on the Live Link. That's about what a stock N/A car will see on 93 octane. It's all about dialing in the WOT fueling.
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  11. the98stang

    the98stang Active Member

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    OMG 11 bottles?!?!?!:rlaugh:

    Do you seriously think that's a lot of spray?
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  12. SamMan

    SamMan New Member

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    I know I am well over 50 with stock timing. I lost count a long time ago.
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  13. Fast Eddie 41

    Fast Eddie 41 New Member

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    Like OMG, his kit was like totally only installed about 3 months ago....like OMG. [​IMG]

    Again, feel free to share with us any personal experience that you have with tuning nitrous cars that may provide some differing evidence or any evidence for that matter.
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  14. jstreet0204

    jstreet0204 Active Member

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    Why would you use the multipliers instead of tuning the MAF curve directly to get the target a/f right, the adjusting the open loop fuel table to get the commaded fuel where you want it. Is this something different about tuning for nitrous?
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  15. LaserRed01GT

    LaserRed01GT Banned

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    I cracked up for about 5 minutes when I saw that friggin GIF. :p

    Let's see, 3 months equals 12 weeks. 11 bottles over 12 weeks is about a bottle per week or 10 lbs per week for the last 3 months. Maybe I need to add another bottle, get a nitrogen push, and add that new Nitrous Express Flux Capacitor 2000 to get my nitrous use up to an accepted status.
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  16. LaserRed01GT

    LaserRed01GT Banned

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    Matt was just citing a few examples of some of the fueling tables that require attention anytime you tune, whether it is nitrous, N/A, or FI. Accounting for a MAF curve adjustment goes without saying and I'm sure that's why he didn't feel the need to mention it. There are dozens of open loop fuel parameters that can be played with in Advantage 3.0.
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  17. jstreet0204

    jstreet0204 Active Member

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    Right, but it is generally considered best practice to avoid the multipliers in the tuning comunities I frequent. Using the wot fuel multiplier is and easy way to get desired a/f ratio while tuning, but it can bite you in the ass when when you have drastic changes in the weather conditions. Dialing in the inj slopes and MAF curve will bring in the fuel trims and make for a much more adaptive tune. I just thought there might be a specific reason to use them for the nitrous tunes since I don't have any experience tuning for it. I can see how it might make sense on a flip chip or something. Just curiuos...
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  18. LaserRed01GT

    LaserRed01GT Banned

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    What he was talking about was the WOT Fuel Multiplier vs RPM not the OL Fuel Multiplier. The OL Fuel multiplier is what they call a global multiplier and it effects multiple scalars and tables. The WOT Fuel Multiplier vs RPM is not global. On a relatively small shot (under 175 shot) one of the scalars we will tweak on will be the WOT Fuel Multiplier vs RPM since it is intrinsically related to any ACT spark modification that may be commanded. Obviously that is just one aspect of tuning the fueling. I hear tuners and other people talk about how multipliers or scalars are not adaptive, but the truth is that they are. In regards to any airflow and/or fueling multipliers, there is always the presence of spark and fueling variables that have the ability to modify the multipliers by means of individual or collective sensor input. A drastic swing in the weather (density altitude) will be adjusted accordingly in the adaptive tables. It can also be compensated for in the scalar/multiplier tables by means of spark/fuel variables.

    The MAF transfer function is the most critical and the most persuasive way of dialing in the a/f. I am not too sure why a tuner would choose to alter the injector high/low slopes when tuning for a small nitrous shot. The injector slope functions are normally used to apply the injector constants, or the fixed injector flow rates. Sometimes the high/low slopes can be slightly altered if the LTFT’s are WAY off. And I have even seen some literature describing a process of uploading a low-impedance injector driver conversion that can be dialed in using minor adjustments to the slopes. Other than that, it wouldn’t make any sense to make fueling corrections using the injector slopes unless, like I said before, the LTFT’s were substantially off or if you were using an alternative MAF scaling device like the MAFia.

    I agree that it is a good idea to use a flip chip for a nitrous street car. It allows you to maximize the nitrous tune, while leaving a good tune for n/a use.
    #18
  19. jstreet0204

    jstreet0204 Active Member

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    This is the same information I have on the slopes. I use a program called EEC Analyzer that reads the through the datalogs and tweeks the slopes and injector offset to bring the fuel trims in as close as possible then you tweak the MAF curve to dial it the rest of the way in.

    As far as using the multipliers, it used to be common practice to dial in the a/f with the wot vs rpm multiplier. This would get a good a/f ratio on the dyno, but left the MAF inaccurate, which in turn left the fuel trims out of wack, which in turn allowed the adaptive to come back and screw up the a/f later on down the road. I didn't mean the multipliers would't allow for adaptive changes, just it should't be used to dial in the a/f. In Fast Eddies original post he didn't mention the MAF curve which is why I questioned it.
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  20. 86bluecobra

    86bluecobra Advanced Member

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    So the nitrous system costs around 500 bucks your car is worth 20,000 plus. Probably a good idea to get a tune. cheap insurance. Run colder plugs as stated. Run a window switch aswell. the reason you do this is because you really don't want to spray below 3500 rpm for fear of puddling. Also you want the nitrous to kick off before the rev limitor kicks in. Think of killing your ignition system for a short period of time while you load every thing up with nitrous. When the spark comes back it could cause issues.
    #20

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