Nitrous fuel pressue info needed

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madmax/6

madmax/6

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I have read ,resurched,talked to tech idiots,and my local nitrous expert that tells me differnt,things every time I talk to him.PLEASE bear with me.This is a slant six car that has 6 national records last year,,,best run all motor is 11.43 at 115. at 2345lbs.I now want the nitrous records.I have installed direct port foggers in my runners with a black pump y ed into carb and solonoid.Am only going to spray it with a 60 shot,16 and 18 jets.This is a 238 cubic inch motor around 12.3 compression..My local guy said one day 5.1/2,open then the next day said 6.5???? dead headed.Then called NX and they said 10 lbs open.ANY advise wanted.I right now have it set at 6 lbs open cause thats the only number i havent heard,,,just the way I am.PLEASE PLEASE,any input or opinion wanted.Guzzi Mark
 
B nitrous record is 12.84.I have B na record at 11.50 so that should bee a easy one.A nitrous is 10.93 at 125 mph,thats the one I really want.Mph is gonne bee hard after i switch from my 4.56 gears to 4.30s.Remember this car has around 270 rwhp.about 305 at the crank.
 
i'll give you a bump mark... not much for the No2... and dont have friends with it either...
 
Do you have an O2 sensor/readout in the car or available? I'd tune the kit so you get a similar AFR as the best runs NA.

Looks like the instructions for an NX direct port 75 shot is 20/20 at 5.5psi and 20/18 at 10psi. Those are usually really safe/fat so there is usually room to lean it out. If you want to lean it out, either smaller fuel jets or lower fuel pressure. Will have the same net result... less fuel introduced.
 
Have o2sensor have tuned with it in past.Somehow my local guru set me up with the motorcyle 6 cyl set up to get me to the lower 60 shot?? I will go with my gut feeling at local 1/8th track and think it will run sub 7,s.Nitrious is totally new to me And I dont know a thing about it..Then again 3 years ago I never even thought about just going down a dragstrip.That was stupid and too easy..go to line,wait for a green light and floor it.I learned very quickly there is more to it.Now I gotta learn how to lift or brake..I have had 4 car lenghts in the past and broken out.My foot doesnt listen to my brain when it tells it too lift.Mark
 
madmax/6 said:
Have o2sensor have tuned with it in past.Somehow my local guru set me up with the motorcyle 6 cyl set up to get me to the lower 60 shot?? I will go with my gut feeling at local 1/8th track and think it will run sub 7,s.Nitrious is totally new to me And I dont know a thing about it..Then again 3 years ago I never even thought about just going down a dragstrip.That was stupid and too easy..go to line,wait for a green light and floor it.I learned very quickly there is more to it.Now I gotta learn how to lift or brake..I have had 4 car lenghts in the past and broken out.My foot doesnt listen to my brain when it tells it too lift.Mark
Click to expand...

That's why I'm a heads-up guy. There's no way I'm lifting unless its way out of shape. Even when I've spun the tires out the hole I'll keep my foot in to see what mph I can run.

Are you retarding the timing for the nitrous at all or is there enough octane to not bother with a small shot?
 
you should begin fat and see what it those read your plug!!!

mine is a nitrous work and like you didnt have alote of info
when I installed it.friend of mine was running a dry kit so couldnt help much
on mine but told me the same as I said to you fat doesnt break parts

with the CR. you have you must used race fuel
be sure its not at is limite of octane before opening the bottle
detonation kill engine thats why most beginner in nitrous broke there
engine

with mine I began at 7 psi was way to fat
lowering it 1/2 psi at the time and end up at 5.5
blew the heads gasket twice because I wasnt running enough octane
and hade detonation

hade a 360 @ 12.33 cr. with 125 shot
switch to pro fuel mark 2 http://www.speedwaybikes.com/sponsors/fuel.htm
and sunoco 110
http://www.racegas.com/fuel/1
never hade problem with this set up
also need to close the spark plug gap a little
went from 45 thousand to 35 thousand
i retard the timing 4*

in your case if you use the right fuel retard it 2* will be enough
like said 2* of retard for every 50 hp shot of nitrous

my 2 cents
Bob
 
recomended is 2 degrees per 50 hp of N2o, and normally we run 5-1/4 to 5-1/2 lbs of pressure flowing thru a holley #72 jet, who's kit do you have.

go to www.yellowbullet.com and look up Monte Smith or Steve Johnson, these 2 guys do siminars on Nitrous all over the country, and very knowledgeable, they will give you some good advice.
 
I second Steve Smith.
Send him your kit and he will blueprint it for you.
Set your bottle and fuel pressure and TUNE with the Jets.
Remember if your bottle pressure go's high you will go into LEAN mode.
Fuel pressure spikes you will go rich.
If your fuel pressure go's low,the system go's lean.
You should have a low fuel shut off switch.
The purge switch is not to look cool at the starting line.
It doe's 2 things.
1 get the Nos to the solinoid to a liquid state and 2 gets the bottle pressure down to where you tuned your system at.

Here's my 67 Dart using a Zex plate and NOS solinoids.
Notice I tee's into the back fuel line going to the carb for my fuel supply to the nos system.

IMGP0230.jpg


Call Steve he's very approachable.
Hope some of this helps.
Marv
 
womanator said:
I second Steve Smith.
Send him your kit and he will blueprint it for you.
Set your bottle and fuel pressure and TUNE with the Jets.
Remember if your bottle pressure go's high you will go into LEAN mode.
Fuel pressure spikes you will go rich.
If your fuel pressure go's low,the system go's lean.
You should have a low fuel shut off switch.
The purge switch is not to look cool at the starting line.
It doe's 2 things.
1 get the Nos to the solinoid to a liquid state and 2 gets the bottle pressure down to where you tuned your system at.

