Dodge SRT Viper Forums : ViperAlley banner
1 - 18 of 18 Posts

·
Registered
Joined
·
3,494 Posts
Discussion Starter · #1 ·
I am about to get serious and actually tune while I am on the dyno instead of just shifting thru the gears. I wanted to get some input regarding how and what the nitrous and fuel jets affect overall hp and tq numbers as well as a/f and what is the recommended path to take when changing out jets.


For instance when I was on the dyno with my car and a 150 shot(TNT kit with 46 n2o and 25 fuel jets) I made a couple of runs:


run 1 made an additional: 116/190 a/f was 10.4

run 2 made an additional: 125/188 a/f was 10.9(I took out some fuel with the vec2)



TNT kits are rear wheel rated numbers so I am leaving some power on the table. I plan on trying different jets, but which ones should I change 1st - nitrous or fuel?


I was thinking as rich as the car was the tq numbers would be on up there and by leaning the car out some it seems the tq numbers are gonna fall(my understanding is that tq is created by adding fuel, could be wrong in this situation).


I need to go over my setup to make sure something fundamentally isn't wrong and that everything is flowing properly. My psi was around 1000 and TNT said they recommend or test at 900 to 950.


Sooooo, assuming my system is working properly should I go up on my n2o jet or go down on my fuel jet to get my a/f where it needs to be and get my hp and tq numbers up? I am not using the vec2 anymore. I want to tune with the jets and around 900 psi to try and avoid big drops in psi as I make runs at the track or street.


The one interesting or confusing thing is that my 100 shot (jets 39/22) made 80/180 with an a/f around 10.8. So why didn't my tq go up with the 150 shot? I see everyone else gaining 200 to 300 or more easily. Granted I have yet to tune the car, but wanted to know what others were doing to get those numbers.
 

·
Registered
Joined
·
2,368 Posts
I don't know squat about tuning NOS, but I know with a supercharger, target [conservative] A/F is 11.5:1 . With NA, it is like 12.2 or something like that. NOS... i'm not sure. but i'd guess you can take some fuel out of that thing.

any of the NOS tuners care to pipe up?

JD
 

·
Registered
Joined
·
444 Posts
J DAWG said:
I am about to get serious and actually tune while I am on the dyno instead of just shifting thru the gears. I wanted to get some input regarding how and what the nitrous and fuel jets affect overall hp and tq numbers as well as a/f and what is the recommended path to take when changing out jets.


For instance when I was on the dyno with my car and a 150 shot(TNT kit with 46 n2o and 25 fuel jets) I made a couple of runs:


run 1 made an additional: 116/190 a/f was 10.4

run 2 made an additional: 125/188 a/f was 10.9(I took out some fuel with the vec2)



TNT kits are rear wheel rated numbers so I am leaving some power on the table. I plan on trying different jets, but which ones should I change 1st - nitrous or fuel?


I was thinking as rich as the car was the tq numbers would be on up there and by leaning the car out some it seems the tq numbers are gonna fall(my understanding is that tq is created by adding fuel, could be wrong in this situation).
That whole thing about running rich building torque is hog wash. HP is just a function of torque over a time span. Your not gonna tune for torque by running rich.

I need to go over my setup to make sure something fundamentally isn't wrong and that everything is flowing properly. My psi was around 1000 and TNT said they recommend or test at 900 to 950.
Are you running a bottle heater? If not I would invest in one. It will keep the pressure regulated and make the car run much more consistantly and also easier to tune.

Sooooo, assuming my system is working properly should I go up on my n2o jet or go down on my fuel jet to get my a/f where it needs to be and get my hp and tq numbers up? I am not using the vec2 anymore. I want to tune with the jets and around 900 psi to try and avoid big drops in psi as I make runs at the track or street.


The one interesting or confusing thing is that my 100 shot (jets 39/22) made 80/180 with an a/f around 10.8. So why didn't my tq go up with the 150 shot? I see everyone else gaining 200 to 300 or more easily. Granted I have yet to tune the car, but wanted to know what others were doing to get those numbers.
To adjust the a/f ratio you want to change the fuel jet. Unless your trying to increase the HP range of the shot leave the nitrous jet where it is.

I'm curious why you aren't using the vec 2 any longer?
 

·
Registered
Joined
·
636 Posts
I would jump up two nitrous jets to one fuel,first.The understanding(answers your question about 100shot jets in comparison to 150shot)of power stroke efficeincy.This is why stockers kill Heads/Cam (modded) cars in nitrous power #'s.If you had a Heads/nitrous cam modded car the jet ratio's would be more consistant.
I like to run with 1000lbs.One reason is you can make more power than 900-950,and secondly you feel the power drop more drastic reminding you of a neede bottle change.
Nitrous ratio's-TOOOFST has dozens/hundreds of nitrous bottles through her,with a perfect compression test and rock solid dyno #'s.The key is not to push the a/f above 11:1,especially with the creampuff pistons.
 

·
Registered
Joined
·
3,494 Posts
Discussion Starter · #5 ·
acrdakota said:
Are you running a bottle heater? If not I would invest in one. It will keep the pressure regulated and make the car run much more consistantly and also easier to tune.

Thanks acr. I do have heater on the car, but was not using a purge at that time. Now I have a purge also.




acrdakota said:
To adjust the a/f ratio you want to change the fuel jet. Unless your trying to increase the HP range of the shot leave the nitrous jet where it is.

I would like to get the 150 rwhp out of the kit. However, I am more concerned about getting the rwtq numbers. I would like to see 275 to 300 like others.



acrdakota said:
I'm curious why you aren't using the vec 2 any longer?

Just trying to keep things simple and next time out I wanted to adjust with the fuel jets instead of having to write cards for fuel throughout the rpm range with the vec2.
 

