nitrious

Old 07-17-2013, 06:31 PM
  #41  
bjuice
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Originally Posted by chevynovaman
I motor purge to make sure everything is on and working. I got to the line last weekend at the mud drags and did a motor purge and it wanted to kill the motor, bottle was accidently closed somehow so I ran on motor only..
Spot on Sir ! chevynova man just gave a perfect example of his run. Had he not purged thru engine it set the stage of dumping tons of raw fuel in the cylinder washing it down..you know the rest. .. :shock:
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Old 07-17-2013, 07:27 PM
  #42  
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I am glad Brian brought this up because EVERYONE it seems that doesn't know what they are doing ( me) assumes that you grenade a NOS motor by going lean.....YOU ALWAYS hear about maki g sure your fuel pump is up to snuff etc....the only thing that has held me up on running nitrous was ignorance....I have no experience with it and respect it enough to not risk my motor on it without having some sort of help.... My next one I am gonna try a small plate.
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Old 07-17-2013, 07:47 PM
  #43  
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Bj looked at the vid and just wanted to ask do you like the hosier tires and have you run M/T and are you running 33/10.5-15w. I'm in need of new ones and looked at hosiers they have 33/10.5-15w reads that they are new tire with c11( Harder) compound. Thoughts if any on the two tires thanks.

Weighs 3100 me in it, older 10.5 car not that that matters.
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Old 07-17-2013, 09:39 PM
  #44  
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Originally Posted by wazup
Bj looked at the vid and just wanted to ask do you like the hosier tires and have you run M/T and are you running 33/10.5-15w. I'm in need of new ones and looked at hosiers they have 33/10.5-15w reads that they are new tire with c11( Harder) compound. Thoughts if any on the two tires thanks.

Weighs 3100 me in it, older 10.5 car not that that matters.
Yes the M/T is the tire of choice. 33/10.5wx15 is the size tire on the car. Although I have run the same 60ft on both Hoosiers and M/T the M/T holds up longer on the overall performance of the side wall which is what goes 1st on these heavier 10.5 cars making good HP. Many of your top notch racers in this class like to get them off the car between 15 and 20 full power passes..Since M/T is the predominate tire in 10.5 racing I think Hoosier is trying to find a few more passes in their tires with the c-11 compound. I would recommend M/T. I also run tubes it provides for better stability with the heavier car running what they do. Many have other opinions on the tube or not to tube but I swear by it. Plus I have run faster all time ET with tubes on 15 inch American double bead lock wheels.
I got a killer deal on those Hoosiers in the vid. The guy we buy thru at the time was selling off the last of the 15 inch stuff. Everyone has gone to 16's
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Old 07-17-2013, 09:59 PM
  #45  
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Old 07-18-2013, 05:17 AM
  #46  
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Not sure if everybody knows that Nitrous Oxide systems changed the jetting chart not to long ago. The new charts have dropped the jetting on the fuel side of the plate. Make sure your using the new chart as I still see old charts on the net yet..
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Old 07-18-2013, 12:54 PM
  #47  
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Thanks Bj. I have 31/10.5 15w and going to the 33s.

This is my input on nitrous is every engine is different as for the cams, comp,heads ect. The first thing is to get a good tune on motor and then work with what ever system your going to use following there guide lines.
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Old 07-18-2013, 08:38 PM
  #48  
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Originally Posted by Swiley383
Somthing I have wondered is what why do a motor purge if you have purge valves is it to clear the solinods out or plugs I see all the guys around here spray big hits do it
You motor purge to get the air out of the fuel lines. The first motor purge is really weak. Usually by the 2nd purge the air bubble are gone. You line purge to get the pressure down. The nitrous is at 950-1050 depending on your tune. The fuel is at 4 1/2 to 5 1/2 depending on your tune. The lower the nitrous pressure the less pressure drop you have while going down the track. I go to the line as close to 1,000psi as I can, motor purge only what I have to make it have a crisp hit then line purge if I need to. You really shouldn't need to motor purge on your 2nd pass, but most people do just to make sure everything is working. I've also forgotten to turn on the 1/4 turn valve. It pruges like a turd pretty quick.
And you do need to motor purge every stage.
A street car that always has gas in the tank / fuel lines really want have air in the lines or need to motor purge. Almost all race cars / trucks drain the gas out after a race. I say drain out, but all I do is cut the fuel pump off, run the carb out of fuel then stick my drum pump in the fuel cell and get out what I can get out.


Originally Posted by chevynovaman
Not sure if everybody knows that Nitrous Oxide systems changed the jetting chart not to long ago. The new charts have dropped the jetting on the fuel side of the plate. Make sure your using the new chart as I still see old charts on the net yet..
I've never seen an NOS jet guide, but i can tell you Speedtech's guide is WAY FAT and will burn your stuff up quick!! Theirs is only a 4 jet spread. I run a 10 jet spread, but every motor is different so you simply can't tell somebody they should run a 4,6,10 etc spread.

What I mean by jet spread is the difference between the nitrous jet and the fuel jet size. Example is 32 Nitrous jet and a 28 fuel jet. That's 4 jet spread.

Let me also tell you most people will LIE to you on their jet spread and hope you try it!!!!


Originally Posted by wazup
Thanks Bj. I have 31/10.5 15w and going to the 33s.

This is my input on nitrous is every engine is different as for the cams, comp,heads ect. The first thing is to get a good tune on motor and then work with what ever system your going to use following there guide lines.
That's true to a point.

It's really hard to run the car / truck on just a motor pass with such a tight converter and tall gear and get a good read on the plugs.
I changed the jets in my carb to lean it out. I went from 95 to 90's square which is too lean if I were to run on motor alone. Leaning out the carb is a huge debate that not everybody agrees with. Some will tell you to leave the carb alone and tune the nitrous / fuel, but most guys like me that have a dedicated nitrous motor (meaning I don't run without nitrous because of the really tight converter and tall gear) lean the carbs out a good bit.

I totally agree with your post for a car that runs nitrous some of the time and on motor some of the time.

Getting the timing correct and phasing the distributor are important things to do too.
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Old 07-18-2013, 10:17 PM
  #49  
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Hotrod you have some GREAT people on here you can ask questions at Any time. Some have already weighed in. Another one on here is Zipper ( John Allen ) Zip has been running since the 60's that I know of..Zipper is a certified World NHRA recorded holder...He knows his stuff...
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Old 07-19-2013, 07:11 AM
  #50  
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Rabbit I agree. My engine is all out nitrous too. I was going on that he was going to run motor and nitrous.

I pretty much run any where from 350 to 700 and like you and Bj check everything every pass. I watch guys at some of the grudge races run pass after pass and never check anything because they don't want anyone to see there engine. Then you got the guys that don't anything that wonder way the engine doesn't sound right after a pass and run it again wondering whats wrong. Bj said it best that there is 196 different things.
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