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NOS lean or rich

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    Default NOS lean or rich

    I am probably going to regret this, but the in the turbo thread peaked my interest. I fully believe that better results are being had with the new "leaner" mixtures the new gurus are running. But is it nitrous only? If you run a blown motor to rich will you lift ring lands? Inquiring minds have to know.

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    Good questions, I'd like some input as well.

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    The goal is to get the A/F mixture correct for what the motor wants. A bit on the rich side is wise for a little safety factor against detonation and may cost a few HP. Being severly rich or lean has negative consequences in any application.

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    Senior Member TurboNova's Avatar
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    Quote Originally Posted by Burnt Sticks View Post
    I am probably going to regret this, but the in the turbo thread peaked my interest. I fully believe that better results are being had with the new "leaner" mixtures the new gurus are running. But is it nitrous only? If you run a blown motor to rich will you lift ring lands? Inquiring minds have to know.
    Ok, I have a question back to you. How rich is rich? How do you know you are rich and how rich are you? Same goes for lean.

    That is a loaded question, are you reading plugs? Do you know how to read plugs? Are you using a wideband O2?

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    Quote Originally Posted by Burnt Sticks View Post
    I am probably going to regret this, but the in the turbo thread peaked my interest. I fully believe that better results are being had with the new "leaner" mixtures the new gurus are running. But is it nitrous only? If you run a blown motor to rich will you lift ring lands? Inquiring minds have to know.
    I would venture to say no on a blown motor. If you had it that rich I don't think it would run..

    I'm in agreement with Turbo Nova. When I first put my Pro fogger together that my oldman let me borrow. We initially had it set up with a 125HP shot. I started out with a .020N & .020F off of one regulator. Big mistake!!!! We don't like running fuel pressure to the carbs under 7 psi and NOS systems are typically around 5 to 6.5 PSI (Lessons learned from Yellowbullet and CS19), so how rich was I?? We initially thought it was a lean miss with a surge so we up'd the pressure to 8psi and along with jet changes and it ran worse (of course). So I would say that's pretty rich!!! I'm now .022N & .018F with 5.5 PSI so I would have to say I was pretty rich!!!!! I know this is a small shot in comparison but rich is rich. I think you have to have a TON of fuel to cause a ring gland to lift. Just my opinion, still learning this not chit!!!
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    Senior Member Schiada 201's Avatar
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    To be safe I usually run the fuel at least 6 steps larger than the nitrous, also a little more retard. Then after watching the plugs make changes if you must. Remember the compression goes to 16-18.1 immediately, so it's necessary to be rich rather than lean.

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    Quote Originally Posted by Schiada 201 View Post
    To be safe I usually run the fuel at least 6 steps larger than the nitrous, also a little more retard. Then after watching the plugs make changes if you must. Remember the compression goes to 16-18.1 immediately, so it's necessary to be rich rather than lean.
    9 out of 10 guys would say this is the norm.

    You see a lot more motors hurt from lean conditions that fat.

    Also what makes running alky a plus. You can run way off the mark & still make a lot of power. Yes dilution becomes a factor. But with a good ring seal I have not had issue with this.
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    Quote Originally Posted by Schiada 201 View Post
    To be safe I usually run the fuel at least 6 steps larger than the nitrous, also a little more retard. Then after watching the plugs make changes if you must. Remember the compression goes to 16-18.1 immediately, so it's necessary to be rich rather than lean.
    6 steps larger? You cant be serious. 6 sizes smaller on the fuel side maybe.

    Companies like Nitrous Pro Flo's and NOS etc. etc. jetting maps recommend square jetting like .028N/.028F at 6-7psi. and that will be dead dead rich in air that we run in, guaranteed. IMO, right off the bat you would want to pull .004 out of the fuel side and run it at a minumum of 5-3/4 psi. and get a plug reading, still rich I bet but it wont kill itself.

    The best method is to send your entire system out to a guy like Steve Johnson, Jeff Prock, Koehler injection, etc. and have the system flowed. They will actuallly flow nitrous and fuel though the system and setup the jetting so its right on the money. There is a nitrous/fuel ratio that you want to target and they will get it there for you. The alternative is do it off of plug readings and that takes alot of laps to get sorted out. You will see nothing like .028/.028 in a system that has been flowed, more like .032/.022 or something like that.