·
Registered
Joined
·
3,494 Posts
Discussion Starter · #6 ·
TOOOFST said:
I would jump up two nitrous jets to one fuel,first.The understanding(answers your question about 100shot jets in comparison to 150shot)of power stroke efficeincy.This is why stockers kill Heads/Cam (modded) cars in nitrous power #'s.If you had a Heads/nitrous cam modded car the jet ratio's would be more consistant.
I like to run with 1000lbs.One reason is you can make more power than 900-950,and secondly you feel the power drop more drastic reminding you of a neede bottle change.
Nitrous ratio's-TOOOFST has dozens/hundreds of nitrous bottles through her,with a perfect compression test and rock solid dyno #'s.The key is not to push the a/f above 11:1,especially with the creampuff pistons.


Hey Scotty. I did forget to mention I have a heads/cam car. Didn't know how that may affect the nitrous results. Like you said I do see stockers putting down close to 300 rwtq with ease. I was just trying to figure out if they targeted more on the n2o or fuel jet to get those results OR are most just using the recommended jets from NX. I have seen one car that put in the 150 NX shot and was incredibly rich (low 10:!) and a very knowledgeable n2o person said they normally drop the fuel jet from a 22 to 18 on a stocker.


Just trying to get this thing tuned so I can lay down a decent time at the track.
 

·
Registered
Joined
·
3,494 Posts
Discussion Starter · #7 ·
JID said:
I don't know squat about tuning NOS, but I know with a supercharger, target [conservative] A/F is 11.5:1 . With NA, it is like 12.2 or something like that. NOS... i'm not sure. but i'd guess you can take some fuel out of that thing.

any of the NOS tuners care to pipe up?

JD


JD, with the power you have been able to create, I will listen to any advice you have to give. Ignorance can be a good thing at times. :thumb:
 

·
Registered
Joined
·
3,494 Posts
Discussion Starter · #9 ·
Phil, I haven't really benefited from it. I think it will be easier (on my setup) to just tune with the jets and leave it at that. I am using a digital window switch instead of the vec as well. It is a nice programmer(VEC2), I just don't think my car needs it.


John
 

·
Registered
Joined
·
3,494 Posts
Discussion Starter · #10 ·
is running higher bottle pressure in essence like running a larger n2o jet? or will the flow/volume still be the same whether it is 900 psi or 1200 psi? gotta be more flow huh?
 

·
Premium Member
Joined
·
1,333 Posts
J DAWG said:
is running higher bottle pressure in essence like running a larger n2o jet? or will the flow/volume still be the same whether it is 900 psi or 1200 psi? gotta be more flow huh?

Same as a garden hose - if you open the faucet more - you get more water
coming out.
 

·
Registered
Joined
·
3,579 Posts
J DAWG said:
is running higher bottle pressure in essence like running a larger n2o jet? or will the flow/volume still be the same whether it is 900 psi or 1200 psi? gotta be more flow huh?


what's up John...I've read some articles about this and if you think of flow thorugh a cylinder (here comes the physics major coming out), you indeed would get more flow...however as there exists a direct relationship between temp and pressure, at 900 psi, your bottleneck would be in the jets I would think, b/c the cross sectional area of the lumen of those jets are much smaller than even an 4A hose...you may be running a 6A which would be worse.
Many manufacturers suggest 900 simply b/c "it's plenty enough" so, yes it's more flow, true, but would you feel better if it were 2000 psi? point being that when is enough flow enough to take it out of the equation? that's the question, and many manufacturers believe it's around 900 or so...

p.s. I wanna race ya soon (and not in the viper either :smiles:...I got sumthin or ya)
 

·
Registered
Joined
·
3,579 Posts
and by the way, when are we dynoing again????

I need your Lm1 software so I can tune the viper baby...I'm not trusting this digital a/f guage I got although it is purty.
 

·
Registered
Joined
·
24,065 Posts
i disagree, things being equal. lines,bottles,temp's,nozzles...more pressure wont equal more volume. or am i wrong
 

·
Registered
Joined
·
3,579 Posts
hey Phil,

i think what John is saying is.....if he increases his pressure, will he get an increase in actual volume of spray.... that would be basic gas laws so the answer is yes, BUT that volume is restricted by lines, and the hoses, etc. so the actual amount that is delivered is not a direct reflection of the "theoretical" amount that would be so if no other variable (restrictions of hoses, etc.) existed.
 

·
Registered
Joined
·
3,494 Posts
Discussion Starter · #17 ·
Norm


I sent the software weeks ago by UPS. You didn't get it. :) J/K. I will get it coming your way. And you know I am always ready for some friendly racing. All I have to say is you better come strong. :thumb:


John


ps - dyno asap.
 

·
Registered
Joined
·
3,579 Posts
J DAWG said:
Norm


I sent the software weeks ago by UPS. You didn't get it. :) J/K. I will get it coming your way. And you know I am always ready for some friendly racing. All I have to say is you better come strong. :thumb:


John


ps - dyno asap.

No software but looking forward to it...


as far as coming strong...Oh brutha you have no idea......sent off for my built tranny (good to 800 +) I am going to go with a 70"ish" turbo and have the manifold, wastegate, bovs, prolly gonna run a methanol kit for now (haven't decided on how I'm going to upgrade my fuel just yet)...

so all the stuff that's in my garage...well, it's going to jut be plain mean....It's gonna be ugly, but ride like a lexus. :nod:

You better be running more than 150 brutha..heheheheheh

spooooooooooooooooooooooooooooooooooooooooooooooooool


You should come to the Luau i'm having this friday night....a ton of people there..quite a few are driving from upstate just to go to this gig..
 
1 - 18 of 18 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top