Here's my 67 Dart using a Zex plate and NOS solinoids.
Notice I tee's into the back fuel line going to the carb for my fuel supply to the nos system.

IMGP0230.jpg


Call Steve he's very approachable.
Hope some of this helps.
Marv
Click to expand...

it looks like your not running a dedicated fuel system for your kit, the kit is running the same pressure as the carb? I've always ran a seperate fuel regulator for the Nitrous kit.
 
I run plates, and they run different than nozzles so I wouldn't use what I use...lol. I would start with Monte. He is THE N2O guy as far as I'm concerned and likes racers. On my buddy's bike, which had a progressive controller and fogger nozzles we ran 5.5. Pushed his 1200cc, no bar Suzuki to 8.65. He was 320lbs at the time...lol. Love the bottle.
 
It depends on your fuel system.
I'm running 1/2 inch line to the regulator.
And a Mallory 220 gph electric pump.
That's enough to run the engine and 200 hp of Nos.

I've run a Carter strip Mechanical pump on a 440 and a plate system @ 150 hp with no problem.

The problem with mechanical pumps are that they pulse so you run the fuel on the rich side.

Trainer car with the mechanical pump.
IMGP1289.jpg


IMGP0501.jpg
 
Keep the fuel and the Nos pressure constant and your tune will stay.
Tune with your jets.
 
I have seperate regulaters and gauges going from y to the carb,and going to solinoid.Evering thing is new.Nitrous express system.Got three 10 lb bottles just hydro tested and re stamped to bee up to specs.All new valves and gauges on bottles.I dont hack stuff together,I try to do it correct the first time.thats why I read, and ask alot of questions.And do alot of reserch,I then gather all the info I get,and do what I think is best.If 10 people tell me to retard it 2 degrees,and 10 other people tell me no retard needed at this level.I will retard it 1 degree.I dont take any 1 persons word on anything I do,but I want ALL Ideas and opinions so I have a chance at doing this right.THANK YOU for your guiedness so far.PLEASE keep it comming.Mark
 
Mark,
I would call up Steve Smith and go to one of his class's.
He use to be the tuner to beat in Pro-mod before R2B2 got his turbo cars running.
Money well spent.
 
madmax/6 said:
I have seperate regulaters and gauges going from y to the carb,and going to solinoid.Evering thing is new.Nitrous express system.Got three 10 lb bottles just hydro tested and re stamped to bee up to specs.All new valves and gauges on bottles.I dont hack stuff together,I try to do it correct the first time.thats why I read, and ask alot of questions.And do alot of reserch,I then gather all the info I get,and do what I think is best.If 10 people tell me to retard it 2 degrees,and 10 other people tell me no retard needed at this level.I will retard it 1 degree.I dont take any 1 persons word on anything I do,but I want ALL Ideas and opinions so I have a chance at doing this right.THANK YOU for your guiedness so far.PLEASE keep it comming.Mark
Click to expand...

Going to a nitrous guru may yield good, quick results but if you're inclined to learn from experience then start with a safe tune, fat jetting, timing retarded 2 degrees and fuel pressure a little on the high side. Then creep up on the best tune bit by bit. Just keep nibbling away at it.
 
Well at a 60 hit i don't think you will knock off those 4 tenths you're looking for...

As for fuel psi, i have always gone higher than recommended and like my results better than what they say should be.
I have always used between 12 and 16psi on a carb motor, i haven't lost, hurt, blown up a motor on n2o since 84, broke one crank on a 2stg 250 and 300 but since that only happened with the one crank it was a faulty crank, and it didn't really break till i took it out...you would think with a 375 base and 250 and 300 woulda made that crank do something bad other than make a noise i couldn't live with anymore.

I wouldn't even touch the timing till i ran it, in my motors i have found even with 5x your hit removing timing doesn't make it better or faster.
I have found that using large hits off idle does hammer bearings and you'll be changing them out sooner than you should, but that's it.

You can safely put 120 without even worrying following NX's advice
 
What does the instructions say on ur kit..... I run 9lbs with a 500shot on my duster.on my 09challenger rt I spray a 75 shot with stock pressure and timing...



I would say 6.5 is a very good start and take 1¤ of timin out it should tell u want pressure to run and how much timing to take out with each diff size shot.... Or just go to zex .com or nx express.com they should have charts there
 
I have the zex kit. It recomends 6lb to the fuel solinoid.
 

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if you take a look at all the company who make nitrous kit
you will end up with diferent pressure at least if you talk
to there tech line

I know NX recommend alote more fuel pressure than all other
 
I run the fuel pressure the same as the carb! The pressure is not as critical as one would think at that low of a hp shot. Tune it to the fuel pressure with your o2 sensor. In my street car I get it in 3rd ( with a co-pilot watching the read out of the o2 sensor ) And I hit it. adjust till your happy with the tune...and then do it again. This time when you hit the spray run it up alittle and kill the engine. coast to the side and pull a plug for Reading if the plug looks good you can trust your o2 guage and should be able to use any time you need it! Also you should use a regulator on your nitrous! NX makes a good one! 900 psi is where I tuned mine at. Bottom line is set your line pressures and tune to your o2 guage. Oh yeah mark my words if a 60 shot feels good than 100 will better...if 100 feels good than 150 will feel great...Its an addiction!!
 
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