    I know of a deal where a supposedly good nitrous tuner had his tune up in this manifold when it was sent out to get flowed, the guy flowing it flowed his existing tune up which was .028/.028 @ 6 psi. and apparently he was running enough fuel in it to support a .040 nitrous jet, nice tune up huh. A tune like that is on the leaner side of what a company like NOS would recommend.... Its hard to hurt them from being lean, Ive activated my system 3-4 times with no fuel at all (mistake) and never hurt a thing, it just laid over and I got off the button.

    I went and helped out on a dyno session with a nitrous motor last year and the manifold had been flowed, after looking at the tune up on paper I was thinking it was gonna be way lean but the A/F ratio was pretty much perfect, a small fuel pressure change and it was dead nuts perfect, well worth the money IMO.

    Just rambling about n20 tune ups....

    CS

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    Quote Originally Posted by Morg View Post
    9 out of 10 guys would say this is the norm.

    You see a lot more motors hurt from lean conditions that fat.
    9 out of 10 guys that know nitrous will not agree....

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    Quote Originally Posted by cs19 View Post
    9 out of 10 guys that know nitrous will not agree....
    Roger that ghost rider.

    I don't know nitrous.
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    Quote Originally Posted by cs19 View Post
    9 out of 10 guys that know nitrous will not agree....
    No one has answered the question how rich is rich?
    What do you think in A/F would it take to lift a ring due to over fueling?

    Most of the time on the NOS stuff anyway we start off by switching the jets Nitrous and Fuel. NOS staggers theirs with the Fuel jet being bigger.

    Wilson and some of the other systems are square jetting, which I think is better anyway.

    It all comes down to actually flowing the systems and making them work, there are lots of machining problems, nozzle problems, jet problems ect.. the quality control on most nitrous systems sucks for anything other than a 200 shot and even not that.

    We started using the Wilson stuff when Brandon worked for them before he went over to Shannon Jenkens crew. He knows his stuff and the Wilson nitrous stuff was top notch at the time.

    Part of the problem I have seen in car drag racing anyway is people don't maximize their engine jetting before they start with the nitrous. So you may have a rich or lean combo with the engine before you start playing with the nitrous. So if you are on the edge of being too rich on the engine and a "safe" tune with the nitrous it might make you too rich when both are on. One can't band aid the other because you didn't invest the time into tuning the engine first.

    Who has played with line length on your Fogger system? We had on we called Dr Suess because the lines curved around like two s shapes. Line length can also affect how hard it hits and the inital mixture when you first hit it.
    Last edited by TurboNova; 01-08-2010 at 09:49 AM.

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    More gas than nitrous unless you want to burn holes thru the pistons.

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    When I played with Nitrous on one of my lake boats a few years ago I learned its a delicate balance between a fatter (safe) tune and being too fat to fully take advantage of the power potential. I'll say the same about timing. I remember the first 175 HP hit I pulled 6 degrees and had the NOS fuel pressure set a 7 PSI and the motor gained 100 RPM on the squeeze. After sneaking up on the tune I ended up at 5 PSI and only pulled 2 degrees and the motor instantly would gain 600 RPM. This was a top end pull deal so I'm comparing peak WOT RPM on / off the bottle. Plugs looked great and I ran that motor for several seasons with no issues.

    Point being why not put in the effort to get the A/F and timing correct so full power potential can be realized at a safe tune? This goes for any type of engine. We all know what can happen if an engine is run too lean and it very common to see glazed cylinder walls and high leakdown #'s caused from running too rich. Plus doing this tuning is fun and rewarding once its dialed in!

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    Quote Originally Posted by TurboNova View Post
    Ok, I have a question back to you. How rich is rich? How do you know you are rich and how rich are you? Same goes for lean.

    That is a loaded question, are you reading plugs? Do you know how to read plugs? Are you using a wideband O2?
    I am not trying to start something. I don't even run nos or a blower. I was asking based on the results people are seeing. In the other thread posted on the turbo thread, from intake solutions, one guy posted he has not seen this effect on blown motors. Maybe its the sudden hit of the nos you can get to a stupid over-rich condition that you don't even realize it. With a blown injected deal you wouldn't even run it. It would be obvious. Also I know that with running a big system, you can reduce signal to the carbs causing the n/a part of the motor to go lean. Maybe not with a single carb, but with duals.

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