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  #1  
Old 06-15-2004, 04:59 PM
Jake Offline
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Smile two stage nitrous tuning questions for NOS Frog, Top Sport, Animal Jim, Mike C., ect.

I have some general two stage nitrous tuning questions for you guys. I have a 85 Camaro that I am planning on running in a local 10.5 tire class. My car has a 540 BBC w/Dart 355 heads in it with a B nozzle Fogger for the first stage and a Bigshot plate as the second stage. The Fogger has 32 Nitrous and 28 Fuel jets at 5.75 PSI. I was told to dial in the first stage and get it running good by itself and then tune the second stage system by itself and get it running good and clean. Then combine them together and that they will probably be a little rich when combined because of the bottle pressure dropping. I was told to lean the second stage down to clean them up when running them together and leave the first stage alone. Is this the correct way? If not please give me some multi stage tuning advice before I hurt some parts and some two-stage timing retard advice. I read the Bad NOS B Nozzle article and that was some good information!

I really appreciate your time and help,

Jake
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Old 06-16-2004, 08:17 AM
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Well, whoever gave you that advice knows what he is talking about. Yes, I highly recommend doing what he says in getting the car to run correctly on each individual system then combine them together while first richening the second stage for safety and then slowly lean it back down while reading the plugs.

If you haven't read my article on reading plugs then I would like to suggest it to you at:

http://www.dragstuff.com/techarticle...ark-plugs.html

Your friend is also correct in the fact that when the two stages are combined you will use more nitrous so the system will richen up itself. The plugs will only show you what was happening in the motor for about the last third of the run so you will notice you plug porcelein darking way down inside so you may have to take a little fuel out of the first stage also.

Watch your blue line on the ground straps of the plugs for timing especially when running the stages independently and then together. it is better to be a tad too retarded to start and then after you see you are getting close on the mixture but just a little rich start taking out some of the retard one degree at a time until the blue line on the ground strap moves to the 90 degree bend then finish adjusting the mixture.

Do one step at a time and be patient. Also remember that you can only use two thirds of the nitrous in a bottle. If you get down into that last one third the tuneup will change and the system will go rich and you will lose power.

Good Luck.
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Old 06-16-2004, 08:20 AM
nosfrog Offline
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Sounds like a good, smart plan. One of the main reasons motors get hurt when using nitrous is due to lack patience when working a combo out. It's real easy to throw big jets at it or turn on 2 stages and go fast but it takes time and patience to get the a happy tune up that will go fast and last.

I wouldn't get too aggressive with the plate--prob no more than 250 hp. There tends to be distribution problems when you start getting into the higher hp ranges and on a 2 stage deal the ET gains will not be that much more anyway. I would start conservative with the timing and work your way higher by adding a degree at a time until the you are happy with the plugs and there are no signs of detonation (look for the timing line on the ground strap--for a safe range it should be between the curve and the top of the ground strap.). For a 32 jet, pulling 10 degrees of timing should be more than safe. Once you add the plate to the mix, I would start by pulling 4 degrees per 100hp. This is probably a lot more than you will end up needing to take out but better to start safe and work your way into it.

On the 1st couple of 2 system passes, I normally only run it to half track or only run the 2nd stage for 3 or 4 seconds. You can then get a read on the plugs and see how things are working without wringing the motor to death. You may need to tweak the fuel pressure on the plate when you're running both stages but run it 1st and see how it acts. Pay close attention for any signs of detonation--usually black specks on the porcelain represent detonation. If you are seeing signs of detonation, you'll need to determine what is causing it and make the proper adjustment to your tuneup (probably timing but not always).

Last edited by nosfrog; 06-16-2004 at 08:23 AM.
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Old 06-19-2004, 09:16 AM
jcrvette Offline
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Like you said, most of us (little guys) don't have a clue about reading plugs, one of the most important aspects of tuning a engine, especialy a nitrous engine. My first N2O engine is almost ready to fire and after a few motor passes, we gonna hit it. After reading these posts it makes me feel alot more comfortable. THANKS!
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Old 06-22-2004, 07:47 PM
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Thanks for including my name on the subject, but my head still hurts from all that info - That was some good reading-
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Old 06-24-2004, 07:18 PM
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Concerning the fuel ring at the base of the porcelin, I was told awhile back that the location of the ring would move up and down a small amount as fuel mixtures were adjusted. Is there any fact or importance to this? Do the plugs need to be changed every time an adjustment to timing or fuel is made, or will they clean up and show the new settings? Also I notice that some of the plug reading tools have a cone tip, while others do not. Does one type work better than another? Thanks Paul@JCR
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Old 06-25-2004, 08:11 AM
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To avoid confusion here we are talking about gasoline motors and not alcohol motors.

The best ever plug reading tool I have found is from Patrick James at Pro-Systems. This is a medical Ottoscope with a brighter more white bulb installed. It is like holding the sun in your hand. When I first bought it it was amazing the difference it made in seeing the base of the porcelein. The white light makes the ring easier to see. The yellow light of a flashlight type viewer tends to hide the fuel ring.
Go up on
http://www.pro-system.com/sparktool.html

Yes, the fuel ring may move up some but only if you were way off on the tuneup and were too rich because too much fuel being splashed on the plug will make it run cooler. The ring will still start at the base of the porcelein but it will extend further down the porcelein and as you move closer to the correct AFR it will shrink down towards the base.

To read plugs correctly you do need a new plug every time. If the cylinders are pretty well balanced or you are way off and trying to get it in you can just put one new plug in and just read that. Once you get close then replace all the plugs and check for balance. I have found on a nitrous motor If you are running close to the correct fuel mixture so the plugs have just barely a hint of a fuel ring or just disappeared (depending on your setup) you can use the same plugs over and over because they will re-color. If it is a NA motor it would take several passes on a used plug to re-color.
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  #8  
Old 08-06-2004, 09:38 AM
Jake Offline
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How much timing retard for the second stage?

How timing should I pull out for the second stage. How many degree's retard per 100 hp of N20 for the second system?

Also what Brand/type race fuel do the Nitrous Pro Mod's use? VP C16, C23, VP NOS, Torco 118 NOS?
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Old 08-06-2004, 10:38 AM
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Pull out at least 4 degress per 100 hp then adjust using the "blue line" on the plug ground strap.

We used VP 23+ without problems
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Old 08-06-2004, 12:07 PM
Eric Larson Offline
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I haven't ever seen any discussion of what happens if the timing is retarded "too much"? Any damage scenarios or just a loss of power?
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  #11  
Old 08-06-2004, 01:05 PM
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Never seen any damage. Yes you will lose power and the EGT's will climb because the flame has been pushed out into the exhaust (moving the heat out of the motor). Have seen them up to 1600+ degrees on a three stage car or a high horsepower 2 stage and the flame will move out the exhaust and will be seen at night by the spectators and they love it. I have had the car go across the finish line with only 5 degrees BTDC in it.
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  #12  
Old 08-23-2004, 11:57 AM
allmotor Offline
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nitrous with alcohol

anyone use nitrous with alcohol. I've heard of some different mixtures, gas and n2o with the motor on alcohol, motor on gas and nitrous mix with alcohol, who makes the best nitrous setup?